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Sample records for adaxial leaf surface

  1. Characterization of photosynthetic gas exchange in leaves under simulated adaxial and abaxial surfaces alternant irradiation.

    PubMed

    Zhang, Zi-Shan; Li, Yu-Ting; Gao, Hui-Yuan; Yang, Cheng; Meng, Qing-Wei

    2016-01-01

    Previous investigations on photosynthesis have been performed on leaves irradiated from the adaxial surface. However, leaves usually sway because of wind. This action results in the alternating exposure of both the adaxial and abaxial surfaces to bright sunlight. To simulate adaxial and abaxial surfaces alternant irradiation (ad-ab-alt irradiation), the adaxial or abaxial surface of leaves were exposed to light regimes that fluctuated between 100 and 1,000 μmol m(-2) s(-1). Compared with constant adaxial irradiation, simulated ad-ab-alt irradiation suppressed net photosynthetic rate (Pn) and transpiration (E) but not water use efficiency. These suppressions were aggravated by an increase in alternant frequency of the light intensity. When leaves were transferred from constant light to simulated ad-ab-alt irradiation, the maximum Pn and E during the high light period decreased, but the rate of photosynthetic induction during this period remained constant. The sensitivity of photosynthetic gas exchange to simulated ad-ab-alt irradiation was lower on abaxial surface than adaxial surface. Under simulated ad-ab-alt irradiation, higher Pn and E were measured on abaxial surface compared with adaxial surface. Therefore, bifacial leaves can fix more carbon than leaves with two "sun-leaf-like" surfaces under ad-ab-alt irradiation. Photosynthetic research should be conducted under dynamic conditions that better mimic nature. PMID:27377989

  2. Characterization of photosynthetic gas exchange in leaves under simulated adaxial and abaxial surfaces alternant irradiation.

    PubMed

    Zhang, Zi-Shan; Li, Yu-Ting; Gao, Hui-Yuan; Yang, Cheng; Meng, Qing-Wei

    2016-07-05

    Previous investigations on photosynthesis have been performed on leaves irradiated from the adaxial surface. However, leaves usually sway because of wind. This action results in the alternating exposure of both the adaxial and abaxial surfaces to bright sunlight. To simulate adaxial and abaxial surfaces alternant irradiation (ad-ab-alt irradiation), the adaxial or abaxial surface of leaves were exposed to light regimes that fluctuated between 100 and 1,000 μmol m(-2) s(-1). Compared with constant adaxial irradiation, simulated ad-ab-alt irradiation suppressed net photosynthetic rate (Pn) and transpiration (E) but not water use efficiency. These suppressions were aggravated by an increase in alternant frequency of the light intensity. When leaves were transferred from constant light to simulated ad-ab-alt irradiation, the maximum Pn and E during the high light period decreased, but the rate of photosynthetic induction during this period remained constant. The sensitivity of photosynthetic gas exchange to simulated ad-ab-alt irradiation was lower on abaxial surface than adaxial surface. Under simulated ad-ab-alt irradiation, higher Pn and E were measured on abaxial surface compared with adaxial surface. Therefore, bifacial leaves can fix more carbon than leaves with two "sun-leaf-like" surfaces under ad-ab-alt irradiation. Photosynthetic research should be conducted under dynamic conditions that better mimic nature.

  3. Characterization of photosynthetic gas exchange in leaves under simulated adaxial and abaxial surfaces alternant irradiation

    PubMed Central

    Zhang, Zi-Shan; Li, Yu-Ting; Gao, Hui-Yuan; Yang, Cheng; Meng, Qing-Wei

    2016-01-01

    Previous investigations on photosynthesis have been performed on leaves irradiated from the adaxial surface. However, leaves usually sway because of wind. This action results in the alternating exposure of both the adaxial and abaxial surfaces to bright sunlight. To simulate adaxial and abaxial surfaces alternant irradiation (ad-ab-alt irradiation), the adaxial or abaxial surface of leaves were exposed to light regimes that fluctuated between 100 and 1,000 μmol m−2 s−1. Compared with constant adaxial irradiation, simulated ad-ab-alt irradiation suppressed net photosynthetic rate (Pn) and transpiration (E) but not water use efficiency. These suppressions were aggravated by an increase in alternant frequency of the light intensity. When leaves were transferred from constant light to simulated ad-ab-alt irradiation, the maximum Pn and E during the high light period decreased, but the rate of photosynthetic induction during this period remained constant. The sensitivity of photosynthetic gas exchange to simulated ad-ab-alt irradiation was lower on abaxial surface than adaxial surface. Under simulated ad-ab-alt irradiation, higher Pn and E were measured on abaxial surface compared with adaxial surface. Therefore, bifacial leaves can fix more carbon than leaves with two “sun-leaf-like” surfaces under ad-ab-alt irradiation. Photosynthetic research should be conducted under dynamic conditions that better mimic nature. PMID:27377989

  4. The Leaf Adaxial-Abaxial Boundary and Lamina Growth

    PubMed Central

    Nakata, Miyuki; Okada, Kiyotaka

    2013-01-01

    In multicellular organisms, boundaries have a role in preventing the intermingling of two different cell populations and in organizing the morphogenesis of organs and the entire organism. Plant leaves have two different cell populations, the adaxial (or upper) and abaxial (or lower) cell populations, and the boundary is considered to be important for lamina growth. At the boundary between the adaxial and abaxial epidermis, corresponding to the margin, margin-specific structures are developed and structurally separate the adaxial and abaxial epidermis from each other. The adaxial and abaxial cells are determined by the adaxial and abaxial regulatory genes (including transcription factors and small RNAs), respectively. Among many lamina-growth regulators identified by recent genetic analyses, it has been revealed that the phytohormone, auxin, and the WOX family transcription factors act at the adaxial-abaxial boundary downstream of the adaxial-abaxial pattern. Furthermore, mutant analyses of the WOX genes shed light on the role of the adaxial-abaxial boundary in preventing the mixing of the adaxial and abaxial features during lamina growth. In this review, we highlight the recent studies on the dual role of the adaxial-abaxial boundary. PMID:27137371

  5. Comparing vegetation indices for remote chlorophyll measurement of white poplar and Chinese elm leaves with different adaxial and abaxial surfaces.

    PubMed

    Lu, Shan; Lu, Xingtong; Zhao, Wenli; Liu, Yu; Wang, Zheyi; Omasa, Kenji

    2015-09-01

    Quick non-destructive assessment of leaf chlorophyll content (LCC) is important for studying phenotypes related to plant growth and stress resistance. This study was undertaken to investigate the quantitative relationship between LCC and different vegetation indices (VIs) on both adaxial and abaxial surfaces of white poplar (Populus alba), which has dense tubular hairs on its abaxial surface, and Chinese elm (Ulmus pumila var. pendula), which does not show obvious superficial differences except for lighter colour on the abaxial surface. Some published and newly developed VIs were tested to relate them to LCC. The results showed that most of the published VIs had strong relationships with LCC on the one-surface dataset, but did not show a clear relationship with LCC when both adaxial and abaxial surface reflectance data were included. Among the reflectance indices tested, the modified Datt index, (R719-R726)/(R719-R743), performed best and is proposed as a new index for remote estimation of chlorophyll content in plants with varying leaf surface structures. It explained 92% of LCC variation in this research, and the root mean square error of the LCC prediction was 5.23 μg/cm(2). This new index is insensitive to the effects of adaxial and abaxial leaf surface structures and is strongly related to the variation in reflectance caused by chlorophyll content.

  6. The ASYMMETRIC LEAVES Complex Employs Multiple Modes of Regulation to Affect Adaxial-Abaxial Patterning and Leaf Complexity[OPEN

    PubMed Central

    Husbands, Aman Y.; Benkovics, Anna H.; Nogueira, Fabio T.S.; Lodha, Mukesh; Timmermans, Marja C.P.

    2015-01-01

    Flattened leaf architecture is not a default state but depends on positional information to precisely coordinate patterns of cell division in the growing primordium. This information is provided, in part, by the boundary between the adaxial (top) and abaxial (bottom) domains of the leaf, which are specified via an intricate gene regulatory network whose precise circuitry remains poorly defined. Here, we examined the contribution of the ASYMMETRIC LEAVES (AS) pathway to adaxial-abaxial patterning in Arabidopsis thaliana and demonstrate that AS1-AS2 affects this process via multiple, distinct regulatory mechanisms. AS1-AS2 uses Polycomb-dependent and -independent mechanisms to directly repress the abaxial determinants MIR166A, YABBY5, and AUXIN RESPONSE FACTOR3 (ARF3), as well as a nonrepressive mechanism in the regulation of the adaxial determinant TAS3A. These regulatory interactions, together with data from prior studies, lead to a model in which the sequential polarization of determinants, including AS1-AS2, explains the establishment and maintenance of adaxial-abaxial leaf polarity. Moreover, our analyses show that the shared repression of ARF3 by the AS and trans-acting small interfering RNA (ta-siRNA) pathways intersects with additional AS1-AS2 targets to affect multiple nodes in leaf development, impacting polarity as well as leaf complexity. These data illustrate the surprisingly multifaceted contribution of AS1-AS2 to leaf development showing that, in conjunction with the ta-siRNA pathway, AS1-AS2 keeps the Arabidopsis leaf both flat and simple. PMID:26589551

  7. Examining the photoprotection hypothesis for adaxial foliar anthocyanin accumulation by revisiting comparisons of green- and red-leafed varieties of coleus (Solenostemon scutellarioides).

    PubMed

    Logan, Barry A; Stafstrom, William C; Walsh, Michael J L; Reblin, Jaret S; Gould, Kevin S

    2015-06-01

    Although plants rely on light to drive energy production via photosynthesis, excess light can be harmful. Plants have evolved photoprotective mechanisms to mitigate this threat, including thermal energy dissipation, the most common form of which involves de-epoxidized constituents of the xanthophyll cycle facilitating the conversion of excess excitation energy to heat. A role in photoprotection has also been proposed for red anthocyanins when they accumulate near the adaxial leaf surface. Here, we compared the response to experimental light stress of a red-leafed (anthocyanin rich) and a green-leafed variety of coleus [Solenostemon scutellarioides (L.) Codd], examining chlorophyll fluorescence emission and pigment composition. After experimentally imposed intense white light, red- and green-leafed coleus exhibited manifestations of light stress (decreased photosystem II quantum efficiency) of a similar magnitude. This, considered alone, could be interpreted as evidence that anthocyanins do not serve a photoprotective role. However, during excess light exposure, the green-leafed variety employed a greater level of thermal energy dissipation and possessed correspondingly higher xanthophyll cycle pool sizes and de-epoxidation states. During exposure to red light, which anthocyanins absorb very poorly, levels of thermal energy dissipation did not differ between coleus varieties. Taken together, our findings suggest that adaxial anthocyanins minimize stress associated with excess light absorption and that the green-leafed variety of coleus compensated for its much lower levels of adaxial anthocyanins by invoking higher levels of energy dissipation. Thus, anthocyanin accumulation should be considered alongside the suite of photoprotective mechanisms employed by photosynthetic tissues. PMID:25862643

  8. Genetic Variation and Divergence of Genes Involved in Leaf Adaxial-Abaxial Polarity Establishment in Brassica rapa

    PubMed Central

    Liang, Jianli; Liu, Bo; Wu, Jian; Cheng, Feng; Wang, Xiaowu

    2016-01-01

    Alterations in leaf adaxial-abaxial (ad-ab) polarity are one of the main factors that influence leaf curvature. In Chinese cabbage, leaf incurvature is an essential prerequisite to the formation of a leafy head. Identifying ad-ab patterning genes and investigating their genetic variation may facilitate elucidation of the mechanisms underlying leaf incurvature during head formation. Comparative genomic analysis of 45 leaf ad-ab patterning genes in Brassica rapa based on 26 homologs of Arabidopsis thaliana indicated that these genes underwent expansion and were retained after whole genome triplication (WGT). We also assessed the nucleotide diversity and selection footprints of these 45 genes in a collection of 94 Brassica rapa accessions that were composed of heading and non-heading morphotypes. Six of the 45 genes showed significant negative Tajima's D indices and nucleotide diversity reduction in heading accessions compared to those in non-heading accessions, indicating that they underwent purifying selection. Further testing of the BrARF3.1 gene, which was one of the selection signals from a larger collection, confirmed that purifying selection did occur. Our results provide genetic evidence that ad-ab patterning genes are involved in leaf incurvature, which is associated with formation of a leafy head, as well as promote an understanding of the genetic mechanism underlying leafy head formation in Chinese cabbage. PMID:26904064

  9. Genetic Variation and Divergence of Genes Involved in Leaf Adaxial-Abaxial Polarity Establishment in Brassica rapa.

    PubMed

    Liang, Jianli; Liu, Bo; Wu, Jian; Cheng, Feng; Wang, Xiaowu

    2016-01-01

    Alterations in leaf adaxial-abaxial (ad-ab) polarity are one of the main factors that influence leaf curvature. In Chinese cabbage, leaf incurvature is an essential prerequisite to the formation of a leafy head. Identifying ad-ab patterning genes and investigating their genetic variation may facilitate elucidation of the mechanisms underlying leaf incurvature during head formation. Comparative genomic analysis of 45 leaf ad-ab patterning genes in Brassica rapa based on 26 homologs of Arabidopsis thaliana indicated that these genes underwent expansion and were retained after whole genome triplication (WGT). We also assessed the nucleotide diversity and selection footprints of these 45 genes in a collection of 94 Brassica rapa accessions that were composed of heading and non-heading morphotypes. Six of the 45 genes showed significant negative Tajima's D indices and nucleotide diversity reduction in heading accessions compared to those in non-heading accessions, indicating that they underwent purifying selection. Further testing of the BrARF3.1 gene, which was one of the selection signals from a larger collection, confirmed that purifying selection did occur. Our results provide genetic evidence that ad-ab patterning genes are involved in leaf incurvature, which is associated with formation of a leafy head, as well as promote an understanding of the genetic mechanism underlying leafy head formation in Chinese cabbage. PMID:26904064

  10. Genetic Variation and Divergence of Genes Involved in Leaf Adaxial-Abaxial Polarity Establishment in Brassica rapa.

    PubMed

    Liang, Jianli; Liu, Bo; Wu, Jian; Cheng, Feng; Wang, Xiaowu

    2016-01-01

    Alterations in leaf adaxial-abaxial (ad-ab) polarity are one of the main factors that influence leaf curvature. In Chinese cabbage, leaf incurvature is an essential prerequisite to the formation of a leafy head. Identifying ad-ab patterning genes and investigating their genetic variation may facilitate elucidation of the mechanisms underlying leaf incurvature during head formation. Comparative genomic analysis of 45 leaf ad-ab patterning genes in Brassica rapa based on 26 homologs of Arabidopsis thaliana indicated that these genes underwent expansion and were retained after whole genome triplication (WGT). We also assessed the nucleotide diversity and selection footprints of these 45 genes in a collection of 94 Brassica rapa accessions that were composed of heading and non-heading morphotypes. Six of the 45 genes showed significant negative Tajima's D indices and nucleotide diversity reduction in heading accessions compared to those in non-heading accessions, indicating that they underwent purifying selection. Further testing of the BrARF3.1 gene, which was one of the selection signals from a larger collection, confirmed that purifying selection did occur. Our results provide genetic evidence that ad-ab patterning genes are involved in leaf incurvature, which is associated with formation of a leafy head, as well as promote an understanding of the genetic mechanism underlying leafy head formation in Chinese cabbage.

  11. Ozone-induced ethylene release from leaf surfaces

    SciTech Connect

    Rodecap, K.D.; Tingey, D.T.

    1986-01-01

    Ozone-induced stress-ethylene emissions from the adaxial and abaxial leaf surfaces of four plant species (Glycine max (L) Merr. cv. Dare, Lycopersicon esculentum Mill cv. Roma VF, Eucalyptus globulus Labill. and Hedera helix L.) were studied to determine if the stress ethylene diffused through the stomata or cuticle. In plants not exposed to ozone, basal ethylene was detected above both the adaxial and abaxial leaf surfaces of all the plant species examined, indicating that some ethylene can diffuse across the leaf cuticle. Oxone-induced stress ethylene production in all species examined. These data indicate that ozone-induced stress ethylene primarily diffuses from the leaf via the stomata.

  12. Pattern Dynamics in Adaxial-Abaxial Specific Gene Expression Are Modulated by a Plastid Retrograde Signal during Arabidopsis thaliana Leaf Development

    PubMed Central

    Tameshige, Toshiaki; Fujita, Hironori; Watanabe, Keiro; Toyokura, Koichi; Kondo, Maki; Tatematsu, Kiyoshi; Matsumoto, Noritaka; Tsugeki, Ryuji; Kawaguchi, Masayoshi; Nishimura, Mikio; Okada, Kiyotaka

    2013-01-01

    The maintenance and reformation of gene expression domains are the basis for the morphogenic processes of multicellular systems. In a leaf primordium of Arabidopsis thaliana, the expression of FILAMENTOUS FLOWER (FIL) and the activity of the microRNA miR165/166 are specific to the abaxial side. This miR165/166 activity restricts the target gene expression to the adaxial side. The adaxial and abaxial specific gene expressions are crucial for the wide expansion of leaf lamina. The FIL-expression and the miR165/166-free domains are almost mutually exclusive, and they have been considered to be maintained during leaf development. However, we found here that the position of the boundary between the two domains gradually shifts from the adaxial side to the abaxial side. The cell lineage analysis revealed that this boundary shifting was associated with a sequential gene expression switch from the FIL-expressing (miR165/166 active) to the miR165/166-free (non-FIL-expressing) states. Our genetic analyses using the enlarged fil expression domain2 (enf2) mutant and chemical treatment experiments revealed that impairment in the plastid (chloroplast) gene expression machinery retards this boundary shifting and inhibits the lamina expansion. Furthermore, these developmental effects caused by the abnormal plastids were not observed in the genomes uncoupled1 (gun1) mutant background. This study characterizes the dynamic nature of the adaxial-abaxial specification process in leaf primordia and reveals that the dynamic process is affected by the GUN1-dependent retrograde signal in response to the failure of plastid gene expression. These findings advance our understanding on the molecular mechanism linking the plastid function to the leaf morphogenic processes. PMID:23935517

  13. Silicification of the adaxial epidermis of leaves of a panicoid grass in relation to leaf position and section and environmental conditions.

    PubMed

    Fernández Honaine, M; Osterrieth, M L

    2012-07-01

    Many studies relate silica content in plants with internal or external factors; however, few works analyse the effect of these factors on the silicification of different cell types. In this study, we examined the effect of leaf section and leaf position, and environmental conditions on the percentages of silicified epidermal cells of a native Pampean panicoid grass, Bothriochloa laguroides D. C. Pilger. Two different environmental situations were selected for the collection of plants: a natural wetland and a quartzite quarry, located in the southeast Buenos Aires province, Argentina. Clarification and staining methodologies were applied so as to study the distribution of silicified cells in different sections of leaves of the plants collected. Two and three-factor anovas were applied to the data. Between 13% and 19% of total cells of the adaxial epidermis of leaf blades were silicified. Typical silica short cells were the largest contributor to total silicified cells (53-98%), while the second largest contributor was bulliform cells (0-30%). Percentages of total silicified cells were higher in superior than in inferior leaves, while values from leaf sections varied. When collection sites were compared, plants growing in Los Padres pond, where the silica content in soils is higher, had the higher percentage of silicified cells. Among all types of cell, bulliform cells showed differences in the proportion of silicified cells between leaf position and section and collection site. These results show that silica availability in soils is an important factor that conditions silica accumulation and overlaps with the transpiration effect.

  14. What do microbes encounter at the plant surface? Chemical composition of pea leaf cuticular waxes.

    PubMed

    Gniwotta, Franka; Vogg, Gerd; Gartmann, Vanessa; Carver, Tim L W; Riederer, Markus; Jetter, Reinhard

    2005-09-01

    In the cuticular wax mixtures from leaves of pea (Pisum sativum) cv Avanta, cv Lincoln, and cv Maiperle, more than 70 individual compounds were identified. The adaxial wax was characterized by very high amounts of primary alcohols (71%), while the abaxial wax consisted mainly of alkanes (73%). An aqueous adhesive of gum arabic was employed to selectively sample the epicuticular wax layer on pea leaves and hence to analyze the composition of epicuticular crystals exposed at the outermost surface of leaves. The epicuticular layer was found to contain 74% and 83% of the total wax on adaxial and abaxial surfaces, respectively. The platelet-shaped crystals on the adaxial leaf surface consisted of a mixture dominated by hexacosanol, accompanied by substantial amounts of octacosanol and hentriacontane. In contrast, the ribbon-shaped wax crystals on the abaxial surface consisted mainly of hentriacontane (63%), with approximately 5% each of hexacosanol and octacosanol being present. Based on this detailed chemical analysis of the wax exposed at the leaf surface, their importance for early events in the interaction with host-specific pathogenic fungi can now be evaluated. On adaxial surfaces, approximately 80% of Erysiphe pisi spores germinated and 70% differentiated appressoria. In contrast, significantly lower germination efficiencies (57%) and appressoria formation rates (49%) were found for abaxial surfaces. In conclusion, the influence of the physical structure and the chemical composition of the host surface, and especially of epicuticular leaf waxes, on the prepenetration processes of biotrophic fungi is discussed.

  15. The effects of leaf roughness, surface free energy and work of adhesion on leaf water drop adhesion.

    PubMed

    Wang, Huixia; Shi, Hui; Li, Yangyang; Wang, Yanhui

    2014-01-01

    The adhesion of water droplets to leaves is important in controlling rainfall interception, and affects a variety of hydrological processes. Leaf water drop adhesion (hereinafter, adhesion) depends not only on droplet formulation and parameters but also on the physical (leaf roughness) and physico-chemical (surface free energy, its components, and work-of-adhesion) properties of the leaf surface. We selected 60 plant species from Shaanxi Province, NW China, as experimental materials with the goal of gaining insight into leaf physical and physico-chemical properties in relation to the adhesion of water droplets on leaves. Adhesion covered a wide range of area, from 4.09 to 88.87 g/m(2) on adaxial surfaces and 0.72 to 93.35 g/m(2) on abaxial surfaces. Distinct patterns of adhesion were observed among species, between adaxial and abaxial surfaces, and between leaves with wax films and wax crystals. Adhesion decreased as leaf roughness increased (r =  -0.615, p = 0.000), but there were some outliers, such as Salix psammophila and Populus simonii with low roughness and low adhesion, and the abaxial surface of Hyoscyamus pusillus and the adaxial surface of Vitex negundo with high roughness and high adhesion. Meanwhile, adhesion was positively correlated with surface free energy (r = 0.535, p = 0.000), its dispersive component (r = 0.526, p = 0.000), and work of adhesion for water (r = 0.698, p = 0.000). However, a significant power correlation was observed between adhesion and the polar component of surface free energy (p = 0.000). These results indicated that leaf roughness, surface free energy, its components, and work-of-adhesion for water played important roles in hydrological characteristics, especially work-of-adhesion for water.

  16. The Effects of Leaf Roughness, Surface Free Energy and Work of Adhesion on Leaf Water Drop Adhesion

    PubMed Central

    Wang, Huixia; Shi, Hui; Li, Yangyang; Wang, Yanhui

    2014-01-01

    The adhesion of water droplets to leaves is important in controlling rainfall interception, and affects a variety of hydrological processes. Leaf water drop adhesion (hereinafter, adhesion) depends not only on droplet formulation and parameters but also on the physical (leaf roughness) and physico-chemical (surface free energy, its components, and work-of-adhesion) properties of the leaf surface. We selected 60 plant species from Shaanxi Province, NW China, as experimental materials with the goal of gaining insight into leaf physical and physico-chemical properties in relation to the adhesion of water droplets on leaves. Adhesion covered a wide range of area, from 4.09 to 88.87 g/m2 on adaxial surfaces and 0.72 to 93.35 g/m2 on abaxial surfaces. Distinct patterns of adhesion were observed among species, between adaxial and abaxial surfaces, and between leaves with wax films and wax crystals. Adhesion decreased as leaf roughness increased (r =  −0.615, p = 0.000), but there were some outliers, such as Salix psammophila and Populus simonii with low roughness and low adhesion, and the abaxial surface of Hyoscyamus pusillus and the adaxial surface of Vitex negundo with high roughness and high adhesion. Meanwhile, adhesion was positively correlated with surface free energy (r = 0.535, p = 0.000), its dispersive component (r = 0.526, p = 0.000), and work of adhesion for water (r = 0.698, p = 0.000). However, a significant power correlation was observed between adhesion and the polar component of surface free energy (p = 0.000). These results indicated that leaf roughness, surface free energy, its components, and work-of-adhesion for water played important roles in hydrological characteristics, especially work-of-adhesion for water. PMID:25198355

  17. Photosystem II efficiency of the palisade and spongy mesophyll in Quercus coccifera using adaxial/abaxial illumination and excitation light sources with wavelengths varying in penetration into the leaf tissue.

    PubMed

    Peguero-Pina, José Javier; Gil-Pelegrín, Eustaquio; Morales, Fermín

    2009-01-01

    The existence of major vertical gradients within the leaf is often overlooked in studies of photosynthesis. These gradients, which involve light heterogeneity, cell composition, and CO(2) concentration across the mesophyll, can generate differences in the maximum potential PSII efficiency (F (V)/F (M) or F (V)/F (P)) of the different cell layers. Evidence is presented for a step gradient of F (V)/F (P) ratios across the mesophyll, from the adaxial (palisade parenchyma, optimal efficiencies) to the abaxial (spongy parenchyma, sub-optimal efficiencies) side of Quercus coccifera leaves. For this purpose, light sources with different wavelengths that penetrate more or less deep within the leaf were employed, and measurements from the adaxial and abaxial sides were performed. To our knowledge, this is the first report where a low photosynthetic performance in the abaxial side of leaves is accompanied by impaired F (V)/F (P) ratios. This low photosynthetic efficiency of the abaxial side could be related to the occurrence of bundle sheath extensions, which facilitates the penetration of high light intensities deep within the mesophyll. Also, leaf morphology (twisted in shape) and orientation (with a marked angle from the horizontal plane) imply direct sunlight illumination of the abaxial side. The existence of cell layers within leaves with different photosynthetic efficiencies makes appropriate the evaluation of how light penetrates within the mesophyll when using Chl fluorescence or gas exchange techniques that use different wavelengths for excitation and/or for driving photosynthesis.

  18. Plastid control of abaxial-adaxial patterning

    PubMed Central

    Mateo-Bonmatí, Eduardo; Casanova-Sáez, Rubén; Quesada, Víctor; Hricová, Andrea; Candela, Héctor; Micol, José Luis

    2015-01-01

    Translational regulation, exerted by the cytosolic ribosome, has been shown to participate in the establishment of abaxial-adaxial polarity in Arabidopsis thaliana: many hypomorphic and null alleles of genes encoding proteins of the cytosolic ribosome enhance the leaf polarity defects of asymmetric leaves1 (as1) and as2 mutants. Here, we report the identification of the SCABRA1 (SCA1) nuclear gene, whose loss-of-function mutations also enhance the polarity defects of the as2 mutants. In striking contrast to other previously known enhancers of the phenotypes caused by the as1 and as2 mutations, we found that SCA1 encodes a plastid-type ribosomal protein that functions as a structural component of the 70S plastid ribosome and, therefore, its role in abaxial-adaxial patterning was not expected. PMID:26522839

  19. PHANTASTICA regulates development of the adaxial mesophyll in Nicotiana leaves.

    PubMed

    McHale, Neil A; Koning, Ross E

    2004-05-01

    Initiation and growth of leaf blades is oriented by an adaxial/abaxial axis aligned with the original axis of polarity in the leaf primordium. To investigate mechanisms regulating this process, we cloned the Nicotiana tabacum ortholog of PHANTASTICA (NTPHAN) and generated a series of antisense transgenics in N. sylvestris. We show that NSPHAN is expressed throughout emerging blade primordia in the wild type and becomes localized to the middle mesophyll in the expanding lamina. Antisense NSPHAN leaves show ectopic expression of NTH20, a class I KNOX gene. Juvenile transgenic leaves have normal adaxial/abaxial polarity and generate leaf blades in the normal position, but the adaxial mesophyll shows disorganized patterns of cell division, delayed maturation of palisade, and ectopic reinitiation of blade primordia along the midrib. Reversal of the phenotype with exogenous gibberellic acid suggests that NSPHAN, acting via KNOX repression, maintains determinacy in the expanding lamina and sustains the patterns of cell proliferation critical to palisade development.

  20. [XPS analysis of tea plant leaf and root surface].

    PubMed

    Fang, Jiang-yu; Wan, Xiao-chun

    2008-09-01

    XPS was applied to analyze the surface chemical composition and structure of the tea plant leaf and root. It was detected that the surface is made up of mainly 4 elements: C, O, N and Al, with little P and F in abaxial leaf. Based on the botanic epidermis structure and the chemical composition, with the help of the standard spectrum data bank on line and the wood XPS study results, and through line Gaussian and Lorentizian the mixed, the binding energy of C(1s) of the leaf surface was classified as 3 types: the first was C1, with the electron binding energy of 285 eV, from C-C or C-H group, representing lipid compound like cutin and wax. C2 with the binding energy of 286.35 eV in the adaxial and 286.61 eV in the abaxial, came from the single bond of carbon and oxygen C-O, mainly standing for cellulose. C3 with the binding energy of approximately 288 eV (288.04 eV in adaxial and 288.09 eV in abaxial) was the sign of C=O group, which is acyl in protein with the confirmation of N(1s) (399-401 eV)and O(1s) analyses. In the root surface, besides the same compounds of cutin and wax (C1, binding energy 285 eV), cellulose (C2, binding energy 286.49 eV) and protein (C3, binding energy 288.78 eV)as in the leaf, there appeared C5 type with the binding energy of 283.32 eV. Because it was lower than C1, it was estimated as carbon linking to metal. Both the leaf and the root surfaces didn't have C4, a type of O-C=O, which is common in wood surface with the highest oxidated carbon of 289-289.5 eV binding energy, indicating that organic acid secreted by the root existed freely on the root surface, without any chemical association with the surface compounds. The results of the separated spectrum of O(1s) supported the above C(1s) results. By the ratio of each type of C, there were more oxygen groups in the abaxial than in the adaxial, implicating more active chemical properties on the abaxial. Compared with the leaf, cutin and wax was little in the root and oxygen groups were many

  1. Evaporation Rate and Development of Wetted Area of Water Droplets with and without Surfactant at Different Locations on Waxy Leaf Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The evaporation and formation of deposit patterns from single droplets deposited at various locations on waxy leaves were investigated under controlled conditions. Leaf locations included the interveinal area, midrib and secondary vein on both adaxial and abaxial surfaces. Tests were conducted with ...

  2. Zeaxanthin concentrations co-segregate with the magnitude of the blue light response of adaxial guard cells and leaf stomatal conductances in an F2 population of pima cotton

    SciTech Connect

    Quinones, M.A.; Lu Zhenmin; Zeiger, E. )

    1993-05-01

    A blue light (BL) response of adaxial (AD) guard cells was investigated in two cotton lines with contrasting rates of stomatal conductances (g). This response is expressed as an enhancement of the red light-induced chlorophyll a fluorescence quenching by BL, and has an action spectrum indicative of a carotenoid photoreceptor. Ad guard cell from the high g, advanced line Pima S-6 have a higher carotenoid content and a larger BL response than those from the low g, primitive cotton, B368. In a growth chamber-grown F2 population of a cross between the two lines (n=30), g of individual plants segregated over a range exceeding the average g of the parental populations. Carotenoid content and the BL response of ad guard cell also segregated. There was a positive, strong correlation (r=0.71) between leaf g and the magnitude of the BL response of ad guard cells, indicating that both parameters are under genetic control, and that the BL response of guard cells contributes to the modulation of g. The concentration of all xanthopylls and [beta]-carotene in the ad guard cells correlated poorly with the BL response, except for zeaxanthin (r=0.71). In all green systems, xanthophylls are located inside the chloroplast which suggests that zeaxanthin functions in these organelle as a blue light photoreceptor for cotton guard cells.

  3. Wettability, polarity, and water absorption of holm oak leaves: effect of leaf side and age.

    PubMed

    Fernández, Victoria; Sancho-Knapik, Domingo; Guzmán, Paula; Peguero-Pina, José Javier; Gil, Luis; Karabourniotis, George; Khayet, Mohamed; Fasseas, Costas; Heredia-Guerrero, José Alejandro; Heredia, Antonio; Gil-Pelegrín, Eustaquio

    2014-09-01

    Plant trichomes play important protective functions and may have a major influence on leaf surface wettability. With the aim of gaining insight into trichome structure, composition, and function in relation to water-plant surface interactions, we analyzed the adaxial and abaxial leaf surface of holm oak (Quercus ilex) as a model. By measuring the leaf water potential 24 h after the deposition of water drops onto abaxial and adaxial surfaces, evidence for water penetration through the upper leaf side was gained in young and mature leaves. The structure and chemical composition of the abaxial (always present) and adaxial (occurring only in young leaves) trichomes were analyzed by various microscopic and analytical procedures. The adaxial surfaces were wettable and had a high degree of water drop adhesion in contrast to the highly unwettable and water-repellent abaxial holm oak leaf sides. The surface free energy and solubility parameter decreased with leaf age, with higher values determined for the adaxial sides. All holm oak leaf trichomes were covered with a cuticle. The abaxial trichomes were composed of 8% soluble waxes, 49% cutin, and 43% polysaccharides. For the adaxial side, it is concluded that trichomes and the scars after trichome shedding contribute to water uptake, while the abaxial leaf side is highly hydrophobic due to its high degree of pubescence and different trichome structure, composition, and density. Results are interpreted in terms of water-plant surface interactions, plant surface physical chemistry, and plant ecophysiology.

  4. Accumulation of particles on the surface of leaves during leaf expansion.

    PubMed

    Wang, Lei; Gong, Huili; Liao, Wenbo; Wang, Zhi

    2015-11-01

    Plants can effectively remove airborne particles from ambient air and consequently improve air quality and human health. The accumulation of particles on the leaf surfaces of three plant species with different epicuticular wax ultrastructures, such as thin films, platelets and tubules, was investigated during leaf expansion in Beijing under extremely high particulate matter (PM) concentration. The accumulation of particles on the leaf surfaces after bud break rapidly reached a high amount within 4-7 days. Rainfall occasionally resulted in a considerable increase in the accumulation of particles on the leaf surfaces at a high PM concentration, which resulted from the wet deposition of PM, and balanced the amount of PM on the leaf surfaces over a longer period. The equilibrium value of the particle cover area on the adaxial leaf surface of the three test species in this study was 10%-50% compared with 3%-35% on the abaxial leaf surface. The epicuticular wax ultrastructures contributed significantly to the PM adsorption of the leaves. The capability of these ultrastructures to capture PM decreased in the following order: thin films, platelets and tubules. The ridges (at a scale of 1-2 μm) on the leaf surfaces were more efficient at accumulating PM, particularly PM2.5, compared with the roughness (P-V distance) at a 5-20-μm scale. PMID:26093221

  5. Accumulation of particles on the surface of leaves during leaf expansion.

    PubMed

    Wang, Lei; Gong, Huili; Liao, Wenbo; Wang, Zhi

    2015-11-01

    Plants can effectively remove airborne particles from ambient air and consequently improve air quality and human health. The accumulation of particles on the leaf surfaces of three plant species with different epicuticular wax ultrastructures, such as thin films, platelets and tubules, was investigated during leaf expansion in Beijing under extremely high particulate matter (PM) concentration. The accumulation of particles on the leaf surfaces after bud break rapidly reached a high amount within 4-7 days. Rainfall occasionally resulted in a considerable increase in the accumulation of particles on the leaf surfaces at a high PM concentration, which resulted from the wet deposition of PM, and balanced the amount of PM on the leaf surfaces over a longer period. The equilibrium value of the particle cover area on the adaxial leaf surface of the three test species in this study was 10%-50% compared with 3%-35% on the abaxial leaf surface. The epicuticular wax ultrastructures contributed significantly to the PM adsorption of the leaves. The capability of these ultrastructures to capture PM decreased in the following order: thin films, platelets and tubules. The ridges (at a scale of 1-2 μm) on the leaf surfaces were more efficient at accumulating PM, particularly PM2.5, compared with the roughness (P-V distance) at a 5-20-μm scale.

  6. Wettability, Polarity, and Water Absorption of Holm Oak Leaves: Effect of Leaf Side and Age1[OPEN

    PubMed Central

    Fernández, Victoria; Sancho-Knapik, Domingo; Guzmán, Paula; Peguero-Pina, José Javier; Gil, Luis; Karabourniotis, George; Khayet, Mohamed; Fasseas, Costas; Heredia-Guerrero, José Alejandro; Heredia, Antonio; Gil-Pelegrín, Eustaquio

    2014-01-01

    Plant trichomes play important protective functions and may have a major influence on leaf surface wettability. With the aim of gaining insight into trichome structure, composition, and function in relation to water-plant surface interactions, we analyzed the adaxial and abaxial leaf surface of holm oak (Quercus ilex) as a model. By measuring the leaf water potential 24 h after the deposition of water drops onto abaxial and adaxial surfaces, evidence for water penetration through the upper leaf side was gained in young and mature leaves. The structure and chemical composition of the abaxial (always present) and adaxial (occurring only in young leaves) trichomes were analyzed by various microscopic and analytical procedures. The adaxial surfaces were wettable and had a high degree of water drop adhesion in contrast to the highly unwettable and water-repellent abaxial holm oak leaf sides. The surface free energy and solubility parameter decreased with leaf age, with higher values determined for the adaxial sides. All holm oak leaf trichomes were covered with a cuticle. The abaxial trichomes were composed of 8% soluble waxes, 49% cutin, and 43% polysaccharides. For the adaxial side, it is concluded that trichomes and the scars after trichome shedding contribute to water uptake, while the abaxial leaf side is highly hydrophobic due to its high degree of pubescence and different trichome structure, composition, and density. Results are interpreted in terms of water-plant surface interactions, plant surface physical chemistry, and plant ecophysiology. PMID:24913938

  7. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  8. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  9. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  10. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  11. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  12. Stomatal crypts may facilitate diffusion of CO(2) to adaxial mesophyll cells in thick sclerophylls.

    PubMed

    Hassiotou, Foteini; Evans, John R; Ludwig, Martha; Veneklaas, Erik J

    2009-11-01

    In some plants, stomata are exclusively located in epidermal depressions called crypts. It has been argued that crypts function to reduce transpiration; however, the occurrence of crypts in species from both arid and wet environments suggests that crypts may play another role. The genus Banksia was chosen to examine quantitative relationships between crypt morphology and leaf structural and physiological traits to gain insight into the functional significance of crypts. Crypt resistance to water vapour and CO(2) diffusion was calculated by treating crypts as an additional boundary layer partially covering one leaf surface. Gas exchange measurements of polypropylene meshes confirmed the validity of this approach. Stomatal resistance was calculated as leaf resistance minus calculated crypt resistance. Stomata contributed significantly more than crypts to leaf resistance. Crypt depth increased and accounted for an increasing proportion of leaf resistance in species with greater leaf thickness and leaf dry mass per area. All Banksia species examined with leaves thicker than 0.6 mm had their stomata in deep crypts. We propose that crypts function to facilitate CO(2) diffusion from the abaxial surface to adaxial palisade cells in thick leaves. This and other possible functions of stomatal crypts, including a role in water use, are discussed.

  13. An Apparent Anomaly in Peanut Leaf Conductance

    PubMed Central

    Pallas, James E.

    1980-01-01

    Conductance to gaseous transfer is normally considered to be greater from the abaxial than from the adaxial side of a leaf. Measurements of the conductance to water vapor of peanut leaves (Arachis hypogaea L.) under well watered and stress conditions in a controlled environment, however, indicated a 2-fold higher conductance from the adaxial side of the leaf than from the abaxial. Studies of conductance as light level was varied showed an increase in conductance from either surface with increasing light level, but conductance was always greater from the adaxial surface at any given light level. In contrast, measurements of soybean (Glycine max [L.] Merr.) and snapbean (Phaseolus vulgaris L.) leaf conductance showed an approximate 2-fold greater conductance from the abaxial surface than from the adaxial. Approximately the same number of stomata were present on both peanut leaf surfaces and stomatal size was similar. Electron microscopic examination of peanut leaves did not reveal any major structural differences between stomata on the two surfaces that would account for the differences in conductance. Light microscope studies of leaf sections revealed an extensive network of bundle sheaths with achloraplastic bundle sheath extensions; the lower epidermis was lined with a single layer of large achloraplastic parenchyma cells. Measurements of net photosynthesis made on upper and lower leaf surfaces collectively and individually indicated that two-thirds of the peanut leaf's total net photosynthesis can be attributed to diffusion of CO2 through the adaxial leaf surface. Possibly the high photosynthetic efficiency of peanut cultivars as compared with certain other C3 species is associated with the greater conductance of CO2 through their upper leaf surfaces. Images PMID:16661294

  14. Yeasts colonizing the leaf surfaces.

    PubMed

    Sláviková, Elena; Vadkertiová, Renata; Vránová, Dana

    2007-08-01

    The yeasts were isolated from the leaf surfaces of ten species of trees. The study site was a forest park (Zelezná Studnicka) of the Small Carpathians mountain range. One hundred and thirty seven yeast strains belonging to 13 genera were isolated from 320 samples of leaves and needles. Seventeen yeast species were isolated, but only seven occurred regularly: Aureobasidium pullulans, Cryptococcus laurentii, Pichia anomala, Metschnikowia pulcherrima, Saccharomyces sp., Lachancea thermotolerans, and Rhodotorula glutinis. The remaining species were isolated from the leaves and needles of three or less tree species. A. pullulans, Cr. laurentii, and P. anomala were the most frequently found species and they occurred on leaves and needles of all ten tree species. Saccharomyces sp. occurred in leaf samples collected from eight kinds of trees. M. pulcherrima and L. thermotolerans were found in samples collected from six species of trees. Both these species occurred almost always on the leaves of deciduous trees. Rh. glutinis was the most frequently isolated carotenoids producing species. We have found out that the ascomycetous and basidiomycetous species were present in the leaf samples in approximately equal frequency, contrary to the soil samples taken from this forest park, where the ascomycetous species were found rarely.

  15. Stomatal penetration by aqueous solutions--an update involving leaf surface particles.

    PubMed

    Burkhardt, Juergen; Basi, Sabin; Pariyar, Shyam; Hunsche, Mauricio

    2012-11-01

    The recent visualization of stomatal nanoparticle uptake ended a 40-yr-old paradigm. Assuming clean, hydrophobic leaf surfaces, the paradigm considered stomatal liquid water transport to be impossible as a result of water surface tension. However, real leaves are not clean, and deposited aerosols may change hydrophobicity and water surface tension. Droplets containing NaCl, NaClO(3), (NH(4))(2) SO(4), glyphosate, an organosilicone surfactant or various combinations thereof were evaporated on stomatous abaxial and astomatous adaxial surfaces of apple (Malus domestica) leaves. The effects on photosynthesis, necrosis and biomass were determined. Observed using an environmental scanning electron microscope, NaCl and NaClO(3) crystals on hydrophobic tomato (Solanum lycopersicum) cuticles underwent several humidity cycles, causing repeated deliquescence and efflorescence of the salts. All physiological parameters were more strongly affected by abaxial than adaxial treatments. Spatial expansion and dendritic crystallization of the salts occurred and cuticular hydrophobicity was decreased more rapidly by NaClO(3) than NaCl. The results confirmed the stomatal uptake of aqueous solutions. Humidity fluctuations promote the spatial expansion of salts into the stomata. The ion-specific effects point to the Hofmeister series: chaotropic ions reduce surface tension, probably contributing to the defoliant action of NaClO(3), whereas the salt spray tolerance of coastal plants is probably linked to the kosmotropic nature of chloride ions. PMID:22985197

  16. Stomatal penetration by aqueous solutions--an update involving leaf surface particles.

    PubMed

    Burkhardt, Juergen; Basi, Sabin; Pariyar, Shyam; Hunsche, Mauricio

    2012-11-01

    The recent visualization of stomatal nanoparticle uptake ended a 40-yr-old paradigm. Assuming clean, hydrophobic leaf surfaces, the paradigm considered stomatal liquid water transport to be impossible as a result of water surface tension. However, real leaves are not clean, and deposited aerosols may change hydrophobicity and water surface tension. Droplets containing NaCl, NaClO(3), (NH(4))(2) SO(4), glyphosate, an organosilicone surfactant or various combinations thereof were evaporated on stomatous abaxial and astomatous adaxial surfaces of apple (Malus domestica) leaves. The effects on photosynthesis, necrosis and biomass were determined. Observed using an environmental scanning electron microscope, NaCl and NaClO(3) crystals on hydrophobic tomato (Solanum lycopersicum) cuticles underwent several humidity cycles, causing repeated deliquescence and efflorescence of the salts. All physiological parameters were more strongly affected by abaxial than adaxial treatments. Spatial expansion and dendritic crystallization of the salts occurred and cuticular hydrophobicity was decreased more rapidly by NaClO(3) than NaCl. The results confirmed the stomatal uptake of aqueous solutions. Humidity fluctuations promote the spatial expansion of salts into the stomata. The ion-specific effects point to the Hofmeister series: chaotropic ions reduce surface tension, probably contributing to the defoliant action of NaClO(3), whereas the salt spray tolerance of coastal plants is probably linked to the kosmotropic nature of chloride ions.

  17. Variations in the polarized leaf reflectance of Sorghum bicolor

    NASA Technical Reports Server (NTRS)

    Grant, Lois; Daughtry, C. S. T.; Vanderbilt, V. C.

    1987-01-01

    The polarized reflectance factor, Rq, of sorghum (Sorghum bicolor, L.) leaves from field-grown plants was measured in situ in the summers of 1983 and 1984. In 1983, three leaves of two randomly selected plants were measured at 2-week intervals. The value of Rq varied, depending on leaf and day of measurement. Measured values of Rq for the adaxial leaf surface ranged from 16 to 53; for the abaxial leaf surface the values ranged from 28 to 69. In 1984, measurements consisted of repeated observations made on the same leaf at biweekly intervals. The values of Rq from the adaxial leaf surface ranged from 26 to 38. Values of Rq from the abaxial leaf surface increased throughout the season, from 16 to 45. Differences in Rq were attributed to changes in surface details of the leaf.

  18. Distinct responses to ozone of abaxial and adaxial stomata in three Euramerican poplar genotypes.

    PubMed

    Dumont, Jennifer; Cohen, David; Gérard, Joëlle; Jolivet, Yves; Dizengremel, Pierre; LE Thiec, Didier

    2014-09-01

    Ozone induces stomatal sluggishness, which impacts photosynthesis and transpiration. Stomatal responses to variation of environmental parameters are slowed and reduced by ozone and may be linked to difference of ozone sensitivity. Here we determine the ozone effects on stomatal conductance of each leaf surface. Potential causes of this sluggish movement, such as ultrastructural or ionic fluxes modification, were studied independently on both leaf surfaces of three Euramerican poplar genotypes differing in ozone sensitivity and in stomatal behaviour. The element contents in guard cells were linked to the gene expression of ion channels and transporters involved in stomatal movements, directly in microdissected stomata. In response to ozone, we found a decrease in the stomatal conductance of the leaf adaxial surface correlated with high calcium content in guard cells compared with a slight decrease on the abaxial surface. No ultrastructural modifications of stomata were shown except an increase in the number of mitochondria. The expression of vacuolar H(+) /Ca(2+) -antiports (CAX1 and CAX3 homologs), β-carbonic anhydrases (βCA1 and βCA4) and proton H(+) -ATPase (AHA11) genes was strongly decreased under ozone treatment. The sensitive genotype characterized by constitutive slow stomatal response was also characterized by constitutive low expression of genes encoding vacuolar H(+) /Ca(2+) -antiports.

  19. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  20. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  1. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  2. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  3. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  4. Chemical Composition of the Epicuticular and Intracuticular Wax Layers on Adaxial Sides of Rosa canina Leaves

    PubMed Central

    Buschhaus, Christopher; Herz, Hubert; Jetter, Reinhard

    2007-01-01

    Background and Aims The waxy cuticle is the first point of contact for many herbivorous and pathogenic organisms on rose plants. Previous studies have reported the average composition of the combined wax extract from both sides of rose leaves. Recently, the compositions of the waxes on the adaxial and abaxial surfaces of Rosa canina leaves were determined separately. In this paper, a first report is made on the compositions of the epicuticular and intracuticular wax layers of Rosa canina leaves. The methods described enable the determination of which compounds are truly available at the surface for plant–organism interactions. METHOD An adhesive was used to mechanically strip the epicuticular wax from the adaxial leaf surface and the removal was visually confirmed using scanning electron microscopy. After the epicuticular wax had been removed, the intracuticular wax was then isolated using standard chemical extraction. Gas chromatography, flame ionization detection and mass spectrometry were used to identify and quantify compounds in the separated wax mixtures. Key Results The epicuticular wax contained higher concentrations of alkanes and alkyl esters but lower concentrations of primary alcohols and alkenols when compared to the intracuticular wax. In addition, the average chain lengths of these compound classes were higher in the epicuticular wax. Secondary alcohols were found only in the epicuticular layer while triterpenoids were restricted mainly to the intracuticular wax. Conclusions A gradient exists between the composition of the epi- and intracuticular wax layers of Rosa canina leaves. This gradient may result from polarity differences, in part caused by differences in chain lengths. The outer wax layer accessible to the phyllosphere showed a unique composition of wax compounds. The ecological consequences from such a gradient may now be probed. PMID:17933845

  5. The Influence of Leaf Angle and Leaf Surface Characteristics on the Process of Rainfall Interception

    NASA Astrophysics Data System (ADS)

    Holder, C.; Ginebra, R.; Webb, R.

    2015-12-01

    Individual choice in plant selection for household landscaping influences differences in runoff from urban watersheds because the variation in plant canopy architecture results in rainfall interception differences. Understanding the variables that influence rainfall interception and understanding the mechanism of rainfall interception are important concepts for sustainable watershed management. The broad objective of this study was to explore the influence of leaf hydrophobicity, water droplet retention, and leaf angle on the mechanism and process of rainfall interception and raindrop impaction on leaf surfaces of common tree species from the semi-arid regions of the western United States. Leaf hydrophobicity is determined by the cohesive forces of the water molecules among themselves and the adhesive forces that result from the molecular interactions between the water droplet and the leaf surface. Water droplet retention is a measure of how easily a water droplet drains off a leaf surface. The specific hypotheses examined were 1) larger raindrops falling on leaf surfaces will deflect the leaf to an angle greater than the water droplet retention angle; 2) an increased leaf angle, whether from natural position or deflection due to droplet impact and retention, reduces interception from raindrop impaction on hydrophobic and hydrophilic leaf surfaces; and 3) increased droplet size and frequency decrease rainfall interception more significantly in the hydrophilic case. These hypotheses were addressed in a laboratory experiment by 1) measuring leaf hydrophobicity and water droplet retention using a goniometer with a tilting base; 2) measuring leaf traits such as leaf area, leaf surface roughness, trichome density, and specific storage capacity; 3) examining raindrop splash on leaf surfaces with varying leaf hydrophobicity, water droplet retention, and leaf angle with a raindrop generator and high-speed video camera; and 4) modeling the impact of raindrop splash on leaf

  6. Simulating droplet motion on virtual leaf surfaces

    PubMed Central

    Mayo, Lisa C.; McCue, Scott W.; Moroney, Timothy J.; Forster, W. Alison; Kempthorne, Daryl M.; Belward, John A.; Turner, Ian W.

    2015-01-01

    A curvilinear thin film model is used to simulate the motion of droplets on a virtual leaf surface, with a view to better understand the retention of agricultural sprays on plants. The governing model, adapted from Roy et al. (2002 J. Fluid Mech. 454, 235–261 (doi:10.1017/S0022112001007133)) with the addition of a disjoining pressure term, describes the gravity- and curvature-driven flow of a small droplet on a complex substrate: a cotton leaf reconstructed from digitized scan data. Coalescence is the key mechanism behind spray coating of foliage, and our simulations demonstrate that various experimentally observed coalescence behaviours can be reproduced qualitatively. By varying the contact angle over the domain, we also demonstrate that the presence of a chemical defect can act as an obstacle to the droplet's path, causing break-up. In simulations on the virtual leaf, it is found that the movement of a typical spray size droplet is driven almost exclusively by substrate curvature gradients. It is not until droplet mass is sufficiently increased via coalescence that gravity becomes the dominating force. PMID:26064657

  7. "Breath figures" on leaf surfaces-formation and effects of microscopic leaf wetness.

    PubMed

    Burkhardt, Juergen; Hunsche, Mauricio

    2013-01-01

    "Microscopic leaf wetness" means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

  8. Leaf architecture and direction of incident light influence mesophyll fluorescence profiles.

    PubMed

    Johnson, Daniel M; Smith, William K; Vogelmann, Thomas C; Brodersen, Craig R

    2005-09-01

    Light propagation and distribution inside leaves have been recognized as important processes influencing photosynthesis. Monochromatic light absorption across the mesophyll was measured using chlorophyll fluorescence generated from illumination of the cut edge (epi-illumination), as well as the adaxial or abaxial surfaces of the leaf. Species were selected that had basic leaf types: laminar leaf with adaxial palisade layer (Rhododendron catawbiense), needle with palisade (Abies fraseri), and needle without palisade (Picea rubens). Fluorescence was more evenly distributed across the mesophyll for adaxially illuminated leaves with a palisade cell layer, as well as for the needles (cylindrical) without palisade, when compared to fluorescence generated by abaxial illumination. Moreover, fluorescence from green light illumination remained high across the mesophyll of adaxially illuminated R. catawbiense, indicating a possible influence of mesophyll structure on internal light distribution beyond that of chlorophyll levels. These data support the idea that light propagation within the mesophyll is associated with asymmetric mesophyll structure, in particular the presence of palisade cell layers. In addition, we propose that the evolution of a more cylindrical leaf form, such as found in conifer species, may be a structural solution to excessive sunlight that replaces the highly differentiated mesophyll found in most laminar-leaved species.

  9. OsLBD3-7 Overexpression Induced Adaxially Rolled Leaves in Rice

    PubMed Central

    Zhang, Chunyu; Shao, Qinghao; Liu, Jun; Liu, Bin; Li, Hongyu

    2016-01-01

    Appropriate leaf rolling enhances erect-leaf habits and photosynthetic efficiency, which consequently improves grain yield. Here, we reported the novel lateral organ boundaries domain (LBD) gene OsLBD3-7, which is involved in the regulation of leaf rolling. OsLBD3-7 works as a transcription activator and its protein is located on the plasma membrane and in the nucleus. Overexpression of OsLBD3-7 leads to narrow and adaxially rolled leaves. Microscopy of flag leaf cross-sections indicated that overexpression of OsLBD3-7 led to a decrease in both bulliform cell size and number. Transcriptional analysis showed that key genes that had been reported to be negative regulators of bulliform cell development were up-regulated in transgenic plants. These results indicated that OsLBD3-7 might acts as an upstream regulatory gene of bulliform cell development to regulate leaf rolling, which will give more insights on the leaf rolling regulation mechanism. PMID:27258066

  10. Replication of Leaf Surface Structures for Light Harvesting

    PubMed Central

    Huang, Zhongjia; Yang, Sai; Zhang, Hui; Zhang, Meng; Cao, Wei

    2015-01-01

    As one of the most important hosts of natural light harvesting, foliage normally has complicated surface structures to capture solar radiances. Bio-mimicking leaf surface structures can provide novel designs of covers in photovoltaic systems. In this article, we reported on replicating leaf surface structures on poly-(methyl methacrylate) polymers to prompt harvesting efficiencies. Prepared via a double transfer process, the polymers were found to have high optical transparencies and transmission hazes, with both values exceeding 80% in some species. Benefiting from optical properties and wrinkled surfaces, the biomimetic polymers brought up to 17% gains to photovoltaic efficiencies. Through Monte-Carlo simulations of light transport, ultrahigh haze values and low reflections were attributed to lightwave guidance schemes lead by the nano- and micro-morphologies which are inherited from master leaves. Thus, leaf surface bio-mimicking can be considered as a strategic direction to design covers of light harvesting systems. PMID:26381702

  11. [PS II photochemical efficiency in flag leaf of wheat varieties and its adaptation to strong sun- light intensity on farmland of Xiangride in Qinghai Province, Northwest China].

    PubMed

    Shi, Sheng-Bo; Chen, Wen-Jie; Shi, Rui; Li, Miao; Zhang, Huai-Gang; Sun, Ya-Nan

    2014-09-01

    Taking four wheat varieties developed by Northwest Institute of Plateau Biology, Chinese Academy of Sciences, as test materials, with the measurement of content of photosynthetic pigments, leaf area, fresh and dry mass of flag leaf, the PS II photochemistry efficiency of abaxial and adaxial surface of flag leaf and its adaptation to strong solar radiation during the period of heading stage in Xiangride region were investigated with the pulse-modulated in-vivo chlorophyll fluorescence technique. The results indicated that flag leaf angle mainly grew in horizontal state in Gaoyuan 314, Gaoyuan 363 and Gaoyuan 584, and mainly in vertical state in Gaoyuan 913 because of its smaller leaf area and larger width. Photosynthetic pigments were different among the 4 varieties, and positively correlated with intrinsic PS II photochemistry efficiencies (Fv/Fm). In clear days, especially at noon, the photosynthetic photoinhibition was more serious in abaxial surface of flag leaf due to directly facing the solar radiation, but it could recover after reduction of sunlight intensity in the afternoon, which meant that no inactive damage happened in PS II reaction centers. There were significant differences of PS II actual and maximum photochemical efficiencies at the actinic light intensity (ΦPS II and Fv'/Fm') between abaxial and adaxial surface, and their relative variation trends were on the contrary. The photochemical and non-photochemical quenching coefficients (qP and NPQ) had a similar tendency in both abaxial and adaxial surfaces. Although ΦPS II and qP were lower in adaxial surface of flag leaf, the Fv'/Fm' was significantly higher, which indicated that the potential PS II capture efficiency of excited energy was higher. The results demonstrated that process of photochemical and non-photochemical quenching could effectively dissipate excited energy caused by strong solar radiation, and there were higher adaptation capacities in wheat varieties natively cultivated in

  12. Effect of Surface-Active Pseudomonas spp. on Leaf Wettability

    PubMed Central

    Bunster, Lillian; Fokkema, Nyckle J.; Schippers, Bob

    1989-01-01

    Different strains of Pseudomonas putida and P. fluorescens isolated from the rhizosphere and phyllosphere were tested for surface activity in droplet cultures on polystyrene. Droplets of 6 of the 12 wild types tested spread over the surface during incubation, and these strains were considered surface active; strains not showing this reaction were considered non-surface active. Similar reactions were observed on pieces of wheat leaves. Supernatants from centrifuged broth cultures behaved like droplets of suspensions in broth; exposure to 100°C destroyed the activity. Average contact angles of the supernatants of surface-active and non-surface-active strains on polystyrene were 24° and 72°, respectively. The minimal surface tension of supernatants of the surface-active strains was about 46 mN/m, whereas that of the non-surface-active strains was 64 mN/m (estimations from Zisman plots). After 6 days of incubation, wheat flag leaves sprayed with a dilute suspension of a surface-active strain of P. putida (WCS 358RR) showed a significant increase in leaf wettability, which was determined by contact angle measurements. Increasing the initial concentration of bacteria and the amount of nutrients in the inoculum sprayed on leaves reduced the contact angles from 138° on leaves treated with antibiotics (control) to 43° on leaves treated with surface-active bacteria. A closely related strain with no surface activity on polystyrene did not affect leaf wettability, although it was present in densities similar to those of the surface-active strain. Nutrients alone could occasionally also increase leaf wettability, apparently by stimulating naturally occurring surface-active bacteria. When estimating densities of Pseudomonas spp. underneath droplets with low contact angles, it appeared that populations on leaves treated with a surface-active strain could vary from about 104 to 106 CFU cm−2, suggesting that the surface effect may be prolonged after a decline of the

  13. Impact of epidermal leaf mining by the aspen leaf miner (Phyllocnistis populiella) on the growth, physiology, and leaf longevity of quaking aspen.

    PubMed

    Wagner, Diane; DeFoliart, Linda; Doak, Patricia; Schneiderheinze, Jenny

    2008-08-01

    The aspen leaf miner, Phyllocnistis populiella, feeds on the contents of epidermal cells on both top (adaxial) and bottom (abaxial) surfaces of quaking aspen leaves, leaving the photosynthetic tissue of the mesophyll intact. This type of feeding is taxonomically restricted to a small subset of leaf mining insects but can cause widespread plant damage during outbreaks. We studied the effect of epidermal mining on aspen growth and physiology during an outbreak of P. populiella in the boreal forest of interior Alaska. Experimental reduction of leaf miner density across two sites and 3 years significantly increased annual aspen growth rates relative to naturally mined controls. Leaf mining damage was negatively related to leaf longevity. Leaves with heavy mining damage abscised 4 weeks earlier, on average, than leaves with minimal mining damage. Mining damage to the top and bottom surfaces of leaves had different effects on physiology. Mining on the top surface of the leaf had no significant effect on photosynthesis or conductance and was unrelated to leaf stable C isotope ratio (delta(13)C). Mining damage to the bottom leaf surface, where stomata are located, had significant negative effects on net photosynthesis and water vapor conductance. Percent bottom mining was positively related to leaf delta(13)C. Taken together, the data suggest that the primary mechanism for the reduction of photosynthesis by epidermal leaf mining by P. populiella is the failure of stomata to open normally on bottom-mined leaves.

  14. Comparative morphology of leaf epidermis in eight populations of Atlas Pistachio (Pistacia atlantica Desf., Anacardiaceae).

    PubMed

    Belhadj, Safia; Derridj, Arezki; Aigouy, Thierry; Gers, Charles; Gauquelin, Thierry; Mevy, Jean-Philippe

    2007-10-01

    A comparative analysis was undertaken to conduct a micromorphological study of Pistacia atlantica leaves by comparing different populations grown under different climatic conditions. Leaf epidermis of eight wild populations was investigated under scanning electron microscope. Micromorphological characteristics (epidermis ornament, stomata type, waxes as well as trichomes) of the adaxial and abaxial leaf surfaces were examined. The epidermis ornament varied among populations and leaf surface, the abaxial leaf surface is reticulate with a striate surface. Messaad site shows a smooth uneven surface. The adaxial leaf surface is smooth but several ornamentations can be seen. The leaflet is amphistomatic; the stomata appeared to be slightly sunken. A variety of stomatal types were recorded; actinocytic and anomocytic types are the most frequent. The indumentum consisted of glandular and nonglandular trichomes. Unicellular glandular trichomes are recorded for P. atlantica leaves in this study. Their density is higher in Oued safene site, located at the highest altitude in comparison with the other populations. The wax occurred in all the sites and its pattern varied according to the populations studied, particularly between Berriane and Messaad. The morphological variability exhibited by the eight populations of P. atlantica may be interpreted as relevant to the ecological plasticity and the physiological mechanisms involved are discussed in this report.

  15. Electron transport efficiency at opposite leaf sides: effect of vertical distribution of leaf angle, structure, chlorophyll content and species in a forest canopy.

