Stamen-derived bioactive gibberellin is essential for male flower development of Cucurbita maxima L.

PubMed Central

Pimenta Lange, Maria João; Knop, Nicole; Lange, Theo

2012-01-01

Gibberellin (GA) signalling during pumpkin male flower development is highly regulated, including biosynthetic, perception, and transduction pathways. GA 20-oxidases, 3-oxidases, and 2-oxidases catalyse the final part of GA synthesis. Additionally, 7-oxidase initiates this part of the pathway in some cucurbits including Cucurbita maxima L. (pumpkin). Expression patterns for these GA-oxidase-encoding genes were examined by competitive reverse transcription-PCR (RT-PCR) and endogenous GA levels were determined during pumpkin male flower development. In young flowers, GA20ox3 transcript levels are high in stamens, followed by high levels of the GA precursor GA9. Later, just before flower opening, transcript levels for GA3ox3 and GA3ox4 increase in the hypanthium and stamens, respectively. In the stamen, following GA3ox4 expression, bioactive GA4 levels rise dramatically. Accordingly, catabolic GA2ox2 and GA2ox3 transcript levels are low in developing flowers, and increase in mature flowers. Putative GA receptor GID1b and DELLA repressor GAIPb transcript levels do not change in developing flowers, but increase sharply in mature flowers. Emasculation arrests floral development completely and leads to abscission of premature flowers. Application of GA4 (but not of its precursors GA12-aldehyde or GA9) restores normal growth of emasculated flowers. These results indicate that de novo GA4 synthesis in the stamen is under control of GA20ox3 and GA3ox4 genes just before the rapid flower growth phase. Stamen-derived bioactive GA is essential and sufficient for male flower development, including the petal and the pedicel growth. PMID:22268154

A Novel Cytoplasmic Male Sterility in Brassica napus (inap CMS) with Carpelloid Stamens via Protoplast Fusion with Chinese Woad

PubMed Central

Kang, Lei; Li, Pengfei; Wang, Aifan; Ge, Xianhong; Li, Zaiyun

2017-01-01

A novel cytoplasmic male sterility (CMS) in Brassica napus (inap CMS) was selected from the somatic hybrid with Isatis indigotica (Chinese woad) by recurrent backcrossing. The male sterility was caused by the conversion of tetradynamous stamens into carpelloid structures with stigmatoid tissues at their tips and ovule-like tissues in the margins, and the two shorter stamens into filaments without anthers. The feminized development of the stamens resulted in the complete lack of pollen grains, which was stable in different years and environments. The pistils of inap CMS displayed normal morphology and good seed-set after pollinated by B. napus. Histological sections showed that the developmental alteration of the stamens initiated at the stage of stamen primordium differentiation. AFLP analysis of the nuclear genomic composition with 23 pairs of selective primers detected no woad DNA bands in inap CMS. Twenty out of 25 mitochondrial genes originated from I. indigotica, except for cox2-2 which was the recombinant between cox2 from woad and cox2-2 from rapeseed. The novel cox2-2 was transcribed in flower buds of inap CMS weakly and comparatively with the fertile B. napus addition line Me harboring one particular woad chromosome. The restorers of other autoplasmic and alloplasmic CMS systems in rapeseed failed to restore the fertility of inap CMS and the screening of B. napus wide resources found no fertility restoration variety, showing its distinct origin and the related mechanism of sterility. The reasons for the mitochondrial rearrangements and the breeding of the restorer for the novel CMS system were discussed. PMID:28428799

Radical scavenging activity and LC-MS metabolic profiling of petals, stamens, and flowers of Crocus sativus L.

PubMed

Montoro, Paola; Maldini, Mariateresa; Luciani, Leonilda; Tuberoso, Carlo I G; Congiu, Francesca; Pizza, Cosimo

2012-08-01

Radical scavenging activities of Crocus sativus petals, stamens and entire flowers, which are waste products in the production of the spice saffron, by employing ABTS radical scavenging method, were determined. At the same time, the metabolic profiles of different extract (obtained by petals, stamens and flowers) were obtained by LC-ESI-IT MS (liquid chromatography coupled with electrospray mass spectrometry equipped with Ion Trap analyser). LC-ESI-MS is a techniques largely used nowadays for qualitative fingerprint of herbal extracts and particularly for phenolic compounds. To compare the different extracts under an analytical point of view a specific method for qualitative LC-MS analysis was developed. The high variety of glycosylated flavonoids found in the metabolic profiles could give value to C. sativus petals, stamens and entire flowers. Waste products obtained during saffron production, could represent an interesting source of phenolic compounds, with respect to the high variety of compounds and their free radical scavenging activity. © 2012 Institute of Food Technologists®

Two new species of Oreocharis (Gesneriaceae) from Fan Si Pan, the highest mountain in Vietnam

PubMed Central

Chen, Wen Hong; Nguyen, Quang Hieu; Chen, Run Zheng; Nguyen, Tien Hiep; Nguyen, Sinh Khang; Nguyen, Van Tap; Möller, Michael; Middleton, David J.; Shui, Yu-Min

2018-01-01

Abstract Two new species of Oreocharis Benth. from Fan Si Pan, the highest mountain in Vietnam (Sa Pa) are described and illustrated. Oreocharis grandiflora W.H.Chen, Q.H.Nguyen & Y.M.Shui, is similar to O. flavida Merr. from Hainan province, China, but differs mainly by its larger and infundibuliform corolla, stamens adnate to the base of the corolla tube and stamens coherent in two pairs. The second, Oreocharis longituba W.H.Chen, Q.H.Nguyen & Y.M.Shui, is similar to O. hirsuta Barnett, endemic to northern Thailand, but mainly differs in its pubescence, coherent stamens and glabrous filaments. PMID:29416424

Separable roles of UFO during floral development revealed by conditional restoration of gene function.

PubMed

Laufs, Patrick; Coen, Enrico; Kronenberger, Jocelyne; Traas, Jan; Doonan, John

2003-02-01

The UNUSUAL FLORAL ORGANS (UFO) gene is required for several aspects of floral development in Arabidopsis including specification of organ identity in the second and third whorls and the proper pattern of primordium initiation in the inner three whorls. UFO is expressed in a dynamic pattern during the early phases of flower development. Here we dissect the role of UFO by ubiquitously expressing it in ufo loss-of-function flowers at different developmental stages and for various durations using an ethanol-inducible expression system. The previously known functions of UFO could be separated and related to its expression at specific stages of development. We show that a 24- to 48-hour period of UFO expression from floral stage 2, before any floral organs are visible, is sufficient to restore normal petal and stamen development. The earliest requirement for UFO is during stage 2, when the endogenous UFO gene is transiently expressed in the centre of the wild-type flower and is required to specify the initiation patterns of petal, stamen and carpel primordia. Petal and stamen identity is determined during stages 2 or 3, when UFO is normally expressed in the presumptive second and third whorl. Although endogenous UFO expression is absent from the stamen whorl from stage 4 onwards, stamen identity can be restored by UFO activation up to stage 6. We also observed floral phenotypes not observed in loss-of-function or constitutive gain-of-function backgrounds, revealing additional roles of UFO in outgrowth of petal primordia.

[Anatomy and development of stamens and carpels of Drimys granadensis (Winteraceae)].

PubMed

Marquínez-Casas, Xavier

2014-09-01

Winteraceae has long been considered a family with early diversification among angiosperms, with characters such as: flowers with many spirally arranged parts and apocarpic ovary formed by plicated carpels with sessile stigma. In Drimys, the presence or absence of conspicuous glands on the connective of the stamens have been used as a taxonomic character, and it is considered a synapomorphy for the clade including Drimys angustifolia, D. brasiliensis, D. granadensis and D. roraimensis (Northeastern clade); however, the anatomy of stamens and carpels has only been studied in detail for D. winteri (Southwestern clade). In this research, the presence and the structure of glands on the connective of stamens was studied in seven species of the genus from herbarium specimens, and a detailed study of the anatomy and development of stamens and carpels was carried out by scanning electron and optic microscopy in Drimys granadensis. We found similarities between D. granadensis and D. winteri for the following characters: Basic type anther wall formation, secretory tapetum that collapses at maturity, intermediate type microsporogenesis with formation of a transient cell plate in telophase I, ascidiated carpel due to the formation of an adaxial lip during development, stigma closed by interdigitation of epidermal cells. We also determined that the large glands on anther mature connective are originated by an overgrowth of subepidermal oil cells; this character is a Northeastern Drimys clade synapomorphy, while it was absent in both Drimys of Southwestern clade (which includes D. andina, D. confertifolia and D. winteri), and the rest of the Winteraceae. We are proposing the hypothesis that the highly variable enviromental conditions in the tropics where Drimys Northeastern clade is distributed, with a wide range of pollinators, would be associated with the emergence of glandular conspicuously stamens; while, as a prediction to be confirmed, temperated Southwestern clade species, without conspicuous glands, should have a smaller range of visitors and/or pollinators, or even be anemophilous species as Drimys confertifolia.

Ricochet pollination in Senna (Fabaceae) - petals deflect pollen jets and promote division of labour among flower structures.

PubMed

Amorim, T; Marazzi, B; Soares, A A; Forni-Martins, E R; Muniz, C R; Westerkamp, C

2017-11-01

Naturalists Fritz and Hermann Müller hypothesised that heteranthery often leads to a division of labour into 'feeding' and 'pollinating' stamens; the latter often being as long as the pistil so as to promote successful pollination on the bees' back. In many buzz-pollinated species of Senna, however, the so-called pollinating stamens are short and not level with the stigma, raising the question of how pollen is shed on the bees' back. Here we explore a mechanism called 'ricochet pollination'. We test whether division of labour is achieved through the interaction between short lower stamens and strongly concave 'deflector petals'. We studied the arrangement and morphology of the floral organs involved in the ricochet pollination, functioning of the flowers through artificial sonication and observed the interactions between bees and flowers in the field. The middle stamens are adapted to eject pollen downwards, which can be readily collected on the bee mid legs. Most of the pollen is ejected towards the deflector petal(s). Pollen from this set of stamens is more likely to contribute to pollination. The pollen grains seem to ricochet multiple times against the deflector petals to eventually reach the bee's back. The pollen ricochet mechanism promotes a division of labour by involving additional floral organs, such as petals, reinforcing the Müllers' division-of-labour hypothesis. However, alternative, non-multiexclusive hypotheses could be explored in genus Senna and other angiosperm species. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Petunia AGAMOUS enhancer-derived chimeric promoters specify a carpel-, stamen- and petal-specific expression pattern sufficient for engineering male and female sterility in tobacco

USDA-ARS?s Scientific Manuscript database

Previous studies have shown that the AtAGIP promoter derived from the Arabidopsis AGAMOUS (AG) second intron/enhancer specifies a carpel- and stamen-specific pattern of expression in its native host species but not in heterologous species, such as tobacco which restricts its application in the engin...

Gibberellin control of stamen development: a fertile field.

PubMed

Plackett, Andrew R G; Thomas, Stephen G; Wilson, Zoe A; Hedden, Peter

2011-10-01

Stamen development is governed by a conserved genetic pathway, within which the role of hormones has been the subject of considerable recent research. Our understanding of the involvement of gibberellin (GA) signalling in this developmental process is further advanced than for the other phytohormones, and here we review recent experimental results in rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana) that have provided insight into the timing and mechanisms of GA regulation of stamen development, identifying the tapetum and developing pollen as major targets. GA signalling governs both tapetum secretory functions and entry into programmed cell death via the GAMYB class of transcription factor, the targets of which integrate with the established genetic framework for the regulation of tapetum function at multiple hierarchical levels. Copyright © 2011 Elsevier Ltd. All rights reserved.

Floral Development of Berberidopsis corallina: a Crucial Link in the Evolution of Flowers in the Core Eudicots

PubMed Central

RONSE DE CRAENE, LOUIS P.

2004-01-01

• Background and Aims On the basis of molecular evidence Berberidopsidaceae have been linked with Aextoxicaceae in an order Berberidopsidales at the base of the core Eudicots. The floral development of Berberidopsis is central to the understanding of the evolution of floral configurations at the transition of the basal Eudicots to the core Eudicots. It lies at the transition of trimerous or dimerous, simplified apetalous forms into pentamerous, petaliferous flowers. • Methods The floral ontogeny of Berberidopsis was studied with a scanning electron microscope. • Key Results Flowers are grouped in terminal racemes with variable development. The relationship between the number of tepals, stamens and carpels is more or less fixed and floral initiation follows a strict 2/5 phyllotaxis. Two bracteoles, 12 tepals, eight stamens and three carpels are initiated in a regular sequence. The number of stamens can be increased by a doubling of stamen positions. • Conclusions The floral ontogeny of Berberidopsis provides support for the shift in floral bauplan from the basal Eudicots to the core Eudicots as a transition of a spiral flower with a 2/5 phyllotaxis to pentamerous flowers with two perianth whorls, two stamen whorls and a single carpel whorl. The differentiation of sepals and petals from bracteotepals is discussed and a comparison is made with other Eudicots with a similar configuration and development. Depending on the resolution of the relationships among the basalmost core Eudicots it is suggested that Berberidopsis either represents a critical stage in the evolution of pentamerous flowers of major clades of Eudicots, or has a floral prototype that may be at the base of evolution of flowers of other core Eudicots. The distribution of a floral Bauplan in other clades of Eudicots similar to Berberidopsidales is discussed. PMID:15451722

Exon skipping of AGAMOUS homolog PrseAG in developing double flowers of Prunus lannesiana (Rosaceae).

PubMed

Liu, Zhixiong; Zhang, Dandan; Liu, Di; Li, Fenglan; Lu, Hai

2013-02-01

KEY MESSAGE : Two transcript isoforms of AGAMOUS homologs, from single and double flower Prunus lannesiana, respectively, showed different functions. The Arabidopsis floral homeotic C function gene AGAMOUS (AG) confers stamen and carpel identity. Loss of AG function results in homeotic conversions of stamens into petals and formation of double flowers. In order to present a molecular dissection of a double-flower cultivar in Prunus lannesiana (Rosaceae), we isolated and identified a single-copy gene, AG homolog from two genetically cognate P. lannesiana bearing single and double flowers, respectively. Sequence analysis revealed that the AG homolog, prseag-1, from double flowers showed a 170-bp exon skipping as compared to PrseAG (Prunus serrulata AGAMOUS) from the single flowers. Genomic DNA sequence revealed that abnormal splicing resulted in mutant prseag-1 protein with the C-terminal AG motifs I and II deletions. In addition, protein sequence alignment and phylogenetic analyses revealed that the PrseAG was grouped into the euAG lineage. A semi-quantitative PCR analysis showed that the expression of PrseAG was restricted to reproductive organs of stamens and carpels in single flowers of P. lannesiana 'speciosa', while the prseag-1 mRNA was highly transcribed throughout the petals, stamens, and carpels in double flowers from 'Albo-rosea'. The transgenic Arabidopsis containing 35S::PrseAG displayed extremely early flowering, bigger stamens and carpels and homeotic conversion of petals into staminoid organs, but ectopic expression of prseag-1 could not mimic the phenotypic ectopic expression of PrseAG in Arabidopsis. In general, this study provides evidences to show that double flower 'Albo-rosea' is a putative C functional ag mutant in P. lannesiana.

A Regulatory Network for Coordinated Flower Maturation

PubMed Central

Ploense, Sara E.; Wu, Miin-Feng; Yadav, Vandana; Tholl, Dorothea; Chételat, Aurore; Haupt, Ina; Kennerley, Brian J.; Hodgens, Charles; Farmer, Edward E.; Nagpal, Punita; Reed, Jason W.

2012-01-01

For self-pollinating plants to reproduce, male and female organ development must be coordinated as flowers mature. The Arabidopsis transcription factors AUXIN RESPONSE FACTOR 6 (ARF6) and ARF8 regulate this complex process by promoting petal expansion, stamen filament elongation, anther dehiscence, and gynoecium maturation, thereby ensuring that pollen released from the anthers is deposited on the stigma of a receptive gynoecium. ARF6 and ARF8 induce jasmonate production, which in turn triggers expression of MYB21 and MYB24, encoding R2R3 MYB transcription factors that promote petal and stamen growth. To understand the dynamics of this flower maturation regulatory network, we have characterized morphological, chemical, and global gene expression phenotypes of arf, myb, and jasmonate pathway mutant flowers. We found that MYB21 and MYB24 promoted not only petal and stamen development but also gynoecium growth. As well as regulating reproductive competence, both the ARF and MYB factors promoted nectary development or function and volatile sesquiterpene production, which may attract insect pollinators and/or repel pathogens. Mutants lacking jasmonate synthesis or response had decreased MYB21 expression and stamen and petal growth at the stage when flowers normally open, but had increased MYB21 expression in petals of older flowers, resulting in renewed and persistent petal expansion at later stages. Both auxin response and jasmonate synthesis promoted positive feedbacks that may ensure rapid petal and stamen growth as flowers open. MYB21 also fed back negatively on expression of jasmonate biosynthesis pathway genes to decrease flower jasmonate level, which correlated with termination of growth after flowers have opened. These dynamic feedbacks may promote timely, coordinated, and transient growth of flower organs. PMID:22346763

Spatial expression dynamics of Men-9 delineate the third floral whorl in male and female flowers of dioecious Silene latifolia.

PubMed

Robertson, S E; Li, Y; Scutt, C P; Willis, M E; Gilmartin, P M

1997-07-01

Sex determination in Silene latifolia is controlled by heteromorphic sex chromosomes. Female flowers have five fused carpels and ten arrested stamen primordia. The male-determining Y chromosome overrides female development to suppress carpel formation and promote stamen development. The isolation and characterization of two S. latifolia. Male enhanced cDNAs, Men-9a and Men-9b, which probably represent different alleles of a novel gene are reported here. Men-9a and Men-9b share 91.8% coding sequence nucleotide identity, yet only 85.4% amino acid identity. The Men-9 cDNAs are related to the previously reported MROS3 cDNA from S. latifolia. However, MROS3 is not present in the S. latifolia population used in these studies and the expression dynamics of Men-9a and Men-9b contrast dramatically with those reported for MROS3. Men-9 cDNAs are expressed primarily in anthers of young male flowers, with highest expression in 1-2 mm buds. Men-9 expression is also observed at a low level in female flowers. In situ hybridization analysis reveals two phases of Men-9 expression. The first phase is during a common stage of early stamen development in male and female flowers prior to stamen arrest in female flowers. The second phase of Men-9 expression is maximal in the epidermis and endothecium of Y chromosome- and Ustilago violacea-induced stamens; expression in male and female flowers extends to the epidermis of the staminal nectaries with strict boundaries at the second and fourth whorls, Men-9 gene expression therefore delineates the boundaries of the third floral whorl in S. latifolia flowers.