    PubMed

    Mänd, Pille; Hallik, Lea; Peñuelas, Josep; Kull, Olevi

    2013-02-01

    We investigated changes in chlorophyll a fluorescence from alternate leaf surfaces to assess the intraleaf light acclimation patterns in combination with natural variations in radiation, leaf angles, leaf mass per area (LMA), chlorophyll content (Chl) and leaf optical parameters. Measurements were conducted on bottom- and top-layer leaves of Tilia cordata Mill. (a shade-tolerant sub-canopy species, sampled at heights of 11 and 16 m) and Populus tremula L. (a light-demanding upper canopy species, sampled at canopy heights of 19 and 26 m). The upper canopy species P. tremula had a six times higher PSII quantum yield (Φ(II)) and ratio of open reaction centres (qP), and a two times higher LMA than T. cordata. These species-specific differences were also present when the leaves of both species were in similar light conditions. Leaf adaxial/abaxial fluorescence ratio was significantly larger in the case of more horizontal leaves. Populus tremula (more vertical leaves), had smaller differences in fluorescence parameters between alternate leaf sides compared with T. cordata (more horizontal leaves). However, optical properties on alternate leaf sides showed a larger difference for P. tremula. Intraspecifically, the measured optical parameters were better correlated with LMA than with leaf Chl. Species-specific differences in leaf anatomy appear to enhance the photosynthetic potential of leaf biochemistry by decreasing the interception of excess light in P. tremula and increasing the light absorptance in T. cordata. Our results indicate that intraleaf light absorption gradient, described here as leaf adaxial/abaxial side ratio of chlorophyll a fluorescence, varies significantly with changes in leaf light environment in a multi-layer multi-species tree canopy. However, this variation cannot be described merely as a simple function of radiation, leaf angle, Chl or LMA, and species-specific differences in light acclimation strategies should also be considered.

  16. Trichomes as sensors: detecting activity on the leaf surface.

    PubMed

    Tooker, John F; Peiffer, Michelle; Luthe, Dawn S; Felton, Gary W

    2010-01-01

    The dramatic movements of some carnivorous plants species are triggered by sensory structures derived from trichomes. While unusual plant species such as the Venus fly trap and sundews may be expected to have elaborate sensors to capture their insect prey, more modest plant species might not be expected to have similar sensory capabilities. Our recent work, however, has revealed that glandular trichomes on tomato (Solanum lycopersicum) appear to have a function similar to trigger hairs of carnivorous species, acting as "early warning" sensors. Using a combination of behavioral, molecular, and biochemical techniques, we determined that caterpillars, moths and mechanical disruption upregulate signaling molecules and defensive genes found in glandular trichomes. Importantly, we discovered that plants whose trichomes have been broken respond more vigorously when their defenses were induced. Taken together, our results suggest that glandular trichomes can act as sensors that detect activity on the leaf surface, and ready plants for herbivore attack.

  17. Quantitative study of Xanthosoma violaceum leaf surfaces using RIMAPS and variogram techniques.

    PubMed

    Favret, Eduardo A; Fuentes, Néstor O; Molina, Ana M

    2006-08-01

    Two new imaging techniques (rotated image with maximum averaged power spectrum (RIMAPS) and variogram) are presented for the study and description of leaf surfaces. Xanthosoma violaceum was analyzed to illustrate the characteristics of both techniques. Both techniques produce a quantitative description of leaf surface topography. RIMAPS combines digitized images rotation with Fourier transform, and it is used to detect patterns orientation and characteristics of surface topography. Variogram relates the mathematical variance of a surface with the area of the sample window observed. It gives the typical scale lengths of the surface patterns. RIMAPS detects the morphological variations of the surface topography pattern between fresh and dried (herbarium) samples of the leaf. The variogram method finds the characteristic dimensions of the leaf microstructure, i.e., cell length, papillae diameter, etc., showing that there are not significant differences between dry and fresh samples. The results obtained show the robustness of RIMAPS and variogram analyses to detect, distinguish, and characterize leaf surfaces, as well as give scale lengths. Both techniques are tools for the biologist to study variations of the leaf surface when different patterns are present. The use of RIMAPS and variogram opens a wide spectrum of possibilities by providing a systematic, quantitative description of the leaf surface topography.

  18. Quantitative study of Xanthosoma violaceum leaf surfaces using RIMAPS and variogram techniques.

    PubMed

    Favret, Eduardo A; Fuentes, Néstor O; Molina, Ana M

    2006-08-01

    Two new imaging techniques (rotated image with maximum averaged power spectrum (RIMAPS) and variogram) are presented for the study and description of leaf surfaces. Xanthosoma violaceum was analyzed to illustrate the characteristics of both techniques. Both techniques produce a quantitative description of leaf surface topography. RIMAPS combines digitized images rotation with Fourier transform, and it is used to detect patterns orientation and characteristics of surface topography. Variogram relates the mathematical variance of a surface with the area of the sample window observed. It gives the typical scale lengths of the surface patterns. RIMAPS detects the morphological variations of the surface topography pattern between fresh and dried (herbarium) samples of the leaf. The variogram method finds the characteristic dimensions of the leaf microstructure, i.e., cell length, papillae diameter, etc., showing that there are not significant differences between dry and fresh samples. The results obtained show the robustness of RIMAPS and variogram analyses to detect, distinguish, and characterize leaf surfaces, as well as give scale lengths. Both techniques are tools for the biologist to study variations of the leaf surface when different patterns are present. The use of RIMAPS and variogram opens a wide spectrum of possibilities by providing a systematic, quantitative description of the leaf surface topography. PMID:16788991

  19. Leaf Area Influence on Surface Layer in a Deciduous Forest. Part 2; Detecting Leaf Area and Surface Resistance During Transition Seasons

    NASA Technical Reports Server (NTRS)

    Sakai, Ricardo K.; Fitzjarrald, David R.; Moore, Kathleen E.; Sicker, John W.; Munger, Willian J.; Goulden, Michael L.; Wofsy, Steven C.

    1996-01-01

    Temperate deciduous forest exhibit dramatic seasonal changes in surface exchange properties following on the seasonal changes in leaf area index. The canopy resistance to water vapor transport r(sub c) decreased abruptly at leaf emergence in each year but then also continued to decrease slowly during the remaining growing season due to slowly increasing LAI. Canopy resistance and PAR-albedo (albedo from photosynthetically active radiation) began to increase about one month before leaf fall with the diminishment of CO2 gradient above the canopy as well. At this time evaporation begun to be controlled as if the canopy were leafless.

  20. The physico-chemical basis of leaf wettability in wheat.

    PubMed

    Netting, A G; von Wettstein-Knowles, P

    1973-12-01

    Wild type wheat (Triticum aestivum L.) and three mutant lines that have reduced glaucousness on the flag leaf sheath have been examined for variations in glaucousness, contact angles, wax chemistry and wax morphology. On the sheath and culm, organs that are glaucous in the wild type, increasing glaucousness is correlated with increasing contact angles, an increasing proportion of β-diketones plus hydroxy-β-diketones in the was and an increasing proportion of wax tubes. Organs that were non-glaucous in all four lines, namely both surfaces of the vegetative leaves and the adaxial surface of the flag leaf, had high contact angles, a dense covering of wax plates and waxes rich in primary alcohols but devoid of β-diketones and hydroxy-β-diketones. The abaxial surface of the flag leaf was the most complex of the organ surfaces studied. In the wild type the glaucousness of the sheath continued onto this surface for 1-2 cm and this was correlated with the other characters studied as it was on the sheath. In the mutants, however, the tubes were absent. Flat ribbons of varying widths, a new wax structure in wheat, as well as various types of plates were found instead. These structures continued to the flag leaf tip and were also present on the abaxial surface of the wild type flag leaf. Changes in contact angle at the tip could not be correlated with the other measured parameters.

  1. Flat leaf formation realized by cell-division control and mutual recessive gene regulation.

    PubMed

    Hayakawa, Yoshinori; Tachikawa, Masashi; Mochizuki, Atsushi

    2016-09-01

    Most of the land plants generally have dorsoventrally flat leaves, maximizing the surface area of both upper (adaxial) side and lower (abaxial) side. The former is specialized for light capturing for photosynthesis and the latter is specialized for gas exchange. From findings of molecular genetics, it has been considered that the coupled dynamics between tissue morphogenesis and gene regulation for cell identity is responsible for making flat leaves. The hypothesis claims that a flat leaf is generated under two assumptions, (i) two mutually recessive groups of genes specify adaxial and abaxial sides of a leaf, (ii) cell divisions are induced at the limited region in the leaf margin where both of two groups are expressed. We examined the plausibility and possibility of this hypothesis from the dynamical point of view. We studied a mathematical model where two processes are coupled, tissue morphogenesis induced by cell division and deformation, and dynamics of gene regulations. From the analysis of the model we found that the classically believed hypothesis is not sufficient to generate flat leaves with high probability. We examined several different modifications and revision of the model. Then we found that a simple additional rule of polarized cell division facilitates flat leaf formation. The result of our analysis gives prediction of possible mechanism, which can be easily verified in experiments. PMID:27287339

  2. Changes in growth, leaf anatomy and pigment concentrations in pea under modulated UV-B field treatments

    SciTech Connect

    Day, T.A.; Howells, B.W.; Ruhland, C.T.

    1995-06-01

    In growth-chamber and greenhouse studies, garden pea is typically quite sensitive to enhanced UV-B radiation (280-320 nm). We assessed whether growth of pea was reduced under more ecologically relevant UV-B enhancements by employing modulated field lampbanks simulating 0, 16 or 24% ozone depletion. We also examined if these UV-B treatments altered leaf anatomy and concentrations of chlorophyll and UV-B-absorbing compounds, and whether this was dependent on leaf age. We used Pisum sativum mutant Argenteum which has an easily detachable epidermis that allowed us to compare concentrations in epidermal and mesophyll tissues. There were no significant UV-B effects on whole-plant growth. Of the 15 leaf-level parameters we examined, UV-B had a strong effect on only two parameters: the ratio of UV-B-absorbing compounds to chlorophyll (which increased with UV-B dose), and stomatal density of the adaxial surface (which decreased with UV-B dose). Chlorophyll concentrations tended to decrease, while the proportion of UV-B-absorbing compounds in the adaxial epidermis tended to increase with UV-B dose (p = 0.11 for both). In contrast to UV-B effects, we found strong leaf-age effects on nearly all parameters except the ratio of UV-B-absorbing compounds to chlorophyll, which remained relatively constant with leaf age.

  3. A System to investigate 3-D droplet impact on leaf surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A system was developed to investigate droplet dynamic impact and retention on leaf surfaces. The system consisted of a uniform droplet generator, two high speed digital video cameras, a constant speed track, a leaf holder, and a cool light source. The droplet generator produced mono-sized droplets r...

  4. Leaf epidermal appendages of desert plant: an ecological perspective

    NASA Astrophysics Data System (ADS)

    Liu, Yubing; Li, Xinrong; Li, Mengmeng

    2014-05-01

    Desert plant often have few, tiny or no leaves, which reduces transpiration. The epidermis of their leaves is often ornamented outgrowths called trichomes or hairs and a thick waxy cuticle. Hairs on the leaf surface trap humidity in dry climates and waxy leaf surfaces reduce water loss. Our present study is to investigate the characteristics of trichomes and waxy cuticle in leaf surface of desert plant, which in the long term acclimation in semi-humid, semi-arid and arid ecosystems of Northern China, from east (Zhangwu county, Liaoning province) to west (Korla city, Xinjiang Uygur Autonomous Region), passing through several provinces including the Inner Mongolia Autonomous Region, Shanxi province, the Ningxia Hui Autonomous Region and Gansu province. 68 shrubs and 7 trees were selected in the natural habitats which were artificial sand fixing vegetation and the adjacent natural vegetation in sandy areas. The leaf epidermis was observed by scanning electron microscopy (SEM) and the cuticle thickness was calculated in the leaf cross-section by transmission electron microscopy (TEM). The results indicated that the epidermis of selected materials was divided into five categories: (1) Trichomes with different forms covered completely on the adaxial and abaxial surfaces of leaf, and any other epidermal appendages could not been observed. (2) Epicuticular wax crystals with different forms almost completely covered in the epistomatal chambers as well as on the surrounding epidermis, and there were no other appendages on the leaf surface. (3) A lot of warty hairs arranged neatly on the surface and the stomatal index was too low. (4) Several or even dozens of papillary epidermal cells covered with waxy crystals enclosed a sunken stomata chamber, therefore the stomatal density is very low. (5) Like ordinary terrestrial plants, epidermal cells and cell outline are clear, with epidermal hairs or not, and the stomata and waxy crystals are visible. TEM showed that desert plants

  5. Effects of CO/sub 2/ enrichment on internal leaf surface area in soybeans

    SciTech Connect

    Leadley, P.W.; Reynolds, J.A.; Thomas, J.F.; Reynolds, J.F.

    1987-06-01

    Internal cell surface areas were measured on fully expanded leaves of soybean seedlings that had been continuously exposed to 348 or 645 ppm CO/sub 2/ environments. Plants grown in the high CO/sub 2/ treatment had thicker leaves but less palisade cell surface area per unit of leaf area. Surface area of the mesophyll per unit leaf area was unaffected by CO/sub 2/. The potential ramifications of these CO/sub 2/-induced changes in leaf anatomy on photosynthesis and water-use efficiency are explored.

  6. Protein adsorption and cell adhesion on polyurethane/Pluronic surface with lotus leaf-like topography.

    PubMed

    Zheng, Jun; Song, Wei; Huang, He; Chen, Hong

    2010-06-01

    Lotus leaf-like polyurethane/Pluronic F-127 surface was fabricated via replica molding using a natural lotus leaf as the template. Water contact angle measurements showed that both the hydrophobicity of the unmodified polyurethane (PU) surface and the hydrophilicity of the PU/Pluronic surface were enhanced by the construction of lotus leaf-like topography. Protein adsorption on the PU/Pluronic surface without topographic modification was significantly lower than on the PU surface. Adsorption was further reduced when lotus leaf-like topography was constructed on the PU/Pluronic surface. Cell culture experiments with L929 cells showed that adhesion on the PU/Pluronic surface with lotus leaf-like topography was low and adherent cells were spherical and of low viability. The PU/Pluronic surface with lotus leaf-like topography thus appears to be resistant to nonspecific protein adsorption and to cell adhesion, and these effects derive from the both chemical composition and topography. The results suggest a new strategy based on surface topography for the design of antifouling materials.

  7. Allometric analysis of the induced flavonols on the leaf surface of wild tobacco (Nicotiana attenuata).

    PubMed

    Roda, Amy L; Oldham, Neil J; Svatos, Ales; Baldwin, Ian T

    2003-02-01

    Trichomes excrete secondary metabolites that may alter the chemical composition of the leaf surface, reducing damage caused by herbivores, pathogens and abiotic stresses. We examined the surface exudates produced by Nicotiana attenuata Torr. Ex Wats., a plant known to contain and secrete a number of secondary metabolites that are toxic or a deterrent to herbivorous insects. Extractions specific to the leaf surface, the trichomes, and the laminar components demonstrated the localization of particular compounds. Diterpene glycosides occurred exclusively in leaf mesophyll, whereas nicotine was found in both the trichomes and mesophyll. Neither rutin nor nicotine was found on the leaf surface. Quercetin and 7 methylated derivatives were found in the glandular trichomes and appeared to be excreted onto the leaf surface. We examined the elicitation of these flavonols on the leaf surface with a surface-area allometric analysis, which measures changes in metabolites independent of the effects of leaf expansion. The flavonols responded differently to wounding, methyl jasmonate (MeJA), herbivore attack and UV-C radiation, and the response patterns corresponded to their compound-specific allometries. Finding greater amounts of quercetin on younger leaves and reduced amounts after herbivore feeding and MeJA treatment, we hypothesized that quercetin may function as an attractant, helping the insects locate a preferred feeding site. Consistent with this hypothesis, mirids (Tupiocoris notatus) were found more often on mature leaves sprayed with quercetin at a concentration typical of young leaves than on unsupplemented mature leaves. The composition of metabolites on the leaf surface of N. attenuata changes throughout leaf development and in response to herbivore attack or environmental stress, and these changes are mediated in part by responses of the glandular trichomes.

  8. Superhydrophobic surfaces developed by mimicking hierarchical surface morphology of lotus leaf.

    PubMed

    Latthe, Sanjay S; Terashima, Chiaki; Nakata, Kazuya; Fujishima, Akira

    2014-01-01

    The lotus plant is recognized as a 'King plant' among all the natural water repellent plants due to its excellent non-wettability. The superhydrophobic surfaces exhibiting the famous 'Lotus Effect', along with extremely high water contact angle (>150°) and low sliding angle (<10°), have been broadly investigated and extensively applied on variety of substrates for potential self-cleaning and anti-corrosive applications. Since 1997, especially after the exploration of the surface micro/nanostructure and chemical composition of the lotus leaves by the two German botanists Barthlott and Neinhuis, many kinds of superhydrophobic surfaces mimicking the lotus leaf-like structure have been widely reported in the literature. This review article briefly describes the different wetting properties of the natural superhydrophobic lotus leaves and also provides a comprehensive state-of-the-art discussion on the extensive research carried out in the field of artificial superhydrophobic surfaces which are developed by mimicking the lotus leaf-like dual scale micro/nanostructure. This review article could be beneficial for both novice researchers in this area as well as the scientists who are currently working on non-wettable, superhydrophobic surfaces. PMID:24714190

  9. Interspecific variation in SO/sub 2/ flux: leaf surface versus internal flux, and components of leaf conductance. [Pisum sativum L. , Lycopersicon esculentum Mill. Flacca, Geranium carolinianum L. , Diplacus aurantiacus (Curtis) Jeps

    SciTech Connect

    Olszyk, D.M.; Tingey, D.T.

    1985-12-01

    The objective of this study was to clarify the relationships among stomatal, residual, and epidermal conductances in determining the flux of SO/sub 2/ air pollution to leaves. Variations in leaf SO/sub 2/ and H/sub 2/O vapor fluxes were determined using four plant species: Pisum sativum L. (garden pea), Lycopersicon esculentum Mill. flacca (mutant of tomato), Geranium carolinianum L. (wild geranium), and Diplacus aurantiacus (Curtis) Jeps. (a native California shrub). Fluxes were measured using the mass-balance approach during exposure to 4.56 micromoles per cubic meter (0.11 microliters per liter) SO/sub 2/ for 2 hours in a controlled environmental chamber. Flux through adaxial and abaxial leaf surfaces with closed stomata ranged from 1.9 to 9.4 nanomoles per square meter per second for SO/sub 2/, and 0.3 to 1.3 millimoles per square meter per second for H/sub 2/O vapor. Flux of SO/sub 2/ into leaves through stomata ranged from approx.0 to 8.5 (dark) and 3.8 to 16.0 (light) millimoles per square meter per second. Flux of H/sub 2/O vapor from leaves through stomata ranged from approx.0 to 0.6 (dark) to 0.4 to 0.9 (light) millimole per square meter per second. Lycopersicon had internal flux rates for both SO/sub 2/ and H/sub 2/O vapor over twice as high as for the other species. Stomatal conductance based on H/sub 2/O vapor flux averaged from 0.07 to 0.13 mole per square meter per second among the four species. Internal conductance of SO/sub 2/ as calculated from SO/sub 2/ flux was from 0.04 mole per square meter per second lower to 0.06 mole per square meter per second higher than stomatal conductance. For Pisum, Geranium, and Diplacus stomatal conductance was the same or slightly higher than internal conductance, indicating that, in general, SO/sub 2/ flux could be predicted from stomatal conductance for H/sub 2/O vapor.

  10. Morphological and anatomical investigations into the mechanism of leaf pair unrolling in Uraria picta (Jacq.) Desv. Ex DC. (Papilionaceae), a medicinal plant in Nigeria.

    PubMed

    Oyesiku, Olubukunola O; Okusanya, Olubukanla T; Olowokudejo, James D

    2013-01-01

    Uraria picta leaf-pair unrolling inside out is a remarkable feat. A leaf-pair was investigated to understand the mechanism of spontaneous reverse inside out act of the plant. The upper (adaxial) and lower (abaxial) surfaces of the leaf-pair were examined using scanning and light microscopy. The scan showed diversity of hairs varying in shape from straight, pointed, curve, and club to hook. There were deposits of wax on both sides of the leaf-pair. The light microscope showed hairs are restricted to the midrib on the adaxial surface of the leaflets. Hooked hairs dominated the entire abaxial surface of the leaflets. The transverse section of the midrib section showed abundance of structural and mechanical tissues, collenchyma and sclerenchyma tissues. Both morphological and anatomical attributes were used to explain the mechanism and how the plant got its Yoruba vernacular name 'Alupayida' as well as its purported use in changing the sex of the unborn child and in breaking up love affairs.

  11. Bacterial leaf spot of radicchio (Cichorium intybus) is caused by Xanthomonas hortorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beginning in 2002 a leaf spot disease of radicchio (Cichorium intybus) was observed in Monterey County, California. Lesions were maroon to dark brown in color; in some cases the margins of brown lesions became dark maroon with aging. Each leaf spot was observable from both adaxial and abaxial leaf s...

  12. Leaf micromorphology of some Phyllanthus L. species (Phyllanthaceae)

    SciTech Connect

    Solihani, N. S. Noraini, T.; Azahana, A.; Nordahlia, A. S.

    2015-09-25

    Comparative leaf micromorphological study was conducted of five chosen Phyllanthus L. (Phyllanthaceae) species, namely P. acidus L., P. elegans Wall. ex Müll. Arg., P. emblica L., P. urinaria L. and P. pulcher Wall. ex Müll. Arg. The objective of this study is to identify the leaf micromorphological characteristics that can be used in species identification. The procedures involve examination under scanning electron microscope. Findings of this study have demonstrated variations in the leaf micromorphological characteristics such as in the types of waxes present on adaxial and abaxial epidermis surfaces, in the stomata and types of trichome. Common character present in all species studied are the presence of a thin film layer and buttress-like waxes on epidermal leaf surfaces. Diagnostics characters found in this study are the presence of papilla in P. elegens, amphistomatic stomata in P. urinaria and flaky waxes in P. pulcher. The result of this study has shown that leaf micromorphological characters have some taxonomic significance and can be used in identification of species in the genus Phyllanthus.

  13. Leaf micromorphology of some Phyllanthus L. species (Phyllanthaceae)

    NASA Astrophysics Data System (ADS)

    Solihani, N. S.; Noraini, T.; Azahana, A.; Nordahlia, A. S.

    2015-09-01

    Comparative leaf micromorphological study was conducted of five chosen Phyllanthus L. (Phyllanthaceae) species, namely P. acidus L., P. elegans Wall. ex Müll. Arg., P. emblica L., P. urinaria L. and P. pulcher Wall. ex Müll. Arg. The objective of this study is to identify the leaf micromorphological characteristics that can be used in species identification. The procedures involve examination under scanning electron microscope. Findings of this study have demonstrated variations in the leaf micromorphological characteristics such as in the types of waxes present on adaxial and abaxial epidermis surfaces, in the stomata and types of trichome. Common character present in all species studied are the presence of a thin film layer and buttress-like waxes on epidermal leaf surfaces. Diagnostics characters found in this study are the presence of papilla in P. elegens, amphistomatic stomata in P. urinaria and flaky waxes in P. pulcher. The result of this study has shown that leaf micromorphological characters have some taxonomic significance and can be used in identification of species in the genus Phyllanthus.

  14. Transport of phenolic compounds from leaf surface of creosotebush and tarbush to soil surface by precipitation.

    PubMed

    Hyder, P W; Fredrickson, E L; Estell, R E; Lucero, M E

    2002-12-01

    During the last 100 years, many desert grasslands have been replaced by shrublands. One possible mechanism by which shrubs outcompete grasses is through the release of compounds that interfere with neighboring plants. Our objective was to examine the movement of secondary compounds from the leaf surface of creosotebush and tarbush to surrounding soil surfaces via precipitation. Units consisting of a funnel and bottle were used to collect stemflow, throughfall, and interspace precipitation samples from 20 creosotebush (two morphotypes) and 10 tarbush plants during three summer rainfall events in 1998. Precipitation samples were analyzed for total phenolics (both species) and nordihydroguaiaretic acid (creosotebush only). Phenolics were detected in throughfall and stemflow of both species with stemflow containing greater concentrations than throughfall (0.088 and 0.086 mg/ml for stemflow and 0.022 and 0.014 mg/ml for throughfall in creosotebush morphotypes U and V, respectively: 0.044 and 0.006 mg/ml for tarbush stemflow and throughfall, respectively). Nordihydroguaiaretic acid was not found in any precipitation collections. The results show that phenolic compounds produced by creosotebush and tarbush can be transported to the soil surface by precipitation, but whether concentrations are ecologically significant is uncertain. Nordihydroguaiaretic acid was not present in the runoff from creosotebush.

  15. Morphology of foliar trichomes of the Chinese cork oak Quercus variabilis by electron microscopy and three-dimensional surface profiling.

    PubMed

    Kim, Ki Woo; Cho, Do-Hyun; Kim, Pan-Gi

    2011-06-01

    Morphology of foliar trichomes was analyzed in Quercus variabilis by electron microscopy and three-dimensional surface profiling. Leaves from suppressed or dominant sprouts of the oak species were collected after a forest fire to unravel the effects of the disturbance factor on sprouting of the oak species. Scanning electron microscopy revealed two types of trichomes depending on the leaf surface. The trichomes on the adaxial surface were branched and constricted, and possessed a single row of thin-walled cells with a collapsed morphology (glandular branched uniseriate trichomes). Meanwhile, the trichomes on the abaxial surface were star-shaped, unfused with each other, and had 6 to 10 rays (nonglandular simple stellate trichomes). An apparent proliferation of trichomes was evident on the adaxial surface of the dominant sprouts. Uniseriate trichomes could be discernable as an elevation from the surface by white light scanning interferometry. By transmission electron microscopy, thin and convoluted cell wall, degenerated cytoplasm, and a single row of cells were characteristic of the trichomes on the adaxial surface. The thick cell walls of the mature trichomes on the abaxial surface represented the nonglandular nature. This is the first report on the morphological and ultrastructural characterization of foliar trichomes of the oak species.

  16. Sclerophylly and leaf anatomical traits of five field-grown olive cultivars growing under drought conditions.

    PubMed

    Bacelar, Eunice A; Correia, Carlos M; Moutinho-Pereira, José M; Gonçalves, Berta C; Lopes, João I; Torres-Pereira, José M G

    2004-02-01

    Leaf-level morphological and structural adaptations to reduce water loss were examined in five olive (Olea europaea L.) tree cultivars (Arbequina, Blanqueta, Cobrançosa, Manzanilla and Negrinha) growing under field conditions with low water availability. Leaf measurements included leaf tissue thickness, stomatal density, leaf area, leaf mass per unit area, density of leaf tissue, relative water content, succulence, water saturation deficit, water content at saturation and cuticular transpiration rate. We found considerable genotypic differences among the cultivars. Negrinha, Manzanilla and Cobrançosa had more morphological and structural leaf adaptations to protect against water loss than the other cultivars. Manzanilla and Negrinha enhanced their sclerophylly by building parenchyma tissues and increasing protective structures like the upper cuticle and both the upper and lower epidermis. Cobrançosa exhibited good protection against water loss through high density of foliar tissue and by thick cuticle and trichome layers. Compared with the Negrinha, Manzanilla and Cobrançosa cultivars, Arbequina leaves had a thinner trichome layer, implying that the leaves were less protected against water loss; however, the development of smaller leaves may reduce water loss at the whole-plant level. Among cultivars, Blanqueta had the largest leaves and some anatomical traits that may lead to high water loss, especially from the adaxial surface. The mechanisms employed by the cultivars to cope with summer stress are discussed at the morpho-structural level. PMID:14676039

  17. In Situ Investigation the Photolysis of the PAHs Adsorbed on Mangrove Leaf Surfaces by Synchronous Solid Surface Fluorimetry

    PubMed Central

    Wang, Ping; Wu, Tun-Hua; Zhang, Yong

    2014-01-01

    An established synchronous solid surface fluorimetry (S-SSF) was utilized for in situ study the photolysis processes of anthracene (An) and pyrene (Py) adsorbed on the leaf surfaces of Kandelia obovata seedlings (Ko) and Aegiceras corniculata (L.) Blanco seedlings (Ac). Experimental results demonstrated that the photolysis of An and Py adsorbed on the leaf surfaces of two mangrove species under the laboratory conditions, followed first-order kinetics with their photolysis rates in the order of Ac>Ko. In addition, with the same amount of substances, the photolysis rate of An adsorbed on the same mangrove leaf surfaces was much faster than the adsorbed Py. In order to investigate further, the photolysis processes of An and Py in water were also studied for comparison. And the photolysis of An and Py in water also followed first-order kinetics. Moreover, for the same initial amount, the photolysis rate of the PAH in water was faster than that adsorbed on the leaf surfaces of two mangrove species. Therefore, photochemical behaviors of PAHs were dependent not only on their molecular structures but also the physical-chemical properties of the substrates on which they are adsorbed. PMID:24404158

  18. Silica nanoparticles aid in structural leaf coloration in the Malaysian tropical rainforest understorey herb Mapania caudata

    PubMed Central

    Strout, Greg; Russell, Scott D.; Pulsifer, Drew P.; Erten, Sema; Lakhtakia, Akhlesh; Lee, David W.

    2013-01-01

    Background and Aims Blue-green iridescence in the tropical rainforest understorey sedge Mapania caudata creates structural coloration in its leaves through a novel photonic mechanism. Known structures in plants producing iridescent blues consist of altered cellulose layering within cell walls and in special bodies, and thylakoid membranes in specialized plastids. This study was undertaken in order to determine the origin of leaf iridescence in this plant with particular attention to nano-scale components contributing to this coloration. Methods Adaxial walls of leaf epidermal cells were characterized using high-pressure-frozen freeze-substituted specimens, which retain their native dimensions during observations using transmission and scanning microscopy, accompanied by energy-dispersive X-ray spectroscopy to identify the role of biogenic silica in wall-based iridescence. Biogenic silica was experimentally removed using aqueous Na2CO3 and optical properties were compared using spectral reflectance. Key Results and Conclusions Blue iridescence is produced in the adaxial epidermal cell wall, which contains helicoid lamellae. The blue iridescence from cell surfaces is left-circularly polarized. The position of the silica granules is entrained by the helicoid microfibrillar layers, and granules accumulate at a uniform position within the helicoids, contributing to the structure that produces the blue iridescence, as part of the unit cell responsible for 2 ° Bragg scatter. Removal of silica from the walls eliminated the blue colour. Addition of silica nanoparticles on existing cellulosic lamellae is a novel mechanism for adding structural colour in organisms. PMID:23960046

  19. Phytotoxicity of Constituents of Glandular Trichomes and the Leaf Surface of Camphorweed, Heterotheca subaxillaris

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Camphorweed, Heterotheca subaxillaris (Lam.) Britt. & Rusby has a camphor-like odor, and its leaf surfaces contain glandular trichomes of the type shown to contain high levels of isoprenoids in other species. Phytotoxic calamenene-type sesquiterpenes (1-4, 8-10), borneol (11) and methylated flavone...

  20. Photosynthetic responses to leaf surface wetness in tropical plant species of Costa Rica with varying leaf traits

    NASA Astrophysics Data System (ADS)

    Aparecido, L. M. T.; Moore, G. W.; Miller, G. R.; Cahill, A. T.

    2015-12-01

    Wet tropical forests are some of the environments with the greatest annual precipitation, but are also considered as the world's major carbon sink; however, literature postulates that phothsynthesis rates are inhibited while leaves are wet. Yet measurements of photosynthesis during wet conditions are challenging to obtain due to equipment limitations and the extreme complexity of canopy-atmosphere interactions in tropical environments. The objective of this study was to evaluate tropical species reactions to simulated leaf wetness and test the hypothesis that leaf wetness reduces rates of photosynthesis. In a central Costa Rica site with an average 4200 mm annual rainfall, we selected six tropical species with distinct leaf traits in which five sun-exposed leaf replicates from each species were subjected to gas exchange measurements using a LI-6400 IRGA (LICOR Inc., Lincoln, NE) under dry and wet/misted leaf conditions. Relationships between photosynthesis (As) and stomatal conductance (gs) with leaf to air temperature difference (DT), VPD, and relative humidity were evaluated using linear regression analysis. We found that the responses varied greatly among species, but all plants maintained a baseline of activity under wet leaf conditions, suggesting that abaxial leaf As was a significant percentage of total leaf As. Stachytarpheta jamaicens had an 18.7% reduction in As, while others, like Zamia skinneri, had a 7% increase in As. Tibouchina heteromalla showed a rapid stomatal recovery of 2 mins, while Carapa guianensis was slower with 7 mins. This variability between species suggests that leaf traits, such as presence or absence of trichomes, water repellency, vein distribution and size and leaf angle variation, may be critical for optimizing photosynthesis under wet conditions. Relative humidity and leaf temperature were the strongest secondary influences on As and gs under wet leaf conditions. While tropical vegetation-atmosphere interactions are complex, such

  1. Superhydrophobic surfaces: From the lotus leaf to the submarine

    NASA Astrophysics Data System (ADS)

    Samaha, Mohamed A.; Tafreshi, Hooman Vahedi; Gad-el-Hak, Mohamed

    2012-01-01

    In this review we discuss the current state of the art in evaluating the fabrication and performance of biomimetic superhydrophobic materials and their applications in engineering sciences. Superhydrophobicity, often referred to as the lotus effect, could be utilized to design surfaces with minimal skin-friction drag for applications such as self-cleaning and energy conservation. We start by discussing the concept of the lotus effect and continue to present a review of the recent advances in manufacturing superhydrophobic surfaces with ordered and disordered microstructures. We then present a discussion on the resistance of the air-water interface to elevated pressures—the phenomenon that enables a water strider to walk on water. We conclude the article by presenting a brief overview of the latest advancements in studying the longevity of submerged superhydrophobic surfaces for underwater applications.

  2. Physicochemical characteristics of ambient particles settling upon leaf surfaces of urban plants in Beijing.

    PubMed

    Wang, Lei; Liu, Lian-you; Gao, Shang-yu; Hasi, Eerdun; Wang, Zhi

    2006-01-01

    Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chinensis, Sophora japonica, A ilanthus altissima, Syringa oblata and Prunus persica had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicus and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM, (particulate matter less than 10 microm in aerodynamic diameter; 98.4%) and PM25 (particulate matter less than 2.5 microm in aerodynamic diameter; 64.2%) which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg(CO3)2, NaCI and 2CaSO4 x H20, SiO2. CaCO3 and CaMg(CO3)2 mainly came from resuspension of road dust. 2CaSO4 x H20 was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt. PMID:17278748

  3. Spatial Patterns of Tungsten and Cobalt on Leaf Surfaces of Trees in Fallon, Nevada

    NASA Astrophysics Data System (ADS)

    Sheppard, P. R.; Hallman, C. L.; Ridenour, G.; Witten, M. L.

    2008-12-01

    Spatial patterns of airborne tungsten and cobalt are described from leaf surface chemistry of trees in Fallon, Nevada, where a cluster of childhood leukemia has been ongoing since 1997. In earlier research, airborne tungsten and cobalt have been shown to be elevated in total suspended particulates, surface dust, and lichens of Fallon. To update spatial patterns of airborne tungsten and cobalt in Fallon, leaves were collected in October 2007 from trees growing throughout Fallon. Collected leaves were measured for metals accumulated onto their surfaces. On Fallon leaf surfaces, tungsten and cobalt show maxima of 17 ppm and 6 ppm, respectively, near the center of town, north of Highway 50 and west of Highway 95. Background levels of tungsten and cobalt on leaves are ~0.50 ppm for both metals. These two peaks overlap spatially, and given the dense and widespread pattern of collection, the source area of these two airborne metals can be pinpointed to the vicinity of a hard-metal industry located north of Highway 50 and west of Highway 95. As an update of environmental research in Fallon, this leaf surface chemistry study adds to years of studies showing elevated airborne tungsten and cobalt in Fallon. Given the cluster of childhood leukemia in Fallon, it stands to reason that additional biomedical research is in order to test directly the leukogenicity of combined airborne tungsten and cobalt particulates.

  4. Microbial rhodopsins on leaf surfaces of terrestrial plants.

    PubMed

    Atamna-Ismaeel, Nof; Finkel, Omri M; Glaser, Fabian; Sharon, Itai; Schneider, Ron; Post, Anton F; Spudich, John L; von Mering, Christian; Vorholt, Julia A; Iluz, David; Béjà, Oded; Belkin, Shimshon

    2012-01-01

    The above-ground surfaces of terrestrial plants, the phyllosphere, comprise the main interface between the terrestrial biosphere and solar radiation. It is estimated to host up to 10(26) microbial cells that may intercept part of the photon flux impinging on the leaves. Based on 454-pyrosequencing-generated metagenome data, we report on the existence of diverse microbial rhodopsins in five distinct phyllospheres from tamarisk (Tamarix nilotica), soybean (Glycine max), Arabidopsis (Arabidopsis thaliana), clover (Trifolium repens) and rice (Oryza sativa). Our findings, for the first time describing microbial rhodopsins from non-aquatic habitats, point towards the potential coexistence of microbial rhodopsin-based phototrophy and plant chlorophyll-based photosynthesis, with the different pigments absorbing non-overlapping fractions of the light spectrum.

  5. Fractal Surfaces of Molecular Crystals Mimicking Lotus Leaf with Phototunable Double Roughness Structures.

    PubMed

    Nishimura, Ryo; Hyodo, Kengo; Sawaguchi, Haruna; Yamamoto, Yoshiaki; Nonomura, Yoshimune; Mayama, Hiroyuki; Yokojima, Satoshi; Nakamura, Shinichiro; Uchida, Kingo

    2016-08-17

    Double roughness structure, the origin of the lotus effect of natural lotus leaf, was successfully reproduced on a diarylethene microcrystalline surface. Static superwater-repellency and dynamic water-drop-bouncing were observed on the surface, in the manner of natural lotus leaves. Double roughness structure was essential for water-drop-bouncing. This ability was not observed on a single roughness microcrystalline surface showing the lotus effect of the same diarylethene derivative. The double roughness structure was reversibly controlled by alternating irradiation with UV and visible light. PMID:27455376

  6. Responses of herbaceous plants to urban air pollution: effects on growth, phenology and leaf surface characteristics.

    PubMed

    Honour, Sarah L; Bell, J Nigel B; Ashenden, Trevor W; Cape, J Neil; Power, Sally A

    2009-04-01

    Vehicle exhaust emissions are a dominant feature of urban environments and are widely believed to have detrimental effects on plants. The effects of diesel exhaust emissions on 12 herbaceous species were studied with respect to growth, flower development, leaf senescence and leaf surface wax characteristics. A diesel generator was used to produce concentrations of nitrogen oxides (NO(x)) representative of urban conditions, in solardome chambers. Annual mean NO(x) concentrations ranged from 77 nl l(-l) to 98 nl l(-1), with NO:NO(2) ratios of 1.4-2.2, providing a good experimental simulation of polluted roadside environments. Pollutant exposure resulted in species-specific changes in growth and phenology, with a consistent trend for accelerated senescence and delayed flowering. Leaf surface characteristics were also affected; contact angle measurements indicated changes in surface wax structure following pollutant exposure. The study demonstrated clearly the potential for realistic levels of vehicle exhaust pollution to have direct adverse effects on urban vegetation.

  7. The complex of ASYMMETRIC LEAVES (AS) proteins plays a central role in antagonistic interactions of genes for leaf polarity specification in Arabidopsis.

    PubMed

    Machida, Chiyoko; Nakagawa, Ayami; Kojima, Shoko; Takahashi, Hiro; Machida, Yasunori

    2015-01-01

    Leaf primordia are born around meristem-containing stem cells at shoot apices, grow along three axes (proximal-distal, adaxial-abaxial, medial-lateral), and develop into flat symmetric leaves with adaxial-abaxial polarity. Axis development and polarity specification of Arabidopsis leaves require a network of genes for transcription factor-like proteins and small RNAs. Here, we summarize present understandings of adaxial-specific genes, ASYMMETRIC LEAVES1 (AS1) and AS2. Their complex (AS1-AS2) functions in the regulation of the proximal-distal leaf length by directly repressing class 1 KNOX homeobox genes (BP, KNAT2) that are expressed in the meristem periphery below leaf primordia. Adaxial-abaxial polarity specification involves antagonistic interaction of adaxial and abaxial genes including AS1 and AS2 for the development of two respective domains. AS1-AS2 directly represses the abaxial gene ETTIN/AUXIN RESPONSE FACTOR3 (ETT/ARF3) and indirectly represses ETT/ARF3 and ARF4 through tasiR-ARF. Modifier mutations have been identified that abolish adaxialization and enhance the defect in the proximal-distal patterning in as1 and as2. AS1-AS2 and its modifiers synergistically repress both ARFs and class 1 KNOXs. Repression of ARFs is critical for establishing adaxial-abaxial polarity. On the other hand, abaxial factors KANADI1 (KAN1) and KAN2 directly repress AS2 expression. These data delineate a molecular framework for antagonistic gene interactions among adaxial factors, AS1, AS2, and their modifiers, and the abaxial factors ARFs as key regulators in the establishment of adaxial-abaxial polarity. Possible AS1-AS2 epigenetic repression and activities downstream of ARFs are discussed.

  8. Spatial scales of interactions among bacteria and between bacteria and the leaf surface.

    PubMed

    Esser, Daniel S; Leveau, Johan H J; Meyer, Katrin M; Wiegand, Kerstin

    2015-03-01

    Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5-20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions.

  9. Spatial scales of interactions among bacteria and between bacteria and the leaf surface

    PubMed Central

    Esser, Daniel S.; Leveau, Johan H.J.; Meyer, Katrin M.; Wiegand, Kerstin

    2014-01-01

    Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5–20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions. PMID:25764562

  10. The response of Trissolcus basalis to footprint contact kairomones from Nezara viridula females is mediated by leaf epicuticular waxes

    NASA Astrophysics Data System (ADS)

    Colazza, Stefano; Lo Bue, Mauro; Lo Giudice, Daniela; Peri, Ezio

    2009-08-01

    Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula’s cuticular hydrocarbons (CHC) and furthermore that the wasp’s ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane ( nC19). In this study, the effect of epicuticular waxes of leaves of broad bean, Vicia faba, on wasp responses to footprints of N. viridula females were investigated. Approximately 20% of T. basalis females displayed an arrestment posture when released on the adaxial leaf surfaces of broad bean plants with intact wax layer and without host chemical contamination; whereas ˜70% of wasps displayed the arrestment posture when intact leaves were contaminated by host female footprints. Adaxial leaf surfaces of broad bean plants dewaxed with an aqueous solution of gum arabic and afterwards contaminated by N. viridula females induced arrestment responses in about 10% of female wasps; the same percentage of arrestment (10%) was observed when the wasps were released on leaves contaminated by host females and subsequently dewaxed. The side of the polymer film that was appressed to the leaf surface, peeled from the contaminated leaves, induced an arrestment posture in about 95% of observed wasps. Scanning electron microscopy (SEM) revealed that the epicuticular waxes occurred as a film densely crystallized as irregularly shaped platelets with spherical granules randomly distributed. These findings demonstrated that epicuticular waxes of broad bean leaves can mediate the foraging behavior of T. basalis females by absorbing contact kairomones of the

  11. Fluid drag reduction and efficient self-cleaning with rice leaf and butterfly wing bioinspired surfaces

    NASA Astrophysics Data System (ADS)

    Bixler, Gregory D.; Bhushan, Bharat

    2013-08-01

    Researchers are continually inspired by living nature to solve complex challenges. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (anisotropic flow leading to low drag) and lotus leaf (superhydrophobic and self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we present an overview of rice leaf and butterfly wing fluid drag and self-cleaning studies. In addition, we examine two other promising aquatic surfaces in nature known for such properties, including fish scales and shark skin. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of wettability, viscosity, and velocity. Liquid repellent coatings are utilized to recreate or combine various effects. Discussion is provided along with conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for applications in the medical, marine, and industrial fields.

  12. Fluid drag reduction and efficient self-cleaning with rice leaf and butterfly wing bioinspired surfaces.

    PubMed

    Bixler, Gregory D; Bhushan, Bharat

    2013-09-01

    Researchers are continually inspired by living nature to solve complex challenges. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (anisotropic flow leading to low drag) and lotus leaf (superhydrophobic and self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we present an overview of rice leaf and butterfly wing fluid drag and self-cleaning studies. In addition, we examine two other promising aquatic surfaces in nature known for such properties, including fish scales and shark skin. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of wettability, viscosity, and velocity. Liquid repellent coatings are utilized to recreate or combine various effects. Discussion is provided along with conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for applications in the medical, marine, and industrial fields.

  13. Leaf surface chemicals fromNicotiana affecting germination ofPeronospora tabacina (adam) sporangia.

    PubMed

    Kennedy, B S; Nielsen, M T; Severson, R F; Sisson, V A; Stephenson, M K; Jackson, D M

    1992-09-01

    A bioassay was used to evaluate the effects of cuticular leaf components, isolated fromN. tabacum, N. glutinosa (accessions 24 and 24a), and 23other Nicotiana species, on germinationof P. tabacina (blue mold). The leaf surface compounds includedα- andβ-4,8,13,-duvatriene-l,3-diols (DVT-diols), (13-E)-labda-13-ene-8α-,15-diol (labdenediol), (12-Z)-labda-12,14-diene-8α-ol (cis-abienol), (13-R)-labda-8,14-diene-13-ol (manool), 2-hydroxymanool, a mixture of (13-R)-labda-14-ene-8α,13-diol (sclareol), and (13-S)-labda-14-ene-8α,13-diol (episclareol), and various glucose and/or sucrose ester isolates. The above in acetone were applied onto leaf disks of the blue moldsusceptibleN. tabacum cv. TI 1406, which was then inoculated with blue mold sporangia. Estimated IC50 values (inhibitory concentration) were 3.0μg/cm(2) forα-DVT-diol, 2.9μ/cm(2) forβ-DVT-diol, 0.4μg/cm(2) for labdenediol and 4.7μg/cm(2) for the sclareol mixture. Manool, 2-hydroxymanool, andcis-abienol at application rates up to 30μg/cm(2) had little or no effect on sporangium germination. Glucose and/or sucrose ester isolates from the cuticular leaf extracts of 23Nicotiana species and three different fractions fromN. bigelovii were also evaluated for antimicrobial activity at a concentration of 30μg/cm(2). Germination was inhibited by >20% when exposed to sugar esters isolated fromN. acuminata, N. benthamiana, N. attenuata, N. clevelandii, andN. miersii, and accessions 10 and 12 ofN. bigelovii. These results imply that a number of compounds may influence resistance to blue mold in tobacco. PMID:24254279

  14. The potential of biomonitoring of air quality using leaf characteristics of white willow (Salix alba L.).

    PubMed

    Wuytack, Tatiana; Verheyen, Kris; Wuyts, Karen; Kardel, Fatemeh; Adriaenssens, Sandy; Samson, Roeland

    2010-12-01

    In this study, we assess the potential of white willow (Salix alba L.) as bioindicator for monitoring of air quality. Therefore, shoot biomass, specific leaf area, stomatal density, stomatal pore surface, and stomatal resistance were assessed from leaves of stem cuttings. The stem cuttings were introduced in two regions in Belgium with a relatively high and a relatively low level of air pollution, i.e., Antwerp city and Zoersel, respectively. In each of these regions, nine sampling points were selected. At each sampling point, three stem cuttings of white willow were planted in potting soil. Shoot biomass and specific leaf area were not significantly different between Antwerp city and Zoersel. Microclimatic differences between the sampling points may have been more important to plant growth than differences in air quality. However, stomatal pore surface and stomatal resistance of white willow were significantly different between Zoersel and Antwerp city. Stomatal pore surface was 20% lower in Antwerp city due to a significant reduction in both stomatal length (-11%) and stomatal width (-14%). Stomatal resistance at the adaxial leaf surface was 17% higher in Antwerp city because of the reduction in stomatal pore surface. Based on these results, we conclude that stomatal characteristics of white willow are potentially useful indicators for air quality.

  15. Pore size regulates operating stomatal conductance, while stomatal densities drive the partitioning of conductance between leaf sides

    PubMed Central

    Fanourakis, Dimitrios; Giday, Habtamu; Milla, Rubén; Pieruschka, Roland; Kjaer, Katrine H.; Bolger, Marie; Vasilevski, Aleksandar; Nunes-Nesi, Adriano; Fiorani, Fabio; Ottosen, Carl-Otto

    2015-01-01

    Background and Aims Leaf gas exchange is influenced by stomatal size, density, distribution between the leaf adaxial and abaxial sides, as well as by pore dimensions. This study aims to quantify which of these traits mainly underlie genetic differences in operating stomatal conductance (gs) and addresses possible links between anatomical traits and regulation of pore width. Methods Stomatal responsiveness to desiccation, gs-related anatomical traits of each leaf side and estimated gs (based on these traits) were determined for 54 introgression lines (ILs) generated by introgressing segments of Solanum pennelli into the S. lycopersicum ‘M82’. A quantitative trait locus (QTL) analysis for stomatal traits was also performed. Key Results A wide genetic variation in stomatal responsiveness to desiccation was observed, a large part of which was explained by stomatal length. Operating gs ranged over a factor of five between ILs. The pore area per stomatal area varied 8-fold among ILs (2–16 %), and was the main determinant of differences in operating gs between ILs. Operating gs was primarily positioned on the abaxial surface (60–83 %), due to higher abaxial stomatal density and, secondarily, to larger abaxial pore area. An analysis revealed 64 QTLs for stomatal traits in the ILs, most of which were in the direction of S. pennellii. Conclusions The data indicate that operating and maximum gs of non-stressed leaves maintained under stable conditions deviate considerably (by 45–91 %), because stomatal size inadequately reflects operating pore area (R2 = 0·46). Furthermore, it was found that variation between ILs in both stomatal sensitivity to desiccation and operating gs is associated with features of individual stoma. In contrast, genotypic variation in gs partitioning depends on the distribution of stomata between the leaf adaxial and abaxial epidermis. PMID:25538116

  16. Explaining Bacterial Dispersion on Leaf Surfaces with an Individual-Based Model (PHYLLOSIM)

    PubMed Central

    van der Wal, Annemieke; Tecon, Robin; Kreft, Jan-Ulrich; Mooij, Wolf M.; Leveau, Johan H. J.

    2013-01-01

    We developed the individual-based model PHYLLOSIM to explain observed variation in the size of bacterial clusters on plant leaf surfaces (the phyllosphere). Specifically, we tested how different ‘waterscapes’ impacted the diffusion of nutrients from the leaf interior to the surface and the growth of individual bacteria on these nutrients. In the ‘null’ model or more complex ‘patchy’ models, the surface was covered with a continuous water film or with water drops of equal or different volumes, respectively. While these models predicted the growth of individual bacterial immigrants into clusters of variable sizes, they were unable to reproduce experimentally derived, previously published patterns of dispersion which were characterized by a much larger variation in cluster sizes and a disproportionate occurrence of clusters consisting of only one or two bacteria. The fit of model predictions to experimental data was about equally poor (<5%) regardless of whether the water films were continuous or patchy. Only by allowing individual bacteria to detach from developing clusters and re-attach elsewhere to start a new cluster, did PHYLLOSIM come much closer to reproducing experimental observations. The goodness of fit including detachment increased to about 70–80% for all waterscapes. Predictions of this ‘detachment’ model were further supported by the visualization and quantification of bacterial detachment and attachment events at an agarose-water interface. Thus, both model and experiment suggest that detachment of bacterial cells from clusters is an important mechanism underlying bacterial exploration of the phyllosphere. PMID:24124501

  17. Superhydrophobic, antiadhesive, and antireflective surfaces mediated by hybrid biomimetic salvinia leaf with moth-eye structures

    NASA Astrophysics Data System (ADS)

    Yang, Cho-Yun; Tsai, Yu-Lin; Yang, Cho-Yu; Sung, Cheng-Kuo; Yu, Peichen; Kuo, Hao-Chung

    2014-08-01

    In this paper, we successfully demonstrate multifunctional surfaces based on scaffolding biomimetic structures, namely, hybrid salvinia leaves with moth-eye structures (HSMSs). The novel fabrication process employs scalable polystyrene nanosphere lithography and a lift-off process. Systematic characterizations show the biomimetic HSMS exhibiting superhydrophobic, self-cleaning, antiadhesive, and antireflective properties. Furthermore, the resulting surface tension gradient (known as the Marangoni effect) leads to a superior air retention characteristic in the HSMS under water droplet impact, compared with the traditional hybrid lotus leaf with a moth-eye structure (HLMS). Such results and learnings pave the way towards the attainment and mass deployment of dielectric surfaces with multiple functionalities for versatile biological and optoelectronic applications.

  18. Evolution and environmental degradation of superhydrophobic aspen and black locust leaf surfaces

    NASA Astrophysics Data System (ADS)

    Tranquada, George Christopher

    The current study is focused on the characterization of four natural leaf species (quaking, bigtooth and columnar european aspen as well as black locust) possessing a unique dual-scale cuticle structure composed of micro- and nano-scale asperities, which are able to effectively resist wetting (superhydrophobic), characteristic of The Lotus Effect. Scanning Electron Microscopy (SEM) was used to track the growth and evolution of their distinctive nano-scale epicuticular wax (ECW) morphologies over one full growing season. In addition, the stability of their superhydrophobic property was tested in various environments. It was determined that the long-term stability of these surfaces is tentatively linked to various environmental stress factors. Specifically, a combination of high temperature and humidity caused the degradation of nanoscale asperities and loss of the superhydrophobic property. The dual-scale surface structure was found to provide a suitable template for the design of future superhydrophobic engineering materials.

  19. Evaporation-induced transition from Nepenthes pitcher-inspired slippery surfaces to lotus leaf-inspired superoleophobic surfaces.

    PubMed

    Zhang, Junping; Wu, Lei; Li, Bucheng; Li, Lingxiao; Seeger, Stefan; Wang, Aiqin

    2014-12-01

    The newly developed Nepenthes pitcher (NP)-inspired slippery surfaces, formed by immobilizing fluoroliquids on lotus leaf (LL)-inspired superoleophobic surfaces, are of great general interest, whereas there are many interesting phenomena and fundamental scientific issues remaining to be unveiled. Here we present our findings of the effects of evaporation of the fluoroliquid, an inevitable process in most cases, -induced transition from NP-inspired to LL-inspired surfaces on the wettability, transparency, and self-cleaning property of the surfaces. The transition is controlled by regulating the evaporation temperature of the model fluoroliquid, Krytox100. The evaporation of Krytox100 has great a influence on the wettability, transparency, and self-cleaning property. An intermediate "sticky" state is observed in the transition process. We believe that our findings in the transition process are helpful in understanding the similarities and differences between the NP-inspired and LL-inspired surfaces and in designing new bioinspired antiwetting surfaces and exploring their potential applications.

  20. Bacterial succession on the leaf surface: a novel system for studying successional dynamics.

    PubMed

    Redford, Amanda J; Fierer, Noah

    2009-07-01

    Succession is a widely studied process in plant and animal systems, but succession in microbial communities has received relatively little attention despite the ubiquity of microorganisms in natural habitats. One important microbial habitat is the phyllosphere, or leaf surface, which harbors large, diverse populations of bacteria and offers unique opportunities for the study of succession and temporal community assembly patterns. To explore bacterial community successional patterns, we sampled phyllosphere communities on cottonwood (Populus deltoides) trees multiple times across the growing season, from leaf emergence to leaf fall. Bacterial community composition was highly variable throughout the growing season; leaves sampled as little as a week apart were found to harbor significantly different communities, and the temporal variability on a given tree exceeded the variability in community composition between individual trees sampled on a given day. The bacterial communities clearly clustered into early-, mid-, and late-season clusters, with early- and late-season communities being more similar to each other than to the mid-season communities, and these patterns appeared consistent from year to year. Although we observed clear and predictable changes in bacterial community composition during the course of the growing season, changes in phyllosphere bacterial diversity were less predictable. We examined the species-time relationship, a measure of species turnover rate, and found that the relationship was fundamentally similar to that observed in plant and invertebrate communities, just on a shorter time scale. The temporal dynamics we observed suggest that although phyllosphere bacterial communities have high levels of phylogenetic diversity and rapid turnover rates, these communities follow predictable successional patterns from season to season. PMID:19221834

  1. The ULTRAPETALA1 trxG factor contributes to patterning the Arabidopsis adaxial-abaxial leaf polarity axis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The SAND domain protein ULTRAPETALA1 (ULT1) functions as a trithorax group factor that regulates a variety of developmental processes in Arabidopsis. We have recently shown that ULT1 regulates developmental patterning in the gynoecia and leaves. ULT1 acts together with the KANADI1 (KAN1) transcripti...

  2. Ecophysiological relevance of cuticular transpiration of deciduous and evergreen plants in relation to stomatal closure and leaf water potential.

    PubMed

    Burghardt, Markus; Riederer, Markus

    2003-08-01

    The water permeability of the leaves of three deciduous plants (Acer campestre, Fagus sylvatica, Quercus petraea) and two evergreen plants (Hedera helix, Ilex aquifolium) was analysed in order to assess its role as a mechanism of drought resistance. Cuticular permeances were determined by measurement of the water loss through adaxial, astomatous leaf surfaces. Minimum conductances after complete stomatal closure were obtained by leaf drying curves. The comparison of the water permeabilities determined with these two experimental systems revealed good agreement in the case of Acer, Fagus, Quercus, and Ilex. For Hedera the minimum conductance was 3-fold higher than the cuticular permeance indicating a significant contribution of residual stomatal transpiration. The leaf water potential was measured as a function of water content and analysed by pressure-volume curves. The influence of water potential as a component of the driving force for transpirational water loss was assessed in order to identify modifications of the cuticular barrier by the leaf water content. The ecophysiological meaning of the water relations parameters describing transpiration under drought conditions (cuticular transpiration, minimum transpiration, residual stomatal transpiration, effect of leaf water content on transpiration) and the water relations parameters derived from pressure-volume curves (osmotic potential at full saturation, turgor loss point, bulk modulus of elasticity) are discussed with regard to adaptations for drought resistance.

  3. Optimization of olive leaf extract obtained by ultrasound-assisted extraction with response surface methodology.

    PubMed

    Şahin, Selin; Samlı, Rüya

    2013-01-01

    In the present article, ultrasound-assisted extraction (UAE) of polyphenols from agricultural and industrial waste of olive oil and table oil productions, olive tree (Olea europaea) leaves were investigated. The aim of the study is to examine the extraction parameters such as solvent concentration (0-100% ethanol (EtOH), v/v), the ratio of solid to solvent (25-50mg/mL) and extraction time (20-60 min), and to obtain the best possible combinations of these parameters through response surface methodology (RSM). The extract yield was stated as mg extract per g of dried leaf (DL). Total phenolic content was expressed in gallic acid equivalent (GAE) per g of dried leaf. Free radical scavenging activity for the antioxidant capacity was tested by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical. The second order polynomial model gave a satisfactory description of the experimental data. 201.2158 mg extract/g DL, 25.0626 mg GAE/g DL, and 95.5610% in respect to inhibition of DPPH radical were predicted at the optimum operating conditions (500 mg solid to 10 mL solvent ratio, 60 min of extraction time and 50% EtOH composition), respectively. PMID:22964032

  4. How does the VPD response of isohydric and anisohydric plants depend on leaf surface particles?

    PubMed

    Burkhardt, J; Pariyar, S

    2016-01-01

    Atmospheric vapour pressure deficit (VPD) is the driving force for plant transpiration. Plants have different strategies to respond to this 'atmospheric drought'. Deposited aerosols on leaf surfaces can interact with plant water relations and may influence VPD response. We studied transpiration and water use efficiency of pine, beech and sunflower by measuring sap flow, gas exchange and carbon isotopes, thereby addressing different time scales of plant/atmosphere interaction. Plants were grown (i) outdoors under rainfall exclusion (OD) and in ventilated greenhouses with (ii) ambient air (AA) or (iii) filtered air (FA), the latter containing <1% ambient aerosol concentrations. In addition, some AA plants were sprayed once with 25 mM salt solution of (NH4 )2 SO4 or NaNO3 . Carbon isotope values (δ(13) C) became more negative in the presence of more particles; more negative for AA compared to FA sunflower and more negative for OD Scots pine compared to other growth environments. FA beech had less negative δ(13) C than AA, OD and NaNO3 -treated beech. Anisohydric beech showed linearly increasing sap flow with increasing VPD. The slopes doubled for (NH4 )2 SO4 - and tripled for NaNO3 -sprayed beech compared to control seedlings, indicating decreased ability to resist atmospheric demand. In contrast, isohydric pine showed constant transpiration rates with increasing VPD, independent of growth environment and spray, likely caused by decreasing gs with increasing VPD. Generally, NaNO3 spray had stronger effects on water relations than (NH4 )2 SO4 spray. The results strongly support the role of leaf surface particles as an environmental factor affecting plant water use. Hygroscopic and chaotropic properties of leaf surface particles determine their ability to form wicks across stomata. Such wicks enhance unproductive water loss of anisohydric plant species and decrease CO2 uptake of isohydric plants. They become more relevant with increasing number of fine particles and

  5. How does the VPD response of isohydric and anisohydric plants depend on leaf surface particles?

    PubMed

    Burkhardt, J; Pariyar, S

    2016-01-01

    Atmospheric vapour pressure deficit (VPD) is the driving force for plant transpiration. Plants have different strategies to respond to this 'atmospheric drought'. Deposited aerosols on leaf surfaces can interact with plant water relations and may influence VPD response. We studied transpiration and water use efficiency of pine, beech and sunflower by measuring sap flow, gas exchange and carbon isotopes, thereby addressing different time scales of plant/atmosphere interaction. Plants were grown (i) outdoors under rainfall exclusion (OD) and in ventilated greenhouses with (ii) ambient air (AA) or (iii) filtered air (FA), the latter containing <1% ambient aerosol concentrations. In addition, some AA plants were sprayed once with 25 mM salt solution of (NH4 )2 SO4 or NaNO3 . Carbon isotope values (δ(13) C) became more negative in the presence of more particles; more negative for AA compared to FA sunflower and more negative for OD Scots pine compared to other growth environments. FA beech had less negative δ(13) C than AA, OD and NaNO3 -treated beech. Anisohydric beech showed linearly increasing sap flow with increasing VPD. The slopes doubled for (NH4 )2 SO4 - and tripled for NaNO3 -sprayed beech compared to control seedlings, indicating decreased ability to resist atmospheric demand. In contrast, isohydric pine showed constant transpiration rates with increasing VPD, independent of growth environment and spray, likely caused by decreasing gs with increasing VPD. Generally, NaNO3 spray had stronger effects on water relations than (NH4 )2 SO4 spray. The results strongly support the role of leaf surface particles as an environmental factor affecting plant water use. Hygroscopic and chaotropic properties of leaf surface particles determine their ability to form wicks across stomata. Such wicks enhance unproductive water loss of anisohydric plant species and decrease CO2 uptake of isohydric plants. They become more relevant with increasing number of fine particles and

  6. Seasonal variations in the chemical composition of vine-grape leaf surface.

    PubMed

    Batovska, D I; Todorova, I T; Bankova, V S; Parushev, S P; Atanassov, A I; Hvarleva, T D; Djakova, G J; Popov, S S

    2008-01-01

    Surface leaf metabolites of two seedlings of a Bulgarian winemaking cultivar Storgozia I(1) were analyzed in two seasons - summer (July) and autumn (October). The resistance towards some fungal pathogens of one of the plants was estimated as superior to the resistance of the other one. Significant seasonal variations in the chemical constituents of the two seedlings were observed. The main metabolites of the summer samples were sterols, terpenes, fatty acids and heterocyclic compounds. In autumn, sterol and fatty acid contents decreased, mono- and diterpenes and heterocyclic compounds disappeared and instead of them hydrocarbons and alcohols were detected. Some individual components - stearic acid, alpha-amyrin, lupeol and squalene - correlated with the estimated resistance and were therefore proposed as biomarkers for the fungal resistance in grape-vine leaves. PMID:18932086

  7. GC-MS analysis of the leaf surface components of four Bulgarian grapevines grown under different conditions.

    PubMed

    Batovska, D I; Todorova, I T; Djakova, G J; Ivanova, I I; Popov, S S

    2010-07-01

    Four grapevine seedlings were propagated and planted both in a greenhouse and in an experimental field. Surface components of their fresh leaves were easily obtained and analysed by gas chromatography-mass spectrometry. In total, 21 surface metabolites were identified. Unlike the greenhouse samples, the field ones possessed semiochemicals and compounds contributing to their survival under environmental stress. This study shows that the leaf surface of the grapevine possesses compounds indicating the conditions of breeding. PMID:20552525

  8. Entrapment of bed bugs by leaf trichomes inspires microfabrication of biomimetic surfaces

    PubMed Central

    Szyndler, Megan W.; Haynes, Kenneth F.; Potter, Michael F.; Corn, Robert M.; Loudon, Catherine

    2013-01-01

    Resurgence in bed bug infestations and widespread pesticide resistance have greatly renewed interest in the development of more sustainable, environmentally friendly methods to manage bed bugs. Historically, in Eastern Europe, bed bugs were entrapped by leaves from bean plants, which were then destroyed; this purely physical entrapment was related to microscopic hooked hairs (trichomes) on the leaf surfaces. Using scanning electron microscopy and videography, we documented the capture mechanism: the physical impaling of bed bug feet (tarsi) by these trichomes. This is distinct from a Velcro-like mechanism of non-piercing entanglement, which only momentarily holds the bug without sustained capture. Struggling, trapped bed bugs are impaled by trichomes on several legs and are unable to free themselves. Only specific, mechanically vulnerable locations on the bug tarsi are pierced by the trichomes, which are located at effective heights and orientations for bed bug entrapment despite a lack of any evolutionary association. Using bean leaves as templates, we microfabricated surfaces indistinguishable in geometry from the real leaves, including the trichomes, using polymers with material properties similar to plant cell walls. These synthetic surfaces snag the bed bugs temporarily but do not hinder their locomotion as effectively as real leaves. PMID:23576783

  9. Theoretical Explanation of the Lotus Effect: Superhydrophobic Property Changes by Removal of Nanostructures from the Surface of a Lotus Leaf.

    PubMed

    Yamamoto, Minehide; Nishikawa, Naoki; Mayama, Hiroyuki; Nonomura, Yoshimune; Yokojima, Satoshi; Nakamura, Shinichiro; Uchida, Kingo

    2015-07-01

    Theoretical study is presented on the wetting behaviors of water droplets over a lotus leaf. Experimental results are interpreted to clarify the trade-offs among the potential energy change, the local pinning energy, and the adhesion energy. The theoretical parameters, calculated from the experimental results, are used to qualitatively explain the relations among surface fractal dimension, surface morphology, and dynamic wetting behaviors. The surface of a lotus leaf, which shows the superhydrophobic lotus effect, was dipped in ethanol to remove the plant waxes. As a result, the lotus effect is lost. The contact angle of a water drop decreased dramatically from 161° of the original surface to 122°. The water droplet was pinned on the surface. From the fractal analysis, the fractal region of the original surface was divided into two regions: a smaller-sized roughness region of 0.3-1.7 μm with D of 1.48 and a region of 1.7-19 μm with D of 1.36. By dipping the leaf in ethanol, the former fractal region, characterized by wax tubes, was lost, and only the latter large fractal region remained. The lotus effect is attributed to a surface structure that is covered with needle-shaped wax tubes, and the remaining surface allows invasion of the water droplet and enlarges the interaction with water. PMID:26075949

  10. Refinement of Eocene lapse rates, fossil-leaf altimetry, and North American Cordilleran surface elevation estimates

    NASA Astrophysics Data System (ADS)

    Feng, Ran; Poulsen, Christopher J.

    2016-02-01

    Estimates of continental paleoelevation using proxy methods are essential for understanding the geodynamic, climatic, and geomorphoric evolution of ancient orogens. Fossil-leaf paleoaltimetry, one of the few quantitative proxy approaches, uses fossil-leaf traits to quantify differences in temperature or moist enthalpy between coeval coastal and inland sites along latitudes. These environmental differences are converted to elevation differences using their rates of change with elevation (lapse rate). Here, we evaluate the uncertainty associated with this method using the Eocene North American Cordillera as a case study. To do so, we develop a series of paleoclimate simulations for the Early (∼55-49 Ma) and Middle Eocene (49-40 Ma) period using a range of elevation scenarios for the western North American Cordillera. Simulated Eocene lapse rates over western North America are ∼5 °C/km and 9.8 kJ/km, close to moist adiabatic rates but significantly different from modern rates. Further, using linear lapse rates underestimates high-altitude (>3 km) temperature variability and loss of moist enthalpy induced by non-linear circulation changes in response to increasing surface elevation. Ignoring these changes leads to kilometer-scale biases in elevation estimates. In addition to these biases, we demonstrate that previous elevation estimates of the western Cordillera are affected by local climate variability at coastal fossil-leaf sites of up to ∼8 °C in temperature and ∼20 kJ in moist enthalpy, a factor which further contributes to elevation overestimates of ∼1 km for Early Eocene floras located in the Laramide foreland basins and underestimates of ∼1 km for late Middle Eocene floras in the southern Cordillera. We suggest a new approach for estimating past elevations by comparing proxy reconstructions directly with simulated distributions of temperature and moist enthalpy under a range of elevation scenarios. Using this method, we estimate mean elevations for

  11. The microbiome of the leaf surface of Arabidopsis protects against a fungal pathogen.

    PubMed

    Ritpitakphong, Unyarat; Falquet, Laurent; Vimoltust, Artit; Berger, Antoine; Métraux, Jean-Pierre; L'Haridon, Floriane

    2016-05-01

    We have explored the importance of the phyllosphere microbiome in plant resistance in the cuticle mutants bdg (BODYGUARD) or lacs2.3 (LONG CHAIN FATTY ACID SYNTHASE 2) that are strongly resistant to the fungal pathogen Botrytis cinerea. The study includes infection of plants under sterile conditions, 16S ribosomal DNA sequencing of the phyllosphere microbiome, and isolation and high coverage sequencing of bacteria from the phyllosphere. When inoculated under sterile conditions bdg became as susceptible as wild-type (WT) plants whereas lacs2.3 mutants retained the resistance. Adding washes of its phyllosphere microbiome could restore the resistance of bdg mutants, whereas the resistance of lacs2.3 results from endogenous mechanisms. The phyllosphere microbiome showed distinct populations in WT plants compared to cuticle mutants. One species identified as Pseudomonas sp isolated from the microbiome of bdg provided resistance to B. cinerea on Arabidopsis thaliana as well as on apple fruits. No direct activity was observed against B. cinerea and the action of the bacterium required the plant. Thus, microbes present on the plant surface contribute to the resistance to B. cinerea. These results open new perspectives on the function of the leaf microbiome in the protection of plants. PMID:26725246

  12. Ontogenic resistance of leaves and fruit, and how leaf folding influences the distribution of powdery mildew on strawberry plants colonized by Podosphaera aphanis.

    PubMed

    Asalf, Belachew; Gadoury, David M; Tronsmo, Anne Marte; Seem, Robert C; Dobson, Andrew; Peres, Natalia A; Stensvand, Arne

    2014-09-01

    Ontogenic or age-related resistance has been noted in many pathosystems but is less often quantified or expressed in a manner that allows the concept to be applied in disease management programs. Preliminary studies indicated that leaves and fruit of three strawberry cultivars rapidly acquired ontogenic resistance to the powdery mildew pathogen, Podosphaera aphanis. In the present study, we quantify the development of ontogenic resistance in controlled inoculations of 10 strawberry cultivars using diverse isolates of P. aphanis in New York and Florida, USA, and in Norway. We report the differential and organ-specific development of ontogenic resistance in the receptacle and externally borne strawberry achenes. We further report that rapid development of ontogenic resistance prior to unfolding of emergent leaves, rather than differential susceptibility of adaxial versus abaxial leaf surfaces, may explain the commonly observed predominance of powdery mildew on the lower leaf surfaces. Susceptibility of leaves and fruit declined exponentially with age. Receptacle tissue of berries inoculated at four phenological stages from bloom to ripe fruit became nearly immune to infection approximately 10 to 15 days after bloom, as fruit transitioned from the early green to the late green or early white stage of berry development, although the achenes remained susceptible for a longer period. Leaves also acquired ontogenic resistance early in their development, and they were highly resistant shortly after unfolding and before the upper surface was fully exposed. No significant difference was found in the susceptibility of the adaxial versus abaxial surfaces. The rapid acquisition of ontogenic resistance by leaves and fruit revealed a narrow window of susceptibility to which management programs might be advantageously adapted.

  13. Ontogenic resistance of leaves and fruit, and how leaf folding influences the distribution of powdery mildew on strawberry plants colonized by Podosphaera aphanis.

    PubMed

    Asalf, Belachew; Gadoury, David M; Tronsmo, Anne Marte; Seem, Robert C; Dobson, Andrew; Peres, Natalia A; Stensvand, Arne

    2014-09-01

    Ontogenic or age-related resistance has been noted in many pathosystems but is less often quantified or expressed in a manner that allows the concept to be applied in disease management programs. Preliminary studies indicated that leaves and fruit of three strawberry cultivars rapidly acquired ontogenic resistance to the powdery mildew pathogen, Podosphaera aphanis. In the present study, we quantify the development of ontogenic resistance in controlled inoculations of 10 strawberry cultivars using diverse isolates of P. aphanis in New York and Florida, USA, and in Norway. We report the differential and organ-specific development of ontogenic resistance in the receptacle and externally borne strawberry achenes. We further report that rapid development of ontogenic resistance prior to unfolding of emergent leaves, rather than differential susceptibility of adaxial versus abaxial leaf surfaces, may explain the commonly observed predominance of powdery mildew on the lower leaf surfaces. Susceptibility of leaves and fruit declined exponentially with age. Receptacle tissue of berries inoculated at four phenological stages from bloom to ripe fruit became nearly immune to infection approximately 10 to 15 days after bloom, as fruit transitioned from the early green to the late green or early white stage of berry development, although the achenes remained susceptible for a longer period. Leaves also acquired ontogenic resistance early in their development, and they were highly resistant shortly after unfolding and before the upper surface was fully exposed. No significant difference was found in the susceptibility of the adaxial versus abaxial surfaces. The rapid acquisition of ontogenic resistance by leaves and fruit revealed a narrow window of susceptibility to which management programs might be advantageously adapted. PMID:24624951

  14. A comparison of two canopy radiative models in land surface processes

    NASA Astrophysics Data System (ADS)

    Dai, Qiudan; Sun, Shufen

    2007-05-01

    This paper compares the predictions by two radiative transfer models—the two-stream approximation model and the generalized layered model (developed by the authors) in land surface processes—for different canopies under direct or diffuse radiation conditions. The comparison indicates that there are significant differences between the two models, especially in the near infrared (NIR) band. Results of canopy reflectance from the two-stream model are larger than those from the generalized model. However, results of canopy absorptance from the two-stream model are larger in some cases and smaller in others compared to those from the generalized model, depending on the cases involved. In the visible (VIS) band, canopy reflectance is smaller and canopy absorptance larger from the two-stream model compared to the generalized model when the Leaf Area Index (LAI) is low and soil reflectance is high. In cases of canopies with vertical leaf angles, the differences of reflectance and absorptance in the VIS and NIR bands between the two models are especially large. Two commonly occurring cases, with which the two-stream model cannot deal accurately, are also investigated. One is for a canopy with different adaxial and abaxial leaf optical properties; and the other is for incident sky diffuse radiation with a non-uniform distribution. Comparison of the generalized model within the same canopy for both uniform and non-uniform incident diffuse radiation inputs shows smaller differences in general. However, there is a measurable difference between these radiation inputs for a canopy with high leaf angle. This indicates that the application of the two-stream model to a canopy with different adaxial and abaxial leaf optical properties will introduce non-negligible errors.

  15. Composition of the epicuticular waxes coating the adaxial side of Phyllostachys aurea leaves: Identification of very-long-chain primary amides.

    PubMed

    Racovita, Radu C; Jetter, Reinhard

    2016-10-01

    The present study presents comprehensive chemical analyses of cuticular wax mixtures of the bamboo Phyllostachys aurea. The epicuticular and intracuticular waxes were sampled selectively from the adaxial side of leaves on young and old plants and investigated by gas chromatography-mass spectrometry and flame ionization detection. The epi- and intracuticular layers on young and old leaves had wax loads ranging from 1.7 μg/cm(2) to 1.9 μg/cm(2). Typical very-long-chain aliphatic wax constituents were found with characteristic chain length patterns, including alkyl esters (primarily C48), alkanes (primarily C29), fatty acids (primarily C28 and C16), primary alcohols (primarily C28) and aldehydes (primarily C30). Alicyclic wax components were identified as tocopherols and triterpenoids, including substantial amounts of triterpenoid esters. Alkyl esters, alkanes, fatty acids and aldehydes were found in greater amounts in the epicuticular layer, while primary alcohols and most terpenoids accumulated more in the intracuticular wax. Alkyl esters occurred as mixtures of metamers, combining C20 alcohol with various acids into shorter ester homologs (C36C40), and a wide range of alcohols with C22 and C24 acids into longer esters (C42C52). Primary amides were identified, with a characteristic chain length profile peaking at C30. The amides were present exclusively in the epicuticular layer and thus at or near the surface, where they may affect plant-herbivore or plant-pathogen interactions. PMID:27402630

  16. Molecular cloning and characterization of OsCHR4, a rice chromatin-remodeling factor required for early chloroplast development in adaxial mesophyll.

    PubMed

    Zhao, Chunfang; Xu, Jiming; Chen, Yue; Mao, Chuanzao; Zhang, Shelong; Bai, Youhuang; Jiang, Dean; Wu, Ping

    2012-10-01

    Mi-2 protein, the central component of the NuRD nucleosome remodeling and histone deacetylase complex, plays a role in transcriptional repression in animals. Mi-2-like genes have been reported in Arabidopsis, though their function in monocots remains largely unknown. In the present study, a rice Mi-2-like gene, OsCHR4 (Oryza sativa Chromatin Remodeling 4, LOC_Os07g03450), was cloned from a rice mutant with adaxial albino leaves. The Oschr4 mutant exhibited defective chloroplasts in adaxial mesophyll, but not in abaxial mesophyll. Ultrastructural observations indicated that proplastid growth and/or thylakoid membrane formation in adaxial mesophyll cells was blocked in the Oschr4 mutant. Subcellular localization revealed that OsCHR4::GFP fusion protein was targeted to the nuclei. OsCHR4 was mainly expressed in the root meristem, flower, vascular bundle, and mesophyll cells by promoter::GUS analysis in transgenic rice. The transcripts of some nuclear- and plastid-encoded genes required for early chloroplast development and photosynthesis were decreased in the adaxial albino mesophyll of the Oschr4 mutant. These observations provide evidence that OsCHR4, the rice Mi-2-like protein, plays an important role in early chloroplast development in adaxial mesophyll cells. The results increase our understanding of the molecular mechanism underlying tissue-specific chloroplast development in plants.

  17. Surface and internalized Escherichia coli O157:H7 on field-grown spinach and lettuce treated with spray-contaminated irrigation water.

    PubMed

    Erickson, Marilyn C; Webb, Cathy C; Diaz-Perez, Juan Carlos; Phatak, Sharad C; Silvoy, John J; Davey, Lindsey; Payton, Alison S; Liao, Jean; Ma, Li; Doyle, Michael P

    2010-06-01

    Numerous field studies have revealed that irrigation water can contaminate the surface of plants; however, the occurrence of pathogen internalization is unclear. This study was conducted to determine the sites of Escherichia coli O157:H7 contamination and its survival when the bacteria were applied through spray irrigation water to either field-grown spinach or lettuce. To differentiate internalized and surface populations, leaves were treated with a surface disinfectant wash before the tissue was ground for analysis of E. coli O157:H7 by direct plate count or enrichment culture. Irrigation water containing E. coli O157:H7 at 10(2), 10(4), or 10(6) CFU/ml was applied to spinach 48 and 69 days after transplantation of seedlings into fields. E. coli O157:H7 was initially detected after application on the surface of plants dosed at 10(4) CFU/ml (4 of 20 samples) and both on the surface (17 of 20 samples) and internally (5 of 20 samples) of plants dosed at 10(6) CFU/ml. Seven days postspraying, all spinach leaves tested negative for surface or internal contamination. In a subsequent study, irrigation water containing E. coli O157:H7 at 10(8) CFU/ml was sprayed onto either the abaxial (lower) or adaxial (upper) side of leaves of field-grown lettuce under sunny or shaded conditions. E. coli O157:H7 was detectable on the leaf surface 27 days postspraying, but survival was higher on leaves sprayed on the abaxial side than on leaves sprayed on the adaxial side. Internalization of E. coli O157:H7 into lettuce leaves also occurred with greater persistence in leaves sprayed on the abaxial side (up to 14 days) than in leaves sprayed on the adaxial side (2 days).

  18. Evaluation of MODIS surface reflectance products for wheat leaf area index (LAI) retrieval

    NASA Astrophysics Data System (ADS)

    Yi, Yonghong; Yang, Dawen; Huang, Jingfeng; Chen, Daoyi

    The accuracy of leaf area index (LAI) retrieval depends critically on the quality of the input reflectance. MODIS Collection 4 (C4) and Collection 5 (C5) land surface reflectance data are used for wheat LAI retrieval. Results are compared with in situ measurements. The uncertainty in the reflectance data of the two collections (C4 and C5) from both Terra and Aqua sensors is analyzed and its influence on LAI retrieval is discussed. The discrepancies of blue and near infrared reflectances between Terra and Aqua in the C5 data are less than the discrepancies between the sensors in the C4 data. For both Terra and Aqua, the C5 data have much lower blue reflectance than do the C4 data. This can be attributed to improvements in the atmospheric correction algorithm for the C5 data including cloud mask definition and aerosol retrieval. Using both empirical vegetation indices and inversion methods, the LAI is derived from the C4 and C5 surface reflectances. For daily C4 data, only Aqua Normalized difference water indices (NDWI) have significant correlations with the LAI (at a 99% confidence level); in contrast, for the daily C5 data, all the vegetation indices have significant correlations with the LAI. A three-layer neural network is used to invert a one-dimensional (1-D) radiative transfer model for LAI estimation. For the daily C4 data, the correlation between the modeled and measured LAIs is poor and the root mean square error (RMSE) is larger than 1.1; in comparison, the RMSE for the daily C5 data is 0.7. For both C4 and C5 collections, the LAI tends to be overestimated when the sensor is operated with a large view zenith angle in the backscattering direction. The error is either due to the mismatch between the measured reflectance and the modeled reflectance from the simple 1-D radiative transfer model in this direction or due to the assumption of a Lambertian surface in the MODIS atmospheric correction. Additionally, for both methods the results from the 8-day

  19. In situ investigation into surfactant effects on the clearance of polycyclic aromatic hydrocarbons adsorbed onto soybean leaf surfaces.

    PubMed

    Sun, Haifeng; Wang, Weipeng; Guo, Shuai; Zhang, Yong

    2016-03-01

    The partitioning of polycyclic aromatic hydrocarbons (PAHs) in agricultural crop leaves, contributes to the exposure of organisms to these chemicals through the dietary pathway. To precisely predict the fate of PAHs and crop safety, the clearance of three-ringed phenanthrene (Phe) and four-ringed pyrene (Pyr) adsorbed individually onto living soybean leaf surfaces, as well as the effects of two surfactants, namely, an ionic surfactant (sodium dodecylbenzene sulfonate, SDBS) and a non-ionic surfactant (polyoxyethyleneglycol dodecyl ether, Brij35), were investigated in situ using the laser-induced nanosecond time-resolved fluorescence (LITRF) method. The effects varied significantly with surfactant types primarily in terms of the elimination rates and the final residues of PAH chemicals. With increasing SDBS and Brij35 concentrations, volatilization rate constants (kC) of both Phe and Pyr initially decreased at fast rates and then at more moderate rates later on, resulting from the plasticizing effect of surfactants adsorbed on leaf surfaces. In addition, the photolysis rate constants (kP) decreased with the presence of SDBS but increased with the presence of Brij35. Overall, the total clearance rates of PAHs (kT) adsorbed onto living soybean leaf surfaces were inhibited by the presence of SDBS but promoted by the presence of Brij35. These observations show that surfactants may significantly alter the clearance of PAHs in agricultural systems, and the potential impact of surfactants on crop safety is closely related to surfactant types in natural environments.

  20. Effects of food surface topography on phage-based magnetoelastic biosensor detection

    NASA Astrophysics Data System (ADS)

    Horikawa, Shin; Chai, Yating; Zhao, Ruiting; Wikle, Howard C.; Chin, Bryan A.

    2014-05-01

    Phage-based magnetoelastic (ME) biosensors have proven useful in rapidly and inexpensively detecting food surface con- tamination. These biosensors are wireless, mass-sensitive biosensors and can be placed directly on food surfaces to detect the presence of target pathogens. Previously, millimeter-scale strip-shaped ME biosensors have been used to demonstrate direct detection of Salmonella Typhimurium on various fresh produce surfaces, including tomatoes, shell eggs, watermel- ons, and spinach leaves. Since the topography of these produce surfaces are different, and the biosensor must come into direct contact with Salmonella bacteria, food surfaces with large roughness and curvatures (e.g., spinach leaf surfaces) may allow the bacteria to avoid direct contact, thereby avoiding detection. The primary objective of this paper is, hence, to investigate the effects of food surface topography on the detection capabilities of the biosensors. Spinach leaf surfaces were selected as model surfaces, and detection experiments were conducted with differently sized biosensors (2 mm, 0.5 mm, and 150 μm in length). Spinach leaf roughness and curvatures of both adaxial (top) and abaxial (underside) surfaces were measured using a confocal laser scanning microscope. The experimental results showed that in spinach as the sen- sor was made smaller, the physical contact between the biosensors and bacteria were improved. Smaller sensors thereby enhance detection capabilities. When proper numbers of biosensors are used, micron-scale biosensors are anticipated to yield improved limits of detection over previously investigated millimeter-scale biosensors.

  1. Fungitoxic effects of nonprotein imino acids on growth of saprophytic fungi isolated from the leaf surface of Calliandra haematocephala.

    PubMed Central

    Brenner, S A; Romeo, J T

    1986-01-01

    Four saprophytic and pathogenic fungi were isolated from the leaf surface of Calliandra haematocephala, a tropical legume known to contain large amounts of rare nonprotein imino acids in its leaves and seeds. The fungi Aspergillus niger, Aspergillus sp., Curvularia sp., and Penicillium sp. were cultured in the laboratory and tested for susceptibility to leaf extracts of the host plant and to proline, pipecolic acid, cis-5-hydroxypipecolic acid, and 2,4-trans-4,5-cis-4,5-dihydroxypipecolic acid. Fungal spore germination and germ tube growth were measured. Aspergillus sp. was inhibited by plant extracts and by pipecolic acid and cis-5-hydroxypipecolic acid. Curvularia sp. growth was stimulated by plant extracts and by pipecolic acid. The other two fungi were unaffected by any of the treatments. The data indicate that imino acids may play a role in the specific resistance of Calliandra spp. to Aspergillus sp. PMID:3707119

  2. Intra-leaf gradients of photoinhibition induced by different color lights: implications for the dual mechanisms of photoinhibition and for the application of conventional chlorophyll fluorometers.

    PubMed

    Oguchi, Riichi; Douwstra, Peter; Fujita, Takashi; Chow, Wah Soon; Terashima, Ichiro

    2011-07-01

    • We studied how different color lights cause gradients of photoinhibition within a leaf, to attempt to resolve the controversy of whether photon absorption by chlorophyll or by manganese (Mn) is the primary cause of photoinhibition, as suggested by the excess-energy hypothesis or the two-step hypothesis, respectively. • Lincomycin-treated leaf discs were photoinhibited by white, blue, green or red light. Combining a microfiber fluorometer, a fiber-thinning technique and a micro-manipulator enabled us to measure the chlorophyll fluorescence signals within a leaf. Photoinhibition gradients were also compared with results from various conventional fluorometers to estimate their depth of signal detection. • The severity of photoinhibition was in the descending order of blue, red and green light near the adaxial surface, and in the descending order of blue, green and red light in the deeper tissue, which correlated with the chlorophyll and the Mn absorption spectrums, respectively. These results cannot be explained by either hypothesis alone. • These data strongly suggest that both the excess-energy and the two-step mechanisms occur in photoinhibition, and fluorometers with red or blue measuring light give overestimated or underestimated F(v)/F(m) values of photoinhibited leaves compared with the whole tissue average, respectively; that is, they measured deeper or shallower leaf tissue, respectively. PMID:21418065

  3. Lotus-leaf-like topography predominates over adsorbed ECM proteins in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) surface/cell interactions.

    PubMed

    Zheng, Jun; Li, Dan; Yuan, Lin; Liu, Xiaoli; Chen, Hong

    2013-06-26

    It is well-known that extracellular matrix (ECM) proteins mediate cell/surface interactions. However, introduction of a specific surface topography may disturb the correlation between ECM proteins adsorption and cells adhesion on a given surface. In present study, lotus-leaf-like topography was introduced on the surface of a biodegradable material, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx). Protein adsorption and cell interactions with this lotus-leaf-like surface (designated PHBHHx-L) were investigated. Water contact angle data indicated that the hydrophobicity of PHBHHx was enhanced by the introduction of lotus-leaf-like topography. The adsorption of extracellular matrix proteins (fibronectin and vitronectin) on PHBHHx-L was measured by enzyme linked immunosorbent assay (ELISA). Compared with flat PHBHHx, adsorption on the PHBHHx-L surface increased by ~260% for fibronectin and ~40% for vitronectin. In contrast, fibroblast and endothelial cell adhesion and proliferation were reduced on the PHBHHx-L compared to the flat polymer surface. These results suggest that the inhibition of cell adhesion and proliferation caused by the lotus-leaf-like topography dominates over the effect of the adsorbed adhesive proteins in promoting adhesion and proliferation. It can be concluded that the lotus-leaf-like topography plays a dominant role in cell/PHBHHx-L interactions. The present findings indicate the complexity of the interplay among surface topography, adsorbed proteins, and cell-surface interactions.

  4. A role for AUXIN RESISTANT3 in the coordination of leaf growth.

    PubMed

    Pérez-Pérez, José Manuel; Candela, Héctor; Robles, Pedro; López-Torrejón, Gema; del Pozo, Juan C; Micol, José Luis

    2010-10-01

    The characteristically flat structure of Arabidopsis thaliana vegetative leaves requires coordinating the growth of the epidermal, palisade mesophyll, spongy mesophyll and vascular tissues. Mutations disrupting such coordination or the specific growth properties of any of these tissues can cause hyponasty, epinasty, waviness or other deviations from flatness. Here, we show that the incurvata6 (icu6) semi-dominant allele of the AUXIN RESISTANT3 (AXR3) gene causes leaf hyponasty. Cotyledons and leaves of icu6/AXR3 plants exhibited reduced size of adaxial pavement cells, and abnormal expansion of palisade mesophyll cells. Enhanced auxin responses in the adaxial domain of icu6/AXR3 developing cotyledons and leaves correlated with increased cell divisions in the adaxial epidermis. Leaf incurvature in icu6/AXR3 leaves was alleviated by loss-of-function alleles of the ASYMMETRIC LEAVES1 (AS1) and AS2 genes, which restrict the expression of class I KNOX genes to the shoot apical meristem and regulate cell proliferation in leaf primordia. Taken together, our results suggest that an interaction between auxin responses and the AS1-AS2 pathway coordinates tissue growth during Arabidopsis thaliana leaf expansion.

  5. Scale effects on the controls on mountain grassland leaf stomatal and ecosystem surface conductance to water vapour

    NASA Astrophysics Data System (ADS)

    Haslwanter, Alois; Hammerle, Albin; Wohlfahrt, Georg

    2010-05-01

    Stomata are the major pathway by which plants exert control on the exchange of trace gases and water vapour with the aerial environment and thus provide a key link between the functioning of terrestrial ecosystems and the state and composition of the atmosphere. Understanding the nature of this control, i.e. how stomatal conductance differs between plant species and ecosystems and how it varies in response to external and internal forcings, is key to predicting feedbacks plants may be providing to changing climatic conditions. Despite a long history of research on stomatal functioning, a fully mechanistic understanding of how stomata function in response to biotic and abiotic controls is still elusive which has led to the development of a large number of (semi-)empirical models of varying complexity. Two of the most widely used models go back to Jarvis (1976) and Ball, Woodrow and Berry (1987), termed J-model and BWB-model, respectively, in the following. The J-model simulates stomatal conductance as some maximal value attenuated by a series of multiplicative functions which are bound between zero and unity, while the BWB-model predicts stomatal conductance as a linear function of photosynthesis, relative humidity and carbon dioxide concentration in the leaf boundary layer. Both models were developed for the prediction of leaf-scale stomatal conductance to water vapour, but have been applied for simulating ecosystem-scale surface conductance as well. The objective of the present paper is to compare leaf- and ecosystem-scale conductances to water vapour and to assess the respective controls using the two above-mentioned models as analysis frameworks. To this end leaf-level stomatal conductance has been measured by means of leaf-gas exchange methods and ecosystem-scale surface conductance by inverting eddy covariance evapotranspiration estimates at a mountain grassland site in Austria. Our major findings are that the proportionality parameter in the BWB-model is

  6. Ultrastructure of Plant Leaf Cuticles in relation to Sample Preparation as Observed by Transmission Electron Microscopy

    PubMed Central

    Guzmán, Paula; Fernández, Victoria; García, María Luisa; Fernández, Agustín; Gil, Luis

    2014-01-01

    The leaf cuticular ultrastructure of some plant species has been examined by transmission electron microscopy (TEM) in only few studies. Attending to the different cuticle layers and inner structure, plant cuticles have been grouped into six general morphological types. With the aim of critically examining the effect of cuticle isolation and preparation for TEM analysis on cuticular ultrastructure, adaxial leaf cuticles of blue-gum eucalypt, grey poplar, and European pear were assessed, following a membrane science approach. The embedding and staining protocols affected the ultrastructure of the cuticles analysed. The solubility parameter, surface tension, and contact angles with water of pure Spurr's and LR-White resins were within a similar range. Differences were however estimated for resin : solvent mixtures, since Spurr's resin is combined with acetone and LR-White resin is mixed with ethanol. Given the composite hydrophilic and lipophilic nature of plant cuticles, the particular TEM tissue embedding and staining procedures employed may affect sample ultrastructure and the interpretation of the results in physicochemical and biological terms. It is concluded that tissue preparation procedures may be optimised to facilitate the observation of the micro- and nanostructure of cuticular layers and components with different degrees of polarity and hydrophobicity. PMID:24895682

  7. A role for PHANTASTICA in medio-lateral regulation of adaxial domain development on tomato and tobacco leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diverse leaf forms in nature can be categorized into two groups: simple and compound. A simple leaf has a single blade unit, whilst a compound leaf is dissected into leaflets. For both simple and compound leaves, a MYB domain transcription factor PHANTASTICA (PHAN) plays an important role in establi...

  8. Defending the leaf surface: intra- and inter-specific differences in silicon deposition in grasses in response to damage and silicon supply

    PubMed Central

    Hartley, Sue E.; Fitt, Rob N.; McLarnon, Emma L.; Wade, Ruth N.

    2015-01-01

    Understanding interactions between grasses and their herbivores is central to the conservation of species-rich grasslands and the protection of our most important crops against pests. Grasses employ a range of defenses against their natural enemies; silicon-based defenses have been shown to be one of the most effective. Silicon (Si) is laid down on the leaf surface as spines and other sharp bodies, known as phytoliths, making grasses abrasive and their foliage indigestible to herbivores. Previous studies on Si defenses found that closely related species may have similar levels of Si in the leaves but differ markedly in abrasiveness. Here we show how the number, shape and distribution of Si-rich phytoliths and spines differ within and between different grass species and demonstrate that species also differ in their ability to change the deposition and distribution of these defenses in response to damage or increases in Si supply. Specifically, we tested the response of two genotypes of Festuca arundinacea known to differ in their surface texture and three different grass species (F. ovina, F. rubra, and Deschampsia cespitosa) differing in their abrasiveness to combined manipulation of leaf damage and Si supply. F. arundinacea plants with a harsh leaf surface had higher Si content and more spines on their leaf surface than soft varieties. F. ovina and D. cespitosa plants increased their leaf Si concentration and produced an increase in the number of leaf spines and phytoliths on the leaf surface in response to Si addition. F rubra also increased leaf Si content in response to treatments, particularly in damaged leaves, but did not deposit this in the form of spines or increased densities of phytoliths. We discuss how the form in which grasses deposit Si may affect their anti-herbivore characteristics and consider the ecological and agricultural implications of the differences in allocation to Si-based defenses between grass species. PMID:25717331

  9. The Effect of Leaf Litter Cover on Surface Runoff and Soil Erosion in Northern China

    PubMed Central

    Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

    2014-01-01

    The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter), four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (p<0.05). Average runoff yield was 29.5% and 31.3% less than bare-soil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, p<0.05), and the efficiency in runoff reduction by litter decreased considerably. Runoff yield and the runoff coefficient increased dramatically by 72.9 and 5.4 times, respectively. The period of time before runoff appeared decreased approximately 96.7% when rainfall intensity increased from 5.7 to 75.6 mm h−1. Broadleaf and needle leaf litter showed similarly relevant effects on runoff and soil erosion control, since no significant differences (p≤0.05) were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (p<0.05) with sediment yield. These results suggest that the protective role of leaf litter in runoff and erosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes. PMID:25232858

  10. The effect of leaf litter cover on surface runoff and soil erosion in Northern China.

    PubMed

    Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

    2014-01-01

    The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter), four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (p<0.05). Average runoff yield was 29.5% and 31.3% less than bare-soil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, p<0.05), and the efficiency in runoff reduction by litter decreased considerably. Runoff yield and the runoff coefficient increased dramatically by 72.9 and 5.4 times, respectively. The period of time before runoff appeared decreased approximately 96.7% when rainfall intensity increased from 5.7 to 75.6 mm h-1. Broadleaf and needle leaf litter showed similarly relevant effects on runoff and soil erosion control, since no significant differences (p≤0.05) were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (p<0.05) with sediment yield. These results suggest that the protective role of leaf litter in runoff and erosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes.

  11. Inactivation of baculovirus by isoflavonoids on chickpea (Cicer arietinum) leaf surfaces reduces the efficacy of nucleopolyhedrovirus against Helicoverpa armigera.

    PubMed

    Stevenson, Philip C; D'Cunha, Reju F; Grzywacz, David

    2010-02-01

    Biological pesticides based on nucleopolyhedroviruses (NPVs) can provide an effective and environmentally benign alternative to synthetic chemicals. On some crops, however, the efficacy and persistence of NPVs is known to be reduced by plant specific factors. The present study investigated the efficacy of Helicoverpa armigera NPV (HearNPV) for control of H. armigera larvae, and showed that chickpea reduced the infectivity of virus occlusion bodies (OBs) exposed to the leaf surface of chickpea for at least 1 h. The degree of inactivation was greater on chickpea than that previously reported on cotton, and the mode of action is different from that of cotton. The effect was observed for larvae that consumed OBs on chickpea leaves, but it also occurred when OBs were removed after exposure to plants and inoculated onto artificial diet, indicating that inhibition was leaf surface-related and permanent. Despite their profuse exudation from trichomes on chickpea leaves and their low pH, organic acids-primarily oxalic and malic acid-caused no inhibition. When HearNPV was incubated with biochanin A and sissotrin, however, two minor constituents of chickpea leaf extracts, OB activity was reduced significantly. These two isoflavonoids increased in concentration by up to 3 times within 1 h of spraying the virus suspension onto the plants and also when spraying only the carrier, indicating induction was in response to spraying and not a specific response to the HearNPV. Although inactivation by the isoflavonoids did not account completely for the level of effect recorded on whole plants, this work constitutes evidence for a novel mechanism of NPV inactivation in legumes. Expanding the use of biological pesticides on legume crops will be dependent upon the development of suitable formulations for OBs to overcome plant secondary chemical effects.

  12. Leaf conductance in relation to rate of CO/sub 2/ assimilation. II. Effects of short-term exposures to different photon flux densities. [Zea mays; Phaseolus vulgaris; Eucalyptus pauciflora

    SciTech Connect

    Wong, S.C.; Cowan, I.R.; Farquhar, G.D.

    1985-01-01

    When photon flux density incident on attached leaves of Zea mays L. was varied from the equivalent of 0.12 of full sunlight to full sunlight, leaf conductance to CO/sub 2/ transfer, g, changed in proportion to the change in rate of CO/sub 2/, assimilation, A, with the result that intercellular partial pressure of CO/sub 2/ remained almost constant. The proportionality was the same as the previously found in g and A measured at one photon flux density in plants of Zea mays L. grown at different levels of mineral nutrition, light intensities, and ambient partial pressures of CO/sub 2/. In shade-grown Phaseolus vulgaris L., plants, A as photon flux density was increased from about 0.12 up to about 0.5 full sunlight, the proportionality being almost the same in plants grown at low and at high light intensity. When photon flux density incident on the adaxial an abaxial surfaces of the isolateral leaves of Eucalyptus pauciflora Sieb. ex Spreng was varied, g and A also varied proportionally. The leaf conductance in a particular surface was affected by the photon flux density at the opposite surface to a greater extent than was expected on the basis of transmittance. The results indicated that stomata may, in some way, be sensitive to the photon flux absorbed within the leaf as a whole. 5 references, 4 figures, 1 table.

  13. Fabrication of lotus-leaf-like superhydrophobic surfaces via Ni-based nano-composite electro-brush plating

    NASA Astrophysics Data System (ADS)

    Liu, Hongtao; Wang, Xuemei; Ji, Hongmin

    2014-01-01

    Superhydrophobic surface has become a research hot topic in recent years due to its excellent performance and wide application prospect. This paper investigates the method to fabricate superhydrophobic surface on carbon steel substrate via two-layer nano-composite electro-brush plating and subsequent surface modification with low free energy materials. The hydrophobic properties of as-prepared coatings were characterized by a water sliding angle (SA) and a water contact angle (CA) measured by the Surface tension instrument. A Scanning electron microscope was used to analyze the surface structure of plating coatings. Anti-corrosion performance of the superhydrophobic coating was characterized by a potentiodynamic polarization curve measured by the Electrochemical workstation. The research result shows that: the superhydrophobic structure can be successfully prepared by plating nano-C/Ni and nano-Cu/Ni two-layer coating on carbon steel substrate under appropriate technology and has similarity with lotus-leaf-like micro/nano composite structure; the contact angle of the as-prepared superhydrophobic coating can be up to 155.5°, the sliding angle is 5°; the coating has better anti-corrosion performance compared with substrate.

  14. Improving winter leaf area index estimation in coniferous forests and its significance in estimating the land surface albedo

    NASA Astrophysics Data System (ADS)

    Wang, Rong; Chen, Jing M.; Pavlic, Goran; Arain, Altaf

    2016-09-01

    Winter leaf area index (LAI) of evergreen coniferous forests exerts strong control on the interception of snow, snowmelt and energy balance. Simulation of winter LAI and associated winter processes in land surface models is challenging. Retrieving winter LAI from remote sensing data is difficult due to cloud contamination, poor illumination, lower solar elevation and higher radiation reflection by snow background. Underestimated winter LAI in evergreen coniferous forests is one of the major issues limiting the application of current remote sensing LAI products. It has not been fully addressed in past studies in the literature. In this study, we used needle lifespan to correct winter LAI in a remote sensing product developed by the University of Toronto. For the validation purpose, the corrected winter LAI was then used to calculate land surface albedo at five FLUXNET coniferous forests in Canada. The RMSE and bias values for estimated albedo were 0.05 and 0.011, respectively, for all sites. The albedo map over coniferous forests across Canada produced with corrected winter LAI showed much better agreement with the GLASS (Global LAnd Surface Satellites) albedo product than the one produced with uncorrected winter LAI. The results revealed that the corrected winter LAI yielded much greater accuracy in simulating land surface albedo, making the new LAI product an improvement over the original one. Our study will help to increase the usability of remote sensing LAI products in land surface energy budget modeling.

  15. Optimization of Total Flavonoid Compound Extraction from Gynura medica Leaf Using Response Surface Methodology and Chemical Composition Analysis

    PubMed Central

    Liu, Wei; Yu, Yanying; Yang, Ruzhen; Wan, Chunpeng; Xu, Binbin; Cao, Shuwen

    2010-01-01

    Optimization of total flavonoid compound (TFC) extraction from Gynura medica leaf was investigated using response surface methodology (RSM) in this paper. The conditions investigated were 30–60% (v/v) ethanol concentration (X1), 85–95 °C extraction temperature (X2) and 30–50 (v/w) liquid-to-solid ratio (X3). Statistical analysis of the experiments indicated that temperature and liquid-to-solid ratio significantly affected TFC extraction (p < 0.01). The Box-Behnken experiment design showed that polynomial regression models were in good agreement with the experimental results, with the coefficients of determination of 0.9325 for TFC yield. The optimal conditions for maximum TFC yield were 55% ethanol, 92 °C and 50 (v/w) liquid-to-solid ratio with a 30 min extraction time. Extracts from these conditions showed a moderate antioxidant value of 54.78 μmol quercetin/g dry material (DM), 137.3 μmol trolox/g DM for 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 108.21 μmol quercetin/g DM, 242.31 μmol trolox/g DM for 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS+), respectively. HPLC-DAD-MS analysis showed that kaempferol-3-O-glucoside was the principal flavonoid compound in Gynura medica leaf. PMID:21151469

  16. Leaf shrinkage: a predictive indicator of the potential variation of the surface area-to-volume ratio according to the leaf moisture content.

    PubMed

    Essaghi, Salaheddine; Hachmi, M'hamed; Yessef, Mohammed; Dehhaoui, Mohammed

    2016-01-01

    Leaf shrinkage provides insights into the potential variation of foliar SVR, within the same species, when leaf moisture content is changing in response to water deficit. Since SVR is among the most significant plant flammability features, leaf shrinkage would be a relevant component of fuel hazard assessment through its influence on SVR, enhancing-if it is taken into account-thereby the wildfire prediction accuracy. The purpose of this work is, first, to consider the leaf shrinkage by characterizing the plant species towards the shrinkability of their leaves, taking account the possible site effect, to characterize the behavior of shrinkage as a function of moisture content and finally to perform a classification for some dominant Mediterranean species based on the shrinkage levels. The assessment of the hierarchical relationships between the dimensional shrinkages is also aimed. Leaves and needles of thirteen tree and shrub species were harvested from six different sites in western Rif Mountains. Leaves dimensions and moisture content were measured regularly during a gradual drying at the laboratory. Dimensional shrinkages were calculated at each moisture content level. Dimensional shrinkages behaved similarly whether in leaf or timber and kept the same reporting relationships between each other. Among the species sampled in different sites, site effect is significant only in Pinus canariensis and Pistacia lentiscus. A classification of the plant species was carried out in three separate classes. Generally, shrinkage class of the plant species studied gave an idea on its flammability ranking reported in the literature, implying thus a cause-and-effect relationship between both parameters. PMID:27536513

  17. Leaf surface structures enable the endemic Namib desert grass Stipagrostis sabulicola to irrigate itself with fog water

    PubMed Central

    Roth-Nebelsick, A.; Ebner, M.; Miranda, T.; Gottschalk, V.; Voigt, D.; Gorb, S.; Stegmaier, T.; Sarsour, J.; Linke, M.; Konrad, W.

    2012-01-01

    The Namib grass Stipagrostis sabulicola relies, to a large degree, upon fog for its water supply and is able to guide collected water towards the plant base. This directed irrigation of the plant base allows an efficient and rapid uptake of the fog water by the shallow roots. In this contribution, the mechanisms for this directed water flow are analysed. Stipagrostis sabulicola has a highly irregular surface. Advancing contact angle is 98° ± 5° and the receding angle is 56° ± 9°, with a mean of both values of approximately 77°. The surface is thus not hydrophobic, shows a substantial contact angle hysteresis and therefore, allows the development of pinned drops of a substantial size. The key factor for the water conduction is the presence of grooves within the leaf surface that run parallel to the long axis of the plant. These grooves provide a guided downslide of drops that have exceeded the maximum size for attachment. It also leads to a minimum of inefficient drop scattering around the plant. The combination of these surface traits together with the tall and upright stature of S. sabulicola contributes to a highly efficient natural fog-collecting system that enables this species to thrive in a hyperarid environment. PMID:22356817

  18. Corrosion inhibition of Eleusine aegyptiaca and Croton rottleri leaf extracts on cast iron surface in 1 M HCl medium

    NASA Astrophysics Data System (ADS)

    Rajeswari, Velayutham; Kesavan, Devarayan; Gopiraman, Mayakrishnan; Viswanathamurthi, Periasamy; Poonkuzhali, Kaliyaperumal; Palvannan, Thayumanavan

    2014-09-01

    The adsorption and corrosion inhibition activities of Eleusine aegyptiaca (E. aegyptiaca) and Croton rottleri (C. rottleri) leaf extracts on cast iron corrosion in 1 M hydrochloric acid solution were studied first time by weight loss and electrochemical techniques viz., Tafel polarization and electrochemical impedance spectroscopy. The results obtained from the weight loss and electrochemical methods showed that the inhibition efficiency increased with inhibitor concentrations. It was found that the extracts acted as mixed-type inhibitors. The addition of halide additives (KCl, KBr, and KI) on the inhibition efficiency has also been investigated. The adsorption of the inhibitors on cast iron surface both in the presence and absence of halides follows the Langmuir adsorption isotherm model. The inhibiting nature of the inhibitors was supported by FT-IR, UV-vis, Wide-angle X-ray diffraction and SEM methods.

  19. In situ determination of the depuration of three- and four-ringed polycyclic aromatic hydrocarbons co-adsorbed onto mangrove leaf surfaces.

    PubMed

    Sun, Haifeng; Shi, Jing; Guo, Shuai; Zhang, Yong; Duan, Lusha

    2016-01-01

    A dual-wavelength fiber-optic fluorimetry for the in situ simultaneous determinations of fluorene (Flu), phenanthrene (Phe) and pyrene (Pyr) adsorbed onto the leaf surfaces of living Avicennia marina (Am) seedling were developed and used to study the depuration kinetics of the three PAHs, adsorbed individually or mixed together, onto living Am leaf surfaces. Limits of detection for the in situ measurements of adsorbed Flu, Phe and Pyr were 4.62, 2.75 and 1.38 ng spot(-1), respectively. The depuration kinetics of the three selected polycyclic aromatic hydrocarbons (PAHs) are divided into rapid and slow phases; both phases followed the same first-order kinetics with relative clearance rates of Flu > Phe > Pyr during the rapid phase, and a clearance rate order of Pyr > Flu > Phe during the slow phase. For the three PAHs co-adsorbed on living Am leaf surfaces, a significant synergistic effect was detected during the rapid phase clearance; conversely, an antagonistic effect was observed during the slow phase. However, the synergistic effect dominated during both phases of the depuration process, and the co-adsorption of PAHs promoted the clearance of all three compounds from the mangrove leaf surfaces. These findings demonstrate a novel analytical method for in situ characterization of multiple PAHs adsorbed onto the plant surfaces.

  20. Equivalent pore radii of hydrophilic foliar uptake routes in stomatous and astomatous leaf surfaces--further evidence for a stomatal pathway.

    PubMed

    Eichert, Thomas; Goldbach, Heiner E

    2008-04-01

    Foliar uptake pathways for hydrophilic solutes were studied by the analysis of co-uptake of 15N-labelled urea, NH4+ or NO3- and 13C-labelled sucrose across leaf surfaces of various plant species. Uptake of N (y) and sucrose (x) were strongly correlated. Curvilinear regression revealed significantly positive intercepts with the y-axis indicating the involvement of a sucrose-excluding pathway consisting of small pores with radii <0.5 nm. Depending on plant species, N source, leaf side and aperture of stomata, these small pores accounted for 6-62% of total N uptake. Regression analysis revealed that in stomatous leaf surfaces of Vicia faba L., Coffea arabica L. and Prunus cerasus L., the remaining N uptake occurred via another pathway with an estimated average pore radius (r(P)) greater than 20 nm. This is two orders of magnitude greater than previous estimations of cuticular r(P), indicating that this pathway, which was only found in stomatous leaf surfaces, was probably not located in the cuticle but at the surfaces of the stomatal pores. In astomatous leaf surfaces of C. arabica and Populus x canadensis Moench, average r(P) was 2.0 and 2.4 nm, respectively, which is four to eight times larger than previous estimations of cuticular r(P). These results indicate that for polar solutes, the size exclusion limits of plant surfaces can be considerably larger than previously estimated. The far-reaching implications of these findings are discussed. PMID:18334002

  1. Leaf Area Index Estimation in Vineyards from Uav Hyperspectral Data, 2d Image Mosaics and 3d Canopy Surface Models

    NASA Astrophysics Data System (ADS)

    Kalisperakis, I.; Stentoumis, Ch.; Grammatikopoulos, L.; Karantzalos, K.

    2015-08-01

    The indirect estimation of leaf area index (LAI) in large spatial scales is crucial for several environmental and agricultural applications. To this end, in this paper, we compare and evaluate LAI estimation in vineyards from different UAV imaging datasets. In particular, canopy levels were estimated from i.e., (i) hyperspectral data, (ii) 2D RGB orthophotomosaics and (iii) 3D crop surface models. The computed canopy levels have been used to establish relationships with the measured LAI (ground truth) from several vines in Nemea, Greece. The overall evaluation indicated that the estimated canopy levels were correlated (r2 > 73%) with the in-situ, ground truth LAI measurements. As expected the lowest correlations were derived from the calculated greenness levels from the 2D RGB orthomosaics. The highest correlation rates were established with the hyperspectral canopy greenness and the 3D canopy surface models. For the later the accurate detection of canopy, soil and other materials in between the vine rows is required. All approaches tend to overestimate LAI in cases with sparse, weak, unhealthy plants and canopy.

  2. Physical and mechanical properties of spinach for whole-surface online imaging inspection

    NASA Astrophysics Data System (ADS)

    Tang, Xiuying; Mo, Chang Y.; Chan, Diane E.; Peng, Yankun; Qin, Jianwei; Yang, Chun-Chieh; Kim, Moon S.; Chao, Kuanglin

    2011-06-01

    The physical and mechanical properties of baby spinach were investigated, including density, Young's modulus, fracture strength, and friction coefficient. The average apparent density of baby spinach leaves was 0.5666 g/mm3. The tensile tests were performed using parallel, perpendicular, and diagonal directions with respect to the midrib of each leaf. The test results showed that the mechanical properties of spinach are anisotropic. For the parallel, diagonal, and perpendicular test directions, the average values for the Young's modulus values were found to be 2.137MPa, 1.0841 MPa, and 0.3914 MPa, respectively, and the average fracture strength values were 0.2429 MPa, 0.1396 MPa, and 0.1113 MPa, respectively. The static and kinetic friction coefficient between the baby spinach and conveyor belt were researched, whose test results showed that the average coefficients of kinetic and maximum static friction between the adaxial (front side) spinach leaf surface and conveyor belt were 1.2737 and 1.3635, respectively, and between the abaxial (back side) spinach leaf surface and conveyor belt were 1.1780 and 1.2451 respectively. These works provide the basis for future development of a whole-surface online imaging inspection system that can be used by the commercial vegetable processing industry to reduce food safety risks.

  3. Compositional analysis of leaf cuticular membranes isolated from tea plants (Camellia sinensis L.).

    PubMed

    Tsubaki, Shuntaro; Sakumoto, Shunichi; Uemura, Norihiro; Azuma, Jun-ichi

    2013-05-01

    Chemical constituents of cuticular membranes (CMs) isolated from three tea cultivars (Camellia sinensis (L.) O. Kuntze cvs. Yabukita, Samidori and Gokou) were compared. All CMs from the adaxial side of the leaves showed higher accumulation of wax, cutin and polysaccharide, while those from the abaxial side were abundant in cutan, showing the adaptation of the adaxial side to abiotic stresses, such as wind and rain, in contrast to the abaxial side, which provides defence against pathogens. Yabukita, a major tea cultivar in Japan, developed thick CMs while Samidori and Gokou, shade-cultivated tea cultivars, had lighter CMs, reflecting their thin and soft leaves. CMs rapidly accumulated 9,10-epoxy-18-hydroxyoctadecanoic acid at a very early stage of leaf development. Additionally, shade treatment did not influence cutin biosynthesis in CMs, reflecting high adaptation of tea leaves under low light levels.

  4. Leaf Area Influence on Surface Layer in a Deciduous Forest. Part I; Site Description

    NASA Technical Reports Server (NTRS)

    Sakai, Ricardo K.; Fitzjarrald, David R.; Moore, Kathleen E.; Sicker, John W.; Munger, William; Goulden, Michael L.; Wofsy, Steven C.

    1996-01-01

    A study over a deciduous forest located in middle Massachusetts (USA) has been performed to examine the role of leaves in the forest-atmosphere interaction. Due to the seasonal presence of leaves, a deciduous forest is a 'good laboratory' to study this interaction. In this first part, a description of a 30 m micrometeorological tower as well a qualitative description of some meteorological parameters are presented. The presence of leaves affects the forest in several ways. There is a decrease of upward PAR (Photosynthetically Active Radiation) due to absorption of visible light in the canopy. Water vapor concentration increases, and the CO2 concentration decreases in the surface layer as the canopy starts to be foliated. The physical presence of the leaves is felt in other quantities such as the global albedo and the subcanopy environment.

  5. Dorsoventral asymmetry of photosynthesis and photoinhibition in flag leaves of two rice cultivars that differ in nitrogen response and leaf angle.

    PubMed

    Kumagai, Etsushi; Hamaoka, Norimitsu; Araki, Takuya; Ueno, Osamu

    2014-08-01

    Rice is believed to show photosynthetic symmetry between adaxial and abaxial leaf sides. To verify this, we re-examined dorsoventral asymmetry in photosynthesis, chlorophyll fluorescence and anatomical traits in flag leaves of two Oryza sativa cultivars that differ in nitrogen (N) response and in leaf angle: 'Akenohoshi', a cultivar that can adapt to low-N (LN), with low leaf angle (more erect leaves), and 'Shirobeniya', a cultivar that is unable to adapt to LN, with higher leaf angle. Plants were grown under standard-N (SN) and LN conditions. LN leaves of both cultivars became more erect than SN, but LN Akenohoshi still had more erect ones than Shirobeniya. Contrary to results of previous studies, leaves of both cultivars showed an asymmetry in photosynthetic rate between adaxial and abaxial sides (higher on the adaxial side) under SN. SN leaves of both cultivars showed lower susceptibility to photoinhibition on the adaxial side than on the abaxial side. However, leaves of Akenohoshi showed less asymmetry in these traits under LN than under SN, whereas leaves of Shirobeniya had similar degrees of asymmetry in these traits under both SN and LN. Both cultivars also showed dorsoventral asymmetry in anatomical traits of mesophyll tissue regardless of N level, but the degree of asymmetry was lower in LN Akenohoshi. These data reveal that rice leaves exhibit dorsoventral asymmetry in photosynthetic and anatomical features, and that the degree of asymmetry varies with cultivar and N level. It is suggested that lower leaf angles (particularly in Akenohoshi) in the presence of LN represent a light acclimation to prevent photoinhibition.

  6. Disruption of N-Αcyl Homoserine Lactone-Mediated Cell Signaling and Iron Acquisition in Epiphytic Bacteria by Leaf Surface Compounds▿

    PubMed Central

    Karamanoli, Katerina; Lindow, Steven E.

    2006-01-01

    Since N-acyl homoserine lactones (AHLs) are key mediators of cell density-dependent regulation of traits involved in virulence and epiphytic fitness in gram-negative bacteria such as Pseudomonas syringae, a variety of plant species were examined to determine their production of leaf surface compounds that could interact with these signaling systems. Leaf washings of 17 of 52 plant species tested stimulated or inhibited AHL-dependent traits in at least one of the bacterial reporter strains used. The active compounds from most plants could be distinguished from known AHLs due to different patterns of mobility during C8 and C18 reverse-phase thin-layer chromatography (TLC) and normal-phase TLC compared to the patterns for authentic bacterial AHLs. All plant extracts were also tested to determine their abilities to sequester iron and trigger bacterial siderophore synthesis on a medium containing abundant iron. Leaf washings from 16 of the 52 plant species, as well as tannic acid solutions, stimulated pyoverdine synthesis in P. syringae in a high-iron medium. These preparations also inhibited the growth of a P. syringae mutant unable to produce pyoverdine siderophores but not the growth of the wild-type bacterium. The stimulation of siderophore production and the growth inhibition by plant extracts and purified tannins were both reversed by addition of ferric chloride to culture media, indicating that iron was made unavailable by the compounds released onto the leaf surface. PMID:16997987

  7. Environmental controls on leaf wax δD ratios in surface peats across the monsoonal region of China

    NASA Astrophysics Data System (ADS)

    Huang, X.; Xue, J.; Wang, X.; Meyers, P. A.

    2015-09-01

    Leaf wax molecular and isotopic ratios are generally considered robust isotopic paleohydrologic proxies. Here we evaluate the proxy value of the molecular distributions and hydrogen isotopic compositions of long chain n-alkanes (δDalk) in surface peats collected from peatlands across a range of annual air temperatures from 1 to 15 °C and a range of annual mean precipitation from 720 to 2070 mm in the monsoonal region of China. The alkane ratios (ACL and CPI) and δDalk values show relatively large variations in multiple samples from a single site, highlighting the complexity of these ratios at a small spatial scale. In the montane Zoigê peatland, the apparent fractionation between precipitation and δDalk is more positive than in the other six sites, which is possibly an effect of the higher conductivity of the water in this high elevation site (3500 m a.s.l.). At a larger spatial scale, the site-averaged CPI ratios and the δDalk values of n-C29 and n-C31 alkanes show significant correlation with the air temperature and precipitation. These results support the application of the CPI ratio and the δDalk ratios of n-C29 and n-C31 alkanes as sensitive paleohydrologic proxies on millennial and larger timescales.

  8. Leaf surface lipophilic compounds as one of the factors of silver birch chemical defense against larvae of gypsy moth.

    PubMed

    Martemyanov, Vyacheslav V; Pavlushin, Sergey V; Dubovskiy, Ivan M; Belousova, Irina A; Yushkova, Yuliya V; Morosov, Sergey V; Chernyak, Elena I; Glupov, Victor V

    2015-01-01

    Plant chemical defense against herbivores is a complex process which involves a number of secondary compounds. It is known that the concentration of leaf surface lipophilic compounds (SLCs), particularly those of flavonoid aglycones are increased with the defoliation treatment of silver birch Betula pendula. In this study we investigated how the alteration of SLCs concentration in the food affects the fitness and innate immunity of the gypsy moth Lymantria dispar. We found that a low SLCs concentrations in consumed leaves led to a rapid larval development and increased females' pupae weight (= fecundity) compared to larvae fed with leaves with high SLCs content. Inversely, increasing the compounds concentration in an artificial diet produced the reverse effects: decreases in both larval weight and larval survival. Low SLCs concentrations in tree leaves differently affected larval innate immunity parameters. For both sexes, total hemocytes count in the hemolymph increased, while the activity of plasma phenoloxidase decreased when larvae consume leaves with reduced content of SLCs. Our results clearly demonstrate that the concentration of SLCs in silver birch leaves affects not only gypsy moth fitness but also their innate immune status which might alter the potential resistance of insects against infections and/or parasitoids. PMID:25816371

  9. Leaf Surface Lipophilic Compounds as One of the Factors of Silver Birch Chemical Defense against Larvae of Gypsy Moth

    PubMed Central

    Martemyanov, Vyacheslav V.; Pavlushin, Sergey V.; Dubovskiy, Ivan M.; Belousova, Irina A.; Yushkova, Yuliya V.; Morosov, Sergey V.; Chernyak, Elena I.; Glupov, Victor V.

    2015-01-01

    Plant chemical defense against herbivores is a complex process which involves a number of secondary compounds. It is known that the concentration of leaf surface lipophilic compounds (SLCs), particularly those of flavonoid aglycones are increased with the defoliation treatment of silver birch Betula pendula. In this study we investigated how the alteration of SLCs concentration in the food affects the fitness and innate immunity of the gypsy moth Lymantria dispar. We found that a low SLCs concentrations in consumed leaves led to a rapid larval development and increased females’ pupae weight (= fecundity) compared to larvae fed with leaves with high SLCs content. Inversely, increasing the compounds concentration in an artificial diet produced the reverse effects: decreases in both larval weight and larval survival. Low SLCs concentrations in tree leaves differently affected larval innate immunity parameters. For both sexes, total hemocytes count in the hemolymph increased, while the activity of plasma phenoloxidase decreased when larvae consume leaves with reduced content of SLCs. Our results clearly demonstrate that the concentration of SLCs in silver birch leaves affects not only gypsy moth fitness but also their innate immune status which might alter the potential resistance of insects against infections and/or parasitoids. PMID:25816371

  10. Leaf surface lipophilic compounds as one of the factors of silver birch chemical defense against larvae of gypsy moth.

    PubMed

    Martemyanov, Vyacheslav V; Pavlushin, Sergey V; Dubovskiy, Ivan M; Belousova, Irina A; Yushkova, Yuliya V; Morosov, Sergey V; Chernyak, Elena I; Glupov, Victor V

    2015-01-01

    Plant chemical defense against herbivores is a complex process which involves a number of secondary compounds. It is known that the concentration of leaf surface lipophilic compounds (SLCs), particularly those of flavonoid aglycones are increased with the defoliation treatment of silver birch Betula pendula. In this study we investigated how the alteration of SLCs concentration in the food affects the fitness and innate immunity of the gypsy moth Lymantria dispar. We found that a low SLCs concentrations in consumed leaves led to a rapid larval development and increased females' pupae weight (= fecundity) compared to larvae fed with leaves with high SLCs content. Inversely, increasing the compounds concentration in an artificial diet produced the reverse effects: decreases in both larval weight and larval survival. Low SLCs concentrations in tree leaves differently affected larval innate immunity parameters. For both sexes, total hemocytes count in the hemolymph increased, while the activity of plasma phenoloxidase decreased when larvae consume leaves with reduced content of SLCs. Our results clearly demonstrate that the concentration of SLCs in silver birch leaves affects not only gypsy moth fitness but also their innate immune status which might alter the potential resistance of insects against infections and/or parasitoids.

  11. Leaf surface factors of transgenic Bt cotton associated with the feeding behaviors of cotton aphids: a case study on non-target effects.

    PubMed

    Xue, Kun; Deng, Su; Wang, RongJiang; Yan, FengMing; Xu, ChongRen

    2008-02-01

    The present paper reports case study results of the risk assessment of transgenic Bt cotton on a non-target pest, cotton aphid, Aphis gossypii. Several types of techniques, i.e., electrical penetration graph (EPG), light and electron microscopy, bioassays and chemical analysis, were applied to investigate physical and chemical leaf factors of 2 transgenic Bt cotton lines (GK12 and GK19) and their parental non-Bt cotton line (Simian3) associated with searching and feeding behaviors of cotton aphids on leaves or leaf extracts of cotton plants. EPG results showed that there were some differences among behaviors of cotton aphids on 2 Bt cotton and 1 non-Bt cotton lines. Cotton aphids performed similarly to leaf surface extracts from 3 cotton lines; and leaf surface chemicals, mainly volatiles and waxes, were almost identical in the components and concentrations among the cotton lines. However, three cotton lines were quite different from each other in the densities of certain kinds of covering trichomes. Therefore, the relationships between the physical characteristics and the searching behaviors of cotton aphids on the three cotton lines were constructed as the regression equations. Glandular trichomes and covering trichomes with 5 branches influenced the cotton aphids' searching behaviors effectively; and other trichomes with other branches affected aphids in varying ways. These results demonstrated that leaf surface physical factors of transgenic Bt cotton lines different from their parental non-Bt line could affect the penetration behaviors of non-target cotton aphids. Cotton aphids penetrate and feed more easily on two Bt cotton lines than on the non-Bt cotton line.