The Complete Plastome Sequences of Four Orchid Species: Insights into the Evolution of the Orchidaceae and the Utility of Plastomic Mutational Hotspots

PubMed Central

Niu, Zhitao; Xue, Qingyun; Zhu, Shuying; Sun, Jing; Liu, Wei; Ding, Xiaoyu

2017-01-01

Orchidaceae (orchids) is the largest family in the monocots, including about 25,000 species in 880 genera and five subfamilies. Many orchids are highly valued for their beautiful and long-lasting flowers. However, the phylogenetic relationships among the five orchid subfamilies remain unresolved. The major dispute centers on whether the three one-stamened subfamilies, Epidendroideae, Orchidoideae, and Vanilloideae, are monophyletic or paraphyletic. Moreover, structural changes in the plastid genome (plastome) and the effective genetic loci at the species-level phylogenetics of orchids have rarely been documented. In this study, we compared 53 orchid plastomes, including four newly sequenced ones, that represent four remote genera: Dendrobium, Goodyera, Paphiopedilum, and Vanilla. These differ from one another not only in their lengths of inverted repeats and small single copy regions but also in their retention of ndh genes. Comparative analyses of the plastomes revealed that the expansion of inverted repeats in Paphiopedilum and Vanilla is associated with a loss of ndh genes. In orchid plastomes, mutational hotspots are genus specific. After having carefully examined the data, we propose that the three loci 5′trnK-rps16, trnS-trnG, and rps16-trnQ might be powerful markers for genera within Epidendroideae, and clpP-psbB and rps16-trnQ might be markers for genera within Cypripedioideae. After analyses of a partitioned dataset, we found that our plastid phylogenomic trees were congruent in a topology where two one-stamened subfamilies (i.e., Epidendroideae and Orchidoideae) were sisters to a multi-stamened subfamily (i.e., Cypripedioideae) rather than to the other one-stamened subfamily (Vanilloideae), suggesting that the living one-stamened orchids are paraphyletic. PMID:28515737

Genetic basis for using Tradescantia clone 4430 as an environmental monitor of mutagens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emmerling-Thompson, M.; Nawrocky, M.M.

1980-01-01

The Tradescantia stamen hair system developed by the late Dr. Arnold H. Sparrow has been used in a wide variety of radiobiological studies, and more recently as an environmental monitor for assessing the potential genetic hazards of various gaseous chemicals of both industrial and natural origin. The use of this system as a genetic monitor necessitates a thorough genetic analysis of the marker employed to measure mutagenicity. The phenotypic change in color from blue to pink in either petal or stamen hair cells has been used as a genetic marker under the assumption that the petal and stamen hair cellsmore » are heterozygous for blue, and if the dominant allele for blue color mutates or is lost, the recessive allele determines that the daughter cells will be pink. It is the purpose of this communication to present the results of genetic tests by conventional breeding methods involving the pink locus in Tradescantia clone 4430, the diploid clone used exclusively in the Mobile Monitoring Vehicle at Brookhaven National Laboratory. Confirmation of a genetic, as opposed to a physiological, origin of the pink color in the petal and stamen hair cells of Tradescantia clone 4430 is essential to evaluating the validity of this test system.« less

Polyamines and Flower Development in the Male Sterile Stamenless-2 Mutant of Tomato (Lycopersicon esculentum Mill.) 1

PubMed Central

Rastogi, Rajeev; Sawhney, Vipen K.

1990-01-01

The floral organs of the male sterile stamenless-2 (sl-2/sl-2) mutant of tomato (Lycopersicon esculentum Mill.) contain significantly higher level of polyamines than those of the normal (R Rastogi, VK Sawhney [1990] Plant Physiol 93: 439-445). The effects of putrescine, spermidine and spermine, and three different inhibitors of polyamine biosynthesis on the in vitro development of floral buds of the normal and sl-2/sl-2 mutant were studied. The polyamines were inhibitory to the in vitro growth and development of both the normal and mutant floral buds and they induced abnormal stamen development in normal flowers. The inhibitors of polyamine biosynthesis also inhibited the growth and development of floral organs of the two genotypes, but the normal flowers showed greater sensitivity than the mutant. The inhibitors also promoted the formation of normal-looking pollen in stamens of some mutant flowers. The effect of the inhibitors on polyamine levels was not determined. The polyamine-induced abnormal stamen development in the normal, and the inhibitor-induced production of normal-looking pollen in mutant flowers support the suggestion that the elevated polyamine levels contribute to abnormal stamen development in the sl-2/sl-2 mutant of tomato. Images Figure 3 Figure 5 PMID:16667486

B-Function Expression in the Flower Center Underlies the Homeotic Phenotype of Lacandonia schismatica (Triuridaceae)[C][W][OA

PubMed Central

Álvarez-Buylla, Elena R.; Ambrose, Barbara A.; Flores-Sandoval, Eduardo; Englund, Marie; Garay-Arroyo, Adriana; García-Ponce, Berenice; de la Torre-Bárcena, Eduardo; Espinosa-Matías, Silvia; Martínez, Esteban; Piñeyro-Nelson, Alma; Engström, Peter; Meyerowitz, Elliot M.

2010-01-01

Spontaneous homeotic transformations have been described in natural populations of both plants and animals, but little is known about the molecular-genetic mechanisms underlying these processes in plants. In the ABC model of floral organ identity in Arabidopsis thaliana, the B- and C-functions are necessary for stamen morphogenesis, and C alone is required for carpel identity. We provide ABC model-based molecular-genetic evidence that explains the unique inside-out homeotic floral organ arrangement of the monocotyledonous mycoheterotroph species Lacandonia schismatica (Triuridaceae) from Mexico. Whereas a quarter million flowering plant species bear central carpels surrounded by stamens, L. schismatica stamens occur in the center of the flower and are surrounded by carpels. The simplest explanation for this is that the B-function is displaced toward the flower center. Our analyses of the spatio-temporal pattern of B- and C-function gene expression are consistent with this hypothesis. The hypothesis is further supported by conservation between the B-function genes of L. schismatica and Arabidopsis, as the former are able to rescue stamens in Arabidopsis transgenic complementation lines, and Ls-AP3 and Ls-PI are able to interact with each other and with the corresponding Arabidopsis B-function proteins in yeast. Thus, relatively simple molecular modifications may underlie important morphological shifts in natural populations of extant plant taxa. PMID:21119062

Molecular genetic analyses of microsporogenesis and microgametogenesis in flowering plants.

PubMed

Ma, Hong

2005-01-01

In flowering plants, male reproductive development requires the formation of the stamen, including the differentiation of anther tissues. Within the anther, male meiosis produces microspores, which further develop into pollen grains, relying on both sporophytic and gametophytic gene functions. The mature pollen is released when the anther dehisces, allowing pollination to occur. Molecular studies have identified a large number of genes that are expressed during stamen and pollen development. Genetic analyses have demonstrated the function of some of these genes in specifying stamen identity, regulating anther cell division and differentiation, controlling male meiosis, supporting pollen development, and promoting anther dehiscence. These genes encode a variety of proteins, including transcriptional regulators, signal transduction proteins, regulators of protein degradation, and enzymes for the biosynthesis of hormones. Although much has been learned in recent decades, much more awaits to be discovered and understood; the future of the study of plant male reproduction remains bright and exciting with the ever-growing tool kits and rapidly expanding information and resources for gene function studies.

Transcriptome Analysis of Flower Sex Differentiation in Jatropha curcas L. Using RNA Sequencing.

PubMed

Xu, Gang; Huang, Jian; Yang, Yong; Yao, Yin-an

2016-01-01

Jatropha curcas is thought to be a promising biofuel material, but its yield is restricted by a low ratio of instaminate/staminate flowers (1/10-1/30). Furthermore, valuable information about flower sex differentiation in this plant is scarce. To explore the mechanism of this process in J. curcas, transcriptome profiling of flower development was carried out, and certain genes related with sex differentiation were obtained through digital gene expression analysis of flower buds from different phases of floral development. After Illumina sequencing and clustering, 57,962 unigenes were identified. A total of 47,423 unigenes were annotated, with 85 being related to carpel and stamen differentiation, 126 involved in carpel and stamen development, and 592 functioning in the later development stage for the maturation of staminate or instaminate flowers. Annotation of these genes provided comprehensive information regarding the sex differentiation of flowers, including the signaling system, hormone biosynthesis and regulation, transcription regulation and ubiquitin-mediated proteolysis. A further expression pattern analysis of 15 sex-related genes using quantitative real-time PCR revealed that gibberellin-regulated protein 4-like protein and AMP-activated protein kinase are associated with stamen differentiation, whereas auxin response factor 6-like protein, AGAMOUS-like 20 protein, CLAVATA1, RING-H2 finger protein ATL3J, auxin-induced protein 22D, and r2r3-myb transcription factor contribute to embryo sac development in the instaminate flower. Cytokinin oxidase, Unigene28, auxin repressed-like protein ARP1, gibberellin receptor protein GID1 and auxin-induced protein X10A are involved in both stages mentioned above. In addition to its function in the differentiation and development of the stamens, the gibberellin signaling pathway also functions in embryo sac development for the instaminate flower. The auxin signaling pathway also participates in both stamen development and embryo sac development. Our transcriptome data provide a comprehensive gene expression profile for flower sex differentiation in Jatropha curcas, as well as new clues and information for further study in this field.