  12. SHALLOT-LIKE1 is a KANADI transcription factor that modulates rice leaf rolling by regulating leaf abaxial cell development.

    PubMed

    Zhang, Guang-Heng; Xu, Qian; Zhu, Xu-Dong; Qian, Qian; Xue, Hong-Wei

    2009-03-01

    As an important agronomic trait, rice (Oryza sativa L.) leaf rolling has attracted much attention from plant biologists and breeders. Moderate leaf rolling increases the photosynthesis of cultivars and hence raises grain yield. However, the relevant molecular mechanism remains unclear. Here, we show the isolation and functional characterization of SHALLOT-LIKE1 (SLL1), a key gene controlling rice leaf rolling. sll1 mutant plants have extremely incurved leaves due to the defective development of sclerenchymatous cells on the abaxial side. Defective development can be functionally rescued by expression of SLL1. SLL1 is transcribed in various tissues and accumulates in the abaxial epidermis throughout leaf development. SLL1 encodes a SHAQKYF class MYB family transcription factor belonging to the KANADI family. SLL1 deficiency leads to defective programmed cell death of abaxial mesophyll cells and suppresses the development of abaxial features. By contrast, enhanced SLL1 expression stimulates phloem development on the abaxial side and suppresses bulliform cell and sclerenchyma development on the adaxial side. Additionally, SLL1 deficiency results in increased chlorophyll and photosynthesis. Our findings identify the role of SLL1 in the modulation of leaf abaxial cell development and in sustaining abaxial characteristics during leaf development. These results should facilitate attempts to use molecular breeding to increase the photosynthetic capacity of rice, as well as other crops, by modulating leaf development and rolling.

  13. SHALLOT-LIKE1 is a KANADI transcription factor that modulates rice leaf rolling by regulating leaf abaxial cell development.

    PubMed

    Zhang, Guang-Heng; Xu, Qian; Zhu, Xu-Dong; Qian, Qian; Xue, Hong-Wei

    2009-03-01

    As an important agronomic trait, rice (Oryza sativa L.) leaf rolling has attracted much attention from plant biologists and breeders. Moderate leaf rolling increases the photosynthesis of cultivars and hence raises grain yield. However, the relevant molecular mechanism remains unclear. Here, we show the isolation and functional characterization of SHALLOT-LIKE1 (SLL1), a key gene controlling rice leaf rolling. sll1 mutant plants have extremely incurved leaves due to the defective development of sclerenchymatous cells on the abaxial side. Defective development can be functionally rescued by expression of SLL1. SLL1 is transcribed in various tissues and accumulates in the abaxial epidermis throughout leaf development. SLL1 encodes a SHAQKYF class MYB family transcription factor belonging to the KANADI family. SLL1 deficiency leads to defective programmed cell death of abaxial mesophyll cells and suppresses the development of abaxial features. By contrast, enhanced SLL1 expression stimulates phloem development on the abaxial side and suppresses bulliform cell and sclerenchyma development on the adaxial side. Additionally, SLL1 deficiency results in increased chlorophyll and photosynthesis. Our findings identify the role of SLL1 in the modulation of leaf abaxial cell development and in sustaining abaxial characteristics during leaf development. These results should facilitate attempts to use molecular breeding to increase the photosynthetic capacity of rice, as well as other crops, by modulating leaf development and rolling. PMID:19304938

  14. Generating and Evaluation Leaf Area Index (LAI) from MODIS MultiAngle Implementation of Atmospheric Correction (MAIAC) Surface Reflectance Dataset

    NASA Astrophysics Data System (ADS)

    Chen, C.; Park, T.; Yan, K.; Lyapustin, A.; Wang, Y.; CHOI, S.; Yang, B.; Knyazikhin, Y.; Myneni, R. B.

    2015-12-01

    This study generates and evaluates prototype Leaf Area Index (LAI) product based on MODerate resolution Imaging Spectroradiometer's (MODIS) Bidirectional Reflectance Factor (BRF, commonly known as surface reflectance) which is a product of MultiAngle Implementation of Atmospheric Correction (MAIAC) package. LAI is a key parameter of vegetation in characterizing interactions of energy and mass between the Earth's surface and atmosphere. On the other hand, MAIAC BRF is retrieved from a new atmospheric correction algorithm, which has higher spatial resolution and is believed to have more reliable cloud/aerosol detection technique than standard MODIS BRF product. Two main objectives of this study are: 1). Maintaining the radiative transfer theory based LAI algorithm's look up table (LUT) unchanged, to compare LAI product retrieved from different versions of BRF products (MODIS collection 5, collection 6 and MAIAC); 2). To adjust the LUT to resolve LAI's possible systematic discrepancies resulting from atmospheric correction methods within the input BRF other than our LAI algorithm. Before the LUT adjusting, comparing to standard MODIS products shows that MAIAC LAI product will overestimate among herbaceous biome types which have low LAI values, while underestimate among woody biome types which have relatively higher values. Based on the theory of radiative transfer of canopy spectral invariants, two biome and MAIAC specific configurable parameters (Single Scattering Albedo and Uncertainty) in the LUT are adjusted to minimize the inconsistency due to input BRFs. Experiments shows that our new result: 1). has good agreement with field measured data (e.g. DIRECT); 2) is consistent with standard MODIS LAI product.

  15. Assimilation of leaf area index and surface soil moisture satellite observations into the SIM hydrological model over France

    NASA Astrophysics Data System (ADS)

    Fairbairn, David; Calvet, Jean-Christophe; Mahfouf, Jean-Francois; Barbu, Alina

    2016-04-01

    Hydrological models have a variety of uses, including flood and drought prediction and water management. The SAFRAN-ISBA-MODCOU (SIM) hydrological model consists of three stages: An atmospheric analysis (SAFRAN) over France, which forces a land surface model (ISBA-A-gs), which then provides drainage and runoff inputs to a hydrological model (MODCOU). The river discharge from MODCOU is validated using observed river discharge over France. Data assimilation (DA) combines a short model forecast from the past with observations to improve the estimate of the model state. The ISBA-A-gs representation of soil moisture and its influence by vegetation can be improved by assimilating surface soil moisture (SSM) and leaf area index (LAI) observations respectively. The Advanced Scatterometer (ASCAT) on board the MetOP satellite measures a low-frequency microwave signal, which is used to retrieve daily SSM over France. The SPOT-VGT sensor observes LAI over France at a temporal frequency of about 10 days. The Simplified Extended Kalman (SEKF) filter combines the model and observed variables by weighting them according to their respective accuracies. Although the SEKF makes incorrect linear assumptions, past experiments have shown that it improves on the model estimates of SSM and LAI. However, due to nonlinearities in the land surface model, improvements in SSM and LAI do not imply improved soil moisture fluxes (drainage, runoff and evapotranspiration). This study indirectly examines the impact of the SEKF on the soil moisture fluxes using the MODCOU hydrological model. The ISBA-A-gs model appears to underestimate the LAI for grasslands in winter and spring, which results in an underestimation (overestimation) of evapotranspiration (drainage and runoff). The excess water flowing into the rivers and aquifers contributes to an overestimation of the MODCOU discharge. Assimilating LAI observations slightly increases the LAI analysis in winter and spring and therefore reduces the

  16. Leaf-galling phylloxera on grapes reprograms host metabolism and morphology

    PubMed Central

    Nabity, Paul D.; Haus, Miranda J.; Berenbaum, May R.; DeLucia, Evan H.

    2013-01-01

    Endoparasitism by gall-forming insects dramatically alters the plant phenotype by altering growth patterns and modifying plant organs in ways that appear to directly benefit the gall former. Because these morphological and physiological changes are linked to the presence of the insect, the induced phenotype is said to function as an extension of the parasite, albeit by unknown mechanisms. Here we report the gall-forming aphid-like parasite phylloxera, Daktulosphaira vitifoliae, induces stomata on the adaxial surface of grape leaves where stomata typically do not occur. We characterized the function of the phylloxera-induced stomata by tracing transport of assimilated carbon. Because induction of stomata suggests a significant manipulation of primary metabolism, we also characterized the gall transcriptome to infer the level of global reconfiguration of primary metabolism and the subsequent changes in downstream secondary metabolism. Phylloxera feeding induced stomata formation in proximity to the insect and promoted the assimilation and importation of carbon into the gall. Gene expression related to water, nutrient, and mineral transport; glycolysis; and fermentation increased in leaf-gall tissues. This shift from an autotrophic to a heterotrophic profile occurred concurrently with decreased gene expression for nonmevalonate and terpenoid synthesis and increased gene expression in shikimate and phenylpropanoid biosynthesis, secondary metabolite systems that alter defense status in grapes. These functional insect-induced stomata thus comprise part of an extended phenotype, whereby D. vitifoliae globally reprograms grape leaf development to alter patterns of primary metabolism, nutrient mobilization, and defense investment in favor of the galling habit. PMID:24067657

  17. Regulation of MIR165/166 by class II and class III homeodomain leucine zipper proteins establishes leaf polarity

    PubMed Central

    Merelo, Paz; Ram, Hathi; Pia Caggiano, Monica; Ohno, Carolyn; Ott, Felix; Straub, Daniel; Graeff, Moritz; Cho, Seok Keun; Yang, Seong Wook; Wenkel, Stephan; Heisler, Marcus G.

    2016-01-01

    A defining feature of plant leaves is their flattened shape. This shape depends on an antagonism between the genes that specify adaxial (top) and abaxial (bottom) tissue identity; however, the molecular nature of this antagonism remains poorly understood. Class III homeodomain leucine zipper (HD-ZIP) transcription factors are key mediators in the regulation of adaxial–abaxial patterning. Their expression is restricted adaxially during early development by the abaxially expressed microRNA (MIR)165/166, yet the mechanism that restricts MIR165/166 expression to abaxial leaf tissues remains unknown. Here, we show that class III and class II HD-ZIP proteins act together to repress MIR165/166 via a conserved cis-element in their promoters. Organ morphology and tissue patterning in plants, therefore, depend on a bidirectional repressive circuit involving a set of miRNAs and its targets. PMID:27698117

  18. Leaf Activities.

    ERIC Educational Resources Information Center

    Mingie, Walter

    Leaf activities can provide a means of using basic concepts of outdoor education to learn in elementary level subject areas. Equipment needed includes leaves, a clipboard with paper, and a pencil. A bag of leaves may be brought into the classroom if weather conditions or time do not permit going outdoors. Each student should pick a leaf, examine…

  19. Investigation of the influence of liquid water films on O3 and PAN deposition on plant leaf surfaces treated with organic / inorganic compounds

    NASA Astrophysics Data System (ADS)

    Sun, Shang; Moravek, Alexander; von der Heyden, Lisa; Held, Andreas; Kesselmeier, Jürgen; Sörgel, Matthias

    2016-04-01

    Liquid water films on environmental surfaces play an important role in various fields of interest (Burkhardt and Eiden, 1994). For example, the deposition of water soluble trace gases could be increased by surface moisture. Chameides and Stelson (1992) found out that the dissolution of trace gases in airborne particulate matter increases with rising water/solid ratio of the particles. Further, Flechard et al. (1999) concluded that deliquescent salt particles represent a potential sink for trace gases, depending on their chemical property. The formation of surface water films and its influence on the gas deposition was proposed by many previous studies (Fuentes and Gillespie, 1992, Burkhardt and Eiden, 1994, van Hove et al., 1989, Burkhardt et al., 1999, Flechard et al., 1999). In this study we investigate the influence of leaf surface water films on the deposition of O3 and PAN under controlled laboratory conditions. A twin cuvette system described in Sun et al. (2015) was used to control the environmental parameters such as light, temperature, trace gas mixing ratio and humidity. Furthermore, the leaf surface was treated with various organic and inorganic solutions to investigate the influence of deposited compounds on the electrical surface conductance of the leaves and the surface deposition of O3 and PAN at various relative humidities. The result shows that RHcrit, where the electrical surface conductance (G) increases exponentially, was 40 % during the light period and 50 % during the dark period. Furthermore, we observed that the formation of the leaf surface liquid film was depended on the deposited compounds on the leaf cuticles. For the O3 deposition on plants (Quercus ilex) a clear enhancement at rising environmental air humidity under light and dark condition was found. The increase during light conditions can be related partly to increasing stomatal conductance with higher RH. From the non-stomatal deposition measured in dark experiments, we could

  20. Surface morphology and chemistry of Prunus laurocerasus L. leaves: a study using X-ray photoelectron spectroscopy, time-of-flight secondary-ion mass spectrometry, atomic-force microscopy and scanning-electron microscopy.

    PubMed

    Perkins, Mark C; Roberts, Clive J; Briggs, David; Davies, Martyn C; Friedmann, Adrian; Hart, Clifford A; Bell, Gordon A

    2005-04-01

    The surface properties of the plant cuticle play a crucial role in plant-pathogen interactions and the retention and penetration of agriculturally important chemicals. This paper describes the use of X-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion mass spectrometry (ToF-SIMS), tapping-mode atomic force microscopy (TM-AFM) and scanning electron microscopy (SEM) to determine surface-specific chemical and material properties of the adaxial surface of Prunus laurocerasus L. leaves. XPS data, derived from the uppermost few nanometres (< 10 nm) of the leaf surface, were consistent with the wax components and functionality known to be present within the waxes. ToF-SIMS provided molecular speciation from the outermost monolayer of the leaf surface, indicating the importance of a family of acetates with chain lengths ranging from C20 to C34. The presence of alkanes with C29 and C31 chain lengths was also confirmed. SEM and TM-AFM topography images revealed a textured granular surface, while simultaneously recorded AFM phase images revealed heterogeneous material properties at the nanoscale. The relevance of these data to plant cuticle development, allelochemistry and agrochemical delivery is discussed.

  1. SHALLOT-LIKE1 Is a KANADI Transcription Factor That Modulates Rice Leaf Rolling by Regulating Leaf Abaxial Cell Development[W][OA

    PubMed Central

    Zhang, Guang-Heng; Xu, Qian; Zhu, Xu-Dong; Qian, Qian; Xue, Hong-Wei

    2009-01-01

    As an important agronomic trait, rice (Oryza sativa L.) leaf rolling has attracted much attention from plant biologists and breeders. Moderate leaf rolling increases the photosynthesis of cultivars and hence raises grain yield. However, the relevant molecular mechanism remains unclear. Here, we show the isolation and functional characterization of SHALLOT-LIKE1 (SLL1), a key gene controlling rice leaf rolling. sll1 mutant plants have extremely incurved leaves due to the defective development of sclerenchymatous cells on the abaxial side. Defective development can be functionally rescued by expression of SLL1. SLL1 is transcribed in various tissues and accumulates in the abaxial epidermis throughout leaf development. SLL1 encodes a SHAQKYF class MYB family transcription factor belonging to the KANADI family. SLL1 deficiency leads to defective programmed cell death of abaxial mesophyll cells and suppresses the development of abaxial features. By contrast, enhanced SLL1 expression stimulates phloem development on the abaxial side and suppresses bulliform cell and sclerenchyma development on the adaxial side. Additionally, SLL1 deficiency results in increased chlorophyll and photosynthesis. Our findings identify the role of SLL1 in the modulation of leaf abaxial cell development and in sustaining abaxial characteristics during leaf development. These results should facilitate attempts to use molecular breeding to increase the photosynthetic capacity of rice, as well as other crops, by modulating leaf development and rolling. PMID:19304938

  2. Leaf gas exchange and water status responses of a native and non-native grass to precipitation across contrasting soil surfaces in the Sonoran Desert.

    PubMed

    Ignace, Danielle D; Huxman, Travis E; Weltzin, Jake F; Williams, David G

    2007-06-01

    Arid and semi-arid ecosystems of the southwestern US are undergoing changes in vegetation composition and are predicted to experience shifts in climate. To understand implications of these current and predicted changes, we conducted a precipitation manipulation experiment on the Santa Rita Experimental Range in southeastern Arizona. The objectives of our study were to determine how soil surface and seasonal timing of rainfall events mediate the dynamics of leaf-level photosynthesis and plant water status of a native and non-native grass species in response to precipitation pulse events. We followed a simulated precipitation event (pulse) that occurred prior to the onset of the North American monsoon (in June) and at the peak of the monsoon (in August) for 2002 and 2003. We measured responses of pre-dawn water potential, photosynthetic rate, and stomatal conductance of native (Heteropogon contortus) and non-native (Eragrostis lehmanniana) C(4) bunchgrasses on sandy and clay-rich soil surfaces. Soil surface did not always amplify differences in plant response to a pulse event. A June pulse event lead to an increase in plant water status and photosynthesis. Whereas the August pulse did not lead to an increase in plant water status and photosynthesis, due to favorable soil moisture conditions facilitating high plant performance during this period. E. lehmanniana did not demonstrate heightened photosynthetic performance over the native species in response to pulses across both soil surfaces. Overall accumulated leaf-level CO(2) response to a pulse event was dependent on antecedent soil moisture during the August pulse event, but not during the June pulse event. This work highlights the need to understand how desert species respond to pulse events across contrasting soil surfaces in water-limited systems that are predicted to experience changes in climate.

  3. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses

    PubMed Central

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo; Atwell, Susanna; Martens, Helle J.; Pedas, Pai R.; Hansen, Sara F.; Nawrath, Christiane; Scheller, Henrik V.; Kliebenstein, Daniel J.; Sakuragi, Yumiko

    2015-01-01

    The epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis. PMID:26257757

  4. Investigation on the effect of RF air plasma and neem leaf extract treatment on the surface modification and antimicrobial activity of cotton fabric

    NASA Astrophysics Data System (ADS)

    Vaideki, K.; Jayakumar, S.; Rajendran, R.; Thilagavathi, G.

    2008-02-01

    A thorough investigation on the antimicrobial activity of RF air plasma and azadirachtin (neem leaf extract) treated cotton fabric has been dealt with in this paper. The cotton fabric was given a RF air plasma treatment to improve its hydrophilicity. The process parameters such as electrode gap, time of exposure and RF power have been varied to study their effect in improving the hydrophilicity of the cotton fabric and they were optimized based on the static immersion test results. The neem leaf extract (azadirachtin) was applied on fabric samples to impart antimicrobial activity. The antimicrobial efficacy of the samples have been analysed and compared with the efficacy of the cotton fabric treated with the antimicrobial finish alone. The investigation reveals that the RF air plasma has modified the surface of the fabric, which in turn increased the antimicrobial activity of the fabric when treated with azadirachtin. The surface modification due to RF air plasma treatment has been analysed by comparing the FTIR spectra of the untreated and plasma treated samples. The molecular interaction between the fabric, azadirachtin and citric acid which was used as a cross linking agent to increase the durability of the antimicrobial finish has also been analysed using FTIR spectra.

  5. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses

    DOE PAGES

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo; Atwell, Susanna; Martens, Helle J.; Pedas, Pai R.; Hansen, Sara F.; Nawrath, Christiane; Scheller, Henrik V.; Kliebenstein, Daniel J.; et al

    2015-07-22

    Here we report that the epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed andmore » surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis.« less

  6. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses

    SciTech Connect

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo; Atwell, Susanna; Martens, Helle J.; Pedas, Pai R.; Hansen, Sara F.; Nawrath, Christiane; Scheller, Henrik V.; Kliebenstein, Daniel J.; Sakuragi, Yumiko

    2015-07-22

    Here we report that the epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis.

  7. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses.

    PubMed

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo; Atwell, Susanna; Martens, Helle J; Pedas, Pai R; Hansen, Sara F; Nawrath, Christiane; Scheller, Henrik V; Kliebenstein, Daniel J; Sakuragi, Yumiko

    2015-01-01

    The epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis. PMID:26257757

  8. Land surface phenology in eastern United States watersheds: relationship between remote sensing metrics, stream chemistry, snow cover, and leaf and bird phenology

    NASA Astrophysics Data System (ADS)

    White, M. A.; Baker, M.; Weller, D.; Jordan, T.

    2006-12-01

    Remote sensing of terrestrial land surfaces has long promised an unprecedented ability to regularly and consistently monitor patterns of vegetation phenology, which in turn implied an ability to develop prognostic phenology models and/or directly to force seasonality within climate models. Within the last five years, though, research has shown that land surface phenology, which is the integral signal of atmospheric, snow, soil, cloud, and vegetation, can be dramatically different than vegetation phenology alone. Consequently, there is a strong need to understand the usually unique relationship between remotely sensed land surface phenology and a continuum of ground-based processes. Here, using a network of watersheds in the Coastal Plain and Piedmont regions of the Chesapeake Bay, we conducted a four-part analysis for the 1997 to 1999 period. First, using a recently developed land surface phenology technique designed to represent a continuum, rather than a specific event (i.e. the start of the growing season), we calculated the daily percent above threshold (PAT), a metric of the percent of the watershed above a locally assigned greenness threshold. Second, we assembled a collection of measured leaf and hummingbird phenology and snow cover data. Third, we obtained weekly measurements of stream flow, total nitrogen (N), organic N, Kjeldahl N, ammonium, nitrate, total phosphorous, organic phosphorous, and phosphate. Fourth, as the stream chemistry data was collected irregularly across watersheds, we then calculated weekly average PAT and stream chemistry values. We found that for these watersheds, observed patterns of PAT increase were unrelated to snow cover and coincident with a continuum of ground-measured leaf phenology and hummingbird appearance. The spring increase in PAT also was consistently related to reductions in nitrate load, but not to other water chemistry measurement, suggesting an interaction between vegetative N demand and stream nitrate.

  9. Vannella epipetala n. sp. isolated from the leaf surface of Spondias mombin (Anacardiaceae) growing in the dry forest of Costa Rica.

    PubMed

    Amaral-Zettler, Linda A; Cole, Jeffrey; Laatsch, Abby D; Nerad, Thomas A; Anderson, O Roger; Reysenbach, Anna-Louise

    2006-01-01

    As part of a Microbial Observatory of Caterpillars located in the Area de Conservacíon Guanacaste (ACG) in northwestern Costa Rica, we isolated a novel species of the genus Vannella associated with the food of the caterpillars of the saturniid moth Rothschildia lebeau, namely the leaves of the dry forest deciduous tree Spondias mombin (Anacardiaceae). The new species can be distinguished from other described species of the genus by the presence of a plasmalemma coated with a thickened, osmiophilic lamina containing glycostyles, and by its unusual habitat, the leaf surfaces or phylosphere of S. mombin. We further established the novelty of our isolate by sequencing its nuclear small-subunit (SSU) rRNA gene and inferring its phylogenetic position among all other currently sequenced members of the genera Vannella and Platyamoeba. Our results reveal that our isolate shares most recent common ancestry with three strains of Platyamoeba placida, the type species of the genus Platyamoeba. Despite this placement, the isolate clearly possesses glycostyles that are the hallmark of the genus Vannella. In addition to the cultured isolate, we also present a closely related sequence from a SSU rRNA gene clone library constructed from a DNA extract of leaf-wash of S. mombin with sterile water.

  10. Leaf Development

    PubMed Central

    2013-01-01

    Leaves are the most important organs for plants. Without leaves, plants cannot capture light energy or synthesize organic compounds via photosynthesis. Without leaves, plants would be unable perceive diverse environmental conditions, particularly those relating to light quality/quantity. Without leaves, plants would not be able to flower because all floral organs are modified leaves. Arabidopsis thaliana is a good model system for analyzing mechanisms of eudicotyledonous, simple-leaf development. The first section of this review provides a brief history of studies on development in Arabidopsis leaves. This history largely coincides with a general history of advancement in understanding of the genetic mechanisms operating during simple-leaf development in angiosperms. In the second section, I outline events in Arabidopsis leaf development, with emphasis on genetic controls. Current knowledge of six important components in these developmental events is summarized in detail, followed by concluding remarks and perspectives. PMID:23864837

  11. A FILAMENTOUS FLOWER orthologue plays a key role in leaf patterning in opium poppy.

    PubMed

    Vosnakis, Nikolaos; Maiden, Afiqah; Kourmpetli, Sofia; Hands, Philip; Sharples, Donna; Drea, Sinéad

    2012-11-01

    The plant-specific YABBY genes were initially defined by their roles in determining abaxial/adaxial cell fate in lateral organs of eudicots, and repressing meristematic genes in differentiating tissues such as leaves. In Arabidopsis thaliana FILAMENTOUS FLOWER (FIL) is also required for inflorescence and floral meristem establishment and flower development in a pathway involving the floral transition and identity genes. Here we describe the characterization of a FIL orthologue from the basal eudicot, Papaver somniferum (the opium poppy), and demonstrate a role for the gene in patterning the highly lobed leaf of the poppy. Silencing of PapsFIL using viral-induced gene silencing resulted in leaves of reduced laminar area, more pronounced margin serration and, in some cases, leaf bifurcation. In contrast, the gene does not appear to affect the development of the flower, and these variations in function are discussed in relation to its taxonomic position as a basal eudicot and its determinate growth habit.

  12. Plant surfaces with cuticular folds and their replicas: influence of microstructuring and surface chemistry on the attachment of a leaf beetle.

    PubMed

    Prüm, Bettina; Florian Bohn, Holger; Seidel, Robin; Rubach, Stephan; Speck, Thomas

    2013-05-01

    Plant surfaces covered either with epicuticular wax crystals or cuticular folds have been shown to strongly reduce the ability of insects to attach to them. However, the relative impact of surface structuring vs. surface chemistry on insect attachment remains unclear. To understand the mechanisms reducing adhesion of insects on plant surfaces in more detail, we performed traction experiments (i) on plant surfaces covered with cuticular folds of different dimensions, and on their (ii) untreated and (iii) hydrophobized replicas. As a reference, measurements were performed on replicas of smooth plant surfaces and of glass. Traction forces were measured with a highly sensitive force transducer, using tethered male Colorado potato beetles (Leptinotarsa decemlineata) as a model insect species. Contact angle measurements with water and diiodomethane were also performed to examine the physicochemical properties of the test surfaces. We found that surface structuring has a strong influence on the magnitude of the attachment force. In contrast, under the chosen experimental conditions, surface chemistry had no significant influence. Our results indicate that attachment of the beetles is reduced solely by the dimensions of the folds, with cuticular folds of about 0.5 μm in both height and width being the most effective. Contrary to the attachment of beetles, the wettability of the surfaces was considerably influenced by both surface structuring and chemistry. These results contribute to a better understanding of plant-insect interactions and the function of microstructured surfaces, and may facilitate the development of biomimetic anti-adhesive surfaces. PMID:23391991

  13. Captive bubble and sessile drop surface characterization of a submerged aquatic plant, Hydrilla verticillata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface energy parameters of the invasive aquatic weed, Hydrilla verticillata, were determined using contact angle measurements using two different methods. The abaxial and adaxial surfaces of the leaves and stem were characterized for the weed while submerged in water using captive air and octa...

  14. “Breath figures” on leaf surfaces—formation and effects of microscopic leaf wetness

    PubMed Central

    Burkhardt, Juergen; Hunsche, Mauricio

    2013-01-01

    “Microscopic leaf wetness” means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past. PMID:24167510

  15. Global estimation of evapotranspiration using a leaf area index-based surface energy and water balance model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies of global hydrologic cycles, carbon cycles and climate change are greatly facilitated when global estimates of evapotranspiration (E) are available. We have developed an air-relative-humidity-based two-source (ARTS) E model that simulates the surface energy balance, soil water balance, and e...

  16. A genetic link between epigenetic repressor AS1-AS2 and a putative small subunit processome in leaf polarity establishment of Arabidopsis.

    PubMed

    Matsumura, Yoko; Ohbayashi, Iwai; Takahashi, Hiro; Kojima, Shoko; Ishibashi, Nanako; Keta, Sumie; Nakagawa, Ayami; Hayashi, Rika; Saéz-Vásquez, Julio; Echeverria, Manuel; Sugiyama, Munetaka; Nakamura, Kenzo; Machida, Chiyoko; Machida, Yasunori

    2016-01-01

    Although the DEAD-box RNA helicase family is ubiquitous in eukaryotes, its developmental role remains unelucidated. Here, we report that cooperative action between the Arabidopsis nucleolar protein RH10, an ortholog of human DEAD-box RNA helicase DDX47, and the epigenetic repressor complex of ASYMMETRIC-LEAVES1 (AS1) and AS2 (AS1-AS2) is critical to repress abaxial (ventral) genes ETT/ARF3 and ARF4, which leads to adaxial (dorsal) development in leaf primordia at shoot apices. Double mutations of rh10-1 and as2 (or as1) synergistically up-regulated the abaxial genes, which generated abaxialized filamentous leaves with loss of the adaxial domain. DDX47 is part of the small subunit processome (SSUP) that mediates rRNA biogenesis. In rh10-1 we found various defects in SSUP-related events, such as: accumulation of 35S/33S rRNA precursors; reduction in the 18S/25S ratio; and nucleolar hypertrophy. Double mutants of as2 with mutations of genes that encode other candidate SSUP-related components such as nucleolin and putative rRNA methyltransferase exhibited similar synergistic defects caused by up-regulation of ETT/ARF3 and ARF4 These results suggest a tight link between putative SSUP and AS1-AS2 in repression of the abaxial-determining genes for cell fate decisions for adaxial development. PMID:27334696

  17. A genetic link between epigenetic repressor AS1-AS2 and a putative small subunit processome in leaf polarity establishment of Arabidopsis

    PubMed Central

    Matsumura, Yoko; Ohbayashi, Iwai; Takahashi, Hiro; Kojima, Shoko; Ishibashi, Nanako; Keta, Sumie; Nakagawa, Ayami; Hayashi, Rika; Saéz-Vásquez, Julio; Echeverria, Manuel; Sugiyama, Munetaka; Nakamura, Kenzo; Machida, Chiyoko

    2016-01-01

    ABSTRACT Although the DEAD-box RNA helicase family is ubiquitous in eukaryotes, its developmental role remains unelucidated. Here, we report that cooperative action between the Arabidopsis nucleolar protein RH10, an ortholog of human DEAD-box RNA helicase DDX47, and the epigenetic repressor complex of ASYMMETRIC-LEAVES1 (AS1) and AS2 (AS1-AS2) is critical to repress abaxial (ventral) genes ETT/ARF3 and ARF4, which leads to adaxial (dorsal) development in leaf primordia at shoot apices. Double mutations of rh10-1 and as2 (or as1) synergistically up-regulated the abaxial genes, which generated abaxialized filamentous leaves with loss of the adaxial domain. DDX47 is part of the small subunit processome (SSUP) that mediates rRNA biogenesis. In rh10-1 we found various defects in SSUP-related events, such as: accumulation of 35S/33S rRNA precursors; reduction in the 18S/25S ratio; and nucleolar hypertrophy. Double mutants of as2 with mutations of genes that encode other candidate SSUP-related components such as nucleolin and putative rRNA methyltransferase exhibited similar synergistic defects caused by up-regulation of ETT/ARF3 and ARF4. These results suggest a tight link between putative SSUP and AS1-AS2 in repression of the abaxial-determining genes for cell fate decisions for adaxial development. PMID:27334696

  18. Integrating ASCAT surface soil moisture and GEOV1 leaf area index into the SURFEX modelling platform: a land data assimilation application over France

    NASA Astrophysics Data System (ADS)

    Barbu, A. L.; Calvet, J.-C.; Mahfouf, J.-F.; Lafont, S.

    2013-07-01

    The land monitoring service of the European Copernicus programme has developed a set of satellite-based biogeophysical products, including surface soil moisture (SSM) and leaf area index (LAI). This study investigates the impact of joint assimilation of remotely sensed SSM derived from ASCAT backscatter data and the GEOV1 satellite-based LAI into the ISBA-A-gs land surface model within the SURFEX modelling platform of Meteo-France. The ASCAT data were bias corrected with respect to the model climatology by using a seasonal-based CDF (Cumulative Distribution Function) matching technique. A multivariate multi-scale land data assimilation system (LDAS) based on the Extended Kalman Filter (EKF) is used for monitoring the soil moisture, terrestrial vegetation, surface carbon and energy fluxes across the France domain at a spatial resolution of 8 km. Each model grid box is divided in a number of land covers, each having its own set of prognostic variables. The filter algorithm is designed to provide a distinct analysis for each land cover while using one observation per grid box. The updated values are aggregated by computing a weighted average. In this study, it is demonstrated that the assimilation scheme works effectively within the ISBA-A-gs model over a four-year period (2008-2011). The EKF is able to extract useful information from the data signal at the grid scale and to distribute the root-zone soil moisture and LAI increments among the mosaic structure of the model. The impact of the assimilation on the vegetation phenology and on the water and carbon fluxes varies from one season to another. The spring drought of 2011 is an interesting case study showing the potential of the assimilation to improve drought monitoring. A comparison between simulated and in situ soil moisture gathered at the twelve SMOSMANIA stations shows improved anomaly correlations for eight stations.

  19. Improvement of oleuropein extractability by optimising steam blanching process as pre-treatment of olive leaf extraction via response surface methodology.

    PubMed

    Stamatopoulos, Konstantinos; Katsoyannos, Evangelos; Chatzilazarou, Arhontoula; Konteles, Spyros J

    2012-07-15

    Impact of steam, hot water blanching and UV-C irradiation as pre-treatments on extraction of oleuropein and related biophenols from olive leaves (OLs), was investigated. Moreover, particle size effect of olive leaves and steam blanching duration were selected as independent variables to optimise steam blanching process in terms of oleuropein content (OC) and antioxidant activity (AC) of ethanolic extracts, by using response surface methodology. Optimum conditions for OC and AC were 10 min steam blanching of 20-11 and 3-1mm olive leaf fraction, respectively. Depending on the extraction procedure, at optimum conditions of steaming the results indicate that steam blanching of OL prior to extraction can significantly increase oleuropein yield from 25 to 35 times compared to non-steam blanched sample, whereas the antioxidant activity increased from 4 to 13 times. No significant UV-C effect was observed in OC and AC, while hot water blanched samples showed significantly higher oleuropein yields and antioxidant activity compared to untreated samples.

  20. Cedar leaf oil poisoning

    MedlinePlus

    Cedar leaf oil is made from some types of cedar trees. Cedar leaf oil poisoning occurs when someone swallows this substance. ... The substance in cedar leaf oil that can be harmful is thujone (a hydrocarbon).

  1. Leaf anatomy and morphometry in three eucalypt clones treated with glyphosate.

    PubMed

    Tuffi Santos, L D; Sant'Anna-Santos, B F; Meira, R M S A; Ferreira, F A; Tiburcio, R A S; Machado, A F L

    2009-02-01

    This work aimed to evaluate the effects of simulated drift of glyphosate on the morphoanatomy of three eucalypt clones and to correlate the intoxication symptoms on a microscopic scale with those observed in this visual analysis. The effects of glyphosate drift were proportional to the five doses tested, with Eucalyptus urophylla being more tolerant to the herbicide than E. grandis and urograndis hybrid. The symptoms of intoxication which were similar for the different clones at 7 and 15 days after application were characterized by leaf wilting, chlorosis and curling and, at the highest rates, by necrosis, leaf senescence and death. Anatomically glyphosate doses higher than 86.4 g.ha-1 caused cellular plasmolysis, hypertrophy and hyperplasia, formation of the cicatrization tissue and dead cells on the adaxial epidermis. The spongy parenchyma had a decrease, and the palisade parenchyma and leaf blade thickness had an increase. The increased thickness in leaf blade and palisade parenchyma may be related to the plant response to glyphosate action, as a form of recovering the photosynthetically active area reduced by necroses and leaf senescence caused by the herbicide. PMID:19347155

  2. Acquisition and diversification of cladodes: leaf-like organs in the genus Asparagus.

    PubMed

    Nakayama, Hokuto; Yamaguchi, Takahiro; Tsukaya, Hirokazu

    2012-03-01

    The genus Asparagus is unusual in producing axillary, determinate organs called cladodes, which may take on either a flattened or cylindrical form. Here, we investigated the evolution of cladodes to elucidate the mechanisms at play in the diversification of shoot morphology. Our observations of Asparagus asparagoides, which has leaf-like cladodes, showed that its cladodes are anatomically and developmentally similar to leaves but differ in the adaxial/abaxial polarity of the vasculature. In addition to the expression of an ortholog of KNAT1, orthologous genes that are normally expressed in leaves, asymmetric leaves1 and HD-ZIPIII, were found to be expressed in cladode primordia in a leaf-like manner. The cylindrical cladodes of Asparagus officinalis showed largely similar expression patterns but showed evidence of being genetically abaxialized. These results provide evidence that cladodes are modified axillary shoots, suggest that the co-option of preexisting gene networks involved in leaf development transferred the leaf-like form to axillary shoots, and imply that altered expression of leaf polarity genes led to the evolution of cylindrical cladodes in the A. officinalis clade.

  3. Acquisition and diversification of cladodes: leaf-like organs in the genus Asparagus.

    PubMed

    Nakayama, Hokuto; Yamaguchi, Takahiro; Tsukaya, Hirokazu

    2012-03-01

    The genus Asparagus is unusual in producing axillary, determinate organs called cladodes, which may take on either a flattened or cylindrical form. Here, we investigated the evolution of cladodes to elucidate the mechanisms at play in the diversification of shoot morphology. Our observations of Asparagus asparagoides, which has leaf-like cladodes, showed that its cladodes are anatomically and developmentally similar to leaves but differ in the adaxial/abaxial polarity of the vasculature. In addition to the expression of an ortholog of KNAT1, orthologous genes that are normally expressed in leaves, asymmetric leaves1 and HD-ZIPIII, were found to be expressed in cladode primordia in a leaf-like manner. The cylindrical cladodes of Asparagus officinalis showed largely similar expression patterns but showed evidence of being genetically abaxialized. These results provide evidence that cladodes are modified axillary shoots, suggest that the co-option of preexisting gene networks involved in leaf development transferred the leaf-like form to axillary shoots, and imply that altered expression of leaf polarity genes led to the evolution of cylindrical cladodes in the A. officinalis clade. PMID:22415273

  4. Assimilation of Cyclopes Leaf Area Index into the ISBA-A-GS Land Surface Model over France

    NASA Astrophysics Data System (ADS)

    Barbu, Alina L.; Calvet, J.-C.; Lafont, S.

    2011-01-01

    In our study the SURFEX modeling platform is used in off-line mode. It contains the land surface model ISBA- A-gs that simulates photosynthesis and plant growth. A version of the Extended Kalman Filter scheme is used for the assimilation in situ and CYCLOPES LAI product de- rived from the SPOT4/VEGETATION sensor within the ISBA-A-gs model. The LAI data is incorporated into the model every 10 days to analyse its impact on vegetation biomass. The experiment is performed over France at a spatial resolution of 8 km. A model grid box is divided in a number of patches each having its own set of prognostic variables. The filter algorithm is designed to provide the analysis for each patches independently by using one observation per grid box. When needed, the updated values are aggregated by computing a weighted average. In this study we demonstrate that the assimilation scheme works effectively within the multi-patch version of our model. An important reduction of the LAI bias between the model and measurements is achieved.

  5. Leaf Level Chlorophyll Fluorescence Emission Spectra: Narrow Band versus Full 650-800 nm Retrievals

    NASA Astrophysics Data System (ADS)

    Middleton, E.; Zhang, Q.; Campbell, P. K.; Huemmrich, K. F.; Corp, L.; Cheng, Y.

    2012-12-01

    Recently, chlorophyll fluorescence (ChlF) retrievals in narrow spectral regions (< 1 nm, between 750-770 nm) of the near infrared (NIR) region of Earth's reflected radiation have been achieved from satellites, including the Japanese GOSAT and the European Space Agency's Sciamachy/Envisat. However, these retrievals sample the total full-spectrum ChlF and are made at non-optimal wavelengths since they are not located at the peak fluorescence emission features. We wish to estimate the total full-spectrum ChlF based on emissions obtained at selected wavelengths. For this, we drew upon leaf emission spectra measured on corn leaves obtained from a USDA experimental cornfield in MD (USA). These emission spectra were determined for the adaxial and abaxial (i.e., top and underside) surfaces of leaves measured throughout the 2008 and 2011 growing seasons (n>400) using a laboratory instrument (Fluorolog-3, Horiba Scientific, USA), recorded in either 1 nm or 5 nm increments with monochromatic excitation wavelengths of either 532 or 420 nm. The total ChlF signal was computed as the area under the continuous spectral emission curves, summing the emission intensities (counts per second) per waveband. The individual narrow (1 or 5 nm) waveband emission intensities were linearly related to full emission values, with variable success across the spectrum. Equations were developed to estimate total ChlF from these individual wavebands. Here, we report the results for the average adaxial/abaxial emissions. Very strong relationships were achieved for the relatively high fluorescence intensities at the red chlorophyll peak, centered at 685 nm (r2= 0.98, RMSE = 5.53 x 107 photons/s) and in the nearby O2-B atmospheric absorption feature centered at 688 nm (r2 = 0.94, RMSE = 4.04 x 107), as well as in the far-red peak centered at 740 nm (r2=0.94, RMSE = 5.98 x107). Very good retrieval success occurred for the O2-A atmospheric absorption feature on the declining NIR shoulder centered at 760

  6. Drag increase and drag reduction found in phytoplankton and bacterial cultures in laminar flow: Are cell surfaces and EPS producing rheological thickening and a Lotus-leaf Effect?

    NASA Astrophysics Data System (ADS)

    Jenkinson, Ian R.; Sun, Jun

    2014-03-01

    The laminar-flow viscosity of ocean and other natural waters consists of a Newtonian aqueous component contributed by water and salts, and a non-Newtonian one contributed mainly by exopolymeric polymers (EPS) derived largely from planktonic algae and bacteria. Phytoplankton and EPS form thin layers in stratified waters, often associated with density discontinuities. A recent model (Jenkinson and Sun, 2011. J. Plankton Res., 33, 373-383) investigated possible thalassorheological control of pycnocline thickness (PT) by EPS secreted by the harmful dinoflagellate Karenia mikimotoi. The model, based on published measurements of viscosity increase by this species, found that whether it can influence PT depends on the relationship between increased viscosity, deformation rates/stresses and length scale, which the present work has investigated. To do this, flow rate vs. hydrostatic pressure (and hence wall stress) was measured in cultures (relative to that in reference water) in capillaries of 5 radii 0.35-1.5 mm, close to oceanic-turbulence Kolmogorov length. We compared cultures of the potentially harmful algae, K. mikimotoi, Alexandrium catenella, Prorocentrum donghaiense, Skeletonema costatum, Phaeodactylum tricornutum and the bacterium Escherichia coli. Drag increase, ascribed to rheological thickening by EPS, occurred in the smallest capillaries, but drag reduction (DR) occurred in the largest ones. Since this occurred at Reynolds numbers Re too small for turbulence (or turbulent DR) to occur, this was laminar-flow DR. It may have been superhydrophobic DR (SDR), associated with the surfaces of the plankton and bacteria. SDR is associated with the self-cleaning Lotus-leaf Effect, in which water and dirt are repelled from surfaces bearing nm- to µm-sized irregularities coated with hydrophobic polymers. Because DR decreased measured viscosity and EPS thickening increased it, we could not validate the model. DR, however, represents hitherto unknown phenomenon in the

  7. Changes in Leaf Trichomes and Epicuticular Flavonoids during Leaf Development in Three Birch Taxa

    PubMed Central

    VALKAMA, ELENA; SALMINEN, JUHA-PEKKA; KORICHEVA, JULIA; PIHLAJA, KALEVI

    2004-01-01

    • Background and Aims Changes in number of trichomes and in composition and concentrations of their exudates throughout leaf development may have important consequences for plant adaptation to abiotic and biotic factors. In the present study, seasonal changes in leaf trichomes and epicuticular flavonoid aglycones in three Finnish birch taxa (Betula pendula, B. pubescens ssp. pubescens, and B. pubescens ssp. czerepanovii) were followed. • Methods Trichome number and ultrastructure were studied by means of light, scanning and transmission electron microscopy, while flavonoid aglycones in ethanolic leaf surface extracts were analysed by high-pressure liquid chromatography. • Key Results Density of both glandular and non-glandular trichomes decreased drastically with leaf expansion while the total number of trichomes per leaf remained constant, indicating that the final number of trichomes is established early in leaf development. Cells of glandular trichomes differentiate before those of the epidermis and produce secreted material only during the relatively short period (around 1–2 weeks) of leaf unfolding and expansion. In fully expanded leaves, glandular trichomes appeared to be at the post-secretory phase and function mainly as storage organs; they contained lipid droplets and osmiophilic material (probably phenolics). Concentrations (mg g−1 d. wt) of surface flavonoids decreased with leaf age in all taxa. However, the changes in total amount (µg per leaf) of flavonoids during leaf development were taxon-specific: no changes in B. pubescens ssp. czerepanovii, increase in B. pendula and in B. pubescens ssp. pubescens followed by the decline in the latter taxon. Concentrations of most of the individual leaf surface flavonoids correlated positively with the density of glandular trichomes within species, suggesting the participation of glandular trichomes in production of surface flavonoids. • Conclusions Rapid decline in the density of leaf trichomes and

  8. Surface Structures Involved in Plant Stomata and Leaf Colonization by Shiga-Toxigenic Escherichia Coli O157:H7

    PubMed Central

    Saldaña, Zeus; Sánchez, Ethel; Xicohtencatl-Cortes, Juan; Puente, Jose Luis; Girón, Jorge A.

    2011-01-01

    Shiga-toxigenic Escherichia coli (STEC) O157:H7 uses a myriad of surface adhesive appendages including pili, flagella, and the type 3 secretion system (T3SS) to adhere to and inflict damage to the human gut mucosa. Consumption of contaminated ground beef, milk, juices, water, or leafy greens has been associated with outbreaks of diarrheal disease in humans due to STEC. The aim of this study was to investigate which of the known STEC O157:H7 adherence factors mediate colonization of baby spinach leaves and where the bacteria reside within tainted leaves. We found that STEC O157:H7 colonizes baby spinach leaves through the coordinated production of curli, the E. coli common pilus, hemorrhagic coli type 4 pilus, flagella, and T3SS. Electron microscopy analysis of tainted leaves revealed STEC bacteria in the internal cavity of the stomata, in intercellular spaces, and within vascular tissue (xylem and phloem), where the bacteria were protected from the bactericidal effect of gentamicin, sodium hypochlorite or ozonated water treatments. We confirmed that the T3S escN mutant showed a reduced number of bacteria within the stomata suggesting that T3S is required for the successful colonization of leaves. In agreement, non-pathogenic E. coli K-12 strain DH5α transformed with a plasmid carrying the locus of enterocyte effacement (LEE) pathogenicity island, harboring the T3SS and effector genes, internalized into stomata more efficiently than without the LEE. This study highlights a role for pili, flagella, and T3SS in the interaction of STEC with spinach leaves. Colonization of plant stomata and internal tissues may constitute a strategy by which STEC survives in a nutrient-rich microenvironment protected from external foes and may be a potential source for human infection. PMID:21887151

  9. Integrating ASCAT surface soil moisture and GEOV1 leaf area index into the SURFEX modelling platform: a land data assimilation application over France

    NASA Astrophysics Data System (ADS)

    Barbu, A. L.; Calvet, J.-C.; Mahfouf, J.-F.; Lafont, S.

    2014-01-01

    The land monitoring service of the European Copernicus programme has developed a set of satellite-based biogeophysical products, including surface soil moisture (SSM) and leaf area index (LAI). This study investigates the impact of joint assimilation of remotely sensed SSM derived from Advanced Scatterometer (ASCAT) backscatter data and the Copernicus Global Land GEOV1 satellite-based LAI product into the the vegetation growth version of the Interactions between Soil Biosphere Atmosphere (ISBA-A-gs) land surface model within the the externalised surface model (SURFEX) modelling platform of Météo-France. The ASCAT data were bias corrected with respect to the model climatology by using a seasonal-based CDF (Cumulative Distribution Function) matching technique. A multivariate multi-scale land data assimilation system (LDAS) based on the extended Kalman Filter (EKF) is used for monitoring the soil moisture, terrestrial vegetation, surface carbon and energy fluxes across the domain of France at a spatial resolution of 8 km. Each model grid box is divided into a number of land covers, each having its own set of prognostic variables. The filter algorithm is designed to provide a distinct analysis for each land cover while using one observation per grid box. The updated values are aggregated by computing a weighted average. In this study, it is demonstrated that the assimilation scheme works effectively within the ISBA-A-gs model over a four-year period (2008-2011). The EKF is able to extract useful information from the data signal at the grid scale and distribute the root-zone soil moisture and LAI increments throughout the mosaic structure of the model. The impact of the assimilation on the vegetation phenology and on the water and carbon fluxes varies from one season to another. The spring drought of 2011 is an interesting case study of the potential of the assimilation to improve drought monitoring. A comparison between simulated and in situ soil moisture gathered at

  10. Effect of herbivore damage on broad leaf motion in wind

    NASA Astrophysics Data System (ADS)

    Burnett, Nicholas; Kothari, Adit

    2015-11-01

    Terrestrial plants regularly experience wind that imposes aerodynamic forces on the plants' leaves. Passive leaf motion (e.g. fluttering) and reconfiguration (e.g. rolling into a cone shape) in wind can affect the drag on the leaf. In the study of passive leaf motion in wind, little attention has been given to the effect of herbivory. Herbivores may alter leaf motion in wind by making holes in the leaf. Also, a small herbivore (e.g. snail) on a leaf can act as a point mass, thereby affecting the leaf's motion in wind. Conversely, accelerations imposed on an herbivore sitting on a leaf by the moving leaf may serve as a defense by dislodging the herbivore. In the present study, we investigated how point masses (>1 g) and holes in leaves of the tuliptree affected passive leaf motion in turbulent winds of 1 and 5 m s-1. Leaf motion was unaffected by holes in the leaf surface (about 10% of leaf area), but an herbivore's mass significantly damped the accelerations of fluttering leaves. These results suggest that an herbivore's mass, but not the damage it inflicts, can affect leaf motion in the wind. Furthermore, the damping of leaf fluttering from an herbivore's mass may prevent passive leaf motions from being an effective herbivore defense.

  11. Stomatal response and leaf injury of Pisum sativum L. with SO/sub 2/ and O/sub 3/ exposures. I. Influence of pollutant level and leaf maturity

    SciTech Connect

    Olszyk, D.M.; Tibbitts, T.W.

    1981-03-01

    Plants of Pisum sativum L. Alsweet were grown under a controlled environment and exposed to SO/sub 2/ and O/sub 3/ to determine whether changes in stomatal aperture during exposure were related to subsequent leaf injury. Stomata consistently closed with injurious levels of SO/sub 2/ and O/sub 3/. Measurements with diffusion porometers demonstrated approx. = 75 and 25% lower conductance with SO/sub 2/ and O/sub 3/ exposures, respectively, compared to the conductance of control plants. Stomata also showed a closing response with noninjurious levels of SO/sub 2/ but an opening response with noninjurious levels of O/sub 3/. Stomata closed to the same degree with combinations of SO/sub 2/ plus O/sub 3/ as with SO/sub 2/ alone. Stomata of expanding leaves closed more during pollutant exposures than stomata of expanded leaves. The abaxial and adaxial stomata both exhibited closure with SO/sub 2/ and combinations of SO/sub 2/ plus O/sub 3/, but abaxial stomata tended to close and adaxial stomata tended to open with exposure to O/sub 3/ alone. The changes in stomatal aperture were not closely correlated with the amount of leaf injury produced by different pollutant levels. Stomata closed, not only with exposure to pollutant levels that caused severe necrosis, but also with levels that caused only a trace of injury. There was no evidence of a reduced amount of closure or even stomatal opening with combinations of SO/sub 2/ and O/sub 3/ compared to plants exposed to the pollutants alone to explain the large amount of injury to plants exposed to pollutant combinations.

  12. Leaf Histology--Two Modern Methods.

    ERIC Educational Resources Information Center

    Freeman, H. E.

    1984-01-01

    Two methods for examining leaf structure are presented; both methods involve use of "superglue." The first method uses the glue to form a thin, permanent, direct replica of a leaf surface on a microscope slide. The second method uses the glue to examine the three-dimensional structure of spongy mesophyll. (JN)

  13. Analysis of leaf area index in the ECMWF land surface model and impact on latent heat and carbon fluxes: Application to West Africa

    NASA Astrophysics Data System (ADS)

    Jarlan, L.; Balsamo, G.; Lafont, S.; Beljaars, A.; Calvet, J. C.; Mougin, E.

    2008-12-01

    A new version of the land surface model of the European Centre for Medium-Range Weather Forecasts (Carbon-TESSEL, or CTESSEL) includes a vegetation growth model. This study describes a leaf area index (LAI) data assimilation system (LDAS) based on CTESSEL and satellite LAI for operational Net Ecosystem Exchange (NEE) predictions. The LDAS is evaluated over West Africa. A preliminary experiment shows a significant impact of the LAI on the CTESSEL NEE. The LAI is compared to two satellite products: the predicted annual cycle is delayed over the Sahel and savannah, and the LAI values differ from the satellite products. Preliminary to their use in the LDAS, the LAI products are rescaled to the CTESSEL predictions. The LDAS simulations are confronted to measurements of biomass and LAI for a site in Mali. The LAI analysis is shown to improve the predicted biomass and the annual cycles of the water (latent heat flux, or LE) and carbon (NEE) fluxes. Afterward, the LDAS is run over West Africa with the Moderate-Resolution Imaging Spectroradiometer products (2001-2005). The analysis of LAI shows a limited impact on LE, but it impacts strongly on NEE. Finally, the CTESSEL NEE are compared to two other models' outputs (simple biosphere (SIB) and Carnegie-Ames-Stanford (CASA)). The order of magnitude of the three data sets agrees well, and the shift in annual cycle of CTESSEL is reduced by the LDAS. It is concluded that a LAI data assimilation system is essential for NEE prediction at seasonal and interannual timescales, while a LAI satellite-based climatology may be sufficient for accurate LE predictions.

  14. Bacterial colonization of the phyllosphere of mediterranean perennial species as influenced by leaf structural and chemical features.

    PubMed

    Yadav, R K P; Karamanoli, K; Vokou, D

    2005-08-01

    In this study, we assessed various leaf structural and chemical features as possible predictors of the size of the phyllosphere bacterial population in the Mediterranean environment. We examined eight perennial species, naturally occurring and coexisting in the same area, in Halkidiki (northern Greece). They are Arbutus unedo, Quercus coccifera, Pistacia lentiscus, and Myrtus communis (evergreen sclerophyllous species), Lavandula stoechas and Cistus incanus (drought semi-deciduous species), and Calamintha nepeta and Melissa officinalis (non-woody perennial species). M. communis, L. stoechas, C. nepeta, and M. officinalis produce essential oil in substantial quantities. We sampled summer leaves from these species and (1) estimated the size of the bacterial population of their phyllosphere, (2) estimated the concentration of different leaf constituents, and (3) studied leaf morphological and anatomical features and expressed them in a quantitative way. The aromatic plants are on average more highly colonized than the other species, whereas the non-woody perennials are more highly colonized than the woody species. The population size of epiphytic bacteria is positively correlated with glandular and non-glandular trichome densities, and with water and phosphorus contents; it is negatively correlated with total phenolics content and the thickness of the leaf, of the mesophyll, and of the abaxial epidermis. No correlation was found with the density of stomata, the nitrogen, and the soluble sugar contents. By regression tree analysis, we found that the leaf-microbe system can be effectively described by three leaf attributes with leaf water content being the primary explanatory attribute. Leaves with water content >73% are the most highly colonized. For leaves with water content <73%, the phosphorus content, with a critical value of 1.34 mg g(-1) d.w., is the next explanatory leaf attribute, followed by the thickness of the adaxial epidermis. Leaves higher in phosphorus

  15. Altitude effect of leaf wax n-alkane δD in surface soils along the Longmen Shan, eastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Bai, Y.

    2015-12-01

    .Stable isotope data from the Tibetan plateau may largely reflect the evolution of air masses sourced from the Pacific Ocean and crossing the eastern plateau margin rather than the Himalayas (Blisniuk and Stern, 2005). We present 30 hydrogen isotope values of leaf wax-derived n-alkanes (δDwax, the abundance-weighted average δD values of C29 and C31 n-alkanes) in surface soils and 23 δD of soil water (δDsw) along the Longmen Shan, eastern Tibetan Plateau (altitude range 780-4200m* above sea level, representing Southeast Asian Monsoon from the Pacific Ocean air mass). Altitude is the predominant factor in determining soil δDwax values, which varied from -160‰ to -223‰ with a lapse rate of -1.8‰/100m (R2= 0.81; n=30). We observed the same correlation for δDsw values with altitude (R2=0.79). These δDwax values were more enriched than the eastern slope of the Gongga Shan transect (-203‰ to -268‰ from 1230 to 4275 m; Bai et al., 2011). Additionally, our ɛwax/sw values of soil (the isotopic fractionation between the δDwax remain approximately constant at -100‰ (ranging between -99 and -101‰), which demonstrates that the isotopic altitude effects of soil water (precipitation) control the n-alkane δDwax altitudinal gradients for all of the sample localities in the Southern Himalaya (SH) and the southern TP (Bai et al., 2015). Additionally, there is a difference in ɛwax-rw with the increasing elevation, and which are smaller at low elevation (with ɛwax/rw of -107‰, average d=4.4) than those at high elevation (with larger ɛwax/rw of -137‰, average d=-0.3). Hence, it is likely that river water may not represent the actual source water on the eastern edge of the Tibetan Plateau, especially above ~3 km, and it is cautious when establish the modern isotope-elevation relationship using river water for any future paleoenvironmental and paleoelevation reconstructions.

  16. A detailed analysis of the leaf rolling mutant sll2 reveals complex nature in regulation of bulliform cell development in rice (Oryza sativa L.).

    PubMed

    Zhang, J-J; Wu, S-Y; Jiang, L; Wang, J-L; Zhang, X; Guo, X-P; Wu, C-Y; Wan, J-M

    2015-03-01

    Bulliform cells are large, thin-walled and highly vacuolated cells, and play an important role in controlling leaf rolling in response to drought and high temperature. However, the molecular mechanisms regulating bulliform cell development have not been well documented. Here, we report isolation and characterisation of a rice leaf-rolling mutant, named shallot-like 2 (sll2). The sll2 plants exhibit adaxially rolled leaves, starting from the sixth leaf stage, accompanied by increased photosynthesis and reduced plant height and tiller number. Histological analyses showed shrinkage of bulliform cells, resulting in inward-curved leaves. The mutant is recessive and revertible at a rate of 9%. The leaf rolling is caused by a T-DNA insertion. Cloning of the insertion using TAIL-PCR revealed that the T-DNA was inserted in the promoter region of LOC_Os07 g38664. Unexpectedly, the enhanced expression of LOC_Os07 g38664 by the 35S enhancer in the T-DNA is not responsible for the leaf rolling phenotype. Further, the enhancer also exerted a long-distance effect, including up-regulation of several bulliform cell-related genes. sll2 suppressed the outward leaf rolling of oul1 in the sll2oul1 double mutant. We conclude that leaf rolling in sll2 could be a result of the combined effect of multi-genes, implying a complex network in regulation of bulliform cell development.

  17. A detailed analysis of the leaf rolling mutant sll2 reveals complex nature in regulation of bulliform cell development in rice (Oryza sativa L.).

    PubMed

    Zhang, J-J; Wu, S-Y; Jiang, L; Wang, J-L; Zhang, X; Guo, X-P; Wu, C-Y; Wan, J-M

    2015-03-01

    Bulliform cells are large, thin-walled and highly vacuolated cells, and play an important role in controlling leaf rolling in response to drought and high temperature. However, the molecular mechanisms regulating bulliform cell development have not been well documented. Here, we report isolation and characterisation of a rice leaf-rolling mutant, named shallot-like 2 (sll2). The sll2 plants exhibit adaxially rolled leaves, starting from the sixth leaf stage, accompanied by increased photosynthesis and reduced plant height and tiller number. Histological analyses showed shrinkage of bulliform cells, resulting in inward-curved leaves. The mutant is recessive and revertible at a rate of 9%. The leaf rolling is caused by a T-DNA insertion. Cloning of the insertion using TAIL-PCR revealed that the T-DNA was inserted in the promoter region of LOC_Os07 g38664. Unexpectedly, the enhanced expression of LOC_Os07 g38664 by the 35S enhancer in the T-DNA is not responsible for the leaf rolling phenotype. Further, the enhancer also exerted a long-distance effect, including up-regulation of several bulliform cell-related genes. sll2 suppressed the outward leaf rolling of oul1 in the sll2oul1 double mutant. We conclude that leaf rolling in sll2 could be a result of the combined effect of multi-genes, implying a complex network in regulation of bulliform cell development. PMID:25213398

  18. Direct observation of bulk and surface chemical morphologies of Ginkgo biloba leaves by Fourier transform mid- and near-infrared microspectroscopic imaging.

    PubMed

    Chen, Jianbo; Sun, Suqin; Zhou, Qun

    2013-11-01

    Fourier transform infrared microspectroscopy is a powerful tool to obtain knowledge about the spatial and/or temporal distributions of the chemical compositions of plants for better understanding of their biological properties. However, the chemical morphologies of plant leaves in the plane of the blade are barely studied, because sections in this plane for mid-infrared transmission measurements are difficult to obtain. Besides, native compositions may be changed by chemical reagents used when plant samples are microtomed. To improve methods for direct infrared microspectroscopic imaging of plant leaves in the plane of the blade, the bulk and surface chemical morphologies of nonmicrotomed Ginkgo biloba leaves were characterized by near-infrared transmission and mid-infrared attenuated total reflection microspectroscopic imaging. A new self-modeling curve resolution procedure was proposed to extract the spectral and concentration information of pure compounds. Primary and secondary metabolites of secretory cavities, veins, and mesophylls of Ginkgo biloba leaf blades were analyzed, and the distributions of cuticle, protein, calcium oxalate, cellulose, and ginkgolic acids on the adaxial surface were determined. By the integration of multiple infrared microspectroscopic imaging and chemometrics methods, it is possible to analyze nonmicrotomed leaves and other plant samples directly to understand their native chemical morphologies in detail.

  19. Distinct palisade tissue development processes promoted by leaf autonomous signalling and long-distance signalling in Arabidopsis thaliana.

    PubMed

    Munekage, Yuri Nakajima; Inoue, Shio; Yoneda, Yuki; Yokota, Akiho

    2015-06-01

    Plants develop palisade tissue consisting of cylindrical mesophyll cells located at the adaxial side of leaves in response to high light. To understand high light signalling in palisade tissue development, we investigated leaf autonomous and long-distance signal responses of palisade tissue development using Arabidopsis thaliana. Illumination of a developing leaf with high light induced cell height elongation, whereas illumination of mature leaves with high light increased cell density and suppressed cell width expansion in palisade tissue of new leaves. Examination using phototropin1 phototropin2 showed that blue light signalling mediated by phototropins was involved in cell height elongation of the leaf autonomous response rather than the cell density increase induced by long-distance signalling. Hydrogen peroxide treatment induced cylindrical palisade tissue cell formation in both a leaf autonomous and long-distance manner, suggesting involvement of oxidative signals. Although constitutive expression of transcription factors involved in systemic-acquired acclimation to excess light, ZAT10 and ZAT12, induced cylindrical palisade tissue cell formation, knockout of these genes did not affect cylindrical palisade tissue cell formation. We conclude that two distinct signalling pathways - leaf autonomous signalling mostly dependent on blue light signalling and long-distance signalling from mature leaves that sense high light and oxidative stress - control palisade tissue development in A. thaliana.