Transcriptome Analysis of Flower Sex Differentiation in Jatropha curcas L. Using RNA Sequencing

PubMed Central

Xu, Gang; Huang, Jian; Yang, Yong; Yao, Yin-an

2016-01-01

Background Jatropha curcas is thought to be a promising biofuel material, but its yield is restricted by a low ratio of instaminate / staminate flowers (1/10-1/30). Furthermore, valuable information about flower sex differentiation in this plant is scarce. To explore the mechanism of this process in J. curcas, transcriptome profiling of flower development was carried out, and certain genes related with sex differentiation were obtained through digital gene expression analysis of flower buds from different phases of floral development. Results After Illumina sequencing and clustering, 57,962 unigenes were identified. A total of 47,423 unigenes were annotated, with 85 being related to carpel and stamen differentiation, 126 involved in carpel and stamen development, and 592 functioning in the later development stage for the maturation of staminate or instaminate flowers. Annotation of these genes provided comprehensive information regarding the sex differentiation of flowers, including the signaling system, hormone biosynthesis and regulation, transcription regulation and ubiquitin-mediated proteolysis. A further expression pattern analysis of 15 sex-related genes using quantitative real-time PCR revealed that gibberellin-regulated protein 4-like protein and AMP-activated protein kinase are associated with stamen differentiation, whereas auxin response factor 6-like protein, AGAMOUS-like 20 protein, CLAVATA1, RING-H2 finger protein ATL3J, auxin-induced protein 22D, and r2r3-myb transcription factor contribute to embryo sac development in the instaminate flower. Cytokinin oxidase, Unigene28, auxin repressed-like protein ARP1, gibberellin receptor protein GID1 and auxin-induced protein X10A are involved in both stages mentioned above. In addition to its function in the differentiation and development of the stamens, the gibberellin signaling pathway also functions in embryo sac development for the instaminate flower. The auxin signaling pathway also participates in both stamen development and embryo sac development. Conclusions Our transcriptome data provide a comprehensive gene expression profile for flower sex differentiation in Jatropha curcas, as well as new clues and information for further study in this field. PMID:26848843

Increasing the applications of Crocus sativus flowers as natural antioxidants.

PubMed

Serrano-Díaz, Jéssica; Sánchez, Ana M; Maggi, Luana; Martínez-Tomé, Magdalena; García-Diz, Luis; Murcia, M Antonia; Alonso, Gonzalo L

2012-11-01

Large amounts of floral bio-residues (92.6 g per 100 g of flowers) are generated and wasted in the production of saffron (Crocus sativus) spice. Progress in mechanization of saffron crop offer the opportunity to expand the uses of C. sativus flowers, beyond the spice (dried stigmas). The antioxidant potential of flowers of saffron, their separate parts (tepals, stamens, styles, and stigmas) and floral bio-residues were evaluated by 4 in vitro assays: lipid peroxidation, deoxyribose assay, Rancimat test, and Trolox equivalent antioxidant capacity. Phenolic content and crocetin ester composition were also determined. All the samples studied showed to be potential antioxidants. The highest phenolic, flavonoid, and anthocyanin contents were observed in tepals. Stamens showed lower phenolic, flavonoid, and anthocyanin contents than those of whole flowers, tepals, and floral bio-residues. Crocetin esters were not found in tepals or stamens. Stamens exhibited the most potent LOO(•) and OH(•) radicals scavenging activity, being higher than those of food antioxidant propyl gallate. Flowers of saffron, tepals, stamens, styles, and floral bio-residues showed LOO(•), OH(•), and ABTS(•-) radicals scavenging activity, while stigmas showed LOO(•) and ABTS(•-) radicals scavenging activity. All samples studied improved the oxidative stability of sunflower oil in Rancimat test. These antioxidant properties could suggest the application of this floral material as functional ingredients with the subsequent added value. Saffron spice, the most valuable spice worldwide, is the dried stigma that only represents 7.4% of Crocus sativus flowers. Other parts of the flowers different to stigmas are discarded. Flower harvest and all the postharvest steps to produce saffron spice are performed manually. Mechanization of flower collection, stigma separation, and dehydration process is a revolution in saffron spice production, which increases the productive capacity making it possible to extend the uses of C. sativus flowers, beyond the production of saffron spice. Flowers possessed high-phenolic content and excellent antioxidant properties that could contribute to their application as functional ingredients. © 2012 Institute of Food Technologists®

Partial redundancy and functional specialization of E-class SEPALLATA genes in an early-diverging eudicot.

PubMed

Soza, Valerie L; Snelson, Corey D; Hewett Hazelton, Kristen D; Di Stilio, Verónica S

2016-11-01

Plant MADS-box genes have duplicated extensively, allegedly contributing to the immense diversity of floral form in angiosperms. In Arabidopsis thaliana (a core eudicot model plant), four SEPALLATA (SEP) genes comprise the E-class from the extended ABCE model of flower development. They are redundantly involved in the development of the four types of floral organs (sepals, petals, stamens and carpels) and in floral meristem determinacy. E-class genes have been examined in other core eudicots and monocots, but have been less investigated in non-core eudicots. Our goal was to functionally characterize the E-class genes in the early-diverging eudicot Thalictrum thalictroides (Ranunculaceae), whose flowers are apetalous. We identified four SEP orthologs, which when placed in a phylogenetic context, resulted from a major gene duplication event before the origin of angiosperms and a subsequent duplication at the origin of the Ranunculales. We used Virus-Induced Gene Silencing (VIGS) to down-regulate the three expressed paralogs individually and in combination to investigate their function and to determine the degree of conservation versus divergence of this important plant transcription factor. All loci were partially redundant in sepal and stamen identity and in promoting petaloidy of sepals, yet the SEP3 ortholog had a more pronounced role in carpel identity and development. The two other paralogs appear to have subfunctionalized in their cadastral roles to keep the boundaries between either sepal and stamen zones or stamen and carpel zones. Double knockdowns had enhanced phenotypes and the triple knockdown had an even more severe phenotype that included partial to complete homeotic conversion of stamens and carpels to sepaloid organs and green sepals, highlighting a role of E-class genes in petaloidy of sepals in this species. While no floral meristem determinacy defects were observed, this could be due to residual amounts of gene expression in the VIGS experiments being sufficient to perform this function or to the masking role of a redundant gene. Copyright © 2016 Elsevier Inc. All rights reserved.

[Morphological and anatomical characterization of a stripe mutant with abnormal floral organs in rice].

PubMed

Chen, De Xi; Ma, Bing Tian; Wang, Yu Ping; Li, Shi Gui; Hao, Ming

2006-08-01

A rice double mutant was derived from the transgenic process,but it does not carry the alien gene. The mutant showed white stripe on stem, leaf and spikelet. In some growing stage,the leaf started to produce fork or curliness. The floret number increased, showing multi-lemma/palea, palea-like or lemma-like lodicules or enlarged lodicules, additional pistil and stamen and the spited floret. With observation of cell ultra structure using electron microscope,the white tissue showed concaved cell wall and abnormal plastid which could not develop normal lamellae and thylakoid. The contents of chlorophyll and net photosynthesis rate in the mutant were obviously lower than those in the wild type. The cells in green sectors grow normally with the exception of the bigger cell volume. The morphogenesis of floral organ was observed by using the scanning electron microscopy (SEM). Results showed that the stamen development was not synchronal and the sizes of stamen primordium were different in mutant, and the carpel was smaller than that of wild type.

Evidence that the oxygen enhancement ratio for pink somatic mutations in Tradescantia stamen hairs may approach unity at very low x-ray doses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Underbrink, A.G.; Woch, B.

1980-11-01

Experimental evidence was found that the oxygen enhancement ratio (OER) for pink somatic mutations in the stamen hairs of Tradescantia clone 02 appears to reach unity at X-ray doses of 2 to 3 rad. There is also a small segment on the dose-response curves from about 3 to 10 rad where the OER appears to be dose-dependent. At higher doses the aerated and hypoxic curves are parallel, and the OER is 3.2 up to doses where the mutation frequency reaches a plateau.

Expression of B-class MADS-box genes in response to variations in photoperiod is associated with chasmogamous and cleistogamous flower development in Viola philippica.

PubMed

Li, Qiaoxia; Huo, Qingdi; Wang, Juan; Zhao, Jing; Sun, Kun; He, Chaoying

2016-07-07

Some plants develop a breeding system that produces both chasmogamous (CH) and cleistogamous (CL) flowers. However, the underlying molecular mechanism remains elusive. In the present study, we observed that Viola philippica develops CH flowers with short daylight, whereas an extended photoperiod induces the formation of intermediate CL and CL flowers. In response to long daylight, the respective number and size of petals and stamens was lower and smaller than those of normally developed CH flowers, and a minimum of 14-h light induced complete CL flowers that had no petals but developed two stamens of reduced fertility. The floral ABC model indicates that B-class MADS-box genes largely influence the development of the affected two-whorl floral organs; therefore, we focused on characterizing these genes in V. philippica to understand this particular developmental transition. Three such genes were isolated and respectively designated as VpTM6-1, VpTM6-2, and VpPI. These were differentially expressed during floral development (particularly in petals and stamens) and the highest level of expression was observed in CH flowers; significantly low levels were detected in intermediate CL flowers, and the lowest level in CL flowers. The observed variations in the levels of expression after floral induction and organogenesis apparently occurred in response to variations in photoperiod. Therefore, inhibition of the development of petals and stamens might be due to the downregulation of B-class MADS-box gene expression by long daylight, thereby inducing the generation of CL flowers. Our work contributes to the understanding of the adaptive evolutionary formation of dimorphic flowers in plants.

Analyses of spontaneous pink mutant events in the stamen hairs of Tradescantia clone BNL 4430 cultivated in a nutrient solution circulating growth chamber.