  20. Biophysical control of leaf temperature

    NASA Astrophysics Data System (ADS)

    Dong, N.; Prentice, I. C.; Wright, I. J.

    2014-12-01

    In principle sunlit leaves can maintain their temperatures within a narrower range than ambient temperatures. This is an important and long-known (but now overlooked) prediction of energy balance theory. Net radiation at leaf surface in steady state (which is reached rapidly) must be equal to the combination of sensible and latent heat exchanges with surrounding air, the former being proportional to leaf-to-air temperature difference (ΔT), the latter to the transpiration rate. We present field measurements of ΔT which confirm the existence of a 'crossover temperature' in the 25-30˚C range for species in a tropical savanna and a tropical rainforest environment. This finding is consistent with a simple representation of transpiration as a function of net radiation and temperature (Priestley-Taylor relationship) assuming an entrainment factor (ω) somewhat greater than the canonical value of 0.26. The fact that leaves in tropical forests are typically cooler than surrounding air, often already by solar noon, is consistent with a recently published comparison of MODIS day-time land-surface temperatures with air temperatures. Theory further predicts a strong dependence of leaf size (which is inversely related to leaf boundary-layer conductance, and therefore to absolute magnitude of ΔT) on moisture availability. Theoretically, leaf size should be determined by either night-time constraints (risk of frost damage to active leaves) or day-time constraints (risk of heat stress damage),with the former likely to predominate - thereby restricting the occurrence of large leaves - at high latitudes. In low latitudes, daytime maximum leaf size is predicted to increase with temperature, provided that water is plentiful. If water is restricted, however, transpiration cannot proceed at the Priestley-Taylor rate, and it quickly becomes advantageous for plants to have small leaves, which do not heat up much above the temperature of their surroundings. The difference between leaf

  1. Different altitude effect of leaf wax n-alkane δD values in surface soils along two vapor transport pathways, southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Bai, Yan; Fang, Xiaomin; Jia, Guodong; Sun, Jimin; Wen, Rong; Ye, Yuqing

    2015-12-01

    Here we present 76 hydrogen isotope values for leaf wax-derived n-alkanes (δDwax, being the abundance-weighted average δD values of C29 and C31n-alkanes) in surface soils along two vapor transport pathway transects running across the southeastern Tibetan Plateau (TP). The first is the South Himalayan (SH) Transect (with an altitude range of 1660-5050 m∗ above sea level, and representing the Southern Himalayan air mass), and the second a combination of the Zayu-Bomi (ZB; altitude 1468-4800 m) and Bayi-Lhasa (BL; altitude 3050-4970 m) transects, together representing the Brahmaputra-Yarlung Zangbo river valley air mass. δDwax values and their relation to altitude did exhibit some variability. Nonetheless, altitude was the predominant factor in determining soil δDwax values, with a lapse rate of -2.2‰/100 m (R2 = 0.78; n = 76) based on overall soil δDwax values, despite changes in precipitation amount, relative humidity (RH) and vegetation type. Furthermore, our εwax/rw values (the isotopic fractionation between the δDwax and δD values of river water (δDrw)) remained approximately constant at -104.5‰ (ranging between -99‰ and -110‰), confirming that the relation between altitude and isotopic hydrology (river water and precipitation) controls the n-alkane δDwax altitudinal gradients for all of the sample localities in the Southern Himalaya (SH) and the southern TP. This endorses the efficacy of using δDwax to reconstruct paleoelevation. Along the SH Transect, soil δDwax values varied from -151‰ to -264‰, with an altitudinal lapse rate of -2.4‰/100 m (R2 = 0.84, n = 32). This was due to the significant change in altitude over short distances. Along the ZB Transect, soil δDwax values varied from -174‰ to -263‰, with a lower lapse rate of -1.9‰/100 m (R2 = 0.68, n = 29). The altitudinal lapse rate was -3.3‰/100 m above 3000 m (R2 = 0.63, n = 19), and -1.35‰/100 m below 3000 m (R2 = 0.64, n = 10); in the lower sub-transect, the

  2. Cladodes, leaf-like organs in Asparagus, show the significance of co-option of pre-existing genetic regulatory circuit for morphological diversity of plants.

    PubMed

    Nakayama, Hokuto; Yamaguchi, Takahiro; Tsukaya, Hirokazu

    2012-08-01

    Plants in the genus Asparagus have determinate leaf-like organs called cladodes in the position of leaf axils. Because of their leaf-like morphology, axillary position, and morphological variation, it has been unclear how this unusual organ has evolved and diversified. In the previous study, we have shown that cladodes in the genus Asparagus are modified axillary shoots and proposed a model that cladodes have arisen by co-option and deployment of genetic regulatory circuit (GRC) involved in leaf development. Moreover, we proposed that the alteration of the expression pattern of genes involved in establishment of adaxial/abaxial polarity has led to the morphological diversification from leaf-like to rod-like form of cladodes in the genus. Thus, these results indicated that the co-option and alteration of pre-existing GRC play an important role in acquisition and subsequent morphological diversification. Here, we present data of further expression analysis of A. asparagoides. The results suggested that only a part of the GRC involved in leaf development appears to have been co-opted into cladode development. Based on our study and several examples of the morphological diversification, we briefly discuss the importance of co-option of pre-existing GRC and its genetic modularity in the morphological diversity of plants during evolution.

  3. Effects of leaf display on light interception and apparent photosynthesis in two contrasting Populus cultivars during their second growing season.

    PubMed

    Dickmann, D. I.; Michael, D. A.; Isebrands, J. G.; Westin, S.

    1990-12-01

    Effects of the contrasting leaf display of poplar cultivars Eugenei (Populus x euramericana) and Tristis (P. tristis x P. balsamifera) on light interception and photosynthesis were studied in the second year of growth in an irrigated plantation near Rhinelander, Wisconsin, USA (lat. 45 degrees N). Leaves on the current terminal (CT) and on proleptic branches were measured between 0900 and 1500 h on five clear days from June to September 1980. Leaf orientation-based differences between these cultivars were evident as the second growing season progressed and the crowns of the trees in the plantation grew together. Leaves of Eugenei are erectophile or tilted from the horizontal. In this cultivar light penetrated throughout the crown; many leaves on the lowest branches were illuminated as fully as those on the upper CT and had higher photosynthetic rates than equivalent leaves in Tristis. However, by early September many of the lower branches on Eugenei trees had abscised. In the planophile Tristis, adaxial photon flux densities (PPFD) of leaves on the lower portion of the CT and on branches were only a fraction of those measured on the upper CT. This pattern became more extreme as the season progressed. Few of the lower branches of Tristis abscised during the growing season. Photosynthesis rates, especially on a whole-leaf basis, were closely related to incident PPFDs in both cultivars. The ecological significance of these results are discussed, as well as the hypothesized effect of leaf inclination on crop productivity.

  4. Spectroscopic Measurement of Leaf Water Status

    NASA Technical Reports Server (NTRS)

    Goetz, Alexander F. H.; Boardman, Joseph W.

    1995-01-01

    A leaf drying experiment was carried out in the laboratory in which simultaneous spectral reflectance in the 350-2450 nm region, and leaf weights, were measured at 10 second intervals over a 40 minute period. As the leaf water weight dropped from approximately 60 to 38%. a nearly-linear rise in reflectance at all wavelengths beyond 1000 nm was observed. A principal components analysis of the time series of spectra in the 2000-2500 nm wavelength region showed that over 99% of the variance in the spectra, that were individually scaled to have a sum equal to that of the mean spectrum and subsequently mean corrected, was in the first component. This result shows that it is feasible to determine leaf water content remotely with an imaging spectrometer independent of the surface irradiance effects caused by topography.

  5. Biometamaterials: Black Ultrathin Gold Film Fabricated on Lotus Leaf

    PubMed Central

    Ebihara, Yuusuke; Ota, Ryoichi; Noriki, Takahiro; Shimojo, Masayuki; Kajikawa, Kotaro

    2015-01-01

    We report on a black metamaterial of gold fabricated on a lotus leaf that was used as a template. In spite of the extremely thin gold coating (10-nm thick) on the lotus leaf, the surface shows reflectivity below 0.01 over the entire visible spectral range. Finite-difference time-domain (FDTD) calculations suggest that the low reflectivity stems from the secondary structures on the lotus leaf, where randomly oriented nanorods are distributed. PMID:26530514

  6. Leaf growth is conformal

    NASA Astrophysics Data System (ADS)

    Alim, Karen; Armon, Shahaf; Shraiman, Boris I.; Boudaoud, Arezki

    2016-10-01

    Growth pattern dynamics lie at the heart of morphogenesis. Here, we investigate the growth of plant leaves. We compute the conformal transformation that maps the contour of a leaf at a given stage onto the contour of the same leaf at a later stage. Based on the mapping we predict the local displacement field in the leaf blade and find it to agree with the experimentally measured displacement field to 92%. This approach is applicable to any two-dimensional system with locally isotropic growth, enabling the deduction of the whole growth field just from observation of the tissue contour.

  7. Leaf growth is conformal.

    PubMed

    Alim, Karen; Armon, Shahaf; Shraiman, Boris I; Boudaoud, Arezki

    2016-01-01

    Growth pattern dynamics lie at the heart of morphogenesis. Here, we investigate the growth of plant leaves. We compute the conformal transformation that maps the contour of a leaf at a given stage onto the contour of the same leaf at a later stage. Based on the mapping we predict the local displacement field in the leaf blade and find it to agree with the experimentally measured displacement field to 92%. This approach is applicable to any two-dimensional system with locally isotropic growth, enabling the deduction of the whole growth field just from observation of the tissue contour. PMID:27597439

  8. Wind increases leaf water use efficiency.

    PubMed

    Schymanski, Stanislaus J; Or, Dani

    2016-07-01

    A widespread perception is that, with increasing wind speed, transpiration from plant leaves increases. However, evidence suggests that increasing wind speed enhances carbon dioxide (CO2 ) uptake while reducing transpiration because of more efficient convective cooling (under high solar radiation loads). We provide theoretical and experimental evidence that leaf water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, thus improving plants' ability to conserve water during photosynthesis. Our leaf-scale analysis suggests that the observed global decrease in near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric CO2 concentrations. However, there is indication that the effect of long-term trends in wind speed on leaf gas exchange may be compensated for by the concurrent reduction in mean leaf sizes. These unintuitive feedbacks between wind, leaf size and water use efficiency call for re-evaluation of the role of wind in plant water relations and potential re-interpretation of temporal and geographic trends in leaf sizes. PMID:26714739

  9. Wind increases leaf water use efficiency.

    PubMed

    Schymanski, Stanislaus J; Or, Dani

    2016-07-01

    A widespread perception is that, with increasing wind speed, transpiration from plant leaves increases. However, evidence suggests that increasing wind speed enhances carbon dioxide (CO2 ) uptake while reducing transpiration because of more efficient convective cooling (under high solar radiation loads). We provide theoretical and experimental evidence that leaf water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, thus improving plants' ability to conserve water during photosynthesis. Our leaf-scale analysis suggests that the observed global decrease in near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric CO2 concentrations. However, there is indication that the effect of long-term trends in wind speed on leaf gas exchange may be compensated for by the concurrent reduction in mean leaf sizes. These unintuitive feedbacks between wind, leaf size and water use efficiency call for re-evaluation of the role of wind in plant water relations and potential re-interpretation of temporal and geographic trends in leaf sizes.

  10. Sites of Action of Elevated CO2 on Leaf Development in Rice: Discrimination between the Effects of Elevated CO2 and Nitrogen Deficiency

    PubMed Central

    Tsutsumi, Koichi; Konno, Masae; Miyazawa, Shin-Ichi; Miyao, Mitsue

    2014-01-01

    Elevated CO2 concentrations (eCO2) trigger various plant responses. Despite intensive studies of these responses, the underlying mechanisms remain obscure. In this work, we investigated when and how leaf physiology and anatomy are affected by eCO2 in rice plants. We analyzed the most recently fully expanded leaves that developed successively after transfer of the plant to eCO2. To discriminate between the effects of eCO2 and those of nitrogen deficiency, we used three different levels of N application. We found that a decline in the leaf soluble protein content (on a leaf area basis) at eCO2 was only observed under N deficiency. The length and width of the leaf blade were reduced by both eCO2 and N deficiency, whereas the blade thickness was increased by eCO2 but was not affected by N deficiency. The change in length by eCO2 became detectable in the secondly fully expanded leaf, and those in width and thickness in the thirdly fully expanded leaf, which were at the leaf developmental stages P4 and P3, respectively, at the onset of the eCO2 treatment. The decreased blade length at eCO2 was associated with a decrease in the epidermal cell number on the adaxial side and a reduction in cell length on the abaxial side. The decreased width resulted from decreased numbers of small vascular bundles and epidermal cell files. The increased thickness was ascribed mainly to enhanced development of bundle sheath extensions at the ridges of vascular bundles. These observations enable us to identify the sites of action of eCO2 on rice leaf development. PMID:24406628

  11. The presence of cutan limits the interpretation of cuticular chemistry and structure: Ficus elastica leaf as an example.

    PubMed

    Guzmán-Delgado, Paula; Graça, José; Cabral, Vanessa; Gil, Luis; Fernández, Victoria

    2016-06-01

    Plant cuticles have been traditionally classified on the basis of their ultrastructure, with certain chemical composition assumptions. However, the nature of the plant cuticle may be misinterpreted in the prevailing model, which was established more than 150 years ago. Using the adaxial leaf cuticle of Ficus elastica, a study was conducted with the aim of analyzing cuticular ultrastructure, chemical composition and the potential relationship between structure and chemistry. Gradual chemical extractions and diverse analytical and microscopic techniques were performed on isolated leaf cuticles of two different stages of development (i.e. young and mature leaves). Evidence for the presence of cutan in F. elastica leaf cuticles has been gained after chemical treatments and tissue analysis by infrared spectroscopy and electron microscopy. Significant calcium, boron and silicon concentrations were also measured in the cuticle of this species. Such mineral elements which are often found in plant cell walls may play a structural role and their presence in isolated cuticles further supports the interpretation of the cuticle as the most external region of the epidermal cell wall. The complex and heterogeneous nature of the cuticle, and constraints associated with current analytical procedures may limit the chance for establishing a relationship between cuticle chemical composition and structure also in relation to organ ontogeny.

  12. Deer predation on leaf miners via leaf abscission

    NASA Astrophysics Data System (ADS)

    Yamazaki, Kazuo; Sugiura, Shinji

    2008-03-01

    The evergreen oak Quercus gilva Blume sheds leaves containing mines of the leaf miner Stigmella sp. (Lepidoptera: Nepticulidae) earlier than leaves with no mines in early spring in Nara, central Japan. The eclosion rates of the leaf miner in abscised and retained leaves were compared in the laboratory to clarify the effects of leaf abscission on leaf miner survival in the absence of deer. The leaf miner eclosed successfully from both fallen leaves and leaves retained on trees. However, sika deer ( Cervus nippon centralis Kishida) feed on the fallen mined leaves. Field observations showed that deer consume many fallen leaves under Q. gilva trees, suggesting considerable mortality of leaf miners due to deer predation via leaf abscission. This is a previously unreported relationship between a leaf miner and a mammalian herbivore via leaf abscission.

  13. Droplet Impacting a Cantilever: A Leaf-Raindrop System

    NASA Astrophysics Data System (ADS)

    Gart, Sean; Mates, Joseph E.; Megaridis, Constantine M.; Jung, Sunghwan

    2015-04-01

    Previous studies show that air pollution and wind erosion, which damage a leaf's epicuticular wax layer, can change leaf surface properties from hydrophobic to hydrophilic. However, the dynamic response of a damaged leaf to a raindrop impact has not been investigated and could clarify the direct influence of changes in wettability on early leaf abscission. In this article, we investigate how leaves with different surface properties respond to falling raindrops, viewing this as a unique system of coupled elasticity and drop dynamics. An elastic beam with tunable surface wettability properties is used as a simple leaf model. We find that wettable beams experience much higher torque and bending energy than nonwettable beams. This is because a drop sticks to a wettable beam, while a drop falls off a nonwettable beam. An analytical model using momentum balance and simple cantilever beam theory quantifies the bending energy and torque experienced by wettable and nonwettable beams. The results elucidate the potential damage caused by raindrops impacting a leaf as a function of its surface wettability and are correlated with environmental factors contributing to premature changes of leaf surface properties.

  14. Mueller matrix of a dicot leaf

    NASA Astrophysics Data System (ADS)

    Vanderbilt, Vern C.; Daughtry, Craig S. T.

    2012-06-01

    A better understanding of the information contained in the spectral, polarized bidirectional reflectance and transmittance of leaves may lead to improved techniques for identifying plant species in remotely sensed imagery as well as better estimates of plant moisture and nutritional status. Here we report an investigation of the optical polarizing properties of several leaves of one species, Cannabis sativa, represented by a 3x3 Mueller matrix measured over the wavelength region 400-2,400 nm. Our results support the hypothesis that the leaf surface alters the polarization of incident light - polarizing off nadir, unpolarized incident light, for example - while the leaf volume tends to depolarized incident polarized light.

  15. Damped leaf flexure hinge

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage.

  16. Damped leaf flexure hinge.

    PubMed

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage. PMID:26026549

  17. Developing multi-tracer approaches to constrain the parameterisation of leaf and soil CO2 and H2O exchange in land surface models

    NASA Astrophysics Data System (ADS)

    Ogée, Jerome; Wehr, Richard; Commane, Roisin; Launois, Thomas; Meredith, Laura; Munger, Bill; Nelson, David; Saleska, Scott; Zahniser, Mark; Wofsy, Steve; Wingate, Lisa

    2016-04-01

    The net flux of carbon dioxide between the land surface and the atmosphere is dominated by photosynthesis and soil respiration, two of the largest gross CO2 fluxes in the carbon cycle. More robust estimates of these gross fluxes could be obtained from the atmospheric budgets of other valuable tracers, such as carbonyl sulfide (COS) or the carbon and oxygen isotope compositions (δ13C and δ18O) of atmospheric CO2. Over the past decades, the global atmospheric flask network has measured the inter-annual and intra-annual variations in the concentrations of these tracers. However, knowledge gaps and a lack of high-resolution multi-tracer ecosystem-scale measurements have hindered the development of process-based models that can simulate the behaviour of each tracer in response to environmental drivers. We present novel datasets of net ecosystem COS, 13CO2 and CO18O exchange and vertical profile data collected over 3 consecutive growing seasons (2011-2013) at the Harvard forest flux site. We then used the process-based model MuSICA (multi-layer Simulator of the Interactions between vegetation Canopy and the Atmosphere) to include the transport, reaction, diffusion and production of each tracer within the forest and exchanged with the atmosphere. Model simulations over the three years captured well the impact of diurnally and seasonally varying environmental conditions on the net ecosystem exchange of each tracer. The model also captured well the dynamic vertical features of tracer behaviour within the canopy. This unique dataset and model sensitivity analysis highlights the benefit in the collection of multi-tracer high-resolution field datasets and the developement of multi-tracer land surface models to provide valuable constraints on photosynthesis and respiration across scales in the near future.

  18. Characterization of Satureja khuzestanica leaf as a herbal medicine.

    PubMed

    Malmir, Maryam; Serrano, Rita; Reza Gohari, Ahmad; Silva, Olga

    2014-10-01

    Dried leaves of Satureja khuzestanica Jamzad are a popular herbal medicine and dental anesthetic among the nomadic inhabitants of southwestern Iran. The present study establishes criteria for identification of S. khuzestanica dried whole, fragmented and powdered leaves for specification as a herbal substance using macroscopic and microscopic characterization. Quantitative microscopy techniques were also considered. Macroscopically leaves exhibit a grayish-green color, are broadly ovate in shape with an acute apex, attenuate base, and ciliate margin and have a surface covered by an indumentum of glandular and non-glandular trichomes. Microscopically leaves have an isobilateral amphistomatic structure containing peltate glandular trichomes consisting of a multiseriate stalk (five cells) and an enlarged secretory head composed of 12 cells, capitate glandular trichomes of variable morphology together with two types of non-glandular trichomes. Oval-shaped hygromorphic diacytic stomata with an adaxial stomatal index of 13.54, collateral vascular bundles consisting of xylem, and three layers of sclerenchymatous tissue close to phloem together with cluster, prismatic and raphide calcium oxalate crystals were also identified as useful pharmacognostic parameters for identification of S. khuzestanica dried leaves.

  19. Wind-induced leaf transpiration

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Wei; Chu, Chia-Ren; Hsieh, Cheng-I.; Palmroth, Sari; Katul, Gabriel G.

    2015-12-01

    While the significance of leaf transpiration (fe) on carbon and water cycling is rarely disputed, conflicting evidence has been reported on how increasing mean wind speed (U) impacts fe from leaves. Here, conditions promoting enhancement or suppression of fe with increasing U for a wide range of environmental conditions are explored numerically using leaf-level gas exchange theories that combine a stomatal conductance model based on optimal water use strategies (maximizing the 'net' carbon gain at a given fe), energy balance considerations, and biochemical demand for CO2. The analysis showed monotonic increases in fe with increasing U at low light levels. However, a decline in modeled fe with increasing U were predicted at high light levels but only in certain instances. The dominant mechanism explaining this decline in modeled fe with increasing U is a shift from evaporative cooling to surface heating at high light levels. New and published sap flow measurements for potted Pachira macrocarpa and Messerschmidia argentea plants conducted in a wind tunnel across a wide range of U (2 - 8 m s-1) and two different soil moisture conditions were also employed to assess how fe varies with increasing U. The radiative forcing imposed in the wind tunnel was only restricted to the lower end of expected field conditions. At this low light regime, the findings from the wind tunnel experiments were consistent with the predicted trends.

  20. Air bubble bursting effect of lotus leaf.

    PubMed

    Wang, Jingming; Zheng, Yongmei; Nie, Fu-Qiang; Zhai, Jin; Jiang, Lei

    2009-12-15

    In this paper, a phenomenon of air bubbles quickly bursting within several milliseconds on a "self-cleaning" lotus leaf was described. This observation prompted the synthesis of artificial surfaces similar to that of the lotus leaf. The artificial leaf surfaces, prepared by photolithography and wet etching, showed a similar air bubble bursting effect. Smooth and rough silicon surfaces with an ordered nanostructure or patterned microstructure were utilized to study the contribution of the micro/nano hierarchical structures to this phenomenon of air bubble bursting. Air bubbles were found to burst on some superhydrophobic surfaces with microstructure (within 220 ms). However, air bubbles burst much more rapidly (within 13 ms) on similar surfaces with micro/nanostructure. The height, width, and spacing of hierarchical structures could also affect air bubble bursting, and the effect of the height was more obvious. When the height of hierarchical structures was around the height found in natural lotus papillae, the width and spacing were significant for air bubble bursting. An original model was proposed to further evaluate the reason why the micro/nano hierarchical rough structures had an excellent air bubble bursting effect, and the validity of the model was theoretically demonstrated.

  1. Accumulation of semi-volatile organic compounds in moss (Sphagnum Species) and spruce needles (Picea Mariana): Whole-leaf absorption vs. surface adsorption processes

    SciTech Connect

    Hornbuckle, K.C.; Eisenreich, S.J.

    1996-12-31

    Vapor exchange of semi-volatile organic compounds (SOCs) with plant surfaces may control the fate of SOCS far from their original sources. For example, plants may act as sinks for released SOCs by adsorbing the compounds and burying them upon the plant`s death. Evidence for this hypothesis lies in the accumulation of SOCs in peat moss. Alternatively, plants may act as temporary {open_quote}resting points{close_quote} for long-range transport of the compounds from warmer regions to cooler regions. Studies that show higher SOC concentrations in plants collected from cooler parts of the globe are evidence for this hypothesis. Whether vapor-phase SOCs are taken up or released by plants is expected to depend on characteristics of the compound, the plant, and the local climate. Theoretically, it has been predicted that temperature and SOC hydrophobicity should dominate vapor exchange. The effect of these two factors on vapor-plant exchange has been examined through two concurrent and related studies. The first study concerns the vapor SOC dynamics in a semi-remote forested bog in northern Minnesota. The second study concerns the measured distribution between vapor and plant-associated SOCs in the same bog.

  2. Maple Leaf Outdoor Centre.

    ERIC Educational Resources Information Center

    Maguire, Molly; Gunton, Ric

    2000-01-01

    Maple Leaf Outdoor Centre (Ontario) has added year-round outdoor education facilities and programs to help support its summer camp for disadvantaged children. Schools, youth centers, religious groups, and athletic teams conduct their own programs, collaborate with staff, or use staff-developed programs emphasizing adventure education and personal…

  3. Bacterial leaf spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot has been reported in Australia (Queensland), Egypt, El Salvador, India, Japan, Nicaragua, Sudan, and the United States (Florida, Iowa, Kansas, Maryland, and Wisconsin). It occasionally causes locally severe defoliation and post-emergence damping-off and stunting. The disease is...

  4. Comparative leaf development in angiosperms.

    PubMed

    Tsukaya, Hirokazu

    2014-02-01

    Recent accumulation of our knowledge on basic leaf development mechanisms in model angiosperm species has allowed us to pursue evolutionary development (evo/devo) studies of various kinds of leaf development. As a result, unexpected findings and clues have been unearthed aiding our understanding of the mechanisms involved in the diversity of leaf morphology, although the covered remain limited. In this review, we highlight recent findings of diversified leaf development in angiosperms.

  5. Pharmacognostic evaluation of Cayratia trifolia (Linn.) leaf

    PubMed Central

    Kumar, Dinesh; Gupta, Jyoti; Kumar, Sunil; Arya, Renu; Kumar, Tarun; Gupta, Ankit

    2012-01-01

    Objective To present a detailed pharmacognostic study of the leaf of Cayratia trifolia (C. trifolia) Linn. (Vitaceae), an important plant in the Indian system of medicine. Methods The macroscopy, microscopy, physiochemical analysis, preliminary testing, fluorescence analysis of powder of the plant and other WHO recommended methods for standardization were investigated. Results Leaves are trifoliolated with petioles (2–3 cm) long. Leaflets are ovate to oblong-ovate, (2–8 cm) long, (1.5–5 cm) wide, pointed at the tip. The leaf surface shows the anisocytic type stomata covered with guard cells followed by epidermis layer. Leaf surface contents including veins, vein islet and vein termination were also determined. Transverse section of leaf shows the epidermis layer followed by cuticle layer and vascular bandles (xylem and phloem). The mesophyll is differentiated into palisade and spongy parenchyma. Abundant covering trichomes emerge from the upper epidermis. Trichomes are uniseriate and multicellular. Strips of collenchyma are present below and upper layer of epidermis. Conclusions It can be concluded that the pharmacognostic profile of the C. trifolia is helpful in developing standards for quality, purity and sample identification. PMID:23569825

  6. A ray tracing model for leaf bidirectional scattering studies

    NASA Technical Reports Server (NTRS)

    Brakke, T. W.; Smith, J. A.

    1987-01-01

    A leaf is modeled as a deterministic two-dimensional structure consisting of a network of circular arcs designed to represent the internal morphology of major species. The path of an individual ray through the leaf is computed using geometric optics. At each intersection of the ray with an arc, the specular reflected and transmitted rays are calculated according to the Snell and Fresnel equations. Diffuse scattering is treated according to Lambert's law. Absorption is also permitted but requires a detailed knowledge of the spectral attenuation coefficients. An ensemble of initial rays are chosen for each incident direction with the initial intersection points on the leaf surface selected randomly. The final equilibrium state after all interactions then yields the leaf bidirectional reflectance and transmittance distributions. The model also yields the internal two dimensional light gradient profile of the leaf.

  7. [Micromorphology of leaf epidermis of some Venezuelan rice cultivars (Poaceae) associated with the mechanical damage of Sogata T. orizicolus (Homoptera: Delphacidae)].

    PubMed

    Velásquez-Salazar, Rosalia; Diamont, Diego

    2014-06-01

    Rice cultivars are affected directly and indirectly by the insect sogata. The mechanical damage or direct loss, is produced after feeding and ovoposition on the young leaves tissues, while the indirect damage is produced after the transmission of the Rice hoja blanca virus. We studied the morpho-anatomic structures associated with the resistance of the mechanical damage produced by the insect, in six rice cultivars, including controls for resistance and susceptibility (Makalioka and Bluebonnet 50), during August 2011, in Fundacion Danac, Venezuela. Samples were taken from leaf 3, where cuticle thickness, presence of macrohair, microhair and silica bodies in the second third of the leaf was evaluated. A significant difference to thickness of the cuticle, the presence of microhair in the leaves, and presence of silica bodies was observed among cultivars, determining a significant correlation among the number of macrohair and microhair in the adaxial leaf blade with the presence of silica bodies, and thickness of the cuticle and number of posed insects. Thickness of the cuticle and presence of silica bodies in the intercostals space of microhair and macrohair showed to be the variables most related to mechanical damage and resistance mechanism. PMID:25102661

  8. On the temporal variation of leaf magnetic parameters: seasonal accumulation of leaf-deposited and leaf-encapsulated particles of a roadside tree crown.

    PubMed

    Hofman, Jelle; Wuyts, Karen; Van Wittenberghe, Shari; Samson, Roeland

    2014-09-15

    Understanding the accumulation behaviour of atmospheric particles inside tree leaves is of great importance for the interpretation of biomagnetic monitoring results. In this study, we evaluated the temporal variation of the saturation isothermal remanent magnetisation (SIRM) of leaves of a roadside urban Platanus × acerifolia Willd. tree in Antwerp, Belgium. We hereby examined the seasonal development of the total leaf SIRM signal as well as the leaf-encapsulated fraction of the deposited dust, by washing the leaves before biomagnetic analysis. On average 38% of the leaf SIRM signal was exhibited by the leaf-encapsulated particles. Significant correlations were found between the SIRM and the cumulative daily average atmospheric PM10 and PM2.5 measurements. Moreover, a steady increase of the SIRM throughout the in-leaf season was observed endorsing the applicability of biomagnetic monitoring as a proxy for the time-integrated PM exposure of urban tree leaves. Strongest correlations were obtained for the SIRM of the leaf-encapsulated particles which confirms the dynamic nature of the leaf surface-accumulated particles.

  9. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  10. Effect of curvature on the backscattering from a leaf

    NASA Technical Reports Server (NTRS)

    Sarabandi, K.; Senior, T. B. A.; Ulaby, F. T.

    1988-01-01

    Using a model previously developed for the backscattering cross section of a planar leaf at X-band frequencies and above, the effect of leaf curvature is examined. For normal incidence on a rectangular section of a leaf curved in one and two dimensions, an integral expression for the backscattered field is evaluated numerically and by a stationary phase approximation, leading to a simple analytical expression for the cross-section reduction produced by the curvature. Numerical results based on the two methods are virtually identical, and in excellent agreement with measured data for rectangular sections of coleus leaves applied to the surfaces of styrofoam cylinders and spheres of different radii.

  11. Predicting leaf traits of herbaceous species from their spectral characteristics

    PubMed Central

    Roelofsen, Hans D; van Bodegom, Peter M; Kooistra, Lammert; Witte, Jan-Philip M

    2014-01-01

    Trait predictions from leaf spectral properties are mainly applied to tree species, while herbaceous systems received little attention in this topic. Whether similar trait–spectrum relations can be derived for herbaceous plants that differ strongly in growing strategy and environmental constraints is therefore unknown. We used partial least squares regression to relate key traits to leaf spectra (reflectance, transmittance, and absorbance) for 35 herbaceous species, sampled from a wide range of environmental conditions. Specific Leaf Area and nutrient-related traits (N and P content) were poorly predicted from any spectrum, although N prediction improved when expressed on a per area basis (mg/m2 leaf surface) instead of mass basis (mg/g dry matter). Leaf dry matter content was moderately to good correlated with spectra. We explain our results by the range of environmental constraints encountered by herbaceous species; both N and P limitations as well as a range of light and water availabilities occurred. This weakened the relation between the measured response traits and the leaf constituents that are truly responsible for leaf spectral behavior. Indeed, N predictions improve considering solely upper or under canopy species. Therefore, trait predictions in herbaceous systems should focus on traits relating to dry matter content and the true, underlying drivers of spectral properties. PMID:24683454

  12. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  13. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  14. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  15. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  16. The maize macrohairless1 locus specifically promotes leaf blade macrohair initiation and responds to factors regulating leaf identity.

    PubMed Central

    Moose, Stephen P; Lauter, Nick; Carlson, Shawn R

    2004-01-01

    The leaf surfaces of almost all plant species possess specialized epidermal cell types that form hairs or trichomes. Maize leaves produce three distinct types of hairs, the most prominent being the macrohairs that serve as a marker for adult leaf identity and may contribute to insect resistance. This report describes the maize macrohairless1 (mhl1) locus, which promotes macrohair initiation specifically in the leaf blade. Each of seven recessive mhl1 mutant alleles significantly reduces or eliminates macrohairs in the leaf blade. The mhl1 mutations block macrohair initiation rather than interfering with macrohair morphogenesis. Genetic mapping placed mhl1 within bin 4 on chromosome 9. A second independently segregating locus was found to partially suppress the mhl1 mutant phenotype in certain genetic backgrounds. Macrohair density was observed to increase during early adult vegetative development and then progressively decline, suggesting macrohair initiation frequency is affected by factors that act throughout shoot development. Genetic analyses demonstrated that mhl1 acts in the same pathway but downstream of factors that either promote or repress adult leaf identity. Thus, mhl1 plays a key role in integrating developmental programs that regulate leaf identity during shoot development with those that specify macrohair initiation within the leaf blade. PMID:15082562

  17. Effects of leaf age within growth stages of pepper and sorghum plants on leaf thickness, water, chlorophyll, and light reflectance. [in spectral vegetation discrimination

    NASA Technical Reports Server (NTRS)

    Gausman, H. W.; Cardenas, R.; Berumen, A.

    1974-01-01

    Pepper and sorghum plants (characterized by porous and compact leaf mesophylls, respectively) were used to study the influence of leaf age on light reflectance. Measurements were limited to the upper five nodal positions within each growth stage, since upper leaves make up most of the reflectance surfaces remotely sensed. The increase in leaf thickness and water content with increasing leaf age was taken into consideration, since each of these factors affects the reflectance as well as the selection of spectral wavelength intervals for optimum discrimination of vegetation.

  18. A simplified GIS approach to modeling global leaf water isoscapes.

    PubMed

    West, Jason B; Sobek, Adam; Ehleringer, James R

    2008-06-18

    The stable hydrogen (delta(2)H) and oxygen (delta(18)O) isotope ratios of organic and inorganic materials record biological and physical processes through the effects of substrate isotopic composition and fractionations that occur as reactions proceed. At large scales, these processes can exhibit spatial predictability because of the effects of coherent climatic patterns over the Earth's surface. Attempts to model spatial variation in the stable isotope ratios of water have been made for decades. Leaf water has a particular importance for some applications, including plant organic materials that record spatial and temporal climate variability and that may be a source of food for migrating animals. It is also an important source of the variability in the isotopic composition of atmospheric gases. Although efforts to model global-scale leaf water isotope ratio spatial variation have been made (especially of delta(18)O), significant uncertainty remains in models and their execution across spatial domains. We introduce here a Geographic Information System (GIS) approach to the generation of global, spatially-explicit isotope landscapes (= isoscapes) of "climate normal" leaf water isotope ratios. We evaluate the approach and the resulting products by comparison with simulation model outputs and point measurements, where obtainable, over the Earth's surface. The isoscapes were generated using biophysical models of isotope fractionation and spatially continuous precipitation isotope and climate layers as input model drivers. Leaf water delta(18)O isoscapes produced here generally agreed with latitudinal averages from GCM/biophysical model products, as well as mean values from point measurements. These results show global-scale spatial coherence in leaf water isotope ratios, similar to that observed for precipitation and validate the GIS approach to modeling leaf water isotopes. These results demonstrate that relatively simple models of leaf water enrichment combined with

  19. Epidermal UV-A absorbance and whole-leaf flavonoid composition in pea respond more to solar blue light than to solar UV radiation.

    PubMed

    Siipola, Sari M; Kotilainen, Titta; Sipari, Nina; Morales, Luis O; Lindfors, Anders V; Robson, T Matthew; Aphalo, Pedro J

    2015-05-01

    Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV-A and UV-B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV-B; (2) attenuate UV-B and UV-A < 370 nm; (3) attenuate UV-B and UV-A; (4) attenuate UV-B, UV-A and blue light; and (5) as a control not attenuating these wavebands. Attenuation of blue light significantly reduced the flavonoid content in leaf adaxial epidermis and reduced the whole-leaf concentrations of quercetin derivatives relative to kaempferol derivatives. In contrast, UV-B responses were not significant. These results show that pea plants regulate epidermal UV-A absorbance and accumulation of individual flavonoids by perceiving complex radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV-B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors.

  20. Epidermal UV-A absorbance and whole-leaf flavonoid composition in pea respond more to solar blue light than to solar UV radiation.

    PubMed

    Siipola, Sari M; Kotilainen, Titta; Sipari, Nina; Morales, Luis O; Lindfors, Anders V; Robson, T Matthew; Aphalo, Pedro J

    2015-05-01

    Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV-A and UV-B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV-B; (2) attenuate UV-B and UV-A < 370 nm; (3) attenuate UV-B and UV-A; (4) attenuate UV-B, UV-A and blue light; and (5) as a control not attenuating these wavebands. Attenuation of blue light significantly reduced the flavonoid content in leaf adaxial epidermis and reduced the whole-leaf concentrations of quercetin derivatives relative to kaempferol derivatives. In contrast, UV-B responses were not significant. These results show that pea plants regulate epidermal UV-A absorbance and accumulation of individual flavonoids by perceiving complex radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV-B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors. PMID:25040832

  1. Leaf hydraulics II: vascularized tissues.

    PubMed

    Rockwell, Fulton E; Holbrook, N Michele; Stroock, Abraham D

    2014-01-01

    Current models of leaf hydration employ an Ohm's law analogy of the leaf as an ideal capacitor, neglecting the resistance to flow between cells, or treat the leaf as a plane sheet with a source of water at fixed potential filling the mid-plane, neglecting the discrete placement of veins as well as their resistance. We develop a model of leaf hydration that considers the average conductance of the vascular network to a representative areole (region bounded by the vascular network), and represent the volume of tissue within the areole as a poroelastic composite of cells and air spaces. Solutions to the 3D flow problem are found by numerical simulation, and these results are then compared to 1D models with exact solutions for a range of leaf geometries, based on a survey of temperate woody plants. We then show that the hydration times given by these solutions are well approximated by a sum of the ideal capacitor and plane sheet times, representing the time for transport through the vasculature and tissue respectively. We then develop scaling factors relating this approximate solution to the 3D model, and examine the dependence of these scaling factors on leaf geometry. Finally, we apply a similar strategy to reduce the dimensions of the steady state problem, in the context of peristomatal transpiration, and consider the relation of transpirational gradients to equilibrium leaf water potential measurements.

  2. Leaf Relative Water Content Estimated from Leaf Reflectance and Transmittance

    NASA Technical Reports Server (NTRS)

    Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

    2016-01-01

    Remotely sensing the water status of plants and the water content of canopies remain long term goals of remote sensing research. In the research we report here, we used optical polarization techniques to monitor the light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both change nonlinearly. The result show that the nonlinearities cancel in the ratio R/T, which appears linearly related to RWC for RWC less than 90%. The results suggest that potentially leaf water status and perhaps even canopy water status could be monitored starting from leaf and canopy optical measurements.

  3. Regulation of Compound Leaf Development

    PubMed Central

    Wang, Yuan; Chen, Rujin

    2013-01-01

    Leaf morphology is one of the most variable, yet inheritable, traits in the plant kingdom. How plants develop a variety of forms and shapes is a major biological question. Here, we discuss some recent progress in understanding the development of compound or dissected leaves in model species, such as tomato (Solanum lycopersicum), Cardamine hirsuta and Medicago truncatula, with an emphasis on recent discoveries in legumes. We also discuss progress in gene regulations and hormonal actions in compound leaf development. These studies facilitate our understanding of the underlying regulatory mechanisms and put forward a prospective in compound leaf studies. PMID:27135488

  4. Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region

    PubMed Central

    Guzmán, Paula; Fernández, Victoria; Graça, José; Cabral, Vanessa; Kayali, Nour; Khayet, Mohamed; Gil, Luis

    2014-01-01

    The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids), coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies. PMID:25278953

  5. Relationship between leaf temperature and photosynthetic ratio of cherry tree

    NASA Astrophysics Data System (ADS)

    Nakashima, Atsushi; Ogura, Yasushi; Fujigaki, Motoharu; Tanikawa, Hiroki; Miwa, Masafumi

    2003-03-01

    We investigated the relations between leaf-air temperature and photosynthetic ratio of cherry trees in order to obtain the fundamental data for applying the biological information to the remote sensing system. Some branches of Prunus jamasakura were cut and put into the water pot prompt once per month from May to October 2001. We measured the surface temperature of ten leaves and photosynthetic ratio every five second for ten minutes every measurement air temperature condition at 20, 25, 30 and 35°C with 1000 PAR light intensity. Result as, there was recognized the small significantly relation between leaf temperature and photosynthetic ratio because leaf temperature is usually changed with air temperature. Although, there was recognized large significantly correlations between the difference of the leaf temperature and air temperature and photosynthetic ratio. It is thought that transpiring in healthy plants are active for absorption of water and it cause to drop the leaf temperature. This research showed that the health of cherry trees could be diagnosed for measurement of the difference of leaf and air temperature.

  6. Leaf domatia mediate mutualism between mites and a tropical tree.

    PubMed

    Romero, Gustavo Q; Benson, Woodruff W

    2004-08-01

    Although associations between mites and leaf domatia have been widely reported, their consequences for plants, especially for natural tree populations, particularly in the tropics, are largely unknown. In experiments with paired Cupania vernalis (Sapindaceae) saplings in a semi-deciduous forest in south-east Brazil, we blocked leaf domatia to examine their effect: (1) on mites and other arthropods, and (2) on damage caused by fungi and herbivorous arthropods. In general, plants with resin-blocked domatia had fewer predaceous mites on leaves than control plants with unaltered domatia, but the total abundances of fungivorous and of phytophagous mites remained unchanged. However, phytophagous eriophyid mites, the most numerous inhabitants of domatia, decreased on leaf surfaces with the blocking treatment. In a second experiment, treated plants lacking functional domatia developed significantly greater numbers and areas of chlorosis, apparently due to increased eriophyid attacks, whereas fungal attack, epiphyll abundance and leaf-area loss were unaffected. This seems to be the first experimental study to demonstrate that leaf domatia can benefit plants against herbivory in a natural system. The possible stabilizing effect of leaf domatia on predator-prey interactions is discussed.

  7. Wheat Leaf Rust Uredospore Production on Adult Plants: Influence of Leaf Nitrogen Content and Septoria tritici Blotch.

    PubMed

    Robert, Corinne; Bancal, Marie-Odile; Lannou, Christian

    2004-07-01

    ABSTRACT Leaf rust uredospore production and lesion size were measured on flag leaves of adult wheat plants in a glasshouse for different lesion densities. We estimated the spore weight produced per square centimeter of infected leaf, per lesion, and per unit of sporulating area. Three levels of fertilization were applied to the plants to obtain different nitrogen content for the inoculated leaves. In a fourth treatment, we evaluated the effect of Septoria tritici blotch on leaf rust uredospore production. The nitrogen and carbon content of the spores was unaffected or marginally affected by lesion density, host leaf nitrogen content, or the presence of Mycosphaerella graminicola on the same leaf. In leaves with a low-nitrogen content, spore production per lesion was reduced, but lesion size was unaffected. A threshold effect of leaf nitrogen content in spore production was however, evident, since production was similar in the medium- and high-fertilizer treatments. In leaves inoculated with M. graminicola and Puccinia triticina, the rust lesions were smaller and produced fewer spores. The relationships among rust lesion density, lesion size, and uredospore production were fitted to a model. We determined that the density effect on spore production resulted mainly from a reduction in lesion size, the spore production per unit of sporulating surface being largely independent of lesion density. These results are consistent with those obtained previously on wheat seedlings. The main difference was that the sporulation period lasted longer in adult leaves.

  8. Hormonal Regulation of Leaf Abscission

    PubMed Central

    Jacobs, William P.

    1968-01-01

    A review is given of the progress made during the last 6 years in elucidating the nature, locus of action, and transport properties of the endogenous hormones that control leaf abscission. PMID:16657014

  9. Experiments in Whole Leaf Photosynthesis

    ERIC Educational Resources Information Center

    Stewart, J. C.; And Others

    1974-01-01

    Described is a simple experimental system, which uses radioactive carbon dioxide to study whole leaf photosynthesis under a variety of conditions. Other experiments and simple apparatus for the experiments are also described. (Author/RH)

  10. The rheology of a growing leaf: stress-induced changes in the mechanical properties of leaves

    PubMed Central

    Sahaf, Michal; Sharon, Eran

    2016-01-01

    We study in situ the mechanics and growth of a leaf. Young Nicotiana tabacum leaves respond to applied mechanical stress by altering both their mechanical properties and the characteristics of their growth. We observed two opposite behaviours, each with its own typical magnitude and timescale. On timescales of the order of minutes, the leaf deforms in response to applied tensile stress. During this phase we found a high correlation between the applied stress field and the local strain field throughout the leaf surface. For times over 12 hours the mechanical properties of the leaf become anisotropic, making it more resilient to deformation and restoring a nearly isotropic growth field despite the highly anisotropic load. These observations suggest that remodelling of the tissue allows the leaf to respond to mechanical perturbations by changing its properties. We discuss the relevance of the observed behaviour to the growth regulation that leads to proper leaf shape during growth. PMID:27651350

  11. Why do leaf-tying caterpillars abandon their leaf ties?

    PubMed

    Sliwinski, Michelle; Sigmon, Elisha

    2013-01-01

    Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats), but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm(2) leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently abandon their leaf

  12. What determines a leaf's shape?

    PubMed

    Dkhar, Jeremy; Pareek, Ashwani

    2014-01-01

    The independent origin and evolution of leaves as small, simple microphylls or larger, more complex megaphylls in plants has shaped and influenced the natural composition of the environment. Significant contributions have come from megaphyllous leaves, characterized usually as flat, thin lamina entrenched with photosynthetic organelles and stomata, which serve as the basis of primary productivity. During the course of evolution, the megaphylls have attained complexity not only in size or venation patterns but also in shape. This has fascinated scientists worldwide, and research has progressed tremendously in understanding the concept of leaf shape determination. Here, we review these studies and discuss the various factors that contributed towards shaping the leaf; initiated as a small bulge on the periphery of the shoot apical meristem (SAM) followed by asymmetric outgrowth, expansion and maturation until final shape is achieved. We found that the underlying factors governing these processes are inherently genetic: PIN1 and KNOX1 are indicators of leaf initiation, HD-ZIPIII, KANADI, and YABBY specify leaf outgrowth while ANGUSTIFOLIA3 and GROWTH-REGULATING FACTOR5 control leaf expansion and maturation; besides, recent research has identified new players such as APUM23, known to specify leaf polarity. In addition to genetic control, environmental factors also play an important role during the final adjustment of leaf shape. This immense amount of information available will serve as the basis for studying and understanding innovative leaf morphologies viz. the pitchers of the carnivorous plant Nepenthes which have evolved to provide additional support to the plant survival in its nutrient-deficient habitat. In hindsight, formation of the pitcher tube in Nepenthes might involve the recruitment of similar genetic mechanisms that occur during sympetaly in Petunia. PMID:25584185

  13. What determines a leaf's shape?

    PubMed

    Dkhar, Jeremy; Pareek, Ashwani

    2014-01-01

    The independent origin and evolution of leaves as small, simple microphylls or larger, more complex megaphylls in plants has shaped and influenced the natural composition of the environment. Significant contributions have come from megaphyllous leaves, characterized usually as flat, thin lamina entrenched with photosynthetic organelles and stomata, which serve as the basis of primary productivity. During the course of evolution, the megaphylls have attained complexity not only in size or venation patterns but also in shape. This has fascinated scientists worldwide, and research has progressed tremendously in understanding the concept of leaf shape determination. Here, we review these studies and discuss the various factors that contributed towards shaping the leaf; initiated as a small bulge on the periphery of the shoot apical meristem (SAM) followed by asymmetric outgrowth, expansion and maturation until final shape is achieved. We found that the underlying factors governing these processes are inherently genetic: PIN1 and KNOX1 are indicators of leaf initiation, HD-ZIPIII, KANADI, and YABBY specify leaf outgrowth while ANGUSTIFOLIA3 and GROWTH-REGULATING FACTOR5 control leaf expansion and maturation; besides, recent research has identified new players such as APUM23, known to specify leaf polarity. In addition to genetic control, environmental factors also play an important role during the final adjustment of leaf shape. This immense amount of information available will serve as the basis for studying and understanding innovative leaf morphologies viz. the pitchers of the carnivorous plant Nepenthes which have evolved to provide additional support to the plant survival in its nutrient-deficient habitat. In hindsight, formation of the pitcher tube in Nepenthes might involve the recruitment of similar genetic mechanisms that occur during sympetaly in Petunia.

  14. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf.

    PubMed

    Simonin, Kevin A; Burns, Emily; Choat, Brendan; Barbour, Margaret M; Dawson, Todd E; Franks, Peter J

    2015-03-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem-leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO₂ concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO₂ concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO₂ on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem-leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO₂ assimilation rate over the diurnal course of evaporative demand.

  15. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf

    PubMed Central

    Simonin, Kevin A.; Burns, Emily; Choat, Brendan; Barbour, Margaret M.; Dawson, Todd E.; Franks, Peter J.

    2015-01-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem–leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO2 concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO2 concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO2 on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem–leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO2 assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  16. Leaf exsertion, leaf elongation, and leaf senescence in Eriophorum vaginatum and Carex Bigelowii

    SciTech Connect

    Shaver, G.R.; Yandow, T.; Laundre, J.

    1990-01-01

    Most of the common sedges of arctic vegetation show a pattern of leaf production in which the exsertion and elongation of new leaves is more or less simultaneous with the senescence of old leaves. The present study was designed to increase our understanding of the variability sequential leaf production by arctic sedges, and to determine some of the controls on that variability. We did this in two ways: first, we compared the sequential patterns of leaf growth and senescence in E. vaginatum with those of Carex Bigelowii Torr. at two tussock tundra sites near Toolik Lake on the North Slope of Alaska. Second, we compared the responses of leaf growth in these species in control and fertilized plots and in two microenvironments thought to differ sharply in nutrient availability and total productivity. 29 refs., 28 figs., 2 tabs.

  17. Association mapping of leaf traits in spinach (Spinacia oleracea L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spinach (Spinacia oleracea L.) is an important leafy vegetable crop grown world-wide. Leaf traits, surface texture (smooth vs. savoy or semi-savoy), petiole color (green vs. purple), and edge shape (serrate vs. entire) are important for spinach. Association mapping of the three traits were conducted...

  18. Throughfall Drop Size Distribution in relation to Leaf Canopy State

    NASA Astrophysics Data System (ADS)

    Hudson, S.; Nanko, K.; Levia, D. F., Jr.

    2014-12-01

    The partitioning of incident precipitation by a forest canopy into throughfall and stemflow varies as a function of meteorological conditions, tree species, leaf morphology and surface roughness. Little work quantified the throughfall drop size signature of precipitation events relative to changes in leaf canopy state of deciduous forests. This is the first study to compare throughfall drop size distributions in the presence and absence of foliage. To quantify individual throughfall drops, a laser disdrometer gauge was deployed below an observed drip point under a Liriodendron tulipifera L. (yellow poplar) tree, in northeastern Maryland, USA. More than 750,000 individual throughfall droplets have been counted and measured from precipitation events generating more than 5 mm gross rainfall over a period of 12 months. Throughfall during leafless events had significantly larger maximum drop diameters (6.74mm leafless, 5.55mm leafed) and median volume diameter of drops (5.44mm leafless, 3.31mm leafed) than throughfall generated when leaves were present. Statistical techniques have demonstrated the substantial influence of canopy state over the drop size spectra. Principal component analysis and factor analysis both resulted in canopy state loading positively with increases in maximum drop diameter while loading negatively with air temperature. Boosted regression trees analysis corroborated these findings. Our findings correspond with the physical conditions of a leafless canopy, and illustrated the greater extent of surface adhesion of intercepted water films on woody surfaces as opposed to foliar surfaces, thereby underscoring the importance of canopy state on throughfall inputs.

  19. Interaction between Silver Nanoparticles and Spinach Leaf

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Li, H.; Zhang, Y.; Riser, E.; He, S.; Zhang, W.

    2013-12-01

    Interactions of engineered nanoparticles (ENPs) with plant surfaces are critical to assessing the bioavailability of ENPs to edible plants and to further evaluating impacts of ENPs on ecological health and food safety. Silver nanoparticles (i.e., nanoAg) could enter the agroecosystems either as an active ingredient in pesticides or from other industrial and consumer applications. Thus, in the events of pesticide application, rainfall, and irrigation, vegetable leaves could become in contact and then interact with nanoAg. The present study was to assess whether the interaction of nanoAg with spinach leaves can be described by classical sorption models and to what extent it depends on and varies with dispersion methods, environmental temperature, and ion release. We investigated the stability and ion release of nanoAg dispersed by sodium dodecyl sulfate (SDS, 1%) and humic acid (HA, 10 mg C/L) solutions, as well as sorption and desorption of nanoAg on and from the fresh spinach leaf. Results showed SDS-nanoAg released about 2%-8% more Ag ion than HA-nanoAg. The sorption of Ag ion, described by the Freundlich model in the initial concentration range of 0.6-50 mg/L, was 2-4 times higher than that of nanoAg. The sorption of nanoAg on spinach leaf can be fitted by the Langmuir model, and the maximum sorption amount of HA-nanoAg and SDS-nanoAg was 0.21 and 0.41 mg/g, respectively. The higher sorption of SDS-nanoAg relative to that of HA-nanoAg could be partially resulted from the higher release of Ag ion from the former. The maximum desorption amount of HA-nanoAg and SDS-nanoAg in 1% SDS solution was 0.08 and 0.10 mg/g, respectively. NanoAg attachment on and its penetration to the spinach leaf was visualized by the Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM-EDS). It is equally important that the less sorption of nanoAg under low environmental temperature could be partially due to the closure of stomata, as verified by SEM-EDS. Cyto

  20. Ontogenetic differences in mesophyll structure and chlorophyll distribution in Eucalyptus globulus ssp. globulus.

    PubMed

    James, S A; Smith, W K; Vogelmann, T C

    1999-02-01

    Mesophyll structure has been associated with the photosynthetic performance of leaves via the regulation of internal light and CO(2) profiles. Differences in mesophyll structure and chlorophyll distribution within three ontogenetically different leaf types of Eucalyptus globulus ssp. globulus were investigated. Juvenile leaves are blue-grey in color, dorsiventral (adaxial palisade layer only), hypostomatous, and approximately horizontal in orientation. In contrast, adult leaves are dark green in color, isobilateral (adaxial and abaxial palisade), amphistomatous, and nearly vertical in orientation. The transitional leaf type has structural features that appear intermediate between the juvenile and adult leaves. The ratio of mesophyll cell surface area per unit leaf surface area (A(mes)/A) of juvenile leaves was maximum at the base of a single, adaxial palisade layer and declined through the spongy mesophyll. Chlorophyll a + b content showed a coincident pattern, while the chlorophyll a:b ratio declined linearly from the adaxial to abaxial epidermis. In comparison, the mesophyll of adult leaves had a bimodal distribution of A(mes)/A, with maxima occurring beneath both the adaxial and abaxial surfaces within the first layer of multiple palisade layers. The distribution of chlorophyll a + b content had a similar pattern, although the maximum ratio of chlorophyll a:b occurred immediately beneath the adaxial and abaxial epidermis. The matching distributions of A(mes)/A and chlorophyll provide further evidence that mesophyll structure may act to influence photosynthetic performance. These changes in internal leaf structure at different life stages of E. globulus may be an adaptation for increased xeromorphy under increasing light exposure experienced from the seedling to adult tree, similar to the characteristics reported for different species according to sunlight exposure and water availability within their native habitats.

  1. Pseudomonas blight caused by Pseudomonas syringae on raspberry in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plantings of red raspberry (Rubus idaeus var. strigosus) exhibited symptoms of a previously undocumented disease. Lesions were observable from both adaxial and abaxial leaf surfaces. As disease progressed, lesions enlarged and coalesced, resulting in significant dark brown to black blighting of the ...

  2. First report of powdery mildew of chickpea (Cicer arietinum) caused by Leveillula taurica in Washington State

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chickpea is an important grain legume worldwide, and an important rotational and specialty crop in the US. In October 2007, powdery mildew was found on chickpea plants in a field near Pullman, Washington. Typical powdery mildew symptoms and signs were observed on petioles and adaxial leaf surfaces....

  3. MODIS Measures Total U.S. Leaf Area

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This composite image over the continental United States was produced with data acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS) during the period March 24 - April 8, 2000. The image is a map of the density of the plant canopy covering the ground. It is the first in a series of images over the continental U.S. produced by the MODIS Land Discipline Group (refer to this site June 2 and 5 for the next two images in the series). The image is a MODIS data product called 'Leaf Area Index,' which is produced by radiometrically measuring the visible and near infrared energy reflected by vegetation. The Leaf Area Index provides information on the structure of plant canopy, showing how much surface area is covered by green foliage relative to total land surface area. In this image, dark green pixels indicate areas where more than 80 percent of the land surface is covered by green vegetation, light green pixels show where leaves cover about 10 to 50 percent of the land surface, and brown pixels show virtually no leaf coverage. The more leaf area a plant has, the more sunlight it can absorb for photosynthesis. Leaf Area Index is one of a new suite of measurements that scientists use to understand how the Earth's land surfaces are changing over time. Their goal is to use these measurements to refine computer models well enough to simulate how the land biosphere influences the natural cycles of water, carbon, and energy throughout the Earth system. This image is the first of its kind from the MODIS instrument, which launched in December 1999 aboard the Terra spacecraft. MODIS began acquiring scientific data on February 24, 2000, when it first opened its aperture door. The MODIS instrument and Terra spacecraft are both managed by NASA's Goddard Space Flight Center, Greenbelt, MD. Image courtesy Steven Running, MODIS Land Group Member, University of Montana

  4. How to pattern a leaf.

    PubMed

    Bolduc, N; O'Connor, D; Moon, J; Lewis, M; Hake, S

    2012-01-01

    Leaf development presents a tremendous resource for tackling the question of patterning in biology. Leaves can be simple or highly dissected. They may have elaborated parts such as the tendrils of a pea leaf or the rolled blade of a carnivorous pitcher plant. Despite the variation in size, shape, and function, all leaves initiate in the same manner: from the flanks of a meristem. The maize leaf is useful for analysis of patterning due to the wealth of mutants and the distinct tissues along the proximal distal axis. The blade is distal, the sheath is proximal, and the ligule forms at the blade/sheath boundary. Establishment of this boundary involves the transcription factors LIGULELESS1 and LIGULELESS2 and the kinase LIGULELESS NARROW. The meristem-specific protein KNOTTED1 (KN1) binds and modulates the lg2 gene. Given the localization of KN1 at the proximal end of the leaf from the time of inception, we hypothesize that KN1 has a role in establishing the very proximal end of the leaf, whereas an auxin maximum guides the growing distal tip. PMID:23174765

  5. Comparative analyses of leaf anatomy of dicotyledonous species in Tibetan and Inner Mongolian grasslands.

    PubMed

    Ma, Jianjing; Ji, Chengjun; Han, Mei; Zhang, Tingfang; Yan, Xuedong; Hu, Dong; Zeng, Hui; He, Jinsheng

    2012-01-01

    Knowledge of the leaf anatomy of grassland plants is crucial for understanding how these plants adapt to the environment. Tibetan alpine grasslands and Inner Mongolian temperate grasslands are two major grassland types in northern China. Tibetan alpine grasslands occur in high-altitude regions where the low temperatures limit plant growth. Inner Mongolian temperate grasslands are found in arid regions where moisture is the limiting factor. Few comparative studies concerning the leaf anatomy of grassland plants of the Tibetan Plateau and Inner Mongolian Plateau have been conducted. We examined leaf characteristics at 71 sites and among 65 species, across the alpine grasslands of the Tibetan Plateau and the temperate grasslands of the Inner Mongolian Plateau. We compared the leaf structures of plants with different life forms and taxonomies, and their adaptation to arid or cold environments. We explored relationships among leaf features and the effects of climatic factors (i.e., growing season temperature and precipitation) on leaf characteristics. Our results showed that (i) there were significant differences in leaf anatomy between Tibetan alpine and Inner Mongolian temperate grasslands. Except for mesophyll cell density, the values obtained for thickness of leaf tissue, surface area and volume of mesophyll cells were larger on the Tibetan Plateau than on the Inner Mongolian Plateau. (ii) Within the same family or genus, leaf anatomy showed significant differences between two regions, and trends were consistent with those of whole species. (iii) Leaf anatomy of woody and herbaceous plants also showed significant differences between the regions. Except for mesophyll cell density, the values obtained for the thickness of leaf tissue, and the surface area and volume of mesophyll cells were larger in herbaceous than in woody plants. (iv) Leaf anatomical traits changed accordingly. Total leaf thickness, thicknesses of lower and upper epidermal cells, and surface area

  6. Transcriptional responses of Pseudomonas syringae to growth in epiphytic versus apoplastic leaf sites

    PubMed Central

    Yu, Xilan; Lund, Steven P.; Scott, Russell A.; Greenwald, Jessica W.; Records, Angela H.; Nettleton, Dan; Lindow, Steven E.; Gross, Dennis C.; Beattie, Gwyn A.

    2013-01-01

    Some strains of the foliar pathogen Pseudomonas syringae are adapted for growth and survival on leaf surfaces and in the leaf interior. Global transcriptome profiling was used to evaluate if these two habitats offer distinct environments for bacteria and thus present distinct driving forces for adaptation. The transcript profiles of Pseudomonas syringae pv. syringae B728a support a model in which leaf surface, or epiphytic, sites specifically favor flagellar motility, swarming motility based on 3-(3-hydroxyalkanoyloxy)alkanoic acid surfactant production, chemosensing, and chemotaxis, indicating active relocation primarily on the leaf surface. Epiphytic sites also promote high transcript levels for phenylalanine degradation, which may help counteract phenylpropanoid-based defenses before leaf entry. In contrast, intercellular, or apoplastic, sites favor the high-level expression of genes for GABA metabolism (degradation of these genes would attenuate GABA repression of virulence) and the synthesis of phytotoxins, two additional secondary metabolites, and syringolin A. These findings support roles for these compounds in virulence, including a role for syringolin A in suppressing defense responses beyond stomatal closure. A comparison of the transcriptomes from in planta cells and from cells exposed to osmotic stress, oxidative stress, and iron and nitrogen limitation indicated that water availability, in particular, was limited in both leaf habitats but was more severely limited in the apoplast than on the leaf surface under the conditions tested. These findings contribute to a coherent model of the adaptations of this widespread bacterial phytopathogen to distinct habitats within its host. PMID:23319638

  7. Leaf hydraulic conductance for a tank bromeliad: axial and radial pathways for moving and conserving water.

    PubMed

    North, Gretchen B; Lynch, Frank H; Maharaj, Franklin D R; Phillips, Carly A; Woodside, Walter T

    2013-01-01

    Epiphytic plants in the Bromeliaceae known as tank bromeliads essentially lack stems and absorptive roots and instead take up water from reservoirs formed by their overlapping leaf bases. For such plants, leaf hydraulic conductance is plant hydraulic conductance. Their simple strap-shaped leaves and parallel venation make them suitable for modeling leaf hydraulic conductance based on vasculature and other anatomical and morphological traits. Plants of the tank bromeliad Guzmania lingulata were investigated in a lowland tropical forest in Costa Rica and a shaded glasshouse in Los Angeles, CA, USA. Stomatal conductance to water vapor and leaf anatomical variables related to hydraulic conductance were measured for both groups. Tracheid diameters and numbers of vascular bundles (veins) were used with the Hagen-Poiseuille equation to calculate axial hydraulic conductance. Measurements of leaf hydraulic conductance using the evaporative flux method were also made for glasshouse plants. Values for axial conductance and leaf hydraulic conductance were used in a model based on leaky cable theory to estimate the conductance of the radial pathway from the vein to the leaf surface and to assess the relative contributions of both axial and radial pathways. In keeping with low stomatal conductance, low stomatal density, low vein density, and narrow tracheid diameters, leaf hydraulic conductance for G. lingulata was quite low in comparison with most other angiosperms. Using the predicted axial conductance in the leaky cable model, the radial resistance across the leaf mesophyll was predicted to predominate; lower, more realistic values of axial conductance resulted in predicted radial resistances that were closer to axial resistance in their impact on total leaf resistance. Tracer dyes suggested that water uptake through the tank region of the leaf was not limiting. Both dye movement and the leaky cable model indicated that the leaf blade of G. lingulata was structurally and

  8. Leaf hydraulic conductance for a tank bromeliad: axial and radial pathways for moving and conserving water.

    PubMed

    North, Gretchen B; Lynch, Frank H; Maharaj, Franklin D R; Phillips, Carly A; Woodside, Walter T

    2013-01-01

    Epiphytic plants in the Bromeliaceae known as tank bromeliads essentially lack stems and absorptive roots and instead take up water from reservoirs formed by their overlapping leaf bases. For such plants, leaf hydraulic conductance is plant hydraulic conductance. Their simple strap-shaped leaves and parallel venation make them suitable for modeling leaf hydraulic conductance based on vasculature and other anatomical and morphological traits. Plants of the tank bromeliad Guzmania lingulata were investigated in a lowland tropical forest in Costa Rica and a shaded glasshouse in Los Angeles, CA, USA. Stomatal conductance to water vapor and leaf anatomical variables related to hydraulic conductance were measured for both groups. Tracheid diameters and numbers of vascular bundles (veins) were used with the Hagen-Poiseuille equation to calculate axial hydraulic conductance. Measurements of leaf hydraulic conductance using the evaporative flux method were also made for glasshouse plants. Values for axial conductance and leaf hydraulic conductance were used in a model based on leaky cable theory to estimate the conductance of the radial pathway from the vein to the leaf surface and to assess the relative contributions of both axial and radial pathways. In keeping with low stomatal conductance, low stomatal density, low vein density, and narrow tracheid diameters, leaf hydraulic conductance for G. lingulata was quite low in comparison with most other angiosperms. Using the predicted axial conductance in the leaky cable model, the radial resistance across the leaf mesophyll was predicted to predominate; lower, more realistic values of axial conductance resulted in predicted radial resistances that were closer to axial resistance in their impact on total leaf resistance. Tracer dyes suggested that water uptake through the tank region of the leaf was not limiting. Both dye movement and the leaky cable model indicated that the leaf blade of G. lingulata was structurally and

  9. Leaf Hydraulic Conductance for a Tank Bromeliad: Axial and Radial Pathways for Moving and Conserving Water

    PubMed Central

    North, Gretchen B.; Lynch, Frank H.; Maharaj, Franklin D. R.; Phillips, Carly A.; Woodside, Walter T.

    2013-01-01

    Epiphytic plants in the Bromeliaceae known as tank bromeliads essentially lack stems and absorptive roots and instead take up water from reservoirs formed by their overlapping leaf bases. For such plants, leaf hydraulic conductance is plant hydraulic conductance. Their simple strap-shaped leaves and parallel venation make them suitable for modeling leaf hydraulic conductance based on vasculature and other anatomical and morphological traits. Plants of the tank bromeliad Guzmania lingulata were investigated in a lowland tropical forest in Costa Rica and a shaded glasshouse in Los Angeles, CA, USA. Stomatal conductance to water vapor and leaf anatomical variables related to hydraulic conductance were measured for both groups. Tracheid diameters and numbers of vascular bundles (veins) were used with the Hagen–Poiseuille equation to calculate axial hydraulic conductance. Measurements of leaf hydraulic conductance using the evaporative flux method were also made for glasshouse plants. Values for axial conductance and leaf hydraulic conductance were used in a model based on leaky cable theory to estimate the conductance of the radial pathway from the vein to the leaf surface and to assess the relative contributions of both axial and radial pathways. In keeping with low stomatal conductance, low stomatal density, low vein density, and narrow tracheid diameters, leaf hydraulic conductance for G. lingulata was quite low in comparison with most other angiosperms. Using the predicted axial conductance in the leaky cable model, the radial resistance across the leaf mesophyll was predicted to predominate; lower, more realistic values of axial conductance resulted in predicted radial resistances that were closer to axial resistance in their impact on total leaf resistance. Tracer dyes suggested that water uptake through the tank region of the leaf was not limiting. Both dye movement and the leaky cable model indicated that the leaf blade of G. lingulata was structurally and

  10. Evaluation of leaf removal as a means to reduce nutrient concentrations and loads in urban stormwater.

    PubMed

    Selbig, William R

    2016-11-15

    While the sources of nutrients to urban stormwater are many, the primary contributor is often organic detritus, especially in areas with dense overhead tree canopy. One way to remove organic detritus before it becomes entrained in runoff is to implement a city-wide leaf collection and street cleaning program. Improving our knowledge of the potential reduction of nutrients to stormwater through removal of leaves and other organic detritus on streets could help tailor more targeted municipal leaf collection programs. This study characterized an upper ideal limit in reductions of total and dissolved forms of phosphorus and nitrogen in stormwater through implementation of a municipal leaf collection and street cleaning program in Madison, WI, USA. Additional measures were taken to remove leaf litter from street surfaces prior to precipitation events. Loads of total and dissolved phosphorus were reduced by 84 and 83% (p<0.05), and total and dissolved nitrogen by 74 and 71% (p<0.05) with an active leaf removal program. Without leaf removal, 56% of the annual total phosphorus yield (winter excluded) was due to leaf litter in the fall compared to 16% with leaf removal. Despite significant reductions in load, total nitrogen showed only minor changes in fall yields without and with leaf removal at 19 and 16%, respectively. The majority of nutrient concentrations were in the dissolved fraction making source control through leaf removal one of the few treatment options available to environmental managers when reducing the amount of dissolved nutrients in stormwater runoff. Subsequently, the efficiency, frequency, and timing of leaf removal and street cleaning are the primary factors to consider when developing a leaf management program.

  11. Evaluation of leaf removal as a means to reduce nutrient concentrations and loads in urban stormwater.

    PubMed

    Selbig, William R

    2016-11-15

    While the sources of nutrients to urban stormwater are many, the primary contributor is often organic detritus, especially in areas with dense overhead tree canopy. One way to remove organic detritus before it becomes entrained in runoff is to implement a city-wide leaf collection and street cleaning program. Improving our knowledge of the potential reduction of nutrients to stormwater through removal of leaves and other organic detritus on streets could help tailor more targeted municipal leaf collection programs. This study characterized an upper ideal limit in reductions of total and dissolved forms of phosphorus and nitrogen in stormwater through implementation of a municipal leaf collection and street cleaning program in Madison, WI, USA. Additional measures were taken to remove leaf litter from street surfaces prior to precipitation events. Loads of total and dissolved phosphorus were reduced by 84 and 83% (p<0.05), and total and dissolved nitrogen by 74 and 71% (p<0.05) with an active leaf removal program. Without leaf removal, 56% of the annual total phosphorus yield (winter excluded) was due to leaf litter in the fall compared to 16% with leaf removal. Despite significant reductions in load, total nitrogen showed only minor changes in fall yields without and with leaf removal at 19 and 16%, respectively. The majority of nutrient concentrations were in the dissolved fraction making source control through leaf removal one of the few treatment options available to environmental managers when reducing the amount of dissolved nutrients in stormwater runoff. Subsequently, the efficiency, frequency, and timing of leaf removal and street cleaning are the primary factors to consider when developing a leaf management program. PMID:27470671

  12. The Influence of Source Biases on Sedimentary Leaf Waxes and Their Stable Isotope Compositions

    NASA Astrophysics Data System (ADS)

    Diefendorf, A. F.; Freimuth, E. J.; Lowell, T. V.; Wiles, G. C.

    2015-12-01

    Leaf waxes and their carbon (δ13C) and hydrogen (δD) isotopic compositions are an important tool to understand past changes in paleoclimate and paleovegetation. Important recent advances in our understanding about the isotopic signal preserved in sedimentary leaf waxes have been inferred from studies made on individual modern plants. However, paleoreconstructions are based on sedimentary leaf waxes, which reflect mixing between multiple sources, such as ablated leaf waxes from nearby or from afar, wind blown leaf litter, and riverine transported leaf waxes. Each of these sources integrates leaf waxes from different species and growth forms, likely resulting in source-specific taphonomic biases on sedimentary leaf wax isotopes. To better understand source biases in sedimentary leaf waxes, we investigated n-alkanes and n-alkanoic acids and their carbon and hydrogen isotopes in vegetation and lake sediments at Brown's Lake and Bog, a 'simple' forested closed-basin lake in northeastern Ohio. Interestingly, we found that tree n-alkane δD varied substantially during the growing season, broadly tracking changes in source water composition. However, δD values of n-alkanes in the tree leaf litter did not match that of the most recent sedimentary n-alkanes. Instead, surface sediment n-alkane δD more closely matched that of the woody shrubs and grasses growing right around the lake. n-Alkanoic acid data is forthcoming. We are currently exploring lake sediment n-alkane accumulation rates against midwestern flux rates of wind blown leaf waxes from afar. Our preliminary results suggest that although studies made on individual leaves are indeed important, we may need to consider additional leaf wax sources that potentially influence sedimentary archives.

  13. Silicified structures affect leaf optical properties in grasses and sedge.

    PubMed

    Klančnik, Katja; Vogel-Mikuš, Katarina; Gaberščik, Alenka

    2014-01-01

    Silicon (Si) is an important structural element that can accumulate at high concentrations in grasses and sedges, and therefore Si structures might affect the optical properties of the leaves. To better understand the role of Si in light/leaf interactions in species rich in Si, we examined the total Si and silica phytoliths, the biochemical and morphological leaf properties, and the reflectance and transmittance spectra in grasses (Phragmites australis, Phalaris arundinacea, Molinia caerulea, Deschampsia cespitosa) and sedge (Carex elata). We show that these grasses contain >1% phytoliths per dry mass, while the sedge contains only 0.4%. The data reveal the variable leaf structures of these species and significant differences in the amount of Si and phytoliths between developing and mature leaves within each species and between grasses and sedge, with little difference seen among the grass species. Redundancy analysis shows the significant roles of the different near-surface silicified leaf structures (e.g., prickle hairs, cuticle, epidermis), phytoliths and Si contents, which explain the majority of the reflectance and transmittance spectra variability. The amount of explained variance differs between mature and developing leaves. The transmittance spectra are also significantly affected by chlorophyll a content and calcium levels in the leaf tissue.

  14. Linkage between canopy water storage and drop size distributions of leaf drips

    NASA Astrophysics Data System (ADS)

    Nanko, Kazuki; Watanabe, Ai; Hotta, Norifumi; Suzuki, Masakazu

    2013-04-01

    Differences in drop size distribution (DSD) of leaf drips among tree species have been estimated and physically interpreted to clarify the leaf drip generation process. Leaf drip generation experiments for nine species were conducted in an indoor location without foliage vibration using an automatic mist spray. Broad-leaved species produced a similar DSD among species whose leaves had a matte surface and a second similar DSD among species whose leaves had a coated surface. The matte broad leaves produced a larger and wider range of DSDs than the coated broad leaves. Coated coniferous needles had a wider range of DSDs than the coated broad leaves and different DSDs were observed for different species. The species with shorter dense needles generated a larger DSD. The leaf drip diameter was calculated through the estimation of a state of equilibrium of a hanging drop on the leaves based on physical theory. The calculations indicated that the maximum diameter of leaf drips was determined by the contact angle, and the range of DSDs was determined by the variation in contact length and the contact diameter at the hanging points. The results revealed that leaf drip DSD changed due to variations in leaf hydrophobicity, leaf roughness, leaf geometry and leaf inclination among the different tree species. This study allows the modelization of throughfall DSD. Furthermore, it indicates the possibility of interpreting canopy water processes from canopy water storage to drainage through the contact angle and leaf drip DSD. The part of this study is published in Nanko et al. (2013, Agric. Forest. Meteorol. 169, 74-84).

  15. Global variability in leaf respiration in relation to climate, plant functional types and leaf traits.

    PubMed

    Atkin, Owen K; Bloomfield, Keith J; Reich, Peter B; Tjoelker, Mark G; Asner, Gregory P; Bonal, Damien; Bönisch, Gerhard; Bradford, Matt G; Cernusak, Lucas A; Cosio, Eric G; Creek, Danielle; Crous, Kristine Y; Domingues, Tomas F; Dukes, Jeffrey S; Egerton, John J G; Evans, John R; Farquhar, Graham D; Fyllas, Nikolaos M; Gauthier, Paul P G; Gloor, Emanuel; Gimeno, Teresa E; Griffin, Kevin L; Guerrieri, Rossella; Heskel, Mary A; Huntingford, Chris; Ishida, Françoise Yoko; Kattge, Jens; Lambers, Hans; Liddell, Michael J; Lloyd, Jon; Lusk, Christopher H; Martin, Roberta E; Maksimov, Ayal P; Maximov, Trofim C; Malhi, Yadvinder; Medlyn, Belinda E; Meir, Patrick; Mercado, Lina M; Mirotchnick, Nicholas; Ng, Desmond; Niinemets, Ülo; O'Sullivan, Odhran S; Phillips, Oliver L; Poorter, Lourens; Poot, Pieter; Prentice, I Colin; Salinas, Norma; Rowland, Lucy M; Ryan, Michael G; Sitch, Stephen; Slot, Martijn; Smith, Nicholas G; Turnbull, Matthew H; VanderWel, Mark C; Valladares, Fernando; Veneklaas, Erik J; Weerasinghe, Lasantha K; Wirth, Christian; Wright, Ian J; Wythers, Kirk R; Xiang, Jen; Xiang, Shuang; Zaragoza-Castells, Joana

    2015-04-01

    Leaf dark respiration (Rdark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark . Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, Rdark at a standard T (25°C, Rdark (25) ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark (25) at a given photosynthetic capacity (Vcmax (25) ) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark (25) values at any given Vcmax (25) or [N] were higher in herbs than in woody plants. The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs).

  16. Global variability in leaf respiration in relation to climate, plant functional types and leaf traits.

    PubMed

    Atkin, Owen K; Bloomfield, Keith J; Reich, Peter B; Tjoelker, Mark G; Asner, Gregory P; Bonal, Damien; Bönisch, Gerhard; Bradford, Matt G; Cernusak, Lucas A; Cosio, Eric G; Creek, Danielle; Crous, Kristine Y; Domingues, Tomas F; Dukes, Jeffrey S; Egerton, John J G; Evans, John R; Farquhar, Graham D; Fyllas, Nikolaos M; Gauthier, Paul P G; Gloor, Emanuel; Gimeno, Teresa E; Griffin, Kevin L; Guerrieri, Rossella; Heskel, Mary A; Huntingford, Chris; Ishida, Françoise Yoko; Kattge, Jens; Lambers, Hans; Liddell, Michael J; Lloyd, Jon; Lusk, Christopher H; Martin, Roberta E; Maksimov, Ayal P; Maximov, Trofim C; Malhi, Yadvinder; Medlyn, Belinda E; Meir, Patrick; Mercado, Lina M; Mirotchnick, Nicholas; Ng, Desmond; Niinemets, Ülo; O'Sullivan, Odhran S; Phillips, Oliver L; Poorter, Lourens; Poot, Pieter; Prentice, I Colin; Salinas, Norma; Rowland, Lucy M; Ryan, Michael G; Sitch, Stephen; Slot, Martijn; Smith, Nicholas G; Turnbull, Matthew H; VanderWel, Mark C; Valladares, Fernando; Veneklaas, Erik J; Weerasinghe, Lasantha K; Wirth, Christian; Wright, Ian J; Wythers, Kirk R; Xiang, Jen; Xiang, Shuang; Zaragoza-Castells, Joana

    2015-04-01

    Leaf dark respiration (Rdark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark . Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, Rdark at a standard T (25°C, Rdark (25) ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark (25) at a given photosynthetic capacity (Vcmax (25) ) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark (25) values at any given Vcmax (25) or [N] were higher in herbs than in woody plants. The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs). PMID:25581061

  17. Assimilation of satellite reflecance dataa into a dynamical leaf model to infer seasonally varying leaf area for climate and carbon models

    SciTech Connect

    Liu, Qing; Gu, Lianhong; Dickinson, Robert E.; Tian, Y; Zhou, L; Post, Wilfred M

    2007-01-01

    Leaf area index is an important input for many climate and carbon models. The widely used leaf area products derived from satellite-observed surface reflectances contain substantial erratic fluctuations in time due to inadequate atmospheric corrections and observational and retrieval uncertainties. These fluctuations are inconsistent with the seasonal dynamics of leaf area, known to be gradual. Their use in process-based terrestrial carbon models corrupts model behavior, making diagnosis of model performance difficult. We propose a data assimilation approach that combines the satellite observations of Moderate Resolution Imaging Spectroradiometer (MODIS) albedo with a dynamical leaf model. Its novelty is that the seasonal cycle of the directly retrieved leaf areas is smooth and consistent with both observations and current understandings of processes controlling leaf area dynamics. The approach optimizes the dynamical model parameters such that the difference between the estimated surface reflectances based on the modeled leaf area and those of satellite observations is minimized. We demonstrate the usefulness and advantage of our new approach at multiple deciduous forest sites in the United States.

  18. Leaf physico-chemical and physiological properties of maize (Zea mays L.) populations from different origins.

    PubMed

    Revilla, Pedro; Fernández, Victoria; Álvarez-Iglesias, Lorena; Medina, Eva T; Cavero, José

    2016-10-01

    In this study we evaluated the leaf surface properties of maize populations native to different water availability environments. Leaf surface topography, wettability and gas exchange performance of five maize populations from the Sahara desert, dry (south) and humid (north-western) areas of Spain were analysed. Differences in wettability, stomatal and trichome densities, surface free energy and solubility parameter values were recorded between populations and leaf sides. Leaves from the humid Spanish population with special regard to the abaxial side, were less wettable and less susceptible to polar interactions. The higher wettability and hydrophilicity of Sahara populations with emphasis on the abaxial leaf surfaces, may favour dew deposition and foliar water absorption, hence improving water use efficiency under extremely dry conditions. Compared to the other Saharan populations, the dwarf one had a higher photosynthesis rate suggesting that dwarfism may be a strategy for improving plant tolerance to arid conditions. The results obtained for different maize populations suggest that leaf surfaces may vary in response to drought, but further studies will be required to examine the potential relationship between leaf surface properties and plant stress tolerance. PMID:27368072

  19. Leaf morphophysiology of a Neotropical mistletoe is shaped by seasonal patterns of host leaf phenology.

    PubMed

    Scalon, Marina Corrêa; Rossatto, Davi Rodrigo; Domingos, Fabricius Maia Chaves Bicalho; Franco, Augusto Cesar

    2016-04-01

    Several mistletoe species are able to grow and reproduce on both deciduous and evergreen hosts, suggesting a degree of plasticity in their ability to cope with differences in intrinsic host functions. The aim of this study was to investigate the influence of host phenology on mistletoe water relations and leaf gas exchange. Mistletoe Passovia ovata parasitizing evergreen (Miconia albicans) hosts and P. ovata parasitizing deciduous (Byrsonima verbascifolia) hosts were sampled in a Neotropical savanna. Photosynthetic parameters, diurnal cycles of stomatal conductance, pre-dawn and midday leaf water potential, and stomatal anatomical traits were measured during the peak of the dry and wet seasons, respectively. P. ovata showed distinct water-use strategies that were dependent on host phenology. For P. ovata parasitizing the deciduous host, water use efficiency (WUE; ratio of photosynthetic rate to transpirational water loss) was 2-fold lower in the dry season than in the wet season; in contrast, WUE was maintained at the same level during the wet and dry seasons in P. ovata parasitizing the evergreen host. Generally, mistletoe and host diurnal cycles of stomatal conductance were linked, although there were clear differences in leaf water potential, with mistletoe showing anisohydric behaviour and the host showing isohydric behaviour. Compared to mistletoes attached to evergreen hosts, those parasitizing deciduous hosts had a 1.4-fold lower stomatal density and 1.2-fold wider stomata on both leaf surfaces, suggesting that the latter suffered less intense drought stress. This is the first study to show morphophysiological differences in the same mistletoe species parasitizing hosts of different phenological groups. Our results provide evidence that phenotypical plasticity (anatomical and physiological) might be essential to favour the use of a greater range of hosts. PMID:26686200

  20. Differences on photosynthetic limitations between leaf margins and leaf centers under potassium deficiency for Brassica napus L.

    PubMed Central

    Lu, Zhifeng; Ren, Tao; Pan, Yonghui; Li, Xiaokun; Cong, Rihuan; Lu, Jianwei

    2016-01-01

    Analyzing the proportions of stomatal (SL), mesophyll conductance (MCL) and biochemical limitations (BL) imposed by potassium (K) deficit, and evaluating their relationships to leaf K status will be helpful to understand the mechanism underlying the inhibition of K deficiency on photosynthesis (A). A quantitative limitation analysis of K deficiency on photosynthesis was performed on leaf margins and centers under K deficiency and sufficient K supply treatments of Brassica napus L. Potassium deficiency decreased A, stomatal (gs) and mesophyll conductance (gm) of margins, SL, MCL and BL accounted for 23.9%, 33.0% and 43.1% of the total limitations. While for leaf centers, relatively low limitations occurred. Nonlinear curve fitting analysis indicated that each limiting factor generated at same leaf K status (1.07%). Although MCL was the main component of limitations when A began to fall, BL replaced it at a leaf K concentration below 0.78%. Up-regulated MCL was related to lower surface area of chloroplasts exposed to intercellular airspaces (Sc/S) and larger cytosol diffusion resistance but not the cell wall thickness. Our results highlighted that photosynthetic limitations appear simultaneously under K deficiency and vary with increasing K deficiency intensity. PMID:26902263

  1. Coordination of Leaf Photosynthesis, Transpiration, and Structural Traits in Rice and Wild Relatives (Genus Oryza).

    PubMed

    Giuliani, Rita; Koteyeva, Nuria; Voznesenskaya, Elena; Evans, Marc A; Cousins, Asaph B; Edwards, Gerald E

    2013-07-01

    The genus Oryza, which includes rice (Oryza sativa and Oryza glaberrima) and wild relatives, is a useful genus to study leaf properties in order to identify structural features that control CO(2) access to chloroplasts, photosynthesis, water use efficiency, and drought tolerance. Traits, 26 structural and 17 functional, associated with photosynthesis and transpiration were quantified on 24 accessions (representatives of 17 species and eight genomes). Hypotheses of associations within, and between, structure, photosynthesis, and transpiration were tested. Two main clusters of positively interrelated leaf traits were identified: in the first cluster were structural features, leaf thickness (Thick(leaf)), mesophyll (M) cell surface area exposed to intercellular air space per unit of leaf surface area (S(mes)), and M cell size; a second group included functional traits, net photosynthetic rate, transpiration rate, M conductance to CO(2) diffusion (g(m)), stomatal conductance to gas diffusion (g(s)), and the g(m)/g(s) ratio.While net photosynthetic rate was positively correlated with gm, neither was significantly linked with any individual structural traits. The results suggest that changes in gm depend on covariations of multiple leaf (S(mes)) and M cell (including cell wall thickness) structural traits. There was an inverse relationship between Thick(leaf) and transpiration rate and a significant positive association between Thick(leaf) and leaf transpiration efficiency. Interestingly, high g(m) together with high g(m)/g(s) and a low S(mes)/g(m) ratio (M resistance to CO(2) diffusion per unit of cell surface area exposed to intercellular air space) appear to be ideal for supporting leaf photosynthesis while preserving water; in addition, thick M cell walls may be beneficial for plant drought tolerance.

  2. Interspecific variation of photosynthesis and leaf characteristics in canopy trees of five species of Dipterocarpaceae in a tropical rain forest.

    PubMed

    Kenzo, Tanaka; Ichie, Tomoaki; Yoneda, Reiji; Kitahashi, Yoshinori; Watanabe, Yoko; Ninomiya, Ikuo; Koike, Takayoshi

    2004-10-01

    Photosynthetic rate, nitrogen concentration and morphological properties of canopy leaves were studied in 18 trees, comprising five dipterocarp species, in a tropical rain forest in Sarawak, Malaysia. Photosynthetic rate at light saturation (Pmax) differed significantly across species, varying from 7 to 18 micro mol m(-2) s(-1). Leaf nitrogen concentration and morphological properties, such as leaf blade and palisade layer thickness, leaf mass per area (LMA) and surface area of mesophyll cells per unit leaf area (Ames/A), also varied significantly across species. Among the relationships with leaf characteristics, Pmax had the strongest correlation with leaf mesophyll parameters, such as palisade cell layer thickness (r2 = 0.76, P < 0.001) and Ames/A (r2 = 0.73, P < 0.001). Leaf nitrogen concentration and Pmax per unit area also had a significant but weaker correlation (r2 = 0.46, P < 0.01), whereas Pmax had no correlation, or only weakly significant correlations, with leaf blade thickness and LMA. Shorea beccariana Burck, which had the highest P(max) of the species studied, also had the thickest palisade layer, with up to five or more layers. We conclude that interspecific variation in photosynthetic capacity in tropical rain forest canopies is influenced more by leaf mesophyll structure than by leaf thickness, LMA or leaf nitrogen concentration.

  3. Behavior of Leaf Meristems and Their Modification

    PubMed Central

    Ichihashi, Yasunori; Tsukaya, Hirokazu

    2015-01-01

    A major source of diversity in flowering plant form is the extensive variability of leaf shape and size. Leaf formation is initiated by recruitment of a handful of cells flanking the shoot apical meristem (SAM) to develop into a complex three-dimensional structure. Leaf organogenesis depends on activities of several distinct meristems that are established and spatiotemporally differentiated after the initiation of leaf primordia. Here, we review recent findings in the gene regulatory networks that orchestrate leaf meristem activities in a model plant Arabidopsis thaliana. We then discuss recent key studies investigating the natural variation in leaf morphology to understand how the gene regulatory networks modulate leaf meristems to yield a substantial diversity of leaf forms during the course of evolution. PMID:26648955

  4. Spectral reflectance relationships to leaf water stress

    NASA Technical Reports Server (NTRS)

    Ripple, William J.

    1986-01-01

    Spectral reflectance data were collected from detached snapbean leaves in the laboratory with a multiband radiometer. Four experiments were designed to study the spectral response resulting from changes in leaf cover, relative water content of leaves, and leaf water potential. Spectral regions included in the analysis were red (630-690 nm), NIR (760-900 nm), and mid-IR (2.08-2.35 microns). The red and mid-IR bands showed sensitivity to changes in both leaf cover and relative water content of leaves. The NIR was only highly sensitive to changes in leaf cover. Results provided evidence that mid-IR reflectance was governed primarily by leaf moisture content, although soil reflectance was an important factor when leaf cover was less than 100 percent. High correlations between leaf water potentials and reflectance were attributed to covariances with relative water content of leaves and leaf cover.

  5. An Innovative Way to Monitor Leaf Age

    NASA Astrophysics Data System (ADS)

    Garnello, A.; Paredes, K.; Trinh, U.; Saleska, S. R.; Wu, J.

    2013-12-01

    Anthony John Garnello, Karina Paredes, Uyen Khanh Ho Trinh, Jin Wu, Scott Saleska Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA Abstract: Leaf age is an important characteristic for controlling plant functional performance and is associated with the changes of leaf physical, chemical, and physiological properties. Understanding how plant physiology changes over time will allow more accurate predictions of growth patterns, and a more comprehensive understanding of vegetative life histories. There still lacks an efficient technique in monitoring leaf age, tagging leaves is still the only way to accurately monitor leaf age. The goal of this study is to develop a multi-metric, accurate technique for better monitoring of leaf age. In order to acquire true leaf age records, 10 individual plant species were selected at the University of Arizona campus, and newly flushing leaves were tagged and monitored during the Monsoon season (from early June, 2013, to mid October, 2013). Every 2 weeks, 10 to 15 leaves in relative age order were harvested from each 1-meter branch to measure multiple key leaf metrics, including leaf thickness (via micrometer), fresh and dry weight, fresh and dry area (via ImageJ software), and leaf hyperspectral reflectance (via a handheld ASD Field Pro). Other leaf traits were also derived from our measurements, such as specific leaf area (SLA), leaf density (fresh weight/leaf volume), water percentage, and shrinkage ratio (1-dry area/fresh area). The hyperspectral version of vegetation index (a ratio derived from two spectral channels) was generated for each branch sample, by randomly selecting two channels from within the spectral domain of 350 nm to 2500 nm. The preliminary result documents three types of hyperspectral vegetation index (VI) which are highly related with leaf relative age order (R2>0.9). These include the sensitive spectral domains correlated with (a) leaf pigments (~550nm) and leaf physical

  6. Linking spatial patterns of leaf litterfall and soil nutrients in a tropical forest: a neighborhood approach.

    PubMed

    Uriarte, María; Turner, Benjamin L; Thompson, Jill; Zimmerman, Jess K

    2015-10-01

    can be used to generate prediction surfaces for leaf litter deposition and quality onto the forest floor, a useful tool for understanding soil-vegetation feedbacks. A better understanding of the role of leaf litter inputs from secondary vegetation in restoring soil nutrient stocks will also assist in managing expanding secondary forests in tropical regions.

  7. Do plant mites commonly prefer the underside of leaves?

    PubMed

    Sudo, Masaaki; Osakabe, Masahiro

    2011-09-01

    The adaxial (upper) and abaxial (lower) surfaces of a plant leaf provide heterogeneous habitats for small arthropods with different environmental conditions, such as light, humidity, and surface morphology. As for plant mites, some agricultural pest species and their natural enemies have been observed to favor the abaxial leaf surface, which is considered an adaptation to avoid rain or solar ultraviolet radiation. However, whether such a preference for the leaf underside is a common behavioral trait in mites on wild vegetation remains unknown. The authors conducted a 2-year survey on the foliar mite assemblage found on Viburnum erosum var. punctatum, a deciduous shrub on which several mite taxa occur throughout the seasons, and 14 sympatric tree or shrub species in secondary broadleaf-forest sites in Kyoto, west-central Japan. We compared adaxial-abaxial surface distributions of mites among mite taxa, seasons, and morphology of host leaves (presence/absence of hairs and domatia). On V. erosum var. punctatum, seven of 11 distinguished mite taxa were significantly distributed in favor of abaxial leaf surfaces and the trend was seasonally stable, except for Eriophyoidea. Mite assemblages on 15 plant species were significantly biased towards the abaxial leaf surfaces, regardless of surface morphology. Our data suggest that many mite taxa commonly prefer to stay on abaxial leaf surfaces in wild vegetation. Oribatida displayed a relatively neutral distribution, and in Tenuipalpidae, the ratio of eggs collected from the adaxial versus the abaxial side was significantly higher than the ratio of the motile individuals, implying that some mite taxa exploit adaxial leaf surfaces as habitat. PMID:21472503

  8. Do plant mites commonly prefer the underside of leaves?

    PubMed

    Sudo, Masaaki; Osakabe, Masahiro

    2011-09-01

    The adaxial (upper) and abaxial (lower) surfaces of a plant leaf provide heterogeneous habitats for small arthropods with different environmental conditions, such as light, humidity, and surface morphology. As for plant mites, some agricultural pest species and their natural enemies have been observed to favor the abaxial leaf surface, which is considered an adaptation to avoid rain or solar ultraviolet radiation. However, whether such a preference for the leaf underside is a common behavioral trait in mites on wild vegetation remains unknown. The authors conducted a 2-year survey on the foliar mite assemblage found on Viburnum erosum var. punctatum, a deciduous shrub on which several mite taxa occur throughout the seasons, and 14 sympatric tree or shrub species in secondary broadleaf-forest sites in Kyoto, west-central Japan. We compared adaxial-abaxial surface distributions of mites among mite taxa, seasons, and morphology of host leaves (presence/absence of hairs and domatia). On V. erosum var. punctatum, seven of 11 distinguished mite taxa were significantly distributed in favor of abaxial leaf surfaces and the trend was seasonally stable, except for Eriophyoidea. Mite assemblages on 15 plant species were significantly biased towards the abaxial leaf surfaces, regardless of surface morphology. Our data suggest that many mite taxa commonly prefer to stay on abaxial leaf surfaces in wild vegetation. Oribatida displayed a relatively neutral distribution, and in Tenuipalpidae, the ratio of eggs collected from the adaxial versus the abaxial side was significantly higher than the ratio of the motile individuals, implying that some mite taxa exploit adaxial leaf surfaces as habitat.

  9. Analysis of Circadian Leaf Movements.

    PubMed

    Müller, Niels A; Jiménez-Gómez, José M

    2016-01-01

    The circadian clock is a molecular timekeeper that controls a wide variety of biological processes. In plants, clock outputs range from the molecular level, with rhythmic gene expression and metabolite content, to physiological processes such as stomatal conductance or leaf movements. Any of these outputs can be used as markers to monitor the state of the circadian clock. In the model plant Arabidopsis thaliana, much of the current knowledge about the clock has been gained from time course experiments profiling expression of endogenous genes or reporter constructs regulated by the circadian clock. Since these methods require labor-intensive sample preparation or transformation, monitoring leaf movements is an interesting alternative, especially in non-model species and for natural variation studies. Technological improvements both in digital photography and image analysis allow cheap and easy monitoring of circadian leaf movements. In this chapter we present a protocol that uses an autonomous point and shoot camera and free software to monitor circadian leaf movements in tomato. PMID:26867616

  10. LEAF: A Microcomputer Program for Constructing the Tukey Stem and Leaf Graph.

    ERIC Educational Resources Information Center

    Pascale, Pietro J.; Smith, Joseph

    1986-01-01

    This paper presents a BASIC microcomputer program that constructs the Tukey (1977) stem and leaf graph. Options within the LEAF program include a modified stem and leaf where the stem is split and a parallel stem and leaf graph where two separate sets of data are displayed from a common stem. (Author)

  11. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole...

  12. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco...

  13. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from...

  14. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap...

  15. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  16. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  17. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  18. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  19. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  20. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  1. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  2. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  3. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  4. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  5. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  6. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  7. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  8. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  9. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  10. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  11. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  12. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  13. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  14. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  15. Leaf Associated Microbial Activities in a Stream Affected by Acid Mine Drainage

    NASA Astrophysics Data System (ADS)

    Schlief, Jeanette

    2004-11-01

    Microbial activity was assessed on birch leaves and plastic strips during 140 days of exposure at three sites in an acidic stream of the Lusatian post-mining landscape, Germany. The sites differed in their degrees of ochre deposition and acidification. The aim of the study was (1) to follow the microbial activities during leaf colonization, (2) to compare the effect of different environmental conditions on leaf associated microbial activities, and (3) to test the microbial availability of leaf litter in acidic mining waters. The activity peaked after 49 days and subsequently decreased gradually at all sites. A formation of iron plaques on leaf surfaces influenced associated microbial activity. It seemed that these plaques inhibit the microbial availability of leaf litter and serve as a microbial habitat by itself. (

  16. Leaf cuticular wax amount and crystal morphology regulate post-harvest water loss in mulberry (Morus species).

    PubMed

    Mamrutha, H M; Mogili, T; Jhansi Lakshmi, K; Rama, N; Kosma, Dylan; Udaya Kumar, M; Jenks, Matthew A; Nataraja, Karaba N

    2010-08-01

    Mulberry leaves are the sole source of food for silkworms (Bombyx mori), and moisture content of the detached leaves fed to silkworms determines silkworm growth and cocoon yield. Since leaf dehydration in commercial sericulture is a serious problem, development of new methods that minimize post-harvest water loss are greatly needed. In the present study, variability in moisture retention capacity (MRC, measured as leaf relative water content after one to 5 h of air-drying) was examined by screening 290 diverse mulberry accessions and the relationship between MRC and leaf surface (cuticular) wax amount was determined. Leaf MRC varied significantly among accessions, and was found to correlate strongly with leaf wax amount. Scanning electron microscopic analysis indicated that leaves having crystalline surface waxes of increased facet size and density were associated with high MRC accessions. Leaf MRC at 5 h after harvest was not related to other parameters such as specific leaf weight, and stomatal frequency and index. This study suggests that mulberry accessions having elevated leaf surface wax amount and crystal size and density exhibit reduced leaf post-harvest water loss, and could provide the foundation for selective breeding of improved cultivars. PMID:20580887

  17. Comparison of half and full-leaf shape feature extraction for leaf classification

    NASA Astrophysics Data System (ADS)

    Sainin, Mohd Shamrie; Ahmad, Faudziah; Alfred, Rayner

    2016-08-01

    Shape is the main information for leaf feature that most of the current literatures in leaf identification utilize the whole leaf for feature extraction and to be used in the leaf identification process. In this paper, study of half-leaf features extraction for leaf identification is carried out and the results are compared with the results obtained from the leaf identification based on a full-leaf features extraction. Identification and classification is based on shape features that are represented as cosines and sinus angles. Six single classifiers obtained from WEKA and seven ensemble methods are used to compare their performance accuracies over this data. The classifiers were trained using 65 leaves in order to classify 5 different species of preliminary collection of Malaysian medicinal plants. The result shows that half-leaf features extraction can be used for leaf identification without decreasing the predictive accuracy.

  18. Distribution of leaf characteristics in relation to orientation within the canopy of woody species

    NASA Astrophysics Data System (ADS)

    Escudero, Alfonso; Fernández, José; Cordero, Angel; Mediavilla, Sonia

    2013-04-01

    Over the last few decades considerable effort has been devoted to research of leaf adaptations to environmental conditions. Many studies have reported strong differences in leaf mass per unit area (LMA) within a single tree depending on the photosynthetic photon flux density (PPFD) incident on different locations in the crown. There are fewer studies, however, of the effects of differences in the timing of light incidence during the day on different crown orientations. Leaves from isolated trees of Quercus suber and Quercus ilex in a cold Mediterranean climate were sampled to analyze differences in LMA and other leaf traits among different crown orientations. Gas-exchange rates, leaf water potentials, leaf temperatures and PPFD incident on leaf surfaces in different crown orientations were also measured throughout one entire summer day for each species. Mean daily PPFD values were similar for the leaves from the eastern and western sides of the canopy. On the western side, PPFD reached maximum values during the afternoon. Maximum leaf temperatures were approximately 10-20% higher on the west side, whereas minimum leaf water potentials were between 10 and 24% higher on the east side. Maximum transpiration rates were approximately 22% greater on the west, because of the greater leaf-to-air vapor pressure deficits (LAVPD). Mean individual leaf area was around 10% larger on the east than on the west side of the trees. In contrast, there were no significant differences in LMA between east and west sides of the crown. Contrary to our expectations, more severe water stress on the west side did not result in increases in LMA, although it was associated with lower individual leaf area. We conclude that increases in LMA measured by other authors along gradients of water stress would be due to differences in light intensity between dry and humid sites.

  19. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  20. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  1. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  2. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  3. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  4. Weak leaf photosynthesis and nutrient content relationships from tropical vegetation

    NASA Astrophysics Data System (ADS)

    Domingues, T. F.; Ishida, F. Y.; Feldpaush, T.; Saiz, G.; Grace, J.; Meir, P.; Lloyd, J.

    2015-12-01

    Evergreen rain forests and savannas are the two major vegetations of tropical land ecosystems, in terms of land area, biomass, biodiversity, biogeochemical cycles and rates of land use change. Mechanistically understanding ecosystem functioning on such ecosystems is still far from complete, but important for generation of future vegetation scenarios in response to global changes. Leaf photosynthetic rates is a key processes usually represented on land surface-atmosphere models, although data from tropical ecosystems is scarce, considering the high biodiversity they contain. As a shortcut, models usually recur to relationships between leaf nutrient concentration and photosynthetic rates. Such strategy is convenient, given the possibility of global datasets on leave nutrients derived from hyperspectral remote sensing data. Given the importance of Nitrogen on enzyme composition, this nutrient is usually used to infer photosynthetic capacity of leaves. Our experience, based on individual measurements on 1809 individual leaves from 428 species of trees and shrubs naturally occurring on tropical forests and savannas from South America, Africa and Australia, indicates that the relationship between leaf nitrogen and its assimilation capacity is weak. Therefore, leaf Nitrogen alone is a poor predictor of photosynthetic rates of tropical vegetation. Phosphorus concentrations from tropical soils are usually low and is often implied that this nutrient limits primary productivity of tropical vegetation. Still, phosphorus (or other nutrients) did not exerted large influence over photosynthetic capacity, although potassium influenced vegetation structure and function. Such results draw attention to the risks of applying universal nitrogen-photosynthesis relationships on biogeochemical models. Moreover, our data suggests that affiliation of plant species within phylogenetic hierarchy is an important aspect in understanding leaf trait variation. The lack of a strong single

  5. Leaf physiognomy and climate: A multivariate analysis

    NASA Astrophysics Data System (ADS)

    Davis, J. M.; Taylor, S. E.

    1980-11-01

    Research has demonstrated that leaf physiognomy is representative of the local or microclimate conditions under which plants grow. The physiognomy of leaf samples from Oregon, Michigan, Missouri, Tennessee, and the Panama Canal Zone has been related to the microclimate using Walter diagrams and Thornthwaite water-budget data. A technique to aid paleoclimatologists in identifying the nature of the microclimate from leaf physiognomy utilizes statistical procedures to classify leaf samples into one of six microclimate regimes based on leaf physiognomy information available from fossilized samples.

  6. Hormonal regulation of leaf senescence in Lilium.

    PubMed

    Arrom, Laia; Munné-Bosch, Sergi

    2012-10-15

    In addition to floral senescence and longevity, the control of leaf senescence is a major factor determining the quality of several cut flowers, including Lilium, in the commercial market. To better understand the physiological process underlying leaf senescence in this species, we evaluated: (i) endogenous variation in the levels of phytohormones during leaf senescence, (ii) the effects of leaf darkening in senescence and associated changes in phytohormones, and (iii) the effects of spray applications of abscisic acid (ABA) and pyrabactin on leaf senescence. Results showed that while gibberellin 4 (GA(4)) and salicylic acid (SA) contents decreased, that of ABA increased during the progression of leaf senescence. However, dark-induced senescence increased ABA levels, but did not affect GA(4) and SA levels, which appeared to correlate more with changes in air temperature and/or photoperiod than with the induction of leaf senescence. Furthermore, spray applications of pyrabactin delayed the progression of leaf senescence in cut flowers. Thus, we conclude that (i) ABA plays a major role in the regulation of leaf senescence in Lilium, (ii) darkness promotes leaf senescence and increases ABA levels, and (iii) exogenous applications of pyrabactin inhibit leaf senescence in Lilium, therefore suggesting that it acts as an antagonist of ABA in senescing leaves of cut lily flowers. PMID:22854182

  7. Hormonal regulation of leaf senescence in Lilium.

    PubMed

    Arrom, Laia; Munné-Bosch, Sergi

    2012-10-15

    In addition to floral senescence and longevity, the control of leaf senescence is a major factor determining the quality of several cut flowers, including Lilium, in the commercial market. To better understand the physiological process underlying leaf senescence in this species, we evaluated: (i) endogenous variation in the levels of phytohormones during leaf senescence, (ii) the effects of leaf darkening in senescence and associated changes in phytohormones, and (iii) the effects of spray applications of abscisic acid (ABA) and pyrabactin on leaf senescence. Results showed that while gibberellin 4 (GA(4)) and salicylic acid (SA) contents decreased, that of ABA increased during the progression of leaf senescence. However, dark-induced senescence increased ABA levels, but did not affect GA(4) and SA levels, which appeared to correlate more with changes in air temperature and/or photoperiod than with the induction of leaf senescence. Furthermore, spray applications of pyrabactin delayed the progression of leaf senescence in cut flowers. Thus, we conclude that (i) ABA plays a major role in the regulation of leaf senescence in Lilium, (ii) darkness promotes leaf senescence and increases ABA levels, and (iii) exogenous applications of pyrabactin inhibit leaf senescence in Lilium, therefore suggesting that it acts as an antagonist of ABA in senescing leaves of cut lily flowers.

  8. The relationship of leaf photosynthetic traits – Vcmax and Jmax – to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study

    PubMed Central

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-01-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (Vcmax) and the maximum rate of electron transport (Jmax). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between Vcmax and Jmax and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between Vcmax and Jmax and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of Vcmax and Jmax with leaf N, P, and SLA. Vcmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of Vcmax to leaf N. Jmax was strongly related to Vcmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm−2), increasing leaf P from 0.05 to 0.22 gm−2 nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of Jmax to Vcmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting. PMID:25473475

  9. The relationship of leaf photosynthetic traits - V cmax and J max - to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study.

    PubMed

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-08-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (V cmax) and the maximum rate of electron transport (J max). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between V cmax and J max and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between V cmax and J max and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of V cmax and J max with leaf N, P, and SLA. V cmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of V cmax to leaf N. J max was strongly related to V cmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm(-2)), increasing leaf P from 0.05 to 0.22 gm(-2) nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of J max to V cmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting.

  10. From buds to litter: seasonal changes in leaf wax concentrations and carbon isotopes and implications for the geologic past

    NASA Astrophysics Data System (ADS)

    Suh, Y. J.; Diefendorf, A. F.

    2014-12-01

    The carbon isotope composition (δ13C) of leaf waxes, such as n-alkanes, have extensively been used in paleoenvironmental studies for reconstruction of the past vegetation, climate and carbon cycling. There is however little information available on the seasonal variation of leaf wax concentration and δ13C in modern plants and when the δ13C signal is set. This lack of information confounds interpretations of leaf wax δ13C in sedimentary archives. To address this gap, this study investigates temporal changes in n-alkane and n-alkanoic acid δ13C values in several species (Acer rubrum, Acer saccharum, Ulmus Americana, Sassafras albidum, and Juniperus virginiana) within a single temperate deciduous forest stand in southern Ohio. We sampled atmospheric air, buds, leaves, leaf litter, and surface soil weekly during leaf flush and biweekly thereafter. In A. rubrum, A. saccharum, and U. Americana, buds had one or two dominant n-alkanes, such as C29 and C31. After leaf flush, the concentrations of shorter n-alkanes (C23~C27) significantly increased relative to the longer chain-lengths. We are currently analyzing remaining samples from the growing season and are analyzing bulk leaf and leaf wax (n-alkanes, n-alkanoic acids) δ13C values. This information will be important for identifying environmental and physiological controls on leaf wax δ13C and will improve interpretations of leaf wax δ13C preserved in the geologic record.

  11. Intra- and inter-community variation in leaf water repellency along a 4000 m elevation transect in the Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Goldsmith, G. R.; Doughty, C.; Bentley, L. P.; Shenkin, A.; Castro-Ccoscco, R. M.; Salinas, N.; Malhi, Y.

    2014-12-01

    Leaf water repellency is a measure of the hydrophobicity, or wettability, of leaf surfaces. At the scale of the plant, leaf water repellency can affect gas exchange, nutrient exchange, and pathogen growth. At the scale of the ecosystem, it can affect canopy water storage, throughfall, and evaporation. To date, very few studies have measured intra- and inter- community variation in leaf water repellency of tropical forest ecosystems. In the context of a broad survey of plant functional traits, we measured leaf water repellency in nine forest plots occurring across a 4000 m elevation gradient in the eastern Andes of Peru. Observed angles of incidence (63 ± 13°) indicate high leaf wettability, with no significant difference between sun and shade leaves. In contrast with previous research along elevation gradients, we find no strong evidence for variation across sites, but rather find high variation within a given site. Finally, we find that leaf water repellency may be predicted using sunlit leaf spectra with a low RMSE (<25% of the mean), indicating that future research on leaf water repellency could be carried out using high resolution hyperspectral remote sensing. As the climate of tropical ecosystems changes, the resultant changes in leaf water repellency will impact plants, communities and ecosystems. Our results inform our understanding of where and to what extent these impacts are most likely to occur.

  12. Leaf Senescence by Magnesium Deficiency

    PubMed Central

    Tanoi, Keitaro; Kobayashi, Natsuko I.

    2015-01-01

    Magnesium ions (Mg2+) are the second most abundant cations in living plant cells, and they are involved in various functions, including photosynthesis, enzyme catalysis, and nucleic acid synthesis. Low availability of Mg2+ in an agricultural field leads to a decrease in yield, which follows the appearance of Mg-deficient symptoms such as chlorosis, necrotic spots on the leaves, and droop. During the last decade, a variety of physiological and molecular responses to Mg2+ deficiency that potentially link to leaf senescence have been recognized, allowing us to reconsider the mechanisms of Mg2+ deficiency. This review focuses on the current knowledge about the physiological responses to Mg2+ deficiency including a decline in transpiration, accumulation of sugars and starch in source leaves, change in redox states, increased oxidative stress, metabolite alterations, and a decline in photosynthetic activity. In addition, we refer to the molecular responses that are thought to be related to leaf senescence. With these current data, we give an overview of leaf senescence induced by Mg deficiency. PMID:27135350

  13. Bidirectional reflectance, leaf optical and physiological properties of prairie vegetation

    NASA Technical Reports Server (NTRS)

    Walter-Shea, E. A.; Blad, B. L.; Starks, P. J; Hays, C. J.; Mesarch, M. A.; Middleton, E. M.

    1990-01-01

    A modular multiband radiometer is used to measure reflected radiation from the vegetative surface of a prairie. The data are compared to estimates of incoming radiation by measuring the reflection from a molded halon panel, and the bidirectional reflectance factors are measured at seven view-zenith angles and various incidence angles. The canopy-reflectance results are compared to leaf-optical and other vegetative physiological properties, and a direct relationship is reported.

  14. LeafJ: an ImageJ plugin for semi-automated leaf shape measurement.

    PubMed

    Maloof, Julin N; Nozue, Kazunari; Mumbach, Maxwell R; Palmer, Christine M

    2013-01-21

    High throughput phenotyping (phenomics) is a powerful tool for linking genes to their functions (see review and recent examples). Leaves are the primary photosynthetic organ, and their size and shape vary developmentally and environmentally within a plant. For these reasons studies on leaf morphology require measurement of multiple parameters from numerous leaves, which is best done by semi-automated phenomics tools. Canopy shade is an important environmental cue that affects plant architecture and life history; the suite of responses is collectively called the shade avoidance syndrome (SAS). Among SAS responses, shade induced leaf petiole elongation and changes in blade area are particularly useful as indices. To date, leaf shape programs (e.g. SHAPE, LAMINA, LeafAnalyzer, LEAFPROCESSOR) can measure leaf outlines and categorize leaf shapes, but can not output petiole length. Lack of large-scale measurement systems of leaf petioles has inhibited phenomics approaches to SAS research. In this paper, we describe a newly developed ImageJ plugin, called LeafJ, which can rapidly measure petiole length and leaf blade parameters of the model plant Arabidopsis thaliana. For the occasional leaf that required manual correction of the petiole/leaf blade boundary we used a touch-screen tablet. Further, leaf cell shape and leaf cell numbers are important determinants of leaf size. Separate from LeafJ we also present a protocol for using a touch-screen tablet for measuring cell shape, area, and size. Our leaf trait measurement system is not limited to shade-avoidance research and will accelerate leaf phenotyping of many mutants and screening plants by leaf phenotyping.

  15. Leaf drop affects herbivory in oaks.

    PubMed

    Pearse, Ian S; Karban, Richard

    2013-11-01

    Leaf phenology is important to herbivores, but the timing and extent of leaf drop has not played an important role in our understanding of herbivore interactions with deciduous plants. Using phylogenetic general least squares regression, we compared the phenology of leaves of 55 oak species in a common garden with the abundance of leaf miners on those trees. Mine abundance was highest on trees with an intermediate leaf retention index, i.e. trees that lost most, but not all, of their leaves for 2-3 months. The leaves of more evergreen species were more heavily sclerotized, and sclerotized leaves accumulated fewer mines in the summer. Leaves of more deciduous species also accumulated fewer mines in the summer, and this was consistent with the idea that trees reduce overwintering herbivores by shedding leaves. Trees with a later leaf set and slower leaf maturation accumulated fewer herbivores. We propose that both leaf drop and early leaf phenology strongly affect herbivore abundance and select for differences in plant defense. Leaf drop may allow trees to dispose of their herbivores so that the herbivores must recolonize in spring, but trees with the longest leaf retention also have the greatest direct defenses against herbivores.

  16. Leaf drop affects herbivory in oaks.

    PubMed

    Pearse, Ian S; Karban, Richard

    2013-11-01

    Leaf phenology is important to herbivores, but the timing and extent of leaf drop has not played an important role in our understanding of herbivore interactions with deciduous plants. Using phylogenetic general least squares regression, we compared the phenology of leaves of 55 oak species in a common garden with the abundance of leaf miners on those trees. Mine abundance was highest on trees with an intermediate leaf retention index, i.e. trees that lost most, but not all, of their leaves for 2-3 months. The leaves of more evergreen species were more heavily sclerotized, and sclerotized leaves accumulated fewer mines in the summer. Leaves of more deciduous species also accumulated fewer mines in the summer, and this was consistent with the idea that trees reduce overwintering herbivores by shedding leaves. Trees with a later leaf set and slower leaf maturation accumulated fewer herbivores. We propose that both leaf drop and early leaf phenology strongly affect herbivore abundance and select for differences in plant defense. Leaf drop may allow trees to dispose of their herbivores so that the herbivores must recolonize in spring, but trees with the longest leaf retention also have the greatest direct defenses against herbivores. PMID:23774946

  17. Correlated evolution of leaf shape and trichomes in Begonia dregei (Begoniaceae).

    PubMed

    McLellan, Tracy

    2005-10-01

    Structural features of leaves, including size, shape, and surfaces, vary greatly throughout the plant kingdom. In both functional and phylogenetic analyses of leaves, the various morphological aspects are often considered independently of each other, although it is likely that many combinations of features do not occur at random due to either functional constraint or genetic correlation. The distribution of variation in leaf morphology in the highly variable Begonia dregei species complex was examined in natural populations and in F(2) offspring from a cross between plants from two populations. Leaf shape was quantified using several morphometric measures, and trichomes on leaves were counted and measured. Correlations between leaf shape and the numbers and size of trichomes were examined. There were significant correlations between the shapes of leaves and the presence, number, and size of trichomes among populations and in hybrid plants. Deeply incised leaves had larger numbers of longer trichomes at the sinuses. Higher numbers of trichomes on upper leaf surfaces occurred together with trichomes at the petiole and on the abaxial surface. The potential for independent evolution of leaf shape and trichomes in this group is limited. Hypotheses to explain the correlated development of leaf shape and trichomes are discussed.

  18. Leaf P increase outpaces leaf N in an Inner Mongolia grassland over 27 years.

    PubMed

    Mi, Zhaorong; Huang, Yuanyuan; Gan, Huijie; Zhou, Wenjia; Flynn, Dan F B; He, Jin-Sheng

    2015-01-01

    The dynamics of leaf nitrogen (N) and phosphorus (P) have been intensively explored in short-term experiments, but rarely at longer timescales. Here, we investigated leaf N : P stoichiometry over a 27-year interval in an Inner Mongolia grassland by comparing leaf N : P concentration of 2006 with that of 1979. Across 80 species, both leaf N and P increased, but the increase in leaf N lagged behind that of leaf P, leading to a significant decrease in the N : P ratio. These changes in leaf N : P stoichiometry varied among functional groups. For leaf N, grasses increased, woody species tended to increase, whereas forbs showed no change. Unlike leaf N, leaf P of grasses and forbs increased, whereas woody species showed no change. Such changes may reflect N deposition and P release induced by soil acidification over the past decades. The interannual effect of precipitation may somewhat have reduced the soil available N, leading to the more modest increase of leaf N than of leaf P. Thus, leaf N : P stoichiometry significantly responded to long-term environmental changes in this temperate steppe, but different functional groups responded differently. Our results indicate that conclusions of plant stoichiometry under short-term N fertilization should be treated with caution when extrapolating to longer timescales.

  19. Leaf breakdown in streams differing in catchment land use

    USGS Publications Warehouse

    Paul, M.J.; Meyer, J.L.; Couch, C.A.

    2006-01-01

    1. The impact of changes in land use on stream ecosystem function is poorly understood. We studied leaf breakdown, a fundamental process of stream ecosystems, in streams that represent a range of catchment land use in the Piedmont physiographic province of the south-eastern United States. 2. We placed bags of chalk maple (Acer barbatum) leaves in similar-sized streams in 12 catchments of differing dominant land use: four forested, three agricultural, two suburban and three urban catchments. We measured leaf mass, invertebrate abundance and fungal biomass in leaf bags over time. 3. Leaves decayed significantly faster in agricultural (0.0465 day-1) and urban (0.0474 day-1) streams than in suburban (0.0173 day-1) and forested (0.0100 day-1) streams. Additionally, breakdown rates in the agricultural and urban streams were among the fastest reported for deciduous leaves in any stream. Nutrient concentrations in agricultural streams were significantly higher than in any other land-use type. Fungal biomass associated with leaves was significantly lower in urban streams; while shredder abundance in leaf bags was significantly higher in forested and agricultural streams than in suburban and urban streams. Storm runoff was significantly higher in urban and suburban catchments that had higher impervious surface cover than forested or agricultural catchments. 4. We propose that processes accelerating leaf breakdown in agricultural and urban streams were not the same: faster breakdown in agricultural streams was due to increased biological activity as a result of nutrient enrichment, whereas faster breakdown in urban streams was a result of physical fragmentation resulting from higher storm runoff. ?? 2006 The Authors.

  20. Classification and quantification of leaf curvature

    PubMed Central

    Liu, Zhongyuan; Jia, Liguo; Mao, Yanfei; He, Yuke

    2010-01-01

    Various mutants of Arabidopsis thaliana deficient in polarity, cell division, and auxin response are characterized by certain types of leaf curvature. However, comparison of curvature for clarification of gene function can be difficult without a quantitative measurement of curvature. Here, a novel method for classification and quantification of leaf curvature is reported. Twenty-two mutant alleles from Arabidopsis mutants and transgenic lines deficient in leaf flatness were selected. The mutants were classified according to the direction, axis, position, and extent of leaf curvature. Based on a global measure of whole leaves and a local measure of four regions in the leaves, the curvature index (CI) was proposed to quantify the leaf curvature. The CI values accounted for the direction, axis, position, and extent of leaf curvature in all of the Arabidopsis mutants grown in growth chambers. Comparison of CI values between mutants reveals the spatial and temporal variations of leaf curvature, indicating the strength of the mutant alleles and the activities of the corresponding genes. Using the curvature indices, the extent of curvature in a complicated genetic background becomes quantitative and comparable, thus providing a useful tool for defining the genetic components of leaf development and to breed new varieties with leaf curvature desirable for the efficient capture of sunlight for photosynthesis and high yields. PMID:20400533

  1. Compound leaf development in model plant species.

    PubMed

    Bar, Maya; Ori, Naomi

    2015-02-01

    Plant leaves develop in accordance with a common basic program, which is flexibly adjusted to the species, developmental stage and environment. Two key stages of leaf development are morphogenesis and differentiation. In the case of compound leaves, the morphogenesis stage is prolonged as compared to simple leaves, allowing for the initiation of leaflets. Here, we review recent advances in the understanding of how plant hormones and transcriptional regulators modulate compound leaf development, yielding a substantial diversity of leaf forms, focusing on four model compound leaf organisms: cardamine (Cardamine hirsuta), tomato (Solanum lycopersicum), medicago (Medicago truncatula) and pea (Pisum sativum).

  2. Ammonia emissions from deciduous forest after leaf fall

    NASA Astrophysics Data System (ADS)

    Hansen, K.; Sørensen, L. L.; Hertel, O.; Geels, C.; Skjøth, C. A.; Jensen, B.; Boegh, E.

    2013-07-01

    to atmospheric NH3 concentration from vegetative surfaces related to leaf fall are of a relatively large magnitude. We therefore conclude that emissions from deciduous forests are important to include in model calculations of atmospheric NH3 for forest ecosystems. Finally, diurnal variations in the measured NH3 concentrations were related to meteorological conditions, forest phenology and the spatial distribution of local anthropogenic NH3 sources. This suggests that an accurate description of ammonia fluxes over forest ecosystems requires a dynamic description of atmospheric and vegetation processes.

  3. Variation in Ginkgo biloba L. leaf characters across a climatic gradient in China.

    PubMed

    Sun, Bainian; Dilcher, David L; Beerling, David J; Zhang, Chengjun; Yan, Defei; Kowalski, Elizabeth

    2003-06-10

    Fossil leaves assigned to the genus Ginkgo are increasingly being used to reconstruct Mesozoic and Tertiary environments based on their stomatal and carbon isotopic characteristics. We sought to provide a more secure basis for understanding variations seen in the plant fossil record by determining the natural variability of these properties of sun and shade leaf morphotypes of Ginkgo biloba trees under the present atmospheric CO2 concentration and a range of contemporary climates in three Chinese locations (Lanzhou, Beijing, and Nanjing). Climate had no major effects on leaf stomatal index (proportion of leaf surface cells that are stomata) but did result in more variable stomatal densities. The effects of climate and leaf morphotype on stomatal index were rather conserved (<1%) and much less than the response of trees to recent CO2 increases. Leaf carbon isotope discrimination (delta) was highest for trees in Nanjing, which experience a warm, moist climate, whereas trees in the most arid site (Lanzhou) had the lowest delta values. Interestingly, the variation in delta shown by leaf populations of trees from China and the United Kingdom was very similar to that of fossil Ginkgo cuticles dating to the Mesozoic and Tertiary, which suggests to us that the physiology of leaf carbon uptake and regulation of water loss in Ginkgo has remained highly conserved despite the potential for evolutionary change over millions of years.

  4. [Applicability analysis of spatially explicit model of leaf litter in evergreen broad-leaved forests].

    PubMed

    Zhao, Qing-Qing; Liu, He-Ming; Jonard, Mathieu; Wang, Zhang-Hua; Wang, Xi-Hua

    2014-11-01

    The spatially explicit model of leaf litter can help to understand its dispersal process, which is very important to predict the distribution pattern of leaves on the surface of the earth. In this paper, the spatially explicit model of leaf litter was developed for 20 tree species using litter trap data from the mapped forest plot in an evergreen broad-leaved forest in Tiantong, Zhejiang Pro- vince, eastern China. Applicability of the model was analyzed. The model assumed an allometric equation between diameter at breast height (DBH) and leaf litter amount, and the leaf litter declined exponentially with the distance. Model parameters were estimated by the maximum likelihood method. Results showed that the predicted and measured leaf litter amounts were significantly correlated, but the prediction accuracies varied widely for the different tree species, averaging at 49.3% and ranging from 16.0% and 74.0%. Model qualities of tree species significantly correlated with the standard deviations of the leaf litter amount per trap, DBH of the tree species and the average leaf dry mass of tree species. There were several ways to improve the forecast precision of the model, such as installing the litterfall traps according to the distribution of the tree to cover the different classes of the DBH and distance apart from the parent trees, determining the optimal dispersal function of each tree species, and optimizing the existing dispersal function. PMID:25898606

  5. Leaf ontogeny and demography explain photosynthetic seasonality in Amazon evergreen forests

    NASA Astrophysics Data System (ADS)

    Wu, J.; Albert, L.; Lopes, A. P.; Restrepo-Coupe, N.; Hayek, M.; Wiedemann, K. T.; Guan, K.; Stark, S. C.; Prohaska, N.; Tavares, J. V.; Marostica, S. F.; Kobayashi, H.; Ferreira, M. L.; Campos, K.; Silva, R. D.; Brando, P. M.; Dye, D. G.; Huxman, T. E.; Huete, A. R.; Nelson, B. W.; Saleska, S. R.