PubMed

Ichikawa, S; Wushur, S

2000-12-20

In order to obtain more fundamental data on Tradescantia clone BNL 4430, one of the most suitable testers for environmental mutagens, the occurrences of spontaneous somatic pink mutations in the stamen hairs were scored for 52 weeks from 12 December 1998 to 10 December 1999, cultivating the young inflorescence-bearing shoots with roots in a nutrient solution circulating (NSC) growth chamber. The environmental conditions in the chamber were 22.0+/-0.5 degrees C during the 16h day with the light intensity of 7.5klx from white fluorescent tubes, and 20.0+/-0.5 degrees C at night. During the scoring period, 697,443 stamen hairs with an average cell number of 25.36 were observed and 2642 pink mutant events (PMEs) were detected. The overall spontaneous mutation frequency was 1.56+/-0.03 PMEs per 10(4) hair-cell divisions, and the frequency was significantly lower in May, July and August and significantly higher in November and December. By analyzing the sectoring patterns of 1856 PMEs (70.25% of PMEs detected), the most of 172 cases of multiple (two to five) pink sectors observed in the same hairs (scored as 232 PMEs for calculating mutation frequency) were found to be the results of events involving somatic recombinations occurred in single cells or cell lineages, rather than those of two or more independent somatic mutations occurred in different cells. This finding clearly shows the significance of somatic recombinations in producing such multiple sectors (382 sectors in total) which occupied 19.0% of the 2006 pink sectors in total analyzed. Somatic recombinations were considered to be playing a significant role also in producing single PMEs in the stamen hairs.

A soybean MADS-box protein modulates floral organ numbers, petal identity and sterility

PubMed Central

2014-01-01

Background The MADS-box transcription factors play fundamental roles in reproductive developmental control. Although the roles of many plant MADS-box proteins have been extensively studied, there are almost no functional studies of them in soybean, an important protein and oil crop in the world. In addition, the MADS-box protein orthologs may have species-specific functions. Controlling male fertility is an important goal in plant hybrid breeding but is difficult in some crops like soybean. The morphological structure of soybean flowers prevents the cross-pollination. Understanding the molecular mechanisms for floral development will aid in engineering new sterile materials that could be applied in hybrid breeding programs in soybean. Result Through microarray analysis, a flower-enriched gene in soybean was selected and designated as GmMADS28. GmMADS28 belongs to AGL9/SEP subfamily of MADS-box proteins, localized in nucleus and showed specific expression patterns in floral meristems as well as stamen and petal primordia. Expression of GmMADS28 in the stamens and petals of a soybean mutant NJS-10Hfs whose stamens are converted into petals was higher than in those of wild-type plants. Constitutive expression of GmMADS28 in tobacco promoted early flowering and converted stamens and sepals to petals. Interestingly, transgenic plants increased the numbers of sepal, petal and stamen from five to six and exhibited male sterility due to the shortened and curly filaments and the failure of pollen release from the anthers. The ectopic expression of GmMADS28 was found to be sufficient to activate expression of tobacco homologs of SOC1, LEAFY, AGL8/FUL, and DEF. In addition, we observed the interactions of GmMADS28 with soybean homologs of SOC1, AP1, and AGL8/FUL proteins. Conclusion In this study, we observed the roles of GmMADS28 in the regulation of floral organ number and petal identity. Compared to other plant AGL9/SEP proteins, GmMADS28 specifically regulates floral organ number, filament length and pollen release. The sterility caused by the ectopic expression of GmMADS28 offers a promising way to genetically produce new sterile material that could potentially be applied in the hybrid breeding of crops like soybean. PMID:24693922

A soybean MADS-box protein modulates floral organ numbers, petal identity and sterility.

PubMed

Huang, Fang; Xu, Guangli; Chi, Yingjun; Liu, Haicui; Xue, Qian; Zhao, Tuanjie; Gai, Junyi; Yu, Deyue

2014-04-02

The MADS-box transcription factors play fundamental roles in reproductive developmental control. Although the roles of many plant MADS-box proteins have been extensively studied, there are almost no functional studies of them in soybean, an important protein and oil crop in the world. In addition, the MADS-box protein orthologs may have species-specific functions. Controlling male fertility is an important goal in plant hybrid breeding but is difficult in some crops like soybean. The morphological structure of soybean flowers prevents the cross-pollination. Understanding the molecular mechanisms for floral development will aid in engineering new sterile materials that could be applied in hybrid breeding programs in soybean. Through microarray analysis, a flower-enriched gene in soybean was selected and designated as GmMADS28. GmMADS28 belongs to AGL9/SEP subfamily of MADS-box proteins, localized in nucleus and showed specific expression patterns in floral meristems as well as stamen and petal primordia. Expression of GmMADS28 in the stamens and petals of a soybean mutant NJS-10Hfs whose stamens are converted into petals was higher than in those of wild-type plants. Constitutive expression of GmMADS28 in tobacco promoted early flowering and converted stamens and sepals to petals. Interestingly, transgenic plants increased the numbers of sepal, petal and stamen from five to six and exhibited male sterility due to the shortened and curly filaments and the failure of pollen release from the anthers. The ectopic expression of GmMADS28 was found to be sufficient to activate expression of tobacco homologs of SOC1, LEAFY, AGL8/FUL, and DEF. In addition, we observed the interactions of GmMADS28 with soybean homologs of SOC1, AP1, and AGL8/FUL proteins. In this study, we observed the roles of GmMADS28 in the regulation of floral organ number and petal identity. Compared to other plant AGL9/SEP proteins, GmMADS28 specifically regulates floral organ number, filament length and pollen release. The sterility caused by the ectopic expression of GmMADS28 offers a promising way to genetically produce new sterile material that could potentially be applied in the hybrid breeding of crops like soybean.

Is polyploidy necessary for tissue differentiation in higher plants. [Triticum, helianthus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, L.S.; Hof, J.V.

1975-01-01

Measurements of relative DNA per nucleus of cells from various tissues show that cell differentiation can occur in the absence of polyploidy in higher plants. In Pisum polyploidy was present in roots, sepals, pods, pistils, and stamens but not in petals or leaves. In Triticum cells of leaves exhibited some polyploidy, but no polyploid cells were present in mature roots. No polyploid cells were found in any tissue of Helianthus examined (roots, cotyledons, stems, sepals, petals, pistils, and stamens). Therefore, as a general rule, polyploidy should not be considered essential in tissue or organ differentiation of higher plants. In Helianthusmore » polyploidy is unnecessary for the completion of the life cycle. (auth)« less

Ectopic expression of SUPERMAN suppresses development of petals and stamens.

PubMed

Yun, Jae-Young; Weigel, Detlef; Lee, Ilha

2002-01-01

The floral regulatory gene SUPERMAN (SUP) encodes a C2H2 type zinc finger protein that is required for maintaining boundaries between floral organs in Arabidopsis. It has been proposed that the main function of SUP is to balance cell proliferation in the third and fourth whorl of developing flowers, thereby maintaining the boundaries between the two whorls. To gain further insight into the function of SUP, we have ectopically expressed SUP using the promoter of APETALA1 (AP1), a gene that is initially expressed throughout floral meristems and later becomes restricted to the first and second whorls. Flowers of AP1::SUP plants have fewer floral organs, consistent with an effect of SUP on cell proliferation. In addition, the AP1::SUP transgene caused the conversion of petals to sepals and suppressed the development of stamens. The expression of the B function homeotic gene APETALA3 (AP3) and its regulator UNUSUAL FLORAL ORGANS (UFO) were delayed and reduced in AP1::SUP flowers. However, SUP does not act merely through UFO, as constitutive expression of UFO did not rescue the defects in petal and stamen development in AP1::SUP flowers. Together, these results suggest that SUP has both indirect and direct effects on the expression of B function homeotic genes.

To B or Not to B a flower: the role of DEFICIENS and GLOBOSA orthologs in the evolution of the angiosperms.

PubMed

Zahn, L M; Leebens-Mack, J; DePamphilis, C W; Ma, H; Theissen, G

2005-01-01

DEFICIENS (DEF) and GLOBOSA (GLO) function in petal and stamen organ identity in Antirrhinum and are orthologs of APETALA3 and PISTILLATA in Arabidopsis. These genes are known as B-function genes for their role in the ABC genetic model of floral organ identity. Phylogenetic analyses show that DEF and GLO are closely related paralogs, having originated from a gene duplication event after the separation of the lineages leading to the extant gymnosperms and the extant angiosperms. Several additional gene duplications followed, providing multiple potential opportunities for functional divergence. In most angiosperms studied to date, genes in the DEF/GLO MADS-box subfamily are expressed in the petals and stamens during flower development. However, in some angiosperms, the expression of DEF and GLO orthologs are occasionally observed in the first and fourth whorls of flowers or in nonfloral organs, where their function is unknown. In this article we review what is known about function, phylogeny, and expression in the DEF/GLO subfamily to examine their evolution in the angiosperms. Our analyses demonstrate that although the primary role of the DEF/GLO subfamily appears to be in specifying the stamens and inner perianth, several examples of potential sub- and neofunctionalization are observed.