    2015-12-01

    Photosynthetic seasonality couples the evolutionary ecology of plant leaves to large-scale rhythms of carbon and water exchanges that are important feedbacks to climate. However, the extent, magnitude, and controls on photosynthetic seasonality of carbon-rich tropical forests are poorly resolved, controversial in the remote sensing literature, and inadequately represented in most earth system models. Here we show that ecosystem-scale phenology (measured by photosynthetic capacity), rather than environmental seasonality, is the primary driver of photosynthetic seasonality at four Amazon evergreen forests spanning gradients in rainfall seasonality, forest composition, and flux seasonality. We further demonstrate that leaf ontogeny and demography explain most of this ecosystem phenology at two central Amazon evergreen forests, using a simple leaf-cohort canopy model that integrates eddy covariance-derived CO2 fluxes, novel near-surface camera-detected leaf phenology, and ground observations of litterfall and leaf physiology. The coordination of new leaf growth and old leaf divestment (litterfall) during the dry season shifts canopy composition towards younger leaves with higher photosynthetic efficiency, driving large seasonal increases (~27%) in ecosystem photosynthetic capacity. Leaf ontogeny and demography thus reconciles disparate observations of forest seasonality from leaves to eddy flux towers to satellites. Strategic incorporation of such whole-plant coordination processes as phenology and ontogeny will improve ecological, evolutionary and earth system theories describing tropical forests structure and function, allowing more accurate representation of forest dynamics and feedbacks to climate in earth system models.

  6. Does citrus leaf miner impair hydraulics and fitness of citrus host plants?

    PubMed

    Raimondo, Fabio; Trifilò, Patrizia; Gullo, Maria A Lo

    2013-12-01

    Gas exchange and hydraulic features were measured in leaves of three different Citrus species (Citrus aurantium L., Citrus limon L., Citrus  ×  paradisii Macfad) infested by Phyllocnistis citrella Staiton, with the aim to quantify the impact of this pest on leaf hydraulics and, ultimately, on plant fitness. Infested leaves were characterized by the presence on the leaf blade of typical snake-shaped mines and, in some cases, of a crumpled leaf blade. Light microscopy showed that leaf crumpling was induced by damage to the cuticular layer. In all three Citrus species examined: (a) the degree of infestation did not exceed 10% of the total surface area of infested plants; (b) control and infested leaves showed similar values of minimum diurnal leaf water potential, leaf hydraulic conductance and functional vein density; and (c) maximum diurnal values of stomatal conductance to water vapour, transpiration rate and photosynthetic rate (An) were similar in both control leaves and the green areas of infested leaves. A strong reduction of An was recorded only in mined leaf areas. Our data suggest that infestation with P. citrella does not cause conspicuous plant productivity reductions in young Citrus plants, at least not in the three Citrus species studied here.

  7. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  8. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  9. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  10. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  11. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  12. 7 CFR 28.464 - Leaf Grade 4.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is within the range represented...

  13. 7 CFR 28.461 - Leaf Grade 1.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is within the range represented...

  14. 7 CFR 28.466 - Leaf Grade 6.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is within the range represented...

  15. 7 CFR 28.465 - Leaf Grade 5.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is within the range represented...

  16. 7 CFR 28.462 - Leaf Grade 2.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is within the range represented...

  17. 7 CFR 28.463 - Leaf Grade 3.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is within the range represented...

  18. 7 CFR 28.467 - Leaf Grade 7.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which is within the range represented...

  19. Do physiological changes at leaf level explain seasonal changes in remotely sensed canopy greenness?

    NASA Astrophysics Data System (ADS)

    Darby, B.; Keenan, T. F.; Felts, E. S.; Hufkens, K.; Friedl, M. A.; Moore, D. J.; Sonnentag, O.; Richardson, A. D.

    2011-12-01

    The PhenoCam (http://phenocam.sr.unh.edu) network uses digital cameras to observe phenological events and track seasonal changes in forest canopy greenness. As a near surface remote sensing platform it acts as an intermediary between leaf level measurements, typically made by a human observer, and satellite based remote sensing products. The cameras typically document a rapid increase in canopy greenness after leaf out, which peaks in early summer and then gradually declines before a rapid decline corresponding to autumn senescence and abscission. Open questions remain, however, as to whether the observed changes in canopy greenness are directly related to changes in leaf physiology and pigmentation, changes in canopy structure (leaf size, shape, and orientation), or some combination thereof. The goal of this study was to investigate how leaf-level structure and function relate to canopy greenness as measured by the cameras in an oak-dominated temperate forest. Sampling was conducted at the Harvard Forest, in central Massachusetts USA. We sampled upper-canopy leaves of three dominant deciduous tree species red oak (Quercus rubra), red maple (Acer rubrum) and yellow birch (Betula alleghaniensis) on a weekly basis for a full growing season, from leaf out to leaf drop. Leaf mass per area, nitrogen content, and chlorophyll fluorescence were measured for each leaf, along with spectral reflectance and transmission at wavelengths from 350 to 2500 nm. Leaf gas exchange measurements were also made weekly and used to derive leaf photosynthetic parameters. Results show that changes in leaf mass per area and photosynthetic capability at leaf-level lag initial increases in greenness measured by the cameras. Spectral indices related to chlorophyll content such as the photochemical reflectance index (PRI) and chlorophyll normalized difference index (Chl NDI), along with chlorophyll fluorescence indicate that chlorophyll content continues to increase after greenness measured by

  20. Machine vision guided sensor positioning system for leaf temperature assessment

    NASA Technical Reports Server (NTRS)

    Kim, Y.; Ling, P. P.; Janes, H. W. (Principal Investigator)

    2001-01-01

    A sensor positioning system was developed for monitoring plants' well-being using a non-contact sensor. Image processing algorithms were developed to identify a target region on a plant leaf. A novel algorithm to recover view depth was developed by using a camera equipped with a computer-controlled zoom lens. The methodology has improved depth recovery resolution over a conventional monocular imaging technique. An algorithm was also developed to find a maximum enclosed circle on a leaf surface so the conical field-of-view of an infrared temperature sensor could be filled by the target without peripheral noise. The center of the enclosed circle and the estimated depth were used to define the sensor 3-D location for accurate plant temperature measurement.

  1. Host Phenology and Leaf Effects on Susceptibility of California Bay Laurel to Phytophthora ramorum.

    PubMed

    Johnston, Steven F; Cohen, Michael F; Torok, Tamas; Meentemeyer, Ross K; Rank, Nathan E

    2016-01-01

    Spread of the plant pathogen Phytophthora ramorum, causal agent of the forest disease sudden oak death, is driven by a few competent hosts that support spore production from foliar lesions. The relationship between traits of a principal foliar host, California bay laurel (Umbellularia californica), and susceptibility to P. ramorum infection were investigated with multiple P. ramorum isolates and leaves collected from multiple trees in leaf-droplet assays. We examined whether susceptibility varies with season, leaf age, or inoculum position. Bay laurel susceptibility was highest during spring and summer and lowest in winter. Older leaves (>1 year) were more susceptible than younger ones (8 to 11 months). Susceptibility was greater at leaf tips and edges than the middle of the leaf. Leaf surfaces wiped with 70% ethanol were more susceptible to P. ramorum infection than untreated leaf surfaces. Our results indicate that seasonal changes in susceptibility of U. californica significantly influence P. ramorum infection levels. Thus, in addition to environmental variables such as temperature and moisture, variability in host plant susceptibility contributes to disease establishment of P. ramorum.

  2. Host Phenology and Leaf Effects on Susceptibility of California Bay Laurel to Phytophthora ramorum.

    PubMed

    Johnston, Steven F; Cohen, Michael F; Torok, Tamas; Meentemeyer, Ross K; Rank, Nathan E

    2016-01-01

    Spread of the plant pathogen Phytophthora ramorum, causal agent of the forest disease sudden oak death, is driven by a few competent hosts that support spore production from foliar lesions. The relationship between traits of a principal foliar host, California bay laurel (Umbellularia californica), and susceptibility to P. ramorum infection were investigated with multiple P. ramorum isolates and leaves collected from multiple trees in leaf-droplet assays. We examined whether susceptibility varies with season, leaf age, or inoculum position. Bay laurel susceptibility was highest during spring and summer and lowest in winter. Older leaves (>1 year) were more susceptible than younger ones (8 to 11 months). Susceptibility was greater at leaf tips and edges than the middle of the leaf. Leaf surfaces wiped with 70% ethanol were more susceptible to P. ramorum infection than untreated leaf surfaces. Our results indicate that seasonal changes in susceptibility of U. californica significantly influence P. ramorum infection levels. Thus, in addition to environmental variables such as temperature and moisture, variability in host plant susceptibility contributes to disease establishment of P. ramorum. PMID:26439707

  3. Foliar micromorphology of Felicia muricata Thunb., A South African medicinal plant.

    PubMed

    Ashafa, A O T; Grierson, D S; Afolayan, A J

    2008-07-01

    The foliar micromorphology of Felicia muricata (Thunb.) Nees (Asteraceae) was observed with the JEOL (JSM-6390LV) Scanning Electron Microscope (SEM). Both the abaxial and adaxial surfaces were characterized by anisocytic stomata which were more prevalent on the abaxial surface than the adaxial surface. The leaves have only one type of multicellular non-glandular trichomes that are long and cylindrical, tapering to a sharp point and running parallel to the leaf surface in the direction of the apices. Crystal deposits were also observed on the surfaces of the leaves near the stomata. Energy dispersive X-ray spectroscopy-SEM shows that Na, Al, Si, and K were the major constituents of the crystal analyzed. Since no glandular trichomes were present on the leaves of this herb, the bioactive components present in this plant may be produced in some other tissues in the leaf other than the trichomes. PMID:18819624

  4. Compensatory responses in plant-herbivore interactions: Impacts of insects on leaf water relations

    NASA Astrophysics Data System (ADS)

    Peschiutta, María L.; Bucci, Sandra J.; Scholz, Fabián G.; Goldstein, Guillermo

    2016-05-01

    Herbivore damage to leaves has been typically evaluated in terms of fractions of area removed; however morpho-physiological changes in the remaining tissues can occur in response to removal. We assessed the effects of partial removal of the leaf mesophyll by Caliroa cerasi (Hymenoptera) on leaf hydraulic conductance (Kleaf), vascular architecture, water relations and leaf size of three Prunus avium cultivars. The insect feeds on the leaf mesophyll leaving the vein network intact (skeletonization). Within each cultivar there were trees without infestations and trees chronically infested, at least over the last three years. Leaf size of intact leaves tended to be similar during leaf expansion before herbivore attack occurs across infested and non-infested trees. However, after herbivore attack and when the leaves were fully expanded, damaged leaves were smaller than leaves from non-infested trees. Damaged area varied between 21 and 31% depending on cultivar. The non-disruption of the vascular system together with either vein density or capacitance increased in damaged leaves resulted in similar Kleaf and stomatal conductance in infested and non-infested trees. Non-stomatal water loss from repeated leaf damage led to lower leaf water potentials in two of the infested cultivars. Lower leaf osmotic potentials and vulnerability to loss of Kleaf were observed in infested plants. Our results show that skeletonization resulted in compensatory changes in terms of water relations and hydraulics traits and in cultivar-specific physiological changes in phylogenetic related P. avium. Our findings indicate that detrimental effects of herbivory on the photosynthetic surface are counterbalanced by changes providing higher drought resistance, which has adaptive significance in ecosystems where water availability is low and furthermore where global climate changes would decrease soil water availability in the future even further.

  5. Bleaching of leaf litter and associated microfungi in subboreal and subalpine forests.

    PubMed

    Hagiwara, Yusuke; Matsuoka, Shunsuke; Hobara, Satoru; Mori, Akira S; Hirose, Dai; Osono, Takashi

    2015-10-01

    Fungal decomposition of lignin leads to the whitening, or bleaching, of leaf litter, especially in temperate and tropical forests, but less is known about such bleaching in forests of cooler regions, such as boreal and subalpine forests. The purposes of the present study were to examine the extent of bleached area on the surface of leaf litter and its variation with environmental conditions in subboreal and subalpine forests in Japan and to examine the microfungi associated with the bleaching of leaf litter by isolating fungi from the bleached portions of the litter. Bleached area accounted for 21.7%-32.7% and 2.0%-10.0% of total leaf area of Quercus crispula and Betula ermanii, respectively, in subboreal forests, and for 6.3% and 18.6% of total leaf area of B. ermanii and Picea jezoensis var. hondoensis, respectively, in a subalpine forest. In subboreal forests, elevation, C/N ratio and pH of the FH layer, and slope aspect were selected as predictor variables for the bleached leaf area. Leaf mass per area and lignin content were consistently lower in the bleached area than in the nonbleached area of the same leaves, indicating that the selective decomposition of acid unhydrolyzable residue (recalcitrant compounds such as lignin, tannins, and cutins) enhanced the mass loss of leaf tissues in the bleached portions. Isolates of a total of 11 fungal species (6 species of Ascomycota and 5 of Basidiomycota) exhibited leaf-litter-bleaching activity under pure culture conditions. Two fungal species (Coccomyces sp. and Mycena sp.) occurred in both subboreal and subalpine forests, which were separated from each other by approximately 1100 km.

  6. An Exploration of Distributed Leaf Wetness and Dew Detection Using Inexpensive Radios

    NASA Astrophysics Data System (ADS)

    Niemeier, J. J.; Rowlandson, T. L.; Kruger, A.; Hornbuckle, B. K.

    2009-12-01

    Our understanding of latent heat transfer between the soil surface and canopy is not complete. A major contributing factor to the uncertainty is the presence and amount of dew on the plant canopy. Improved measurements of dew duration, and possibly amount would help refine land surface process models. There are automated leaf wetness sensors available that consist of a simple sensor that attempts to simulate a single leaf. The electrical resistivity of the sensor is a function of the amount of liquid water that has condensed on its surface. These sensors generally provide reliable dew/no dew indication, but do not provide good information on dew amount. It may be possible to obtain dew amount from such sensors, but that would require careful calibration, because of the nonlinear relationship between dew amount and resistivity. The alternative is traditional measurements that require manually sampling and measuring dew amount. This latter is time-consuming and labor-intensive. Further, all these methods are point measurements that suffer from sampling errors. We are exploring the use of very inexpensive radios that operate in the unlicensed industrial, scientific, and medical (ISM) band as leaf wetness sensors. Our hypothesis is that dew on plant leafs attenuates the radio signals, and by recording the received signal strength, one can detect changes in leaf wetness. Further, such measurements are distributed/volume measurements that counter sampling errors inherent in point measurements. By using directional antennas, there is the exciting possibility to perform tomographic dew measurements. To test our hypothesis, we have deployed a number of radios operating at 2.4 GHz and 900 MHz, collocated with traditional leaf-wetness sensors in a corn field near Ames, Iowa. We have also made a large number of traditional leaf wetness/dew amount measurements at this location. Preliminary data analysis for the radio-based technique is promising. In this work, we present and

  7. High Diversity Revealed in Leaf-Associated Protists (Rhizaria: Cercozoa) of Brassicaceae.

    PubMed

    Ploch, Sebastian; Rose, Laura E; Bass, David; Bonkowski, Michael

    2016-09-01

    The largest biological surface on earth is formed by plant leaves. These leaf surfaces are colonized by a specialized suite of leaf-inhabiting microorganisms, recently termed "phyllosphere microbiome". Microbial prey, however, attract microbial predators. Protists in particular have been shown to structure bacterial communities on plant surfaces, but virtually nothing is known about the community composition of protists on leaves. Using newly designed specific primers targeting the 18S rDNA gene of Cercozoa, we investigated the species richness of this common protist group on leaves of four Brassicaceae species from two different locations in a cloning-based approach. The generated sequences revealed a broad diversity of leaf-associated Cercozoa, mostly bacterial feeders, but also including known plant pathogens and a taxon of potential endophytes that were recently described as algal predators in freshwater systems. This initial study shows that protists must be regarded as an integral part of the microbial diversity in the phyllosphere of plants.

  8. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.2...

  9. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.2...

  10. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.2...

  11. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.2...

  12. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.2...

  13. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco....

  14. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

  15. Evolutionary and Environmental Forces Sculpting Leaf Development.

    PubMed

    Chitwood, Daniel H; Sinha, Neelima R

    2016-04-01

    Leaf shape is spectacularly diverse. As a major component of plant architecture and an interface for light capture, gas exchange, and thermoregulation, the potential contributions of leaves to plant fitness are innumerable. Particularly because of their intimate association and interaction with the surrounding environment, both the plasticity of leaf shape during the lifetime of a plant and the evolution of leaf shape over geologic time are revealing with respect to leaf function. Leaf shapes arise within a developmental context that constrains both their evolution and environmental plasticity. Quantitative models capturing genetic diversity, developmental context, and environmental plasticity will be required to fully understand the evolution and development of leaf shape and its response to environmental pressures. In this review, we discuss recent literature demonstrating that distinct molecular pathways are modulated by specific environmental inputs, the output of which regulates leaf dissection. We propose a synthesis explaining both historical patterns in the paleorecord and conserved plastic responses in extant plants. Understanding the potential adaptive value of leaf shape, and how to molecularly manipulate it, will prove to be invaluable in designing crops optimized for future climates. PMID:27046820

  16. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  17. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  18. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  19. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  20. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  1. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  2. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  3. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  4. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  5. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  6. Possible Roles of Strigolactones during Leaf Senescence

    PubMed Central

    Yamada, Yusuke; Umehara, Mikihisa

    2015-01-01

    Leaf senescence is a complicated developmental process that involves degenerative changes and nutrient recycling. The progress of leaf senescence is controlled by various environmental cues and plant hormones, including ethylene, jasmonic acid, salicylic acid, abscisic acid, cytokinins, and strigolactones. The production of strigolactones is induced in response to nitrogen and phosphorous deficiency. Strigolactones also accelerate leaf senescence and regulate shoot branching and root architecture. Leaf senescence is actively promoted in a nutrient-poor soil environment, and nutrients are transported from old leaves to young tissues and seeds. Strigolactones might act as important signals in response to nutrient levels in the rhizosphere. In this review, we discuss the possible roles of strigolactones during leaf senescence. PMID:27135345

  7. Cross-scale modelling of transpiration from stomata via the leaf boundary layer

    PubMed Central

    Defraeye, Thijs; Derome, Dominique; Verboven, Pieter; Carmeliet, Jan; Nicolai, Bart

    2014-01-01

    Background and Aims Leaf transpiration is a key parameter for understanding land surface–climate interactions, plant stress and plant structure–function relationships. Transpiration takes place at the microscale level, namely via stomata that are distributed discretely over the leaf surface with a very low surface coverage (approx. 0·2–5 %). The present study aims to shed more light on the dependency of the leaf boundary-layer conductance (BLC) on stomatal surface coverage and air speed. Methods An innovative three-dimensional cross-scale modelling approach was applied to investigate convective mass transport from leaves, using computational fluid dynamics. The gap between stomatal and leaf scale was bridged by including all these scales in the same computational model (10−5–10−1 m), which implies explicitly modelling individual stomata. Key Results BLC was strongly dependent on stomatal surface coverage and air speed. Leaf BLC at low surface coverage ratios (CR), typical for stomata, was still relatively high, compared with BLC of a fully wet leaf (hypothetical CR of 100 %). Nevertheless, these conventional BLCs (CR of 100 %), as obtained from experiments or simulations on leaf models, were found to overpredict the convective exchange. In addition, small variations in stomatal CR were found to result in large variations in BLCs. Furthermore, stomata of a certain size exhibited a higher mass transfer rate at lower CRs. Conclusions The proposed cross-scale modelling approach allows us to increase our understanding of transpiration at the sub-leaf level as well as the boundary-layer microclimate in a way currently not feasible experimentally. The influence of stomatal size, aperture and surface density, and also flow-field parameters can be studied using the model, and prospects for further improvement of the model are presented. An important conclusion of the study is that existing measures of conductances (e.g. from artificial leaves) can be

  8. Relating Stomatal Conductance to Leaf Functional Traits

    PubMed Central

    Kröber, Wenzel; Plath, Isa; Heklau, Heike; Bruelheide, Helge

    2015-01-01

    Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species' physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants’ regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES

  9. Relating Stomatal Conductance to Leaf Functional Traits.

    PubMed

    Kröber, Wenzel; Plath, Isa; Heklau, Heike; Bruelheide, Helge

    2015-10-12

    Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species' physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants' regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES.

  10. Two WUSCHEL-related homeobox genes, narrow leaf2 and narrow leaf3, control leaf width in rice.

    PubMed

    Ishiwata, Aiko; Ozawa, Misa; Nagasaki, Hiroshi; Kato, Makio; Noda, Yusaku; Yamaguchi, Takahiro; Nosaka, Misuzu; Shimizu-Sato, Sae; Nagasaki, Akie; Maekawa, Masahiko; Hirano, Hiro-Yuki; Sato, Yutaka

    2013-05-01

    Leaf shape is one of the key determinants of plant architecture. Leaf shape also affects the amount of sunlight captured and influences photosynthetic efficiency; thus, it is an important agronomic trait in crop plants. Understanding the molecular mechanisms governing leaf shape is a central issue of plant developmental biology and agrobiotechnology. Here, we characterized the narrow-leaf phenotype of FL90, a linkage tester line of rice (Oryza sativa). Light and scanning electron microscopic analyses of FL90 leaves revealed defects in the development of marginal regions and a reduction in the number of longitudinal veins. The narrow-leaf phenotype of FL90 shows a two-factor recessive inheritance and is caused by the loss of function of two WUSCHEL-related homeobox genes, NAL2 and NAL3 (NAL2/3), which are duplicate genes orthologous to maize NS1 and NS2 and to Arabidopsis PRS. The overexpression of NAL2/3 in transgenic rice plants results in wider leaves containing increased numbers of veins, suggesting that NAL2/3 expression regulates leaf width. Thus, NAL2/3 can be used to modulate leaf shape and improve agronomic yield in crop plants. PMID:23420902

  11. A model for leaf initiation

    PubMed Central

    Abraham-Shrauner, Barbara; Pickard, Barbara G

    2011-01-01

    A biophysical model is proposed for how leaf primordia are positioned on the shoot apical
    meristem in both spiral and whorl phyllotaxes. Primordia are initiated by signals that propagate
    in the epidermis in both azimuthal directions away from the cotyledons or the most recently
    specified primordia. The signals are linear waves as inferred from the spatial periodicity of the
    divergence angle and a temporal periodicity. The periods of the waves, which represent actively
    transported auxin, are much smaller than the plastochron interval. Where oppositely directed
    waves meet at one or more angular positions on the periphery of the generative circle, auxin
    concentration builds and as in most models this stimulates local movement of auxin to
    underlying cells, where it promotes polarized cell division and expansion. For higher order
    spirals the wave model requires asymmetric function of auxin transport; that is, opposite wave
    speeds differ. An algorithm for determination of the angular positions of leaves in common leaf
    phyllotaxic configurations is proposed. The number of turns in a pattern repeat, number of leaves
    per level and per pattern repeat, and divergence angle are related to speed of auxin transport and
    radius of the generative circle. The rule for composition of Fibonacci or Lucas numbers
    associated with some phyllotaxes is discussed. A subcellular model suggests how the shoot
    meristem might specify either symmetric or asymmetric transport of auxin away from the
    forming primordia that produce it. Biological tests that could make or break the mathematical
    and molecular hypotheses are proposed. PMID:22212121

  12. Enhanced permeation, leaf retention, and plant protease inhibitor activity with bicontinuous microemulsions.

    PubMed

    Tamhane, Vaijayanti A; Dhaware, Deepika G; Khandelwal, Neha; Giri, Ashok P; Panchagnula, Venkateswarlu

    2012-10-01

    Bicontinuous microemulsions (BCMEs) have excellent solubulizing properties along with low interfacial tension and aqueous content that can be controlled. In this work, water soluble plant protease inhibitor (PI), well characterized for its activity against insect pests, was incorporated into a BCME system and explored for permeation on hydrophobic leaf surfaces and protease inhibition activity. The bicontinuous nature of the microemulsion containing water:2-propanol:1-butanol (55:35:10 w/w) was characterized using conductivity and self-diffusion coefficient measurements. The PI was soluble in the water-rich bicontinuous domains, stable in the microemulsions, and protease inhibition activity was retained for a prolonged duration. The microemulsions ensured greater wettability and a wider spread of the PI on hydrophobic leaf surfaces as revealed by contact angle measurements. Significantly, trypsin inhibition activity assays of the PI recovered from the leaves after delivery from the microemulsion indicated a significant increase in the PI retention on the leaf. This BCME enabled greater leaf permeation and retention of the PI can be attributed to a temporary disruption of the waxy leaf surface followed by self-repair without causing any long term damage to the plant.

  13. Simulated acid rain affects birch leaf endophyte populations.

    PubMed

    Helander, M L; Neuvonen, S; Sieber, T; Petrini, O

    1993-11-01

    Endophytes were frequently isolated from mountain birch (Betula pubescens var. tortuosa (Ledeb.) Nyman) leaves at a subarctic site where natural air pollution is low. We tested whether simulated acid rain had any influence on the occurrence of endophytes. Dry controls with only ambient rain and irrigated controls treated with spring water of pH 6 were compared with acid treatments at pH 3 and pH 4, prepared by adding both sulphuric and nitric acids. Treatments began in 1985 and leaf samples were taken twice during the summer of 1992. Leaves were surface sterilized, five leaf disks from each leaf placed on malt extract agar, and growing colonies were counted and identified. The most frequently isolated endophyte from birch leaves was a Fusicladium anamorph of Venturia sp. (88% of all the isolates in July and 75% of all the isolates in August), followed by a sterile mycelium and Melanconium sp. The number of endophytes isolated and the species number increased from July to August. Endophytes were most frequently isolated from the basal part of the midrib. The percentage of colonization by endophytes was similar in short and long shoots. More endophytes were isolated from leaves of branches taken at 1 m height than at 2 m height. The stronger acid rain treatment (pH 3) reduced by approximately 25% the number of isolated endophytes in August. Treatments did not have any effect on species composition of endophyte assemblages in birch leaves.

  14. Leaf Epicuticular Waxes of the Eceriferum Mutants in Arabidopsis.

    PubMed Central

    Jenks, M. A.; Tuttle, H. A.; Eigenbrode, S. D.; Feldmann, K. A.

    1995-01-01

    Wild-type Arabidopsis leaf epicuticular wax (EW) occurs as a smooth layer over the epidermal surface, whereas stem EW has a crystalline microstructure. Wild-type EW load was more than 10-fold lower on leaves than on stems. Compared with the EW on wild-type stems, EW on wild-type leaves had a much higher proportion of their total EW load in the form of alkanes and 1-alcohols; a large reduction in secondary alcohols, ketones, and esters; and a chain-length distribution for major EW classes that was skewed toward longer lengths. The eceriferum (cer) mutations often differentially affected leaf and stem EW chemical compositions. For example, the cer2 mutant EW phenotype was expressed on the stem but not on the leaf. Compared to wild type, the amount of primary alcohols on cer9 mutants was reduced on leaves but elevated on stems, whereas an opposite differential effect for primary alcohols was observed on cer16 leaves and stems. Putative functions for CER gene products are discussed. The CER4 and CER6 gene products may be involved in fatty aldehyde reduction and C26 fatty acylcoenzyme A elongation, respectively. CER1, CER8, CER9, and CER16 gene products may be involved in EW substrate transfer. The CER3 gene product may be involved in release of fatty acids from elongase complexes. CER2 gene product may have regulatory functions. PMID:12228482

  15. Lifting Entry & Atmospheric Flight (LEAF) Applications at Solar System Bodies.

    NASA Astrophysics Data System (ADS)

    Lee, G.; Sen, B.; Polidan, R. S.

    2015-12-01

    Introduction: Northrop Grumman and L'Garde have continued the development of a hypersonic entry, maneuverable platform capable of performing long-duration (months to a year) in situ and remote measurements at any solar system body that possesses an atmosphere. The Lifting Entry & Atmospheric Flight (LEAF) family of vehicles achieve this capability by using a semi-buoyant, ultra-low ballistic coefficient vehicle whose lifting entry allows it to enter the atmosphere without an aeroshell. In this presentation, we discuss the application of the LEAF system at various solar system bodies: Venus, Titan, Mars, and Earth. We present the key differences in platform design as well as operational differences required by the various target environments. The Venus implementation includes propulsive capability to reach higher altitudes during the day and achieves full buoyancy in the "habitable layers" of Venus' atmosphere at night. Titan also offers an attractive operating environment, allowing LEAF designs that can target low, medium, or high altitude operations, also with propulsive capabilities to roam within each altitude regime. The Mars version is a glider that descends gradually, allowing targeted delivery of payloads to the surface. Finally, an Earth version could remain in orbit in a stowed state until activated, allowing rapid response type deployments to any region of the globe.

  16. Preliminary validation of leaf area index sensor in Huailai

    NASA Astrophysics Data System (ADS)

    Cai, Erli; Li, Xiuhong; Liu, Qiang; Dou, Baocheng; Chang, Chongyan; Niu, Hailin; Lin, Xingwen; Zhang, Jialin

    2015-12-01

    Leaf area index (LAI) is a key variable in many land surface models that involve energy and mass exchange between vegetation and the environment. In recent years, extracting vegetation structure parameters from digital photography becomes a widely used indirect method to estimate LAI for its simplicity and ease of use. A Leaf Area Index Sensor (LAIS) system was developed to continuously monitor the growth of crops in several sampling points in Huailai, China. The system applies 3G/WIFI communication technology to remotely collect crop photos in real-time. Then the crop photos are automatically processed and LAI is estimated based on the improved leaf area index of Lang and Xiang (LAILX) algorithm in LAIS. The objective of this study is to primarily verify the LAI estimated from LAIS (Lphoto) through comparing them with the destructive green LAI (Ldest). Ldest was measured across the growing season ntil maximum canopy development while plants are still green. The preliminary verification shows that Lphoto corresponds well with the Ldest (R2=0.975). In general, LAI could be accurately estimated with LAIS and its LAI shows high consistency compared with the destructive green LAI. The continuous LAI measurement obtained from LAIS could be used for the validation of remote sensing LAI products.

  17. Characterization of Leaf Blade- and Leaf Sheath-Associated Bacterial Communities and Assessment of Their Responses to Environmental Changes in CO2, Temperature, and Nitrogen Levels under Field Conditions

    PubMed Central

    Ikeda, Seishi; Tokida, Takeshi; Nakamura, Hirofumi; Sakai, Hidemitsu; Usui, Yasuhiro; Okubo, Takashi; Tago, Kanako; Hayashi, Kentaro; Sekiyama, Yasuyo; Ono, Hiroshi; Tomita, Satoru; Hayatsu, Masahito; Hasegawa, Toshihiro; Minamisawa, Kiwamu

    2015-01-01

    Rice shoot-associated bacterial communities at the panicle initiation stage were characterized and their responses to elevated surface water-soil temperature (ET), low nitrogen (LN), and free-air CO2 enrichment (FACE) were assessed by clone library analyses of the 16S rRNA gene. Principal coordinate analyses combining all sequence data for leaf blade- and leaf sheath-associated bacteria revealed that each bacterial community had a distinct structure, as supported by PC1 (61.5%), that was mainly attributed to the high abundance of Planctomycetes in leaf sheaths. Our results also indicated that the community structures of leaf blade-associated bacteria were more sensitive than those of leaf sheath-associated bacteria to the environmental factors examined. Among these environmental factors, LN strongly affected the community structures of leaf blade-associated bacteria by increasing the relative abundance of Bacilli. The most significant effect of FACE was also observed on leaf blade-associated bacteria under the LN condition, which was explained by decreases and increases in Agrobacterium and Pantoea, respectively. The community structures of leaf blade-associated bacteria under the combination of FACE and ET were more similar to those of the control than to those under ET or FACE. Thus, the combined effects of environmental factors need to be considered in order to realistically assess the effects of environmental changes on microbial community structures. PMID:25740174

  18. Leaf wetness distribution within a potato crop

    NASA Astrophysics Data System (ADS)

    Heusinkveld, B. G.

    2010-07-01

    The Netherlands has a mild maritime climate and therefore the major interest in leaf wetness is associated with foliar plant diseases. During moist micrometeorological conditions (i.e. dew, fog, rain), foliar fungal diseases may develop quickly and thereby destroy a crop quickly. Potato crop monocultures covering several hectares are especially vulnerable to such diseases. Therefore understanding and predicting leaf wetness in potato crops is crucial in crop disease control strategies. A field experiment was carried out in a large homogeneous potato crop in the Netherlands during the growing season of 2008. Two innovative sensor networks were installed as a 3 by 3 grid at 3 heights covering an area of about 2 hectares within two larger potato crops. One crop was located on a sandy soil and one crop on a sandy peat soil. In most cases leaf wetting starts in the top layer and then progresses downward. Leaf drying takes place in the same order after sunrise. A canopy dew simulation model was applied to simulate spatial leaf wetness distribution. The dew model is based on an energy balance model. The model can be run using information on the above-canopy wind speed, air temperature, humidity, net radiation and within canopy air temperature, humidity and soil moisture content and temperature conditions. Rainfall was accounted for by applying an interception model. The results of the dew model agreed well with the leaf wetness sensors if all local conditions were considered. The measurements show that the spatial correlation of leaf wetness decreases downward.

  19. Antimicrobial effect of Pistacia atlantica leaf extract

    PubMed Central

    Ali Roozegar, Mohamad; Azizi Jalilian, Farid; Reza Havasian, Mohamad; Panahi, Jafar; Pakzad, Iraj

    2016-01-01

    The antimicrobial effect of the mastic tree (Pistacia atlantica) under in vitro conditions has been reported. Therefore, it is of interest to evaluate the effect of the plant leaf extract (aqueous) on bacterial load in mouth and saliva. The leaf of the Pistacia atlantica plant was collected and cleaned, dried at 40⁰c and then powdered. The extraction was carried out using the maceration method in vacuum with the rotary evaporator device. Bacterial inhibition (Streptococcus species) by the leaf extract was studied using the disc diffusion and embedding sink diffusion methods. The values of MIC and MBC were determined. The collected data was further analyzed using t-test and repeated measure statistical tests. The disc diffusion technique showed a significant inhibitory effect for Pistacia atlantica leaf extract on S. mutans (ATCC 35668) and S. mitis (ATCC 49456) with inhibition zones of 19 and 25 millimeters, respectively. This is for the highest leaf extract concentration used in this study (p<0.01). The values of MIC and MBC for S.mutans was 60, 90 μg/ml and for S. mitis was 75, 110 μg/ml (p<0.01 significance). The leaf extract has no significant effect on S. salivarius (ATCC 13419). Thus, the antimicrobial properties of the aqueous leaf extract from Pistacia atlantica is demonstrated in this study. PMID:27212840

  20. Deciduous leaf drop reduces insect herbivory.

    PubMed

    Karban, Richard

    2007-08-01

    Deciduous leaf fall is thought to be an adaptation that allows plants living in seasonal environments to reduce water loss and damage during unfavorable periods while increasing photosynthetic rates during favorable periods. Observations of natural variation in leaf shedding suggest that deciduous leaf fall may also allow plants to reduce herbivory. I tested this hypothesis by experimentally manipulating leaf retention for Quercus lobata and observing natural rates of herbivory. Quercus lobata is primarily deciduous although individuals show considerable natural variation in leaf retention. Oak saplings with no leaves through winter experienced reduced attack by cynipid gall makers the following spring. This pattern was consistent with the positive correlation between natural leaf persistence and gall numbers. These cynipids do not overwinter on the leaves that trees retain through winter, although they appear to use persistent leaves as oviposition cues. If these results are general for woody plants in continental temperate habitats, they suggest that an important and unrecognized consequence of deciduous leaf shedding may be a reduction in herbivore damage, and that this effect should be included in models of deciduous and evergreen behavior. PMID:17375327

  1. Antimicrobial effect of Pistacia atlantica leaf extract.

    PubMed

    Ali Roozegar, Mohamad; Azizi Jalilian, Farid; Reza Havasian, Mohamad; Panahi, Jafar; Pakzad, Iraj

    2016-01-01

    The antimicrobial effect of the mastic tree (Pistacia atlantica) under in vitro conditions has been reported. Therefore, it is of interest to evaluate the effect of the plant leaf extract (aqueous) on bacterial load in mouth and saliva. The leaf of the Pistacia atlantica plant was collected and cleaned, dried at 40⁰c and then powdered. The extraction was carried out using the maceration method in vacuum with the rotary evaporator device. Bacterial inhibition (Streptococcus species) by the leaf extract was studied using the disc diffusion and embedding sink diffusion methods. The values of MIC and MBC were determined. The collected data was further analyzed using t-test and repeated measure statistical tests. The disc diffusion technique showed a significant inhibitory effect for Pistacia atlantica leaf extract on S. mutans (ATCC 35668) and S. mitis (ATCC 49456) with inhibition zones of 19 and 25 millimeters, respectively. This is for the highest leaf extract concentration used in this study (p<0.01). The values of MIC and MBC for S.mutans was 60, 90 μg/ml and for S. mitis was 75, 110 μg/ml (p<0.01 significance). The leaf extract has no significant effect on S. salivarius (ATCC 13419). Thus, the antimicrobial properties of the aqueous leaf extract from Pistacia atlantica is demonstrated in this study. PMID:27212840

  2. On the concept of leaf boundary layer resistance for forced convection

    PubMed

    Vesala

    1998-09-01

    The definition of leaf boundary layer resistance is reconsidered in respect of the three-dimensional diffusion-controlled mass transport region just above the leaf surface. Due to the existence of this superstomatal air layer, the conventional convective boundary layer is not in direct contact with the surface. Thus, in terms of plant physiology, the diffusive "end correction" to the stomatal resistance should be included in the boundary layer resistance. This is true for laminar as well as turbulent flows. When the surface mole fraction of an exchanged gas is estimated using the boundary layer resistance ignoring the diffusive term may lead to a noticeable error. The self-consistent approach is used to clarify the problems of the boundary layer formation and stomatal interference. If the correction is taken into account, the boundary layer resistance becomes dependent also on stomatal shape and distribution on the leaf. The traditional semiempirical formula corrected by the superstomatal diffusion is applied in numerical calculations. In estimates of the water vapour mole fraction on the surface of a transpiring leaf the relative error ranges from insignificant (quiescent air, large leaf and large stomatal pores) to 20 % (low humidity, strong wind, small leaf and small elliptic pores). The boundary layer resistance can decrease by a factor of 3 when the semiaxis lengths of the stomata increase from 1 and 0.5 &mgr;m to 10 and 5 &mgr;m. The effective thickness of the superstomatal air layer is maximally several millimetres (small stomatal surface concentration and small pores). Copyright 1998 Academic Press Limited PMID:9778427

  3. On the concept of leaf boundary layer resistance for forced convection

    PubMed

    Vesala

    1998-09-01

    The definition of leaf boundary layer resistance is reconsidered in respect of the three-dimensional diffusion-controlled mass transport region just above the leaf surface. Due to the existence of this superstomatal air layer, the conventional convective boundary layer is not in direct contact with the surface. Thus, in terms of plant physiology, the diffusive "end correction" to the stomatal resistance should be included in the boundary layer resistance. This is true for laminar as well as turbulent flows. When the surface mole fraction of an exchanged gas is estimated using the boundary layer resistance ignoring the diffusive term may lead to a noticeable error. The self-consistent approach is used to clarify the problems of the boundary layer formation and stomatal interference. If the correction is taken into account, the boundary layer resistance becomes dependent also on stomatal shape and distribution on the leaf. The traditional semiempirical formula corrected by the superstomatal diffusion is applied in numerical calculations. In estimates of the water vapour mole fraction on the surface of a transpiring leaf the relative error ranges from insignificant (quiescent air, large leaf and large stomatal pores) to 20 % (low humidity, strong wind, small leaf and small elliptic pores). The boundary layer resistance can decrease by a factor of 3 when the semiaxis lengths of the stomata increase from 1 and 0.5 &mgr;m to 10 and 5 &mgr;m. The effective thickness of the superstomatal air layer is maximally several millimetres (small stomatal surface concentration and small pores). Copyright 1998 Academic Press Limited

  4. Validating LiDAR Derived Estimates of Canopy Height, Structure and Fractional Cover in Riparian Areas: A Comparison of Leaf-on and Leaf-off LiDAR Data

    NASA Astrophysics Data System (ADS)

    Wasser, L. A.; Chasmer, L. E.; Taylor, A.; Day, R.

    2010-12-01

    Characterization of riparian buffers is integral to understanding the landscape scale impacts of disturbance on wildlife and aquatic ecosystems. Riparian buffers may be characterized using in situ plot sampling or via high resolution remote sensing. Field measurements are time-consuming and may not cover a broad range of ecosystem types. Further, spectral remote sensing methods introduce a compromise between spatial resolution (grain) and area extent. Airborne LiDAR can be used to continuously map and characterize riparian vegetation structure and composition due to the three-dimensional reflectance of laser pulses within and below the canopy, understory and at the ground surface. The distance between reflections (or ‘returns’) allows for detection of narrow buffer corridors at the landscape scale. There is a need to compare leaf-off and leaf-on surveyed LiDAR data with in situ measurements to assess accuracy in landscape scale analysis. These comparisons are particularly important considering increased availability of leaf-off surveyed LiDAR datasets. And given this increased availability, differences between leaf-on and leaf-off derived LiDAR metrics are largely unknown for riparian vegetation of varying composition and structure. This study compares the effectiveness of leaf-on and leaf-off LiDAR in characterizing riparian buffers of varying structure and composition as compared to field measurements. Field measurements were used to validate LiDAR derived metrics. Vegetation height, canopy cover, density and overstory and understory species composition were recorded in 80 random plots of varying vegetation type, density and structure within a Pennsylvania watershed (-77.841, 40.818). Plot data were compared with LiDAR data collected during leaf on and leaf off conditions to determine 1) accuracy of LiDAR derived metrics compared to field measures and 2) differences between leaf-on and leaf-off LiDAR metrics. Results illustrate that differences exist between

  5. Global Climatic Controls On Leaf Size

    NASA Astrophysics Data System (ADS)

    Wright, I. J.; Prentice, I. C.; Dong, N.; Maire, V.

    2015-12-01

    Since the 1890s it's been known that the wet tropics harbour plants with exceptionally large leaves. Yet the observed latitudinal gradient of leaf size has never been fully explained: it is still unclear which aspects of climate are most important for understanding geographic trends in leaf size, a trait that varies many thousand-fold among species. The key is the leaf-to-air temperature difference, which depends on the balance of energy inputs (irradiance) and outputs (transpirational cooling, losses to the night sky). Smaller leaves track air temperatures more closely than larger leaves. Widely cited optimality-based theories predict an advantage for smaller leaves in dry environments, where transpiration is restricted, but are silent on the latitudinal gradient. We aimed to characterize and explain the worldwide pattern of leaf size. Across 7900 species from 651 sites, here we show that: large-leaved species predominate in wet, hot, sunny environments; smaller-leaved species typify hot, sunny environments only when arid; small leaves are required to avoid freezing in high latitudes and at high elevation, and to avoid overheating in dry environments. This simple pattern was unclear in earlier, more limited analyses. We present a simple but robust, fresh approach to energy-balance modelling for both day-time and night-time leaf-to-air temperature differences, and thus risk of overheating and of frost damage. Our analysis shows night-chilling is important as well as day-heating, and simplifies leaf temperature modelling. It provides both a framework for modelling leaf size constraints, and a solution to one of the oldest conundrums in ecology. Although the path forward is not yet fully clear, because of its role in controlling leaf temperatures we suggest that climate-related leaf size constraints could usefully feature in the next generation of land ecosystem models.

  6. Titan LEAF: A Sky Rover Granting Targeted Access to Titan's Lakes and Plains

    NASA Astrophysics Data System (ADS)

    Ross, Floyd; Lee, Greg; Sokol, Daniel; Goldman, Benjamin; Bolisay, Linden

    2016-10-01

    Northrop Grumman, in collaboration with L'Garde Inc. and Global Aerospace Corporation (GAC), has been developing the Titan Lifting Entry Atmospheric Flight (T-LEAF) sky rover to roam the atmosphere and observe at close quarters the lakes and plains of Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in situ instruments to the surface.T-LEAF is a maneuverable, buoyant air vehicle. Its aerodynamic shape provides its maneuverability, and its internal helium envelope reduces propulsion power requirements and also the risk of crashing. Because of these features, T-LEAF is not restricted to following prevailing wind patterns. This freedom of mobility allows it be commanded to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations.T-LEAF utilizes a variable power propulsion system, from high power at ~200W to low power at ~50W. High power mode uses the propellers and control surfaces for additional mobility and maneuverability. It also allows the vehicle to hover over specific locations for long duration surface observations. Low power mode utilizes GAC's Titan Winged Aerobot (TWA) concept, currently being developed with NASA funding, which achieves guided flight without the use of propellers or control surfaces. Although slower than high powered flight, this mode grants increased power to science instruments while still maintaining control over direction of travel.Additionally, T-LEAF is its own entry vehicle, with its leading edges protected by flexible thermal protection system (f-TPS) materials already being tested by NASA's Hypersonic Inflatable Aerodynamic Decelerator (HIAD) group. This f-TPS technology allows T-LEAF to inflate in space, like HIAD, and then enter the atmosphere fully deployed. This approach accommodates entry velocities from as low as ~1.8 km/s if entering from Titan orbit, up to ~6 km/s if entering directly from Saturn orbit, like the Huygens probe

  7. Evolutionary and molecular aspects of Indian tomato leaf curl virus coat protein.

    PubMed

    Kumar, Sivakumar Prasanth; Patel, Saumya K; Kapopara, Ravi G; Jasrai, Yogesh T; Pandya, Himanshu A

    2012-01-01

    Tomato leaf curl disease (ToLCD) is manifested by yellowing of leaf lamina with upward leaf curl, leaf distortion, shrinking of the leaf surface, and stunted plant growth caused by tomato leaf curl virus (ToLCV). In the present study, using computational methods we explored the evolutionary and molecular prospects of viral coat protein derived from an isolate of Vadodara district, Gujarat (ToLCGV-[Vad]), India. We found that the amino acids in coat protein required for systemic infection, viral particle formation, and insect transmission to host cells were conserved amongst Indian strains. Phylogenetic studies on Indian ToLCV coat proteins showed evolutionary compatibility with other viral taxa. Modeling of coat protein revealed a topology similar to characteristic Geminate viral particle consisting of antiparallel β-barrel motif with N-terminus α-helix. The molecular interaction of coat protein with the viral DNA required for encapsidation and nuclear shuttling was investigated through sequence- and structure-based approaches. We further emphasized the role of loops in coat protein structure as molecular recognition interface.

  8. The effect of leaf size on the microwave backscattering by corn

    NASA Technical Reports Server (NTRS)

    Paris, J. F.

    1986-01-01

    Attema and Ulaby (1978) proposed the cloud model to predict the microwave backscattering properties of vegetation. This paper describes a modification in which the biophysical properties and microwave properties of vegetation are related at the level of the individual scatterer (e.g., the leaf or the stalk) rather than at the level of the aggregated canopy (e.g., the green leaf area index). Assuming that the extinction cross section of an average leaf was proportional to its water content, that a power law relationship existed between the backscattering cross section of an average green corn leaf and its area, and that the backscattering coefficient of the surface was a linear function of its volumetric soil moisture content, it is found that the explicit inclusion of the effects of corn leaf size in the model led to an excellent fit between the observed and predicted backscattering coefficients. Also, an excellent power law relationship existed between the backscattering cross section of a corn leaf and its area.

  9. Leaf nitrogen and phosphorus of temperate desert plants in response to climate and soil nutrient availability.

    PubMed

    He, Mingzhu; Dijkstra, Feike A; Zhang, Ke; Li, Xinrong; Tan, Huijuan; Gao, Yanhong; Li, Gang

    2014-11-06

    In desert ecosystems, plant growth and nutrient uptake are restricted by availability of soil nitrogen (N) and phosphorus (P). The effects of both climate and soil nutrient conditions on N and P concentrations among desert plant life forms (annual, perennial and shrub) remain unclear. We assessed leaf N and P levels of 54 desert plants and measured the corresponding soil N and P in shallow (0-10 cm), middle (10-40 cm) and deep soil layers (40-100 cm), at 52 sites in a temperate desert of northwest China. Leaf P and N:P ratios varied markedly among life forms. Leaf P was higher in annuals and perennials than in shrubs. Leaf N and P showed a negative relationship with mean annual temperature (MAT) and no relationship with mean annual precipitation (MAP), but a positive relationship with soil P. Leaf P of shrubs was positively related to soil P in the deep soil. Our study indicated that leaf N and P across the three life forms were influenced by soil P. Deep-rooted plants may enhance the availability of P in the surface soil facilitating growth of shallow-rooted life forms in this N and P limited system, but further research is warranted on this aspect.

  10. Quantitative phenotyping of leaf margins in three dimensions, demonstrated on KNOTTED and TCP trangenics in Arabidopsis

    PubMed Central

    Sharon, Eran

    2014-01-01

    The geometry of leaf margins is an important shape characteristic that distinguishes among different leaf phenotypes. Current definitions of leaf shape are qualitative and do not allow quantification of differences in shape between phenotypes. This is especially true for leaves with some non-trivial three-dimensional (3D) configurations. Here we present a novel geometrical method novel geometrical methods to define, measure, and quantify waviness and lobiness of leaves. The method is based on obtaining the curve of the leaf rim from a 3D surface measurement and decomposing its local curvature vector into the normal and geodesic components. We suggest that leaf waviness is associated with oscillating normal curvature along the margins, while lobiness is associated with oscillating geodesic curvature. We provide a way to integrate these local measures into global waviness and lobiness quantities. Using these novel definitions, we analysed the changes in leaf shape of two Arabidopsis genotypes, either as a function of gene mis-expression induction level or as a function of time. These definitions and experimental methods open the way for a more quantitative study of the shape of leaves and other growing slender organs. PMID:24706720

  11. Quantifying Shape Changes and Tissue Deformation in Leaf Development1[C][W][OPEN

    PubMed Central

    Rolland-Lagan, Anne-Gaëlle; Remmler, Lauren; Girard-Bock, Camille

    2014-01-01

    The analysis of biological shapes has applications in many areas of biology, and tools exist to quantify organ shape and detect shape differences between species or among variants. However, such measurements do not provide any information about the mechanisms of shape generation. Quantitative data on growth patterns may provide insights into morphogenetic processes, but since growth is a complex process occurring in four dimensions, growth patterns alone cannot intuitively be linked to shape outcomes. Here, we present computational tools to quantify tissue deformation and surface shape changes over the course of leaf development, applied to the first leaf of Arabidopsis (Arabidopsis thaliana). The results show that the overall leaf shape does not change notably during the developmental stages analyzed, yet there is a clear upward radial deformation of the leaf tissue in early time points. This deformation pattern may provide an explanation for how the Arabidopsis leaf maintains a relatively constant shape despite spatial heterogeneities in growth. These findings highlight the importance of quantifying tissue deformation when investigating the control of leaf shape. More generally, experimental mapping of deformation patterns may help us to better understand the link between growth and shape in organ development. PMID:24710066

  12. Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model.

    PubMed

    Bridge, L J; Franklin, K A; Homer, M E

    2013-08-01

    Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana, these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity.

  13. Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model

    PubMed Central

    Bridge, L. J.; Franklin, K. A.; Homer, M. E.

    2013-01-01

    Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana, these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity. PMID:23720538

  14. Patterns of effective permeability of leaf cuticles to acids

    SciTech Connect

    Hauser, H.D.; Walters, K.D.; Berg, V.S. )

    1993-01-01

    Plants in the field are frequently exposed to anthropogenic acid precipitation with pH values of 4 and below. For the acid to directly affect leaf tissues, it must pass through the leaf cuticle, but little is known about the permeability of cuticles to protons, of about the effect of different anions on this permeability. We investigated the movement of protons through isolated astomatous leaf cuticles of grapefruit (Citrus x paradisi Macfady.), rough lemon (Citrus limon [L.] Burm. fils cv Ponderosa), and pear (Pyrus communis L.) using hydrochloric, sulfuric, and nitric acids. Cuticles were enzymically isolated from leaves and placed in a diffusion apparatus with pH 4 acid on the morphological outer surface of the cuticle and degassed distilled water on the inner surface. Changes in pH of the solution on the inner surface were used to determine rates of effective permeability of the cuticles to the protons of these acids. Most cuticles exhibited an initial low permeability, lasting hours to days, then after a short transition displayed a significant higher permeability, which persisted until equilibrium was approached. The change in effective permeability appears to be reversible. Effective permeabilities were higher for sulfuric acid than for the others. A model of the movement of protons through the cuticle is presented, proposing that dissociated acid groups in channels within the cutin are first protonated by the acid, accounting for the low initial effective permeability; then protons pass freely through the channels, resulting in a higher effective permeability. 26 refs., 6 figs., 2 tabs.

  15. Influence of tillage on adult and immature pea leaf weevil (Coleoptera: Curculionidae) densities in pea.

    PubMed

    Hanavan, Ryan P; Bosque-Pérez, Nilsa A; Schotzko, Dennis J; Eigenbrode, Sanford D

    2010-06-01

    The pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), has been a major pest of pea, Pisum sativum L., in eastern Washington and northern Idaho since its introduction to the region in the early 1970s. Eggs are deposited in the spring on the soil surface and first instars hatch and move to pea root nodules, where larvae feed before they pupate and adults emerge in mid- to late summer. No-tillage practices are known to reduce pea leaf weevil colonization in pea, but the effects of tillage on larval densities and subsequent adult emergence have not been examined. During 2005, 2006, and 2007, we compared densities of colonizing adult and immature pea leaf weevils on pea plots grown using conventional tillage and no-tillage. In 2005 and 2006, emergence of adult pea leaf weevil was monitored in the same plots. Densities of colonizing adult and immature pea leaf weevil were significantly higher in conventional tillage plots. Larvae in conventional tillage were further along in development than larvae in no-tillage plots during June and July. Densities of emerging adult pea leaf weevil were significantly greater from conventional tillage than no-tillage plots. Based on densities of colonizing and subsequent emerging adults, survival of weevils from egg through adult was greater in conventional tillage plots. Soils under no-tillage are cooler, resulting in later emergence of the pea crop and delayed root nodule development, possibly affecting the ability of first-instar pea leaf weevil to locate host plant roots. Our results indicate no-tillage fields are less suitable for pea leaf weevil colonization and survival than conventional tillage fields.

  16. Mercury in leaf litter in typical suburban and urban broadleaf forests in China.

    PubMed

    Niu, Zhenchuan; Zhang, Xiaoshan; Wang, Zhangwei; Ci, Zhijia

    2011-01-01

    To study the role of leaf litter in the mercury (Hg) cycle in suburban broadleaf forests and the distribution of Hg in urban forests, we collected leaf litter and soil from suburban evergreen and deciduous broadleaf forests and from urban forests in Beijing. The Hg concentrations in leaf litter from the suburban forests varied from 8.3 to 205.0 ng/g, with an average (avg) of (49.7 +/- 36.9) ng/g. The average Hg concentration in evergreen broadleaf forest leaf litter (50.8 + 39.4) ng/g was higher than that in deciduous broadleaf forest leaf litter (25.8 +/- 10.1) ng/g. The estimated Hg fluxes of leaf litter in suburban evergreen and deciduous broadleaf forests were 179.0 and 83.7 mg/(ha x yr), respectively. The Hg concentration in organic horizons (O horizons) ((263.1 +/- 237.2) ng/g) was higher than that in eluvial horizons (A horizons) ((83.9 +/- 52.0) ng/g). These results indicated that leaf litterfall plays an important role in transporting atmospheric mercury to soil in suburban forests. For urban forests in Beijing, the Hg concentrations in leaf litter ranged from 8.8-119.0 (avg 28.1 +/- 16.6) ng/g, with higher concentrations at urban sites than at suburban sites for each tree. The Hg concentrations in surface soil in Beijing were 32.0-25300.0 ng/g and increased from suburban sites to urban sites, with the highest value from Jingshan (JS) Park at the centre of Beijing. Therefore, the distribution of Hg in Beijing urban forests appeared to be strongly influenced by anthropogenic activities.

  17. Evaluation of Methane from Sisal Leaf Residue and Palash Leaf Litter

    NASA Astrophysics Data System (ADS)

    Arisutha, S.; Baredar, P.; Deshpande, D. M.; Suresh, S.

    2014-12-01

    The aim of this study is to evaluate methane production from sisal leaf residue and palash leaf litter mixed with different bulky materials such as vegetable market waste, hostel kitchen waste and digested biogas slurry in a laboratory scale anaerobic reactor. The mixture was prepared with 1:1 proportion. Maximum methane content of 320 ml/day was observed in the case of sisal leaf residue mixed with vegetable market waste as the feed. Methane content was minimum (47 ml/day), when palash leaf litter was used as feed. This was due to the increased content of lignin and polyphenol in the feedstock which were of complex structure and did not get degraded directly by microorganisms. Sisal leaf residue mixtures also showed highest content of volatile fatty acids (VFAs) as compared to palash leaf litter mixtures. It was observed that VFA concentration in the digester first increased, reached maximum (when pH was minimum) and then decreased.

  18. Wheat leaf photosynthesis loss due to leaf rust, with respect to lesion development and leaf nitrogen status.

    PubMed

    Robert, Corinne; Bancal, Marie-Odile; Ney, Bertrand; Lannou, Christian

    2005-01-01

    In wheat (Triticum aestivum cv. Soissons) plants grown under three different fertilisation treatments, we quantified the effect of leaf rust (Puccinia triticina) on flag leaf photosynthesis during the whole sporulation period. Bastiaans' model: Y = (1 - x)beta was used to characterize the relationship between relative leaf photosynthesis (Y) and disease severity (x). The evolution of the different types of symptoms induced by the pathogen (sporulating, chlorotic and necrosed tissues) was evaluated using image analysis. The beta-values varied from 2 to 11, 1.4-2, and 0.8-1 during the sporulation period, when considering the proportion of sporulating, sporulating + necrotic, and total diseased area, respectively. Leaf nitrogen (N) content did not change the effect of the disease on host photosynthesis. We concluded that leaf rust has no global effect on the photosynthesis of the symptomless parts of the leaves and that the large range in the quantification of leaf rust effect on the host, which is found in the literature, can be accounted for by considering the different symptom types. We discuss how our results could improve disease assessments and damage prediction in a wheat crop.

  19. Structural assessment of the impact of environmental constraints on Arabidopsis thaliana leaf growth: a 3D approach.

    PubMed

    Wuyts, Nathalie; Massonnet, Catherine; Dauzat, Myriam; Granier, Christine

    2012-09-01

    Light and soil water content affect leaf surface area expansion through modifications in epidermal cell numbers and area, while effects on leaf thickness and mesophyll cell volumes are far less documented. Here, three-dimensional imaging was applied in a study of Arabidopsis thaliana leaf growth to determine leaf thickness and the cellular organization of mesophyll tissues under moderate soil water deficit and two cumulative light conditions. In contrast to surface area, thickness was highly conserved in response to water deficit under both low and high cumulative light regimes. Unlike epidermal and palisade mesophyll tissues, no reductions in cell number were observed in the spongy mesophyll; cells had rather changed in volume and shape. Furthermore, leaf features of a selection of genotypes affected in leaf functioning were analysed. The low-starch mutant pgm had very thick leaves because of unusually large palisade mesophyll cells, together with high levels of photosynthesis and stomatal conductance. By means of an open stomata mutant and a 9-cis-epoxycarotenoid dioxygenase overexpressor, it was shown that stomatal conductance does not necessarily have a major impact on leaf dimensions and cellular organization, pointing to additional mechanisms for the control of CO(2) diffusion under high and low stomatal conductance, respectively.

  20. An economical non-destructive method for estimating eelgrass, Zostera marina (Potamogetonaceae) leaf growth rates: formal development and use in northwestern Baja California.

    PubMed

    Solana-Arellano, Elena; Echavarria-Heras, Héctor; Franco-Vizcaíno, Ernesto

    2008-09-01

    Seagrass beds provide much of the primary production in estuaries; host many fishes and fish larvae, and abate erosion. The present study presents original analytical methods for estimating mean leaf-growth rates of eelgrass (Zostera marina). The method was calibrated by using data collected in a Z. marina meadow at Punta Banda estuary in Baja California, Mexico. The analytical assessments were based on measurements of leaf length and standard regression procedures. We present a detailed explanation of the formal procedures involved in the derivation of these analytical methods. The measured daily leaf-growth rate was 10.9 mm d(-1) leaf(-1). The corresponding value projected by our method was 10.2 mm d(-1) leaf(-). The associated standard errors were of 0.53 and 0.56 mm d(-1) leaf(-1) respectively. The method was validated by projecting leaf-growth rates from an independent data set, which gave consistent results. The use of the method to obtain the mean leaf growth rate of a transplanted plot is also illustrated. Comparison of our leaf-growth data with previously reported assessments show the significant forcing of sea-surface temperature on eelgrass leaf dynamics. The formal constructs provided here are of general scope and can be applied to equivalent eelgrass data sets in a straightforward manner. PMID:19419023

  1. An economical non-destructive method for estimating eelgrass, Zostera marina (Potamogetonaceae) leaf growth rates: formal development and use in northwestern Baja California.

    PubMed

    Solana-Arellano, Elena; Echavarria-Heras, Héctor; Franco-Vizcaíno, Ernesto

    2008-09-01

    Seagrass beds provide much of the primary production in estuaries; host many fishes and fish larvae, and abate erosion. The present study presents original analytical methods for estimating mean leaf-growth rates of eelgrass (Zostera marina). The method was calibrated by using data collected in a Z. marina meadow at Punta Banda estuary in Baja California, Mexico. The analytical assessments were based on measurements of leaf length and standard regression procedures. We present a detailed explanation of the formal procedures involved in the derivation of these analytical methods. The measured daily leaf-growth rate was 10.9 mm d(-1) leaf(-1). The corresponding value projected by our method was 10.2 mm d(-1) leaf(-). The associated standard errors were of 0.53 and 0.56 mm d(-1) leaf(-1) respectively. The method was validated by projecting leaf-growth rates from an independent data set, which gave consistent results. The use of the method to obtain the mean leaf growth rate of a transplanted plot is also illustrated. Comparison of our leaf-growth data with previously reported assessments show the significant forcing of sea-surface temperature on eelgrass leaf dynamics. The formal constructs provided here are of general scope and can be applied to equivalent eelgrass data sets in a straightforward manner.