Evolution of Perianth and Stamen Characteristics with Respect to Floral Symmetry in Ranunculales

PubMed Central

Damerval, Catherine; Nadot, Sophie

2007-01-01

Background and Aims Floral symmetry presents two main states in angiosperms, namely polysymmetry and monosymmetry. Monosymmetry is thought to have evolved several times independently from polysymmetry, possibly in co-adaptation with specialized pollinators. Monosymmetry commonly refers to the perianth, even though associated androecium modifications have been reported. The evolution of perianth symmetry is examined with respect to traits of flower architecture in the Ranunculales, the sister group to all other eudicots, which present a large diversity of floral forms. Methods Characters considered were perianth merism, calyx, corolla and androecium symmetry, number of stamens and spurs. Character evolution was optimized on a composite phylogenetic tree of Ranunculales using maximum parsimony. Key Results The ancestral state for merism could not be inferred because the basalmost Eupteleaceae lack a perianth and have a variable number of stamens. The Papaveraceae are dimerous, and the five other families share a common trimerous ancestor. Shifts from trimery to dimery (or reverse) are observed. Pentamery evolved in Ranunculaceae. Ranunculales except Eupteleaceae, present a polysymmetric ancestral state. Monosymmetry evolved once within Papaveraceae, Ranunculaceae and Menispermaceae (female flowers only). Oligandry is the ancestral state for all Ranunculales, and polyandry evolved several times independently, in Papaveraceae, Menispermaceae, Berberidaceae and Ranunculaceae, with two reversions to oligandry in the latter. The ancestral state for androecium symmetry is ambiguous for the Ranunculales, while polysymmetry evolved immediately after the divergence of Eupteleaceae. A disymmetric androecium evolved in Papaveraceae. The ancestral state for spurs is none. Multiple spurs evolved in Papaveraceae, Berberidaceae and Ranunculaceae, and single spurs occur in Papaveraceae and Ranunculaceae. Conclusions The evolution of symmetry appears disconnected from changes in merism and stamen number, although monosymmetry never evolved in the context of an open ground plan. In bisexual species, monosymmetry evolved coincidently with single spurs, allowing us to propose an evolutionary scenario for Papaveraceae. PMID:17428835

Further yearly analyses of spontaneous pink mutant events in the stamen hairs of tradescantia clone BNL 4430 cultivated in the NSC growth chamber.

PubMed

Ichikawa, S; Wushur, S

2001-06-01

In order to confirm the results obtained in the previous 1-year-term (December 12, 1998, through December 10, 1999) scorings and analyses of spontaneous pink mutant events (PMEs) in the stamen hairs of Tradescantia clone BNL 4430 cultivated in a nutrient solution circulating (NSC) growth chamber, similar scorings and analyses were continued for another 52-week period from December 11, 1999, through December 8, 2000. The environmental conditions were not changed, except for a minor modification in the method of supplying the nutrient solution used. During the scoring period, 732,128 stamen hairs with an average cell number of 24.90 cells were observed, and 2,368 PMEs were detected. The overall spontaneous somatic mutation frequency was 1.35 +/- 0.03 PMEs per 10(4) hair-cell divisions, which was significantly lower than the value of 1.56 +/- 0.03 determined in the previous 52-week period, and the frequencies were lower during April through September than in other months, the period showing lower frequencies lasting 1-month longer than in the previous year. The present results reconfirmed the occurrence of a clear seasonal variation in the spontaneous mutation frequency in the NSC growth chamber, and the lower overall frequency, probably related to the minor modification in supplying the nutrient solution, is helpful for conducting mutagenicity tests at low levels, offering a lower background level. The analyses of the sectoring patterns of all these PMEs showed that the most of the 203 cases of multiple (two to five) pink sectors observed in the same stamen hairs (scored as 253 PMEs for calculating mutation frequency) were the results of events involving somatic recombinations occurred in single cells or cell lineages, rather than those of two or more independent somatic mutations occurred in different cells, agreeing with our previous study, and the significance of somatic recombinations in causing single PMEs was also reconfirmed.

Floral meristem size and organ number correlation in Eucryphia (Cunoniaceae).

PubMed

Bull-Hereñu, Kester; Ronse de Craene, Louis; Pérez, Fernanda

2018-05-01

We present a comparative flower ontogenetic study in five species of the genus Eucryphia with the aim of testing whether differences in the organ number observed can be explained by changes in the meristematic size of floral meristem and floral organs. Species native to Oceania, viz. E. milliganii, E. lucida and E. moorei, have the smallest gynoecia with ca. 6 carpels, while the Chilean E. glutinosa and E. cordifolia present more than ten carpels. E. milliganii has the smallest flower with the lowest stamen number (ca. 50), while the other species produce around 200 stamens and more. Standardized measurements of meristematic sectors were taken in 49 developing flowers that were classified into three well-defined ontogenetic stages. Sizes of meristems varied significantly among species within each developmental stage as revealed by ANOVA analyses. Significant regressions between organ number and corresponding meristem size were consistent with the premise that a larger meristem size prior to organ initiation could be determining for a higher organ number. Flower organogenesis in Eucryphia also involves relevant meristem expansion while the organs are initiated, which results in a particular androecium patterning with a chaotic stamen arrangement. Meristem expansion also appears to be slower but more extensive in species with larger initial meristematic size, suggesting that flower phenotype can be determined in ontogeny by this heterochronic interplay of space and time.

Allopolyploidization and evolution of species with reduced floral structures in Lepidium L. (Brassicaceae)

PubMed Central

Lee, Ji-Young; Mummenhoff, Klaus; Bowman, John L.

2002-01-01

Understanding the pattern of speciation in a group of plants is critical for understanding its morphological evolution. Lepidium is the genus with the largest variation in floral structure in Brassicaceae, a family in which the floral ground plan is remarkably stable. However, flowers in more than half of Lepidium species have reduced stamen numbers, and most of these also have reduced petals. The species with reduced flowers are geographically biased, distributed mostly in the Americas and Australia/ New Zealand. Previous phylogenetic studies using noncoding regions of chloroplast DNA and rDNA internal transcribed spacer were incongruent in most New World species relationships. These data, combined with the presence of many polyploid Lepidium species, implied a reticulate history of the genus but did not provide enough information to infer the evolutionary pattern of flower structures. To address this question more thoroughly, sequences of the first intron of a single copy nuclear gene, PISTILLATA, were determined from 43 species. Phylogenetic analysis of the PI intron suggests that many species in the New World have originated from allopolyploidization, and that this is correlated with floral reduction. Interspecific hybrids were generated to understand why allopolyploidization is associated with reduced flowers. The phenotypes of F1 flowers indicate allelic dominance of the absence of lateral stamens, suggesting that propagation of dominant alleles through interspecific hybridization could account for the abundance of the allopolyploid species without lateral stamens. PMID:12481035

Conservation of class C function of floral organ development during 300 million years of evolution from gymnosperms to angiosperms.

PubMed

Zhang, Pingyu; Tan, Hugh T W; Pwee, Keng-Hock; Kumar, Prakash P

2004-02-01

Flower development in angiosperms is regulated by the family of MADS-box transcription factors. MADS-box genes have also been reported from gymnosperms, another major group of seed plants. AGAMOUS (AG) is the class C MADS-box floral organ identity gene controlling the stamen and carpel development in Arabidopsis. We report the characterization of an ortholog of the AG gene, named Cycas AGAMOUS (CyAG), from the primitive gymnosperm Cycas edentata. The expression pattern of CyAG in Cycas parallels that of AG in Arabidopsis. Additionally, the gene structure, including the number and location of the introns, is conserved in CyAG and other AG orthologs known. Most importantly, functional analysis shows that CyAG driven by the AG promoter can rescue the loss-of-function ag mutant of Arabidopsis. However, the ectopic expression of CyAG in ag mutant Arabidopsis cannot produce the carpeloid and stamenoid organs in the first and second whorls, although the stamen and carpel are rescued in the third and fourth whorls of the transformants. These observations show that the molecular mechanism of class C function controlling reproductive organ identity (stamen and carpel of angiosperms or microsporophyll and megasporophyll of gymnosperms) arose before the divergence of angiosperms and gymnosperms, and has been conserved during 300 million years of evolution thereafter.

Drops moving along and across a filament

NASA Astrophysics Data System (ADS)

Sahu, Rakesh P.; Sinha-Ray, Suman; Yarin, Alexander; Pourdeyhimi, Behnam

2013-11-01

The present work is devoted to the experimental study of oil drop motion both along and across a filament due to the air jet blowing. In case of drop moving along the filament, phenomena such as drop stick-slip motion, shape oscillations, shedding of a tail along the filament, the tail capillary instability and drop recoil motion were observed which were rationalized in the framework of simplified models. Experiments with cross-flow of the surrounding gas relative to the filament with an oil drop on it were conducted, with air velocity in the range of 7.23 to 22.7 m s-1. The Weber number varied from 2 to 40 and the Ohnesorge number varied from 0.07 to 0.8. The lower and upper critical Weber numbers were introduced to distinguish between the beginning of the drop blowing off the filament and the onset of the bag-stamen breakup. The range of the Weber number between these two critical values is filled with three types of vibrational breakup: V1 (a balloon-like drop being blown off), V2 (a drop on a single stamen being blown off), and V3 (a drop on a double stamen being blown off). The Weber number/Ohnesorge number plane was delineated into domains of different breakup regimes. The work is supported by the Nonwovens Cooperative Research Center (NCRC).

Clastogenecity evaluation of water of Lake Sevan (Armenia) using Tradescantia micronucleus assay.

PubMed

Aghajanyan, E A; Avalyan, R E; Simonyan, A E; Atoyants, A L; Gabrielyan, B K; Aroutiounian, R M; Khosrovyan, A

2018-05-24

The clastogenic effects of water samples in seven locations of Lake Sevan (Armenia) with the application of Trad-MCN (micronuclei) bioassay using Tradescantia (clone 02) were investigated. A significant increase in the frequency of micronuclei in tetrads of pollen microspores and tetrads with micronuclei exposed to the test samples compared to the control has been revealed. A multivariate analysis indicated linkage between the frequencies of occurrence of micronuclei in the cells and Ni and Co ions. The results were compared with the endpoints of another Tradescantia-based test system (stamen hair mutation test) performed on the same water samples and generation of the plant: occurrences of micronuclei in sporogenic cells coincided with that of non-surviving stamen hair. Copyright © 2018 Elsevier Ltd. All rights reserved.

'Who's who' in two different flower types of Calluna vulgaris (Ericaceae): morphological and molecular analyses of flower organ identity

PubMed Central

2009-01-01

Background The ornamental crop Calluna vulgaris is of increasing importance to the horticultural industry in the northern hemisphere due to a flower organ mutation: the flowers of the 'bud-flowering' phenotype remain closed i.e. as buds throughout the total flowering period and thereby maintain more colorful flowers for a longer period of time than the wild-type. This feature is accompanied and presumably caused by the complete lack of stamens. Descriptions of this botanical particularity are inconsistent and partially conflicting. In order to clarify basic questions of flower organ identity in general and stamen loss in detail, a study of the wild-type and the 'bud-flowering' flower type of C. vulgaris was initiated. Results Flowers were examined by macro- and microscopic techniques. Organ development was investigated comparatively in both the wild-type and the 'bud-flowering' type by histological analyses. Analysis of epidermal cell surface structure of vegetative tissues and perianth organs using scanning electron microscopy revealed that in wild-type flowers the outer whorls of colored organs may be identified as sepals, while the inner ones may be identified as petals. In the 'bud-flowering' type, two whorls of sepals are directly followed by the gynoecium. Both, petals and stamens, are completely missing in this flower type. The uppermost whorl of green leaves represents bracts in both flower types. In addition, two MADS-box genes (homologs of AP3/DEF and SEP1/2) were identified in C. vulgaris using RACE-PCR. Expression analysis by qRT-PCR was conducted for both genes in leaves, bracts, sepals and petals. These experiments revealed an expression pattern supporting the organ classification based on morphological characteristics. Conclusions Organ identity in both wild-type and 'bud-flowering' C. vulgaris was clarified using a combination of microscopic and molecular methods. Our results for bract, sepal and petal organ identity are supported by the 'ABCDE model'. However, loss of stamens in the 'bud-flowering' phenotype is an exceptional flower organ modification that cannot be explained by modified spatial expression of known organ identity genes. PMID:20003430

Molecular basis of floral petaloidy: insights from androecia of Canna indica

PubMed Central

Fu, Qian; Liu, Huanfang; Almeida, Ana M. R.; Kuang, Yanfeng; Zou, Pu; Liao, Jingping

2014-01-01

Floral organs that take on the characteristics of petals can occur in all whorls of the monocot order Zingiberales. In Canna indica, the most ornamental or ‘petaloid’ parts of the flowers are of androecial origin and are considered staminodes. However, the precise nature of these petaloid organs is yet to be determined. In order to gain a better understanding of the genetic basis of androecial identity, a molecular investigation of B- and C-class genes was carried out. Two MADS-box genes GLOBOSA (GLO) and AGAMOUS (AG) were isolated from young inflorescences of C. indica by 3′ rapid amplification of cDNA ends polymerase chain reaction (3′-RACE PCR). Sequence characterization and phylogenetic analyses show that CiGLO and CiAG belong to the B- and C-class MADS-box gene family, respectively. CiAG is expressed in petaloid staminodes, the labellum, the fertile stamen and carpels. CiGLO is expressed in petals, petaloid staminodes, the labellum, the fertile stamen and carpels. Expression patterns in mature tissues of CiGLO and CiAG suggest that petaloid staminodes and the labellum are of androecial identity, in agreement with their position within the flower and with described Arabidopsis thaliana expression patterns. Although B- and C-class genes are important components of androecial determination, their expression patterns are not sufficient to explain the distinct morphology observed in staminodes and the fertile stamen in C. indica. PMID:24876297

Radiobiological studies of plants orbited in Biosatellite II.

PubMed

Schairer, L A; Sparrow, A H; Marimuthu, K M

1970-01-01

The Biosatellite II Tradescantia experiment probed the effects of the space environment on spontaneous and radiation-induced mutation rates and on cytological changes in Tradescantia clone 02. Thirty two young flowering plants arranged in a plastic housing with the roots immersed in nutrient solution were exposed to gamma radiation from an on-board 85 Strontium source during the two-day orbital flight. Unirradiated plants were flown in a package in the spacecraft behind a tungsten radiation shield and identical non-flight control packages (with and without irradiation) were maintained at the launch site. After retrieval of the spacecraft near Hawaii, samples of root tip, ovary and stamen tissues were collected. These and the intact plants were flown to the Brookhaven National Laboratory for observations on the following end points: somatic mutation, cell size, loss of reproductive integrity resulting in stunted stamen hairs, pollen grain mortality, frequency of micronuclei in pollen, disturbed mitotic spindle function and chromosome aberrations. Analysis of data on somatic mutation, cell size and chromosome aberration end points showed no significant differences between flight and non-flight samples. However, pollen abortion, frequency of micronuclei in pollen and loss of reproductive integrity (stamen hair stunting) showed increases associated with weightlessness in irradiated material. Root tip and microspore cells showed effects of disturbed mitotic spindle function in orbited plants both with and without irradiation. Clearly differences exist between flight and non-flight material and the significance and possible mechanisms for these effects are being studied in continuing non-flight tests.

Critical Roles of Vacuolar Invertase in Floral Organ Development and Male and Female Fertilities Are Revealed through Characterization of GhVIN1-RNAi Cotton Plants1[OPEN

PubMed Central

2016-01-01

Seed number and quality are key traits determining plant fitness and crop yield and rely on combined competence in male and female fertilities. Sucrose metabolism is central to reproductive success. It remains elusive, though, how individual sucrose metabolic enzymes may regulate the complex reproductive processes. Here, by silencing vacuolar invertase (VIN) genes in cotton (Gossypium hirsutum) reproductive organs, we revealed diverse roles that VIN plays in multiple reproductive processes. A set of phenotypic and genetic studies showed significant reductions of viable seeds in GhVIN1-RNAi plants, attributed to pollination failure and impaired male and female fertilities. The former was largely owing to the spatial mismatch between style and stamen and delayed pollen release from the anthers, whereas male defects came from poor pollen viability. The transgenic stamen exhibited altered expression of the genes responsible for starch metabolism and auxin and jasmonic acid signaling. Further analyses identified the reduction of GhVIN expression in the seed coat as the major cause for the reduced female fertility, which appeared to disrupt the expression of some key genes involved in trehalose and auxin metabolism and signaling, leading to programmed cell death or growth repression in the filial tissues. Together, the data provide an unprecedented example of how VIN is required to synchronize style and stamen development and the formation of male and female fertilities for seed development in a crop species, cotton. PMID:26969720

Sex allocation and functional bias of quaternary and quinary flowers on same inflorescence in the hermaphrodite Ruta graveolens

NASA Astrophysics Data System (ADS)

Tang, Jing-Yu; Ren, Ming-Xun

2011-09-01

Intra-inflorescence variation in floral traits is important to understand the pollination function of an inflorescence and the real reproductive outputs of a plant. Ruta graveolens (Rutaceae) produce both quaternary (four petals and eight stamens) and quinary (five petals and ten stamens) flowers on the same cymes, while their pollination roles and the effects on the reproductive success remained unexplored. We experimentally examined the biomass of female versus male organs and pollen viability and stigma receptivity to explore the sex allocation patterns between the flowers. The breeding systems and reproductive outputs through either female function (seed set) or male function (pollen dispersal) were also studied for quinary and quaternary flowers to determine whether there was functional bias. The results showed that R. graveolens was protandrous, with a mixed mating system. Its stamens could slowly move one by one and only dehisce when positioning at the flower center, which could greatly enhance pollen dispersal. The first-opened quinary flower allocated significantly higher resources (dry biomass) in female organs while quaternary flowers allocated more resource in male organs. The quaternary flowers experienced higher pollen limitation in seed production but were more successful in pollen dispersal and the quinary flowers reproduced both through female and male functions. Our data suggested that quinary and quaternary flower on same inflorescence in R. graveolens functioned mainly as the sex role that most resources were allocated, which probably reflect an adaptation for floral phenology and pollination process in this plant.

Arabidopsis and Tobacco SUPERMAN regulate hormone signalling and mediate cell proliferation and differentiation

PubMed Central

Nibau, Candida; Di Stilio, Verónica S.; Wu, Hen-ming; Cheung, Alice Y.

2011-01-01

Arabidopsis thaliana SUPERMAN (SUP) plays an important role during flower development by maintaining the boundary between stamens and carpels in the inner two whorls. It was proposed that SUP maintains this boundary by regulating cell proliferation in both whorls, as loss-of-function superman mutants produce more stamens at the expense of carpels. However, the cellular mechanism that underlies SUP function remains unknown. Here Arabidopsis or tobacco (Nicotiana tabacum) SUP was overexpressed in tobacco plants to substantiate SUP's role as a regulator of cell proliferation and boundary definition and provide evidence that its biological role may be mediated via hormonal changes. It was found that moderate levels of SUP stimulated cell growth and proliferation, whereas high levels were inhibitory. SUP stimulated auxin- and cytokinin-regulated processes, and cells overexpressing SUP displayed reduced hormone dependency for proliferation and regeneration into plants. SUP also induced proliferation of female traits in the second and third flower whorls and promoted differentiation of petaloid properties in sepals, further supporting a role for SUP as a boundary regulator. Moreover, cytokinin suppressed stamen development and promoted differentiation of carpeloid tissues, suggesting that SUP may regulate male and female development via its effect on cytokinin signalling. Taken together, these observations suggest a model whereby the effect of SUP on cell growth and proliferation involves the modulation of auxin- and cytokinin-regulated processes. Furthermore, differential SUP expression or different sensitivities of different cell types to SUP may determine whether SUP stimulates or suppresses their proliferation. PMID:20980362

The evolution of sex ratio differences and inflorescence architectures in Begonia (Begoniaceae).

PubMed

Twyford, Alex D; Ennos, Richard A; White, Chris D; Ali, Mobina Shaukat; Kidner, Catherine A

2014-02-01

A major benefit conferred by monoecy is the ability to alter floral sex ratio in response to selection. In monoecious species that produce flowers of a given sex at set positions on the inflorescence, floral sex ratio may be related to inflorescence architecture. We studied the loci underlying differences in inflorescence architecture between two monoecious Begonia species and related this to floral sex ratios. We performed trait comparisons and quantitative trait locus (QTL) mapping in a segregating backcross population between Central American Begonia plebeja and B. conchifolia. We focused on traits related to inflorescence architecture, sex ratios, and other reproductive traits. The inflorescence branching pattern of B. conchifolia was more asymmetric than B. plebeja, which in turn affects the floral sex ratio. Colocalizing QTLs of moderate effect influenced both the number of male flowers and the fate decisions of axillary meristems, demonstrating the close link between inflorescence architecture and sex ratio. Additional QTLs were found for stamen number (30% variance explained, VE) and pollen sterility (12.3% VE). One way in which Begonia species develop different floral sex ratios is through modifications of their inflorescence architecture. The potential pleiotropic action of QTL on inflorescence branching and floral sex ratios may have major implications for trait evolution and responses to selection. The presence of a single QTL of large effect on stamen number may allow rapid divergence for this key floral trait. We propose candidate loci for stamen number and inflorescence branching for future characterization.

Ontogeny of floral organs in flax (Linum usitatissimum; Linaceae).

PubMed

Schewe, Lauren C; Sawhney, Vipen K; Davis, Arthur R

2011-07-01

Flax (Linum usitatissimum) is an important crop worldwide; however, a detailed study on flower development of this species is lacking. Here we describe the pattern of initiation and a program of key developmental events in flax flower ontogeny. This study provides important fundamental information for future research in various aspects of flax biology and biotechnology. Floral buds and organs were measured throughout development and examined using scanning electron microscopy. Floral organs were initiated in the following sequence: sepals, stamens and petals, gynoecium, and nectaries. The five sepals originated in a helical pattern, followed evidently by simultaneous initiation of five stamens and five petals, the former opposite of the sepals and the latter alternate to them. The gynoecium, with five carpels, was produced from the remaining, central region of the floral apex. Stamens at early stages were dominated by anther growth but filaments elongated rapidly shortly before anthesis. Early gynoecium development occurred predominantly in the ovary, and ovule initiation began prior to enclosure of carpels. A characteristic feature was the twisted growth of styles, accompanied by the differentiation of papillate stigmas. Petal growth lagged behind that of other floral organs, but petals eventually grew rapidly to enclose the inner whorls after style elongation. Flask-shaped nectaries bearing stomata developed on the external surface of the filament bases. This is the first detailed study on flax floral organ development and has established a key of 12 developmental stages, which should be useful to flax researchers.

Defensive strategies in Geranium sylvaticum. Part 1: organ-specific distribution of water-soluble tannins, flavonoids and phenolic acids.

PubMed

Tuominen, Anu; Toivonen, Eija; Mutikainen, Pia; Salminen, Juha-Pekka

2013-11-01

A combination of high-resolution mass spectrometry and modern HPLC column technology, assisted by diode array detection, was used for accurate characterization of water-soluble polyphenolic compounds in the pistils, stamens, petals, sepals, stems, leaves, roots and seeds of Geranium sylvaticum. The organs contained a large variety of polyphenols, five types of tannins (ellagitannins, proanthocyanidins, gallotannins, galloyl glucoses and galloyl quinic acids) as well as flavonoids and simple phenolic acids. In all, 59 compounds were identified. Geraniin and other ellagitannins dominated in all the green photosynthetic organs. The other organs seem to produce distinctive polyphenol groups: pistils accumulated gallotannins; petals acetylglucose derivatives of galloylglucoses; stamens kaempferol glycosides, and seeds and roots accumulated proanthocyanidins. The intra-plant distribution of the different polyphenol groups may reflect the different functions and importance of various types of tannins as the defensive chemicals against herbivory. Copyright © 2013 Elsevier Ltd. All rights reserved.

Critical Roles of Vacuolar Invertase in Floral Organ Development and Male and Female Fertilities Are Revealed through Characterization of GhVIN1-RNAi Cotton Plants.

PubMed

Wang, Lu; Ruan, Yong-Ling

2016-05-01

Seed number and quality are key traits determining plant fitness and crop yield and rely on combined competence in male and female fertilities. Sucrose metabolism is central to reproductive success. It remains elusive, though, how individual sucrose metabolic enzymes may regulate the complex reproductive processes. Here, by silencing vacuolar invertase (VIN) genes in cotton (Gossypium hirsutum) reproductive organs, we revealed diverse roles that VIN plays in multiple reproductive processes. A set of phenotypic and genetic studies showed significant reductions of viable seeds in GhVIN1-RNAi plants, attributed to pollination failure and impaired male and female fertilities. The former was largely owing to the spatial mismatch between style and stamen and delayed pollen release from the anthers, whereas male defects came from poor pollen viability. The transgenic stamen exhibited altered expression of the genes responsible for starch metabolism and auxin and jasmonic acid signaling. Further analyses identified the reduction of GhVIN expression in the seed coat as the major cause for the reduced female fertility, which appeared to disrupt the expression of some key genes involved in trehalose and auxin metabolism and signaling, leading to programmed cell death or growth repression in the filial tissues. Together, the data provide an unprecedented example of how VIN is required to synchronize style and stamen development and the formation of male and female fertilities for seed development in a crop species, cotton. © 2016 American Society of Plant Biologists. All Rights Reserved.

Effects of tissue-preparation-induced callose synthesis on estimates of plasmodesma size exclusion limits.

PubMed

Radford, J E; White, R G

2001-01-01

Plasmodesmata are often characterised by their size exclusion limit (SEL), which is the molecular weight of the largest dye, introduced by microinjection, that will move from cell to cell. In this study, we investigated whether commonly used techniques for isolation and manipulation of tissues, and microinjection of fluorescent dyes, affected the SEL, and whether any such effects could be ameliorated by inhibiting callose deposition. We examined young root epidermal cells of Arabidopsis thaliana and staminal hair cells of Tradescantia virginiana, two tissues often used in experiments on symplastic transport. Transport in root tips dissected from the main plant body and in stamen hairs removed from the base of the stamen filament was compared with transport in undissected roots and stamen hairs attached to the base of the filament, respectively. Tissues were microinjected with fluorescent dyes (457 Da to > 3 kDa) with or without prior incubation in the callose deposition inhibitors 2-deoxy-D-glucose or aniline blue fluorochrome. In both tissues, dissection reduced the SEL, which was largely prevented by prior incubation in 2-deoxy-D-glucose but not by incubation in aniline blue fluorochrome. Thus, standard methods for tissue preparation can cause sufficient callose deposition to reduce cell-to-cell transport, and this needs to be considered in studies employing microinjection. Introduction of the dyes by pressure injection rather than iontophoresis decreased the SEL in A. thaliana but increased it in T. virginiana, showing that these two injection techniques do not necessarily give identical results and that plasmodesmata in different tissues may respond differently to similar experimental procedures.

Allocation to male vs female floral function varies by currency and responds differentially to density and moisture stress.

PubMed

Brock, M T; Winkelman, R L; Rubin, M J; Edwards, C E; Ewers, B E; Weinig, C

2017-11-01

Allocation of finite resources to separate reproductive functions is predicted to vary across environments and affect fitness. Biomass is the most commonly measured allocation currency; however, in comparison with nutrients it may be less limited and express different environmental and evolutionary responses. Here, we measured carbon, nitrogen, phosphorus, and biomass allocation among floral whorls in recombinant inbred lines of Brassica rapa in multiple environments to characterize the genetic architecture of floral allocation, including its sensitivity to environmental heterogeneity and to choice of currency. Mass, carbon, and nitrogen allocation to female whorls (pistils and sepals) decreased under high density, whereas nitrogen allocation to male organs (stamens) decreased under drought. Phosphorus allocation decreased by half in pistils under drought, while stamen phosphorus was unaffected by environment. While the contents of each currency were positively correlated among whorls, selection to improve fitness through female (or male) function typically favored increased allocation to pistils (or stamens) but decreased allocation to other whorls. Finally, genomic regions underlying correlations among allocation metrics were mapped, and loci related to nitrogen uptake and floral organ development were located within mapped quantitative trait loci. Our candidate gene identification suggests that nutrient uptake may be a limiting step in maintaining male allocation. Taken together, allocation to male vs female function is sensitive to distinct environmental stresses, and the choice of currency affects the interpretation of floral allocation responses to the environment. Further, genetic correlations may counter the evolution of allocation patterns that optimize fitness through female or male function.

Tropism in azalea and lily flowers

NASA Astrophysics Data System (ADS)

Shimizu, M.; Tomita-Yokotani, K.; Nakamura, T.; Yamashita, M.

Flowers have coevolved with pollinator animals. Some flowers have the up-down directional features in their form and orientation, which results the higher success of pollination under the influence of gravity. Azalea, Rhododendron pulchrum, flower responds against gravity, and orients the specific petal at its top. This petal with honey mark guides pollinator animals to nectary of the flower. Pistil and stamen bend upward by sensing gravity, and increase probability