  2. Independence of stem and leaf hydraulic traits in six Euphorbiaceae tree species with contrasting leaf phenology.

    PubMed

    Chen, Jun-Wen; Zhang, Qiang; Li, Xiao-Shuang; Cao, Kun-Fang

    2009-08-01

    Hydraulic traits and hydraulic-related structural properties were examined in three deciduous (Hevea brasiliensis, Macaranga denticulate, and Bischofia javanica) and three evergreen (Drypetes indica, Aleurites moluccana, and Codiaeum variegatum) Euphorbiaceae tree species from a seasonally tropical forest in south-western China. Xylem water potential at 50% loss of stem hydraulic conductivity (P50(stem)) was more negative in the evergreen tree, but leaf water potential at 50% loss of leaf hydraulic conductivity (P50(leaf)) did not function as P50(stem) did. Furthermore, P50(stem) was more negative than P50(leaf) in the evergreen tree; contrarily, this pattern was not observed in the deciduous tree. Leaf hydraulic conductivity overlapped considerably, but stem hydraulic conductivity diverged between the evergreen and deciduous tree. Correspondingly, structural properties of leaves overlapped substantially; however, structural properties of stem diverged markedly. Consequently, leaf and stem hydraulic traits were closely correlated with leaf and stem structural properties, respectively. Additionally, stem hydraulic efficiency was significantly correlated with stem hydraulic resistance to embolism; nevertheless, such a hydraulic pattern was not found in leaf hydraulics. Thus, these results suggest: (1) that the evergreen and deciduous tree mainly diverge in stem hydraulics, but not in leaf hydraulics, (2) that regardless of leaf or stem, their hydraulic traits result primarily from structural properties, and not from leaf phenology, (3) that leaves are more vulnerable to drought-induced embolism than stem in the evergreen tree, but not always in the deciduous tree and (4) that there exists a trade-off between hydraulic efficiency and safety for stem hydraulics, but not for leaf hydraulics.

  3. The red edge of plant leaf reflectance

    NASA Technical Reports Server (NTRS)

    Horler, D. N. H.; Dockray, M.; Barber, J.

    1983-01-01

    A detailed study of the red edge spectral feature of green vegetation based on laboratory reflectance spectrophotometry is presented. A parameter lambda is defined as the wavelength is defined as the wavelength of maximum slope and found to be dependent on chlorophyll concentration. Species, development stage, leaf layering, and leaf water content of vegetation also influences lambda. The maximum slope parameter is found to be independent of simulated ground area coverage. The results are interpreted in terms of Beer's Law and Kubelka-Munk theory. The chlorophyll concentration dependence of lambda seems to be explained in terms of a pure absorption effect, and it is suggested that the existence of two lambda components arises from leaf scattering properties. The results indicate that red edge measurements will be valuable for assessment of vegetative chlorophyll status and leaf area index independently of ground cover variations, and will be particularly suitable for early stress detection.

  4. Monitoring Air Quality with Leaf Yeasts.

    ERIC Educational Resources Information Center

    Richardson, D. H. S.; And Others

    1985-01-01

    Proposes that leaf yeast serve as quick, inexpensive, and effective techniques for monitoring air quality. Outlines procedures and provides suggestions for data analysis. Includes results from sample school groups who employed this technique. (ML)

  5. Reflectance model of a plant leaf

    NASA Technical Reports Server (NTRS)

    Kumar, R.; Silva, L.

    1973-01-01

    A light ray, incident at 5 deg to the normal, is geometrically plotted through the drawing of the cross section of a soybean leaf using Fresnel's Equations and Snell's Law. The optical mediums of the leaf considered for ray tracing are: air, cell sap, chloroplast, and cell wall. The above ray is also drawn through the same leaf cross section considering cell wall and air as the only optical mediums. The values of the reflection and transmission found from ray tracing agree closely with the experimental results obtained using a Beckman DK-2A Spectroreflectometer. Similarly a light ray, incident at about 60 deg to the normal, is drawn through the palisade cells of a soybean leaf to illustrate the pathway of light, incident at an oblique angle, through the palisade cells.

  6. Photosynthesis and Respiration in Leaf Slices.

    ERIC Educational Resources Information Center

    Brown, Simon

    1998-01-01

    Demonstrates how leaf slices provide an inexpensive material for illustrating several fundamental points about the biochemistry of photosynthesis and respiration. Presents experiments that illustrate the effects of photon flux density and herbicides and carbon dioxide concentration. (DDR)

  7. 7 CFR 29.3647 - Heavy Leaf (B Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic... Leaf. Mature, medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity.... Underripe, medium body, close leaf structure, rough, lean in oil, dull finish, pale color...

  8. 7 CFR 29.3647 - Heavy Leaf (B Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic... Leaf. Mature, medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity.... Underripe, medium body, close leaf structure, rough, lean in oil, dull finish, pale color...

  9. 7 CFR 29.3647 - Heavy Leaf (B Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic... Leaf. Mature, medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity.... Underripe, medium body, close leaf structure, rough, lean in oil, dull finish, pale color...

  10. Effect of harvest timing and leaf hairiness on fiber quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent concerns over leaf grades have generated questions of how both time of day cotton is harvested, as well as leaf hairiness levels of certain varieties, influence fiber quality. To address this, two smooth leaf varieties and two varieties with higher levels of leaf pubescence were harvested at...

  11. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Smoking Leaf (H Group). 29.1163 Section 29.1163... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.1163 Smoking Leaf (H Group). This group consists of... Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil, strong color...

  12. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Smoking Leaf (H Group). 29.1163 Section 29.1163... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.1163 Smoking Leaf (H Group). This group consists of... Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil, strong color...

  13. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Smoking Leaf (H Group). 29.1163 Section 29.1163... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.1163 Smoking Leaf (H Group). This group consists of... Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil, strong color...

  14. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Smoking Leaf (H Group). 29.1163 Section 29.1163... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.1163 Smoking Leaf (H Group). This group consists of... Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil, strong color...

  15. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Smoking Leaf (H Group). 29.1163 Section 29.1163... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.1163 Smoking Leaf (H Group). This group consists of... Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil, strong color...

  16. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  17. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  18. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  19. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  20. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  1. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish, deep color intensity, semielastic, spready, 90 percent uniform, and 10 percent injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth,...

  2. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish, deep color intensity, semielastic, spready, 90 percent uniform, and 10 percent injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth,...

  3. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish, deep color intensity, semielastic, spready, 90 percent uniform, and 10 percent injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth,...

  4. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish, deep color intensity, semielastic, spready, 90 percent uniform, and 10 percent injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth,...

  5. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish, deep color intensity, semielastic, spready, 90 percent uniform, and 10 percent injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth,...

  6. 7 CFR 28.512 - Leaf Grade No. 2.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 2. 28.512 Section 28.512 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall be American Pima cotton which...

  7. 7 CFR 28.511 - Leaf Grade No. 1.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 1. 28.511 Section 28.511 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall be American Pima cotton which...

  8. What Is a Leaf? An Online Tutorial and Tests

    ERIC Educational Resources Information Center

    Burrows, Geoffrey

    2008-01-01

    A leaf is a fundamental unit in botany and understanding what constitutes a leaf is fundamental to many plant science activities. My observations and subsequent testing indicated that many students could not confidently and consistently recognise a leaf from a leaflet, or recognise basic leaf arrangements and the various types of compound or…

  9. 7 CFR 28.515 - Leaf Grade No. 5.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 5. 28.515 Section 28.515 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall be American Pima cotton which...

  10. 7 CFR 28.513 - Leaf Grade No. 3.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 3. 28.513 Section 28.513 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.513 Leaf Grade No. 3. Leaf grade No. 3 shall be American Pima cotton which...

  11. 7 CFR 28.514 - Leaf Grade No. 4.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 4. 28.514 Section 28.514 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall be American Pima cotton which...

  12. 7 CFR 28.517 - Leaf Grade No. 7.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 7. 28.517 Section 28.517 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.517 Leaf Grade No. 7. American Pima cotton which in leaf is inferior to...

  13. 7 CFR 28.516 - Leaf Grade No. 6.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 6. 28.516 Section 28.516 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall be American Pima cotton which...

  14. 7 CFR 29.3647 - Heavy Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic, narrow, 70..., medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic... Leaf. Mature, heavy, close leaf structure, rough, lean in oil, dull finish, pale color...

  15. Leaf structural traits of tropical woody species resistant to cement dust.

    PubMed

    Siqueira-Silva, Advanio Inácio; Pereira, Eduardo Gusmão; Modolo, Luzia Valentina; Paiva, Elder Antonio Sousa

    2016-08-01

    Cement industries located nearby limestone outcrops in Brazil have contributed to the coating of cement dust over native plant species. However, little is known about the extent of the response of tropical woody plants to such environmental pollutant particularly during the first stages of plant development and establishment. This work focused on the investigation of possible alterations in leaf structural and ultrastructural traits of 5-month-old Guazuma ulmifolia Lam. (Malvaceae), 6-month-old Myracrodruon urundeuva Allemão (Anacardiaceae), and 9-month-old Trichilia hirta L. (Meliaceae) challenged superficially with cement dust during new leaf development. Leaf surface of plants, the soil or both (leaf plus soil), were treated (or not) for 60 days, under controlled conditions, with cement dust at 2.5 or 5.0 mg cm(-2). After exposure, no significant structural changes were observed in plant leaves. Also, no plant death was recorded by the end of the experiment. There was also some evidence of localized leaf necrosis in G. ulmifolia and T. hirta, leaf curling in M. urundeuva and T. hirta, and bulges formation on epidermal surface of T. hirta, after cement dust contact with plant shoots. All species studied exhibited stomata obliteration while T. hirta, in particular, presented early leaf abscission, changes in cellular relief, and organization and content of midrib cells. No significant ultrastructural alterations were detected under the experimental conditions studied. Indeed, mesophyll cells presented plastids with intact membrane systems. The high plant survival rates, together with mild morphoanatomic traits alterations in leaves, indicate that G. ulmifolia is more resistant to cement dust pollutant, followed by M. urundeuva and T. hirta. Thus, the three plant species are promising for being used to revegetate areas impacted by cement industries activities. PMID:27146683

  16. Cleanup of trimethylamine (fishy odor) from contaminated air by various species of Sansevieria spp. and their leaf materials.

    PubMed

    Boraphech, Phattara; Suksabye, Parinda; Kulinfra, Nipaporn; Kongsang, Wascharangkoon; Thiravetyan, Paitip

    2016-10-01

    Removal of trimethylamine (TMA) by 10 different living Sansevieria spp. and their dried leaf materials was studied. The results showed that living Sansevieria kirkii was the most effective plant while Sansevieria masoniana was the least effective in TMA removal. Two major pathways were involved in stomata opening and epicuticular wax on the leaf surface. In the presence of TMA, the stomata opening in Sansevieria spp. was induced, which enhanced TMA removal under light conditions. Dried leaf powders of Sansevieria spp. adsorbed TMA through their waxes. Therefore, both living and non-living Sansevieria spp. can be effectively used for removal of TMA. PMID:27294282

  17. Semi-Rolled Leaf2 modulates rice leaf rolling by regulating abaxial side cell differentiation.

    PubMed

    Liu, Xiaofei; Li, Ming; Liu, Kai; Tang, Ding; Sun, Mingfa; Li, Yafei; Shen, Yi; Du, Guijie; Cheng, Zhukuan

    2016-04-01

    Moderate leaf rolling maintains the erectness of leaves and minimizes the shadowing between leaves which is helpful to establish ideal plant architecture. Here, we describe asrl2(semi-rolled leaf2) rice mutant, which has incurved leaves due to the presence of defective sclerenchymatous cells on the abaxial side of the leaf and displays narrow leaves and reduced plant height. Map-based cloning revealed that SRL2 encodes a novel plant-specific protein of unknown biochemical function.SRL2 was mainly expressed in the vascular bundles of leaf blades, leaf sheaths, and roots, especially in their sclerenchymatous cells. The transcriptional activities of several leaf development-related YABBY genes were significantly altered in the srl2 mutant. Double mutant analysis suggested that SRL2 and SHALLOT-LIKE1(SLL1)/ROLLED LEAF9(RL9) function in distinct pathways that regulate abaxial-side leaf development. Hence, SRL2 plays an important role in regulating leaf development, particularly during sclerenchymatous cell differentiation.

  18. Semi-Rolled Leaf2 modulates rice leaf rolling by regulating abaxial side cell differentiation

    PubMed Central

    Liu, Xiaofei; Li, Ming; Liu, Kai; Tang, Ding; Sun, Mingfa; Li, Yafei; Shen, Yi; Du, Guijie; Cheng, Zhukuan

    2016-01-01

    Moderate leaf rolling maintains the erectness of leaves and minimizes the shadowing between leaves which is helpful to establish ideal plant architecture. Here, we describe a srl2 (semi-rolled leaf2) rice mutant, which has incurved leaves due to the presence of defective sclerenchymatous cells on the abaxial side of the leaf and displays narrow leaves and reduced plant height. Map-based cloning revealed that SRL2 encodes a novel plant-specific protein of unknown biochemical function. SRL2 was mainly expressed in the vascular bundles of leaf blades, leaf sheaths, and roots, especially in their sclerenchymatous cells. The transcriptional activities of several leaf development-related YABBY genes were significantly altered in the srl2 mutant. Double mutant analysis suggested that SRL2 and SHALLOT-LIKE1 (SLL1)/ROLLED LEAF9 (RL9) function in distinct pathways that regulate abaxial-side leaf development. Hence, SRL2 plays an important role in regulating leaf development, particularly during sclerenchymatous cell differentiation. PMID:26873975

  19. Semi-Rolled Leaf2 modulates rice leaf rolling by regulating abaxial side cell differentiation.

    PubMed

    Liu, Xiaofei; Li, Ming; Liu, Kai; Tang, Ding; Sun, Mingfa; Li, Yafei; Shen, Yi; Du, Guijie; Cheng, Zhukuan

    2016-04-01

    Moderate leaf rolling maintains the erectness of leaves and minimizes the shadowing between leaves which is helpful to establish ideal plant architecture. Here, we describe asrl2(semi-rolled leaf2) rice mutant, which has incurved leaves due to the presence of defective sclerenchymatous cells on the abaxial side of the leaf and displays narrow leaves and reduced plant height. Map-based cloning revealed that SRL2 encodes a novel plant-specific protein of unknown biochemical function.SRL2 was mainly expressed in the vascular bundles of leaf blades, leaf sheaths, and roots, especially in their sclerenchymatous cells. The transcriptional activities of several leaf development-related YABBY genes were significantly altered in the srl2 mutant. Double mutant analysis suggested that SRL2 and SHALLOT-LIKE1(SLL1)/ROLLED LEAF9(RL9) function in distinct pathways that regulate abaxial-side leaf development. Hence, SRL2 plays an important role in regulating leaf development, particularly during sclerenchymatous cell differentiation. PMID:26873975

  20. Antibacterial activity on Citrullus colocynthis Leaf extract

    PubMed Central

    gowri, S. Shyamala; Priyavardhini, S.; Vasantha, K.; Umadevi, M.

    2009-01-01

    Studies on the antibacterial activities of the leaf extract of Citrullus colocynthis (Cucurbitaceae), a medicinal plant used for the treatment of various ailments was carried out using agar disc diffusion technique. The results revealed that the crude acetone extract exhibited antibacterial activities against Pseudomonas aeruginosa with zones of inhibition measuring 14.0mm. The chloroform leaf extract exhibited no antibacterial activity against Staphylococcus aureus. The minimum inhibitory concentration for the chloroform extract was 4.0mm for Escherichia coli. PMID:22557336

  1. Remote sensing of leaf water status

    NASA Technical Reports Server (NTRS)

    Ripple, William J.; Schrumpf, Barry J.

    1987-01-01

    Relative water content (RWC) measurements were made concurrently with spectral reflectance measurements from individual snapbean leaves. The relationships between spectra and RWC were described using second order polynomial equations. The middle infrared bands most sensitive to changes in leaf RWC also had the highest water absorption coefficients, as published by Curcio Petty (1951). The relationship between reflectance at 2100nm and total water potential for a single leaf was found to be linear.

  2. GLUTAMATE RECEPTOR-LIKE genes mediate leaf-to-leaf wound signalling.

    PubMed

    Mousavi, Seyed A R; Chauvin, Adeline; Pascaud, François; Kellenberger, Stephan; Farmer, Edward E

    2013-08-22

    Wounded leaves communicate their damage status to one another through a poorly understood process of long-distance signalling. This stimulates the distal production of jasmonates, potent regulators of defence responses. Using non-invasive electrodes we mapped surface potential changes in Arabidopsis thaliana after wounding leaf eight and found that membrane depolarizations correlated with jasmonate signalling domains in undamaged leaves. Furthermore, current injection elicited jasmonoyl-isoleucine accumulation, resulting in a transcriptome enriched in RNAs encoding key jasmonate signalling regulators. From among 34 screened membrane protein mutant lines, mutations in several clade 3 GLUTAMATE RECEPTOR-LIKE genes (GLRs 3.2, 3.3 and 3.6) attenuated wound-induced surface potential changes. Jasmonate-response gene expression in leaves distal to wounds was reduced in a glr3.3 glr3.6 double mutant. This work provides a genetic basis for investigating mechanisms of long-distance wound signalling in plants and indicates that plant genes related to those important for synaptic activity in animals function in organ-to-organ wound signalling.

  3. Association of tomato leaf curl Sudan virus with leaf curl disease of tomato in Jeddah, Saudi Arabia.

    PubMed

    Sohrab, Sayed Sartaj; Yasir, Muhammad; El-Kafrawy, Sherif Ali; Abbas, Ayman T; Mousa, Magdi Ali Ahmed; Bakhashwain, Ahmed A

    2016-06-01

    Tomato is an important vegetable crop and its production is adversely affected by leaf curl disease caused by begomovirus. Leaf curl disease is a serious concern for tomato crops caused by begomovirus in Jeddah, Kingdom of Saudi Arabia. Tomato leaf curl disease has been shown to be mainly caused either by tomato leaf curl Sudan virus or tomato yellow leaf curl virus as well as tomato leaf curl Oman virus. Many tomato plants infected with monopartite begomoviruses were also found to harbor a symptom enhancing betasatellites. Here we report the association of tomato leaf curl Sudan virus causing leaf curl disease of tomato in Jeddah, Kingdom of Saudi Arabia. The complete genome sequence analysis showed highest (99.9 %) identity with tomato leaf curl Sudan virus causing leaf curl disease in Arabian Peninsula. In phylogenetic relationships analysis, the identified virus formed closest cluster with tomato leaf curl Sudan virus. In recombination analysis study, the major parent was identified as tomato leaf curl Sudan virus. Findings of this study strongly supports the associated virus is a variant of tomato leaf curl Sudan virus causing disease in Sudan, Yemen and Arabian Peninsula. The betasatellites sequence analysis showed highest identity (99.8 %) with tomato leaf curl betasatellites-Amaranthus-Jeddah. The phylogenetic analysis result based on betasatellites formed closed cluster with tomato yellow leaf curl Oman betasatellites. The importance of these findings and occurrence of begomovirus in new geographic regions causing leaf curl disease of tomato in Jeddah, Kingdom of Saudi Arabia are discussed.

  4. Association of tomato leaf curl Sudan virus with leaf curl disease of tomato in Jeddah, Saudi Arabia.

    PubMed

    Sohrab, Sayed Sartaj; Yasir, Muhammad; El-Kafrawy, Sherif Ali; Abbas, Ayman T; Mousa, Magdi Ali Ahmed; Bakhashwain, Ahmed A

    2016-06-01

    Tomato is an important vegetable crop and its production is adversely affected by leaf curl disease caused by begomovirus. Leaf curl disease is a serious concern for tomato crops caused by begomovirus in Jeddah, Kingdom of Saudi Arabia. Tomato leaf curl disease has been shown to be mainly caused either by tomato leaf curl Sudan virus or tomato yellow leaf curl virus as well as tomato leaf curl Oman virus. Many tomato plants infected with monopartite begomoviruses were also found to harbor a symptom enhancing betasatellites. Here we report the association of tomato leaf curl Sudan virus causing leaf curl disease of tomato in Jeddah, Kingdom of Saudi Arabia. The complete genome sequence analysis showed highest (99.9 %) identity with tomato leaf curl Sudan virus causing leaf curl disease in Arabian Peninsula. In phylogenetic relationships analysis, the identified virus formed closest cluster with tomato leaf curl Sudan virus. In recombination analysis study, the major parent was identified as tomato leaf curl Sudan virus. Findings of this study strongly supports the associated virus is a variant of tomato leaf curl Sudan virus causing disease in Sudan, Yemen and Arabian Peninsula. The betasatellites sequence analysis showed highest identity (99.8 %) with tomato leaf curl betasatellites-Amaranthus-Jeddah. The phylogenetic analysis result based on betasatellites formed closed cluster with tomato yellow leaf curl Oman betasatellites. The importance of these findings and occurrence of begomovirus in new geographic regions causing leaf curl disease of tomato in Jeddah, Kingdom of Saudi Arabia are discussed. PMID:27366765

  5. Direct leaf wetness measurements and its numerical analysis using a multi-layer atmosphere-soil-vegetation model at a grassland site in pre-alpine region in Germany

    NASA Astrophysics Data System (ADS)

    Katata, Genki; Held, Andreas; Mauder, Matthias

    2014-05-01

    The wetness of plant leaf surfaces (leaf wetness) is important in meteorological, agricultural, and environmental studies including plant disease management and the deposition process of atmospheric trace gases and particles. Although many models have been developed to predict leaf wetness, wetness data directly measured at the leaf surface for model validations are still limited. In the present study, the leaf wetness was monitored using seven electrical sensors directly clipped to living leaf surfaces of thin and broad-leaved grasses. The measurements were carried out at the pre-alpine grassland site in TERestrial ENvironmental Observatories (TERENO) networks in Germany from September 20 to November 8, 2013. Numerical simulations of a multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) developed by the authors were carried out for analyzing the data. For numerical simulations, the additional routine meteorological data of wind speed, air temperature and humidity, radiation, rainfall, long-wave radiative surface temperature, surface fluxes, ceilometer backscatter, and canopy or snow depth were used. The model reproduced well the observed leaf wetness, net radiation, momentum and heat, water vapor, and CO2 fluxes, surface temperature, and soil temperature and moisture. In rain-free days, a typical diurnal cycle as a decrease and increase during the day- and night-time, respectively, was observed in leaf wetness data. The high wetness level was always monitored under rain, fog, and snowcover conditions. Leaf wetness was also often high in the early morning due to thawing of leaf surface water frozen during a cold night. In general, leaf wetness was well correlated with relative humidity (RH) in condensation process, while it rather depended on wind speed in evaporation process. The comparisons in RH-wetness relations between leaf characteristics showed that broad-leaved grasses tended to be wetter than thin grasses.

  6. Biomass Accretion and Yield of Erect Leafed and Conventional Sorghum at Low and High Population Densities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two sorghum isolines, a wild type (BTx 623) and an erect leaf mutant line (ERL 20) isolated from the wild type were field grown in rectilinear arrays at low (25 plants m-2) and high (12 plants/m-2) densities with sub-surface drip irrigation in an effort to eliminate confounding drought effects. Cano...

  7. Estimating leaf area index from Landsat using MODIS LAI products and field measurements as reference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf area index (LAI) is a key biophysical parameter used in most land surface models. Operationally, LAI products currently used typically come from coarse resolution sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS). While coarse resolution data at the kilometer scale are o...

  8. Factors affecting survival of bacteriophage on tomato leaf surfaces.

    PubMed

    Iriarte, F B; Balogh, B; Momol, M T; Smith, L M; Wilson, M; Jones, J B

    2007-03-01

    The ability of bacteriophage to persist in the phyllosphere for extended periods is limited by many factors, including sunlight irradiation, especially in the UV zone, temperature, desiccation, and exposure to copper bactericides. The effects of these factors on persistence of phage and formulated phage (phage mixed with skim milk) were evaluated. In field studies, copper caused significant phage reduction if applied on the day of phage application but not if applied 4 or 7 days in advance. Sunlight UV was evaluated for detrimental effects on phage survival on tomato foliage in the field. Phage was applied in the early morning, midmorning, early afternoon, and late evening, while UVA plus UVB irradiation and phage populations were monitored. The intensity of UV irradiation positively correlated with phage population decline. The protective formulation reduced the UV effect. In order to demonstrate direct effects of UV, phage suspensions were exposed to UV irradiation and assayed for effectiveness against bacterial spot of tomato. UV significantly reduced phage ability to control bacterial spot. Ambient temperature had a pronounced effect on nonformulated phage but not on formulated phages. The effects of desiccation and fluorescent light illumination on phage were investigated. Desiccation caused a significant but only slight reduction in phage populations after 60 days, whereas fluorescent light eliminated phages within 2 weeks. The protective formulation eliminated the reduction caused by both of these factors. Phage persistence was dramatically affected by UV, while the other factors had less pronounced effects. Formulated phage reduced deleterious effects of the studied environmental factors. PMID:17259361

  9. [Influence of photosynthetic parameters on leaf longevity].

    PubMed

    Vasfilov, S P

    2015-01-01

    Higher plants show a wide range of leaf lifespan (LL) variability. LL is calculated as a sum of functional LL(f) (corresponding to the time of active photosynthesis and CO2 accumulation in the leaf) and nonfunctional LL(n) (the time of photosynthetic activity absence). For evergreen species of boreal zones, LL(n) corresponds to the period of winter rest. Photosynthetic potential of leaf (PPL), interpreted as the maximum possible amount of CO2 that can be fixed during its life, can be estimated on the basis of maximum photosynthesis rate (P(a)) dynamics during LL(f); the maximum (P(a max)) being achieved in mature leaf. Photosynthetic potential depends on LL(f) more strongly than on P(a max). The PPL/LL(f) ratio is indicative of the rate of PPL realization over leaf lifespan. As LL(f) shows strong positive correlation with LL, the latter parameter can also characterize the rate of PPL realization. Long LL(f) in evergreen species provides higher PPL, which is advantageous by comparison with deciduous ones. In evergreen species, the PPL itself is realized slower than in deciduous ones. The increase in LL(f) and LL is accompanied by the increase in leaf constructional cost (LCC(a)) as well as the decrease in photosynthesis rate. At that, photosynthesis rate per unit of dry weight (P(m)) decreases much faster than that per unit of leaf area (P(a)). Apparently, when considering dry leaf weight, the apoplast share seems to be much higher in long-living leaves of evergreen species than in short-living leaves of deciduous species. The leaf payback (LP) may be stabilized by unidirectional shifts in PPL and LCC(a). Species with short/long LL(f) and high/low PPL realization rate are typical for early/late succession stages and for habitats with the environmental conditions favorable/adverse for photosynthesis and growth. If the conditions for photosynthesis and growth are favorable, high PPL realization rate provides advantage in competition. The PPL realization rate is

  10. Final report on the safety assessment of AloeAndongensis Extract, Aloe Andongensis Leaf Juice,aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice,aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract.

    PubMed

    2007-01-01

    Plant materials derived from the Aloe plant are used as cosmetic ingredients, including Aloe Andongensis Extract, Aloe Andongensis Leaf Juice, Aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice, Aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract. These ingredients function primarily as skin-conditioning agents and are included in cosmetics only at low concentrations. The Aloe leaf consists of the pericyclic cells, found just below the plant's skin, and the inner central area of the leaf, i.e., the gel, which is used for cosmetic products. The pericyclic cells produce a bitter, yellow latex containing a number of anthraquinones, phototoxic compounds that are also gastrointestinal irritants responsible for cathartic effects. The gel contains polysaccharides, which can be acetylated, partially acetylated, or not acetylated. An industry established limit for anthraquinones in aloe-derived material for nonmedicinal use is 50 ppm or lower. Aloe-derived ingredients are used in a wide variety of cosmetic product types at concentrations of raw material that are 0.1% or less, although can be as high as 20%. The concentration of Aloe in the raw material also may vary from 100% to a low of 0.0005%. Oral administration of various anthraquinone components results in a rise in their blood concentrations, wide systemic distribution, accumulation in the liver and kidneys, and excretion in urine and feces; polysaccharide components are distributed systemically and metabolized into smaller molecules. aloe-derived material has fungicidal, antimicrobial, and antiviral activities, and has been effective in wound healing and infection treatment in animals. Aloe barbadensis (also known as Aloe vera)-derived ingredients were not toxic

  11. Seasonality and phenology alter functional leaf traits.

    PubMed

    McKown, Athena D; Guy, Robert D; Azam, M Shofiul; Drewes, Eric C; Quamme, Linda K

    2013-07-01

    In plant ecophysiology, functional leaf traits are generally not assessed in relation to phenological phase of the canopy. Leaf traits measured in deciduous perennial species are known to vary between spring and summer seasons, but there is a knowledge gap relating to the late-summer phase marked by growth cessation and bud set occurring well before fall leaf senescence. The effects of phenology on canopy physiology were tested using a common garden of over 2,000 black cottonwood (Populus trichocarpa) individuals originating from a wide geographical range (44-60ºN). Annual phenological events and 12 leaf-based functional trait measurements were collected spanning the entire summer season prior to, and following, bud set. Patterns of seasonal trait change emerged by synchronizing trees using their date of bud set. In particular, photosynthetic, mass, and N-based traits increased substantially following bud set. Most traits were significantly different between pre-bud set and post-bud set phase trees, with many traits showing at least 25% alteration in mean value. Post-bud set, both the significance and direction of trait-trait relationships could be modified, with many relating directly to changes in leaf mass. In Populus, these dynamics in leaf traits throughout the summer season reflected a shift in whole plant physiology, but occurred long before the onset of leaf senescence. The marked shifts in measured trait values following bud set underscores the necessity to include phenology in trait-based ecological studies or large-scale phenotyping efforts, both at the local level and larger geographical scale.

  12. Leaf endophyte load and fungal garden development in leaf-cutting ants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous work has shown that leaf-cutting ants prefer to cut leaf material that is relatively low in fungal endophyte content. Such a preference suggests that fungal endophytes exact a cost on the ants or on the development of their colonies. We hypothesized that endophytes may play a role in thei...

  13. Reaction of sorghum lines to zonate leaf spot and rough leaf spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abundant, frequent rains, along with humid and cloudy conditions during the early part of the 2015 growing season, provided conducive conditions for an unusually severe outbreak of zonate leaf spot and rough leaf spot in a block of sorghum lines at the Texas A&M AgriLife Research Farm, Burleson Coun...

  14. Estimating global specific leaf area from MODIS leaf area index and model-simulated foliage mass

    NASA Astrophysics Data System (ADS)

    Baruah, P. J.; Yasuoka, Y.; Ito, A.; Dye, D.

    2006-12-01

    Specific leaf area (SLA) is an important leaf trait that is universally correlated positively to leaf nitrogen, leaf turnover rates, relative growth rate and most importantly, photosynthetic capacity. Though SLA is genetically encoded, it is often spatially variable within a species and within a single biome due to variable environmental conditions. However, without a global SLA map, global ecosystem models that use SLA, generally fix a single value for a particular biome. In this study, we develop a methodology to estimate global SLA from a remote sensing-derived key ecosystem variable, leaf area index and foliage mass estimated by a terrestrial ecosystem model SimCYCLE. SimCYCLE uses climatic inputs, land-cover data and biomass-allocation to estimate leaf biomass in a process-based scheme. Model-estimated foliage mass and MODIS leaf area index are assumed to represent the most-accurate ground condition to estimate SLA for the entire globe at 0.5 degree resolution. Validation of estimated specific leaf area is done with a published field-sampled global dataset, and additional field-sampled SLA data collected from published literatures. The validation data is also used for rectification of unrealistic values of estimated SLA to produce a global SLA map, which we strongly believe, would be valuable to improve estimates of carbon dynamic across individual biomes upon assimilation with the ecosystem models.

  15. Differences between water permeability of astomatous and stomatous cuticular membranes: effects of air humidity in two species of contrasting drought-resistance strategy

    PubMed Central

    Karbulková, Jana; Schreiber, Lukas; Macek, Petr; Šantrůček, Jiří

    2008-01-01

    Cuticular water permeabilities of adaxial and abaxial leaf surfaces and their dependence on relative air humidity (RH) applied in long-term and short-term regimes have been analysed for Hedera helix, native in a temperate climate, and Zamioculcas zamiifolia, native in subtropical regions. The water permeability of cuticular membranes (CM) isolated from the adaxial (astomatous) and abaxial (stomatous) leaf sides was measured using a method which allowed the separation of water diffusion through the remnants of the original stomatal pores from water diffusion through the solid cuticle. The long-term effects of low (20–40%) or high (60–80%) RH applied during plant growth and leaf ontogeny (‘growth RH’) and the short-term effects of applying 2% or 100% RH while measuring permeability (‘measurement RH’) were investigated. With both species, water permeability of the solid stomatous CM was significantly higher than the permeability of the astomatous CM. Adaxial cuticles of plants grown in humid air were more permeable to water than those from dry air. The adaxial CM of the drought-tolerant H. helix was more permeable and more sensitive to growth RH than the adaxial CM of Z. zamiifolia, a species avoiding water stress. However, permeability of the solid abaxial CM was similar in both species and independent of growth RH. The lack of a humidity response in the abaxial CM is attributed to a higher degree of cuticular hydration resulting from stomatal transpiration. The ecophysiological significance of higher permeability of the solid stomatous CM compared to the astomatous CM is discussed. PMID:18836141

  16. Leaf size and leaf display of thirty-eight tropical tree species.

    PubMed

    Poorter, Lourens; Rozendaal, Danaë M A

    2008-11-01

    Trees forage for light through optimal leaf display. Effective leaf display is determined by metamer traits (i.e., the internode, petiole, and corresponding leaf), and thus these traits strongly co-determine carbon gain and as a result competitive advantage in a light-limited environment. We examined 11 metamer traits of sun and shade trees of 38 coexisting moist forest tree species and determined the relative strengths of intra- and interspecific variation. Species-specific metamer traits were related to two variables that represent important life history variation; the regeneration light requirements and average leaf size of the species. Metamer traits varied strongly across species and, in contrast to our expectation, showed only modest changes in response to light. Intra- and interspecific responses to light were only congruent for a third of the traits evaluated. Four traits, amongst which leaf size, specific leaf area (SLA), and leaf area ratio at the metamer level (LAR) showed even opposite intra- and interspecific responses to light. Strikingly, these are classic traits that are thought to be of paramount importance for plant performance but that have completely different consequences within and across species. Sun trees of a given species had small leaves to reduce the heat load, but light-demanding species had large leaves compared to shade-tolerants, probably to outcompete their neighbors. Shade trees of a given species had a high SLA and LAR to capture more light in a light-limited environment, whereas shade-tolerant species have well-protected leaves with a low SLA compared to light-demanding species, probably to deter herbivores and enhance leaf lifespan. There was a leaf-size-mediated trade-off between biomechanical and hydraulic safety, and the efficiency with which species can space their leaves and forage for light. Unexpectedly, metamer traits were more closely linked to leaf size than to regeneration light requirements, probably because leaf

  17. Influence of environmental pollution on leaf properties of urban plane trees, Platanus orientalis L.

    PubMed

    Pourkhabbaz, Alireza; Rastin, Nayerah; Olbrich, Andrea; Langenfeld-Heyser, Rosemarie; Polle, Andrea

    2010-09-01

    To investigate whether leaves of plane trees (Platanus orientalis) are damaged by traffic pollution, trees from a megacity (Mashhad, Iran) and a rural area were investigated. Soil and air from the urban centre showed enrichment of several toxic elements, but only lead was enriched in leaves. Leaf size and stomata density were lower at the urban site. At the urban site leaf surfaces were heavily loaded by dust particles but the stomata were not occluded; the cuticle was thinner; other anatomical properties were unaffected suggesting that plane trees can cope with traffic exhaust in megacities.

  18. Influence of Environmental Pollution on Leaf Properties of Urban Plane Trees, Platanus orientalis L.

    PubMed Central

    Pourkhabbaz, Alireza; Rastin, Nayerah; Olbrich, Andrea; Langenfeld-Heyser, Rosemarie

    2010-01-01

    To investigate whether leaves of plane trees (Platanus orientalis) are damaged by traffic pollution, trees from a megacity (Mashhad, Iran) and a rural area were investigated. Soil and air from the urban centre showed enrichment of several toxic elements, but only lead was enriched in leaves. Leaf size and stomata density were lower at the urban site. At the urban site leaf surfaces were heavily loaded by dust particles but the stomata were not occluded; the cuticle was thinner; other anatomical properties were unaffected suggesting that plane trees can cope with traffic exhaust in megacities. PMID:20577871

  19. How do leaf veins influence the worldwide leaf economic spectrum? Review and synthesis.

    PubMed

    Sack, Lawren; Scoffoni, Christine; John, Grace P; Poorter, Hendrik; Mason, Chase M; Mendez-Alonzo, Rodrigo; Donovan, Lisa A

    2013-10-01

    Leaf vein traits are implicated in the determination of gas exchange rates and plant performance. These traits are increasingly considered as causal factors affecting the 'leaf economic spectrum' (LES), which includes the light-saturated rate of photosynthesis, dark respiration, foliar nitrogen concentration, leaf dry mass per area (LMA) and leaf longevity. This article reviews the support for two contrasting hypotheses regarding a key vein trait, vein length per unit leaf area (VLA). Recently, Blonder et al. (2011, 2013) proposed that vein traits, including VLA, can be described as the 'origin' of the LES by structurally determining LMA and leaf thickness, and thereby vein traits would predict LES traits according to specific equations. Careful re-examination of leaf anatomy, published datasets, and a newly compiled global database for diverse species did not support the 'vein origin' hypothesis, and moreover showed that the apparent power of those equations to predict LES traits arose from circularity. This review provides a 'flux trait network' hypothesis for the effects of vein traits on the LES and on plant performance, based on a synthesis of the previous literature. According to this hypothesis, VLA, while virtually independent of LMA, strongly influences hydraulic conductance, and thus stomatal conductance and photosynthetic rate. We also review (i) the specific physiological roles of VLA; (ii) the role of leaf major veins in influencing LES traits; and (iii) the role of VLA in determining photosynthetic rate per leaf dry mass and plant relative growth rate. A clear understanding of leaf vein traits provides a new perspective on plant function independently of the LES and can enhance the ability to explain and predict whole plant performance under dynamic conditions, with applications towards breeding improved crop varieties.

  20. The INDETERMINATE DOMAIN Protein BROAD LEAF1 Limits Barley Leaf Width by Restricting Lateral Proliferation.

    PubMed

    Jöst, Moritz; Hensel, Götz; Kappel, Christian; Druka, Arnis; Sicard, Adrien; Hohmann, Uwe; Beier, Sebastian; Himmelbach, Axel; Waugh, Robbie; Kumlehn, Jochen; Stein, Nils; Lenhard, Michael

    2016-04-01

    Variation in the size, shape, and positioning of leaves as the major photosynthetic organs strongly impacts crop yield, and optimizing these aspects is a central aim of cereal breeding [1, 2]. Leaf growth in grasses is driven by cell proliferation and cell expansion in a basal growth zone [3]. Although several factors influencing final leaf size and shape have been identified from rice and maize [4-14], what limits grass leaf growth in the longitudinal or transverse directions during leaf development remains poorly understood. To identify factors involved in this process, we characterized the barley mutant broad leaf1 (blf1). Mutants form wider but slightly shorter leaves due to changes in the numbers of longitudinal cell files and of cells along the leaf length. These differences arise during primordia outgrowth because of more cell divisions in the width direction increasing the number of cell files. Positional cloning, analysis of independent alleles, and transgenic complementation confirm that BLF1 encodes a presumed transcriptional regulator of the INDETERMINATE DOMAIN family. In contrast to loss-of-function mutants, moderate overexpression of BLF1 decreases leaf width below wild-type levels. A functional BLF1-vYFP fusion protein expressed from the endogenous promoter shows a dynamic expression pattern in the shoot apical meristem and young leaf primordia. Thus, we propose that the BLF1 gene regulates barley leaf size by restricting cell proliferation in the leaf-width direction. Given the agronomic importance of canopy traits in cereals, identifying functionally different BLF1 alleles promises to allow for the generation of optimized cereal ideotypes. PMID:26996502

  1. Measurement of leaf relative water content by infrared reflectance

    NASA Technical Reports Server (NTRS)

    Hunt, E. Raymond, Jr.; Rock, Barrett N.; Nobel, Park S.

    1987-01-01

    From basic considerations and Beer's law, a leaf water content index incorporating reflectances of wavelengths from 0.76 to 0.90 microns and from 1.55 to 1.75 microns was developed that relates leaf reflectance to leaf relative water content. For the leaf succulent, Agave deserti, the leaf water content index was not significantly different from the relative water content for either individual leaves or an entire plant. Also, the relative water contents of intact plants of Encelia farinosa and Hilaria rigida in the field were estimated by the leaf water content index; variations in the proportion of living to dead leaf area could cause large errors in the estimate of relative water content. Thus, the leaf water content index may be able to estimate average relative water content of canopies when TM4 and TM5 are measured at a known relative water content and fraction of dead leaf material.

  2. Computer vision cracks the leaf code

    PubMed Central

    Wilf, Peter; Zhang, Shengping; Chikkerur, Sharat; Little, Stefan A.; Wing, Scott L.; Serre, Thomas

    2016-01-01

    Understanding the extremely variable, complex shape and venation characters of angiosperm leaves is one of the most challenging problems in botany. Machine learning offers opportunities to analyze large numbers of specimens, to discover novel leaf features of angiosperm clades that may have phylogenetic significance, and to use those characters to classify unknowns. Previous computer vision approaches have primarily focused on leaf identification at the species level. It remains an open question whether learning and classification are possible among major evolutionary groups such as families and orders, which usually contain hundreds to thousands of species each and exhibit many times the foliar variation of individual species. Here, we tested whether a computer vision algorithm could use a database of 7,597 leaf images from 2,001 genera to learn features of botanical families and orders, then classify novel images. The images are of cleared leaves, specimens that are chemically bleached, then stained to reveal venation. Machine learning was used to learn a codebook of visual elements representing leaf shape and venation patterns. The resulting automated system learned to classify images into families and orders with a success rate many times greater than chance. Of direct botanical interest, the responses of diagnostic features can be visualized on leaf images as heat maps, which are likely to prompt recognition and evolutionary interpretation of a wealth of novel morphological characters. With assistance from computer vision, leaves are poised to make numerous new contributions to systematic and paleobotanical studies. PMID:26951664

  3. Computer vision cracks the leaf code.

    PubMed

    Wilf, Peter; Zhang, Shengping; Chikkerur, Sharat; Little, Stefan A; Wing, Scott L; Serre, Thomas

    2016-03-22

    Understanding the extremely variable, complex shape and venation characters of angiosperm leaves is one of the most challenging problems in botany. Machine learning offers opportunities to analyze large numbers of specimens, to discover novel leaf features of angiosperm clades that may have phylogenetic significance, and to use those characters to classify unknowns. Previous computer vision approaches have primarily focused on leaf identification at the species level. It remains an open question whether learning and classification are possible among major evolutionary groups such as families and orders, which usually contain hundreds to thousands of species each and exhibit many times the foliar variation of individual species. Here, we tested whether a computer vision algorithm could use a database of 7,597 leaf images from 2,001 genera to learn features of botanical families and orders, then classify novel images. The images are of cleared leaves, specimens that are chemically bleached, then stained to reveal venation. Machine learning was used to learn a codebook of visual elements representing leaf shape and venation patterns. The resulting automated system learned to classify images into families and orders with a success rate many times greater than chance. Of direct botanical interest, the responses of diagnostic features can be visualized on leaf images as heat maps, which are likely to prompt recognition and evolutionary interpretation of a wealth of novel morphological characters. With assistance from computer vision, leaves are poised to make numerous new contributions to systematic and paleobotanical studies. PMID:26951664

  4. BOREAS TE-9 NSA Leaf Chlorophyll Density

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Sy, Mikailou

    2000-01-01

    The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. These data were collected to help provide an explanation of potential seasonal and spatial changes of leaf pigment properties in boreal forest species at the NSA. At different dates (FFC-Winter, FFC-Thaw, IFC-1, IFC-2, and IMC-3), foliage samples were collected from the upper third of the canopy for five NSA sites (YJP, OJP, OBS, UBS, and OA) near Thompson, Manitoba. Subsamples of 100 needles for black spruce, 20 needles for jack pine, and single leaf for trembling aspen were cut into pieces and immersed in a 20-mL DMF aliquot in a Nalgene test tube. The extracted foliage materials were then oven-dried at 68 C for 48 hours and weighed. Extracted leaf dry weight was converted to a total leaf area basis to express the chlorophyll content in mg/sq cm of total leaf area. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  5. Computer vision cracks the leaf code.

    PubMed

    Wilf, Peter; Zhang, Shengping; Chikkerur, Sharat; Little, Stefan A; Wing, Scott L; Serre, Thomas

    2016-03-22

    Understanding the extremely variable, complex shape and venation characters of angiosperm leaves is one of the most challenging problems in botany. Machine learning offers opportunities to analyze large numbers of specimens, to discover novel leaf features of angiosperm clades that may have phylogenetic significance, and to use those characters to classify unknowns. Previous computer vision approaches have primarily focused on leaf identification at the species level. It remains an open question whether learning and classification are possible among major evolutionary groups such as families and orders, which usually contain hundreds to thousands of species each and exhibit many times the foliar variation of individual species. Here, we tested whether a computer vision algorithm could use a database of 7,597 leaf images from 2,001 genera to learn features of botanical families and orders, then classify novel images. The images are of cleared leaves, specimens that are chemically bleached, then stained to reveal venation. Machine learning was used to learn a codebook of visual elements representing leaf shape and venation patterns. The resulting automated system learned to classify images into families and orders with a success rate many times greater than chance. Of direct botanical interest, the responses of diagnostic features can be visualized on leaf images as heat maps, which are likely to prompt recognition and evolutionary interpretation of a wealth of novel morphological characters. With assistance from computer vision, leaves are poised to make numerous new contributions to systematic and paleobotanical studies.

  6. Leaf seal for inner and outer casings of a turbine

    DOEpatents

    Schroder, Mark Stewart; Leach, David

    2002-01-01

    A plurality of arcuate, circumferentially extending leaf seal segments form an annular seal spanning between annular sealing surfaces of inner and outer casings of a turbine. The ends of the adjoining seal segments have circumferential gaps to enable circumferential expansion and contraction of the segments. The end of a first segment includes a tab projecting into a recess of a second end of a second segment. Edges of the tab seal against the sealing surfaces of the inner and outer casings have a narrow clearance with opposed edges of the recess. An overlying cover plate spans the joint. Leakage flow is maintained at a minimum because of the reduced gap between the radially spaced edges of the tab and recess, while the seal segments retain the capacity to expand and contract circumferentially.

  7. Acylsucrose-Producing Tomato Plants Forces Bemisia tabaci to Shift Its Preferred Settling and Feeding Site

    PubMed Central

    Rodríguez-López, Maria Jose; Garzo, Elisa; Bonani, Jean Patrick; Fernández-Muñoz, Rafael; Moriones, Enrique; Fereres, Alberto

    2012-01-01

    Background The whitefly Bemisia tabaci (Genn.) causes dramatic damage to plants by transmitting yield-limiting virus diseases. Previous studies proved that the tomato breeding line ABL 14-8 was resistant to B. tabaci, the vector of tomato yellow leaf curl disease (TYLCD). This resistance is based on the presence of type IV glandular trichomes and acylsucrose production. These trichomes deter settling and probing of B. tabaci in ABL 14-8, which reduces primary and secondary spread of TYLCD. Methodology/Principal Findings Whitefly settlement preference was evaluated on the adaxial and abaxial leaf surfaces of nearly-isogenic tomato lines with and without B. tabaci-resistance traits, ‘ABL 14-8 and Moneymaker’ respectively, under non-choice and free-choice conditions. In addition, the Electrical Penetration Graph technique was used to study probing and feeding activities of B. tabaci on the adaxial and abaxial leaf surfaces of the same genotypes. B. tabaci preferred to settle on the abaxial than on the adaxial surface of ‘Moneymaker’ leaves, whereas no such preference was observed on ABL 14-8 tomato plants at the ten-leaf growth stage. Furthermore, B. tabaci preferred to feed on the abaxial than on the adaxial leaf surface of ‘Moneymarker’ susceptible tomato plants as shown by a higher number of sustained phloem feeding ingestion events and a shorter time to reach the phloem. However, B. tabaci standard probing and feeding behavior patterns were altered in ABL 14-8 plants and whiteflies were unable to feed from the phloem and spent more time in non-probing activities when exposed to the abaxial leaf surface. Conclusions/Significance The distorted behavior of B. tabaci on ABL 14-8 protects tomato plants from the transmission of phloem-restricted viruses such as Tomato yellow leaf curl virus (TYLCV), and forces whiteflies to feed on the adaxial side of leaves where they feed less efficiently and become more vulnerable to natural enemies. PMID:22427950

  8. Leaf epidermal characters of Solanum sect. polytrichum (Solanaceae) as taxonomic evidence.

    PubMed

    Nurit-Silva, Kiriaki; De Fátima Agra, Maria

    2011-12-01

    The morphological similarities among the species of Solanum are remarkable, and are often very difficult one clear distinction between them. This paper presents a comparative anatomical study of the leaf epidermis of five Brazilian species of Solanum sect. Polytrichum, carried out using light and scanning electron microscopy. The leaf epidermis surfaces were investigated to evaluate their taxonomic significance to be used for separation and delimitation of the species of the section. As results, some micro-morphological characters of the leaf epidermis, such as density, distribution and type of stellate trichomes, and the anticlinal walls of epidermal cells, and also the type and distribution of stomata proved to be the most useful and distinctive characters for the separation and delimitation of the species, and also may contribute as an additional support to the interspecific taxonomy and systematic of Solanum sect. Polytrichum.

  9. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Bindhu, M. R.; Umadevi, M.

    2013-01-01

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

  10. Stomatal Density Influences Leaf Water and Leaf Wax D/H Values in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Lee, H.; Feakins, S. J.; Sternberg, L. O.

    2014-12-01

    The hydrogen isotopic composition (δD) of plant leaf wax is a powerful tool to study the hydrology of past and present environments. The δD value of leaf waxes is known to primarily reflect the δD value of source water, modified by biological fractionations commonly summarized as the 'net or apparent' fractionation. It remains a challenge, however, to quantitatively relate the isotopic composition of the end product (wax) back to that of the precursor (water) because multiple isotope effects contributing to the net fractionation are not yet well understood. Transgenic variants have heretofore unexplored potential to isolate individual isotope effects. Here we report the first hydrogen isotopic measurements from transgenic Arabidopsis thaliana plants with calculations of leaf water enrichment, net and biosynthetic fractionation values from measured δD of plant waters and leaf wax n-alkanes. We employed transgenic Arabidopsis leaves, engineered to have different stomatal density, by differential expression of the stomatal growth hormone stomagen. Comparison of variants and wild types allow us to isolate the effects of stomatal density on leaf water and the net fractionation expressed by leaf wax biomarkers. Results show that transgenic leaves with denser pores have more enriched leaf water and leaf wax δD values than wild type and even more so than transgenic leaves with sparse stomata (difference of 10 ‰). Our findings that stomatal density controls leaf water and leaf wax δD values adds insights into the cause of variations in net fractionations between species, as well as suggesting that geological variations in stomatal density may modulate the sedimentary leaf wax δD record. In nature, stomatal density varies between species and environments, and all other factors being equal, this will contribute to variations in fractionations observed. Over geological history, lower stomatal densities occur at times of elevated pCO2; our findings predict reduced leaf

  11. Spring leaf phenology and the diurnal temperature range in a temperate maple forest.

    PubMed

    Hanes, Jonathan M

    2014-03-01

    Spring leaf phenology in temperate climates is intricately related to numerous aspects of the lower atmosphere [e.g., surface energy balance, carbon flux, humidity, the diurnal temperature range (DTR)]. To further develop and improve the accuracy of ecosystem and climate models, additional investigations of the specific nature of the relationships between spring leaf phenology and various ecosystem and climate processes are required in different environments. This study used visual observations of maple leaf phenology, below-canopy light intensities, and micrometeorological data collected during the spring seasons of 2008, 2009, and 2010 to examine the potential influence of leaf phenology on a seasonal transition in the trend of the DTR. The timing of a reversal in the DTR trend occurred near the time when the leaves were unfolding and expanding. The results suggest that the spring decline in the DTR can be attributed primarily to the effect of canopy closure on daily maximum temperature. These findings improve our understanding of the relationship between leaf phenology and the diurnal temperature range in temperate maple forests during the spring. They also demonstrate the necessity of incorporating accurate phenological data into ecosystem and climate models and warrant a careful examination of the extent to which canopy phenology is currently incorporated into existing models.

  12. Modeling light and temperature effects on leaf emergence in wheat and barley

    NASA Technical Reports Server (NTRS)

    Volk, T.; Bugbee, B.

    1991-01-01

    Phenological development affects canopy structure, radiation interception, and dry matter production; most crop simulation models therefore incorporate leaf emergence rate as a basic parameter. A recent study examined leaf emergence rate as a function of temperature and daylength among wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivars. Leaf emergence rate and phyllochron were modeled as functions of temperature alone, daylength alone, and the interaction between temperature and daylength. The resulting equations contained an unwieldy number of constants. Here we simplify by reducing the constants by > 70%, and show leaf emergence rate as a single response surface with temperature and daylength. In addition, we incorporate the effect of photosynthetic photon flux into the model. Generic fits for wheat and barley show cultivar differences less than +/- 5% for wheat and less than +/- 10% for barley. Barley is more sensitive to daylength changes than wheat for common environmental values of daylength, which may be related to the difference in sensitivity to daylength between spring and winter cultivars. Differences in leaf emergence rate between cultivars can be incorporated into the model by means of a single, nondimensional factor for each cultivar.

  13. Modeling light and temperature effects on leaf emergence in wheat and barley.

    PubMed

    Volk, T; Bugbee, B

    1991-01-01

    Phenological development affects canopy structure, radiation interception, and dry matter production; most crop simulation models therefore incorporate leaf emergence rate as a basic parameter. A recent study examined leaf emergence rate as a function of temperature and daylength among wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivars. Leaf emergence rate and phyllochron were modeled as functions of temperature alone, daylength alone, and the interaction between temperature and daylength. The resulting equations contained an unwieldy number of constants. Here we simplify by reducing the constants by > 70%, and show leaf emergence rate as a single response surface with temperature and daylength. In addition, we incorporate the effect of photosynthetic photon flux into the model. Generic fits for wheat and barley show cultivar differences less than +/- 5% for wheat and less than +/- 10% for barley. Barley is more sensitive to daylength changes than wheat for common environmental values of daylength, which may be related to the difference in sensitivity to daylength between spring and winter cultivars. Differences in leaf emergence rate between cultivars can be incorporated into the model by means of a single, nondimensional factor for each cultivar. PMID:11537630

  14. Leaf and stem morphoanatomy of Petiveria alliacea.

    PubMed

    Duarte, M R; Lopes, J F

    2005-12-01

    Petiveria alliacea is a perennial herb native to the Amazonian region and used in traditional medicine for different purposes, such as diuretic, antispasmodic and anti-inflammatory. The morphoanatomical characterization of the leaf and stem was carried out, in order to contribute to the medicinal plant identification. The plant material was fixed, freehand sectioned and stained either with toluidine blue or astra blue and basic fuchsine. Microchemical tests were also applied. The leaf is simple, alternate and elliptic. The blade exhibits paracytic stomata on the abaxial side, non-glandular trichomes and dorsiventral mesophyll. The midrib is biconvex and the petiole is plain-convex, both traversed by collateral vascular bundles adjoined with sclerenchymatic caps. The stem, in incipient secondary growth, presents epidermis, angular collenchyma, starch sheath and collateral vascular organization. Several prisms of calcium oxalate are seen in the leaf and stem.

  15. The failure of the Penman-Monteith equation in explaining leaf transpiration

    NASA Astrophysics Data System (ADS)

    Schymanski, Stanislaus J.; Or, Dani

    2016-04-01

    The vast majority of current global land surface models, hydrological models and inverse approaches to deduce evaporation from remote sensing data employ an analytical solution for the latent heat flux from plant leaves derived by Monteith (1965), based on an earlier formulation for a wet surface by Penman (1948). This so-called Penman-Monteith (PM) equation was most commonly evaluated at the canopy scale, where aerodynamic and canopy resistance to water vapour are difficult to estimate, leading to various empirical corrections when scaling from leaf to canopy. Here we evaluated the PM equation directly at the leaf scale, using a controlled, insulated wind tunnel and artificial leaves with pre-defined stomatal conductance. Experimental results were consistent with a detailed leaf energy balance model, but we measured consistent deviations from PM-predicted fluxes, which pointed to fundamental problems with the PM equation. Detailed analysis of the derivation by Monteith (1965) and later amendments revealed inconsistencies concerning the effect of stomata and the two-sided exchange of sensible heat. A corrected set of analytical solutions for leaf temperature as well as latent and sensible heat flux is presented and comparison with the original PM equation indicates a major improvement in reproducing experimental results at the leaf scale. The inconsistencies in the original PM equation and its failure to reproduce experimental results at the leaf scale (for which it was originally derived) lets us conclude that the PM equation does not constitute an accurate representation of atmospheric forcing on transpiration and should be regarded as a semi-empirical equation.

  16. Autumn coloring, photosynthetic performance and leaf development of deciduous broad-leaved trees in relation to forest succession.

    PubMed

    Koike, T.

    1990-12-01

    Autumn coloring of deciduous broad-leaved trees in northern Japan was found to develop either from the inner part of the crown outward (inner-type), or from the outer part of the crown inward (outer-type). Inner-type trees had early-successional characteristics, whereas outer-type trees had late-successional characteristics. Although alders (Alnus hirsuta (Spach) Rupr. and A. japonica (Thunb.) Steud.) did not change color in the fall, these early-successional species were also studied. Both chlorophyll content and chlorophyll a/b ratio increased then decreased with increasing leaf age. In early fall, however, chlorophyll content of leaves on the same branch decreased from older to younger leaves only in the inner-type species. Net photosynthetic rates at light saturation of individual leaves increased then decreased at a greater rate in inner-type species than in outer-type species. Leaf dry weight per unit area decreased more before leaf fall in outer-type species than in inner-type species. Inner-type species have younger leaves at the outer surface of crowns, whereas in outer-type species, leaf age is similar throughout the crown. Leaf senescence of outer-type species began in the outer surface of crowns. The pattern of leaf senescence and the development of fall colorations may be related to the growth strategy of the species.

  17. 3D leaf water content mapping using terrestrial laser scanner backscatter intensity with radiometric correction

    NASA Astrophysics Data System (ADS)

    Zhu, Xi; Wang, Tiejun; Darvishzadeh, Roshanak; Skidmore, Andrew K.; Niemann, K. Olaf

    2015-12-01

    Leaf water content (LWC) plays an important role in agriculture and forestry management. It can be used to assess drought conditions and wildfire susceptibility. Terrestrial laser scanner (TLS) data have been widely used in forested environments for retrieving geometrically-based biophysical parameters. Recent studies have also shown the potential of using radiometric information (backscatter intensity) for estimating LWC. However, the usefulness of backscatter intensity data has been limited by leaf surface characteristics, and incidence angle effects. To explore the idea of using LiDAR intensity data to assess LWC we normalized (for both angular effects and leaf surface properties) shortwave infrared TLS data (1550 nm). A reflectance model describing both diffuse and specular reflectance was applied to remove strong specular backscatter intensity at a perpendicular angle. Leaves with different surface properties were collected from eight broadleaf plant species for modeling the relationship between LWC and backscatter intensity. Reference reflectors (Spectralon from Labsphere, Inc.) were used to build a look-up table to compensate for incidence angle effects. Results showed that before removing the specular influences, there was no significant correlation (R2 = 0.01, P > 0.05) between the backscatter intensity at a perpendicular angle and LWC. After the removal of the specular influences, a significant correlation emerged (R2 = 0.74, P < 0.05). The agreement between measured and TLS-derived LWC demonstrated a significant reduction of RMSE (root mean square error, from 0.008 to 0.003 g/cm2) after correcting for the incidence angle effect. We show that it is possible to use TLS to estimate LWC for selected broadleaved plants with an R2 of 0.76 (significance level α = 0.05) at leaf level. Further investigations of leaf surface and internal structure will likely result in improvements of 3D LWC mapping for studying physiology and ecology in vegetation.

  18. Effect of NaCl on leaf salt secretion and antioxidative enzyme level in roots of a mangrove, Aegiceras corniculatum.

    PubMed

    Mishra, Sujatarani; Das, A B

    2003-02-01

    Short-term salt (NaCl) treatment on Aegiceras corniculatum in roots and leaves showed no change in fresh and dry weight of leaves, roots and leaf area. There was no significant change in total soluble root protein, photosynthetic pigments of leaves and spectral characteristics of thylakoids. However, the activity of antioxidative enzymes (catalase, ascorbate peroxidase and guaiacol peroxidase) in roots decreased by 72, 58 and 80% respectively after 96 hr of treatment (300 mM of NaCl). Secretion of salts from the leaf salt glands and salt accumulation on upper surface of the leaves were quantified that revealed linear increase of salt secretion of leaf with increase in period of salt treatment. It was concluded that loss of activities of antioxidative enzymes at high salt treatment, caused leaf senescence in spite of high rates of salt secretion by Aegiceras corniculatum. PMID:15255609

  19. Improving and validating 3D models for the leaf energy balance in canopy-scale problems with complex geometry

    NASA Astrophysics Data System (ADS)

    Bailey, B.; Stoll, R., II; Miller, N. E.; Pardyjak, E.; Mahaffee, W.

    2014-12-01

    Plants cover the majority of Earth's land surface, and thus play a critical role in the surface energy balance. Within individual plant communities, the leaf energy balance is a fundamental component of most biophysical processes. Absorbed radiation drives the energy balance and provides the means by which plants produce food. Available energy is partitioned into sensible and latent heat fluxes to determine surface temperature, which strongly influences rates of metabolic activity and growth. The energy balance of an individual leaf is coupled with other leaves in the community through longwave radiation emission and advection through the air. This complex coupling can make scaling models from leaves to whole-canopies difficult, specifically in canopies with complex, heterogeneous geometries. We present a new three-dimensional canopy model that simultaneously resolves sub-tree to whole-canopy scales. The model provides spatially explicit predictions of net radiation exchange, boundary-layer and stomatal conductances, evapotranspiration rates, and ultimately leaf surface temperature. The radiation model includes complex physics such as anisotropic emission and scattering. Radiation calculations are accelerated by leveraging graphics processing unit (GPU) technology, which allows canopy-scale problems to be performed on a standard desktop workstation. Since validating the three-dimensional distribution of leaf temperature can be extremely challenging, we used several independent measurement techniques to quantify errors in measured and modeled values. When compared with measured leaf temperatures, the model gave a mean error of about 2°C, which was close to the estimated measurement uncertainty.

  20. Use of thermal imaging to determine leaf conductance along a canopy gradient in European beech (Fagus sylvatica).

    PubMed

    Reinert, Stefan; Bögelein, Rebekka; Thomas, Frank M

    2012-03-01

    Using an infrared camera, we measured the leaf temperature across different canopy positions of a 23-m-tall deciduous forest tree (Fagus sylvatica L.) including typical sun and shade leaves as well as intermediate leaf forms, which differed significantly in specific leaf area (SLA). We calculated a temperature index (I(G)) and a crop water stress index (CWSI) using the surface temperatures of wet and dry reference leaves. Additional indices were computed using air temperature plus 5 °C (I(G) + 5, CWSI + 5) as dry references. The minimum temperature of the wet leaf and the maximum temperature of the dry leaf proved to be most suitable as reference values. We correlated the temperature indices with leaf area-related conductance to water vapor (g(L)) using porometry at the leaf level and using xylem sap flow at the branch level. At the leaf and at the branch level, I(G) and CWSI were equally well suited as proxies of g(L), whereas the relationships of I(G) + 5 and CWSI + 5 with g(L) were only weak or even insignificant. At the leaf level, the correlations of I(G) and CWSI with g(L) were significant in all parts of the crown. The slopes of g(L) vs. I(G) and CWSI did not differ significantly among the crown parts; this indicates that they were not influenced by SLA or irradiance. At the branch level, close correlations (r > 0.8) were found between temperature indices and g(L) across the crown. These results demonstrate that satisfactory relationships between temperature indices and g(L) can be established in tall trees even in those canopy parts that are exposed to relatively low levels of irradiance and exhibit relatively low values of g(L). PMID:22427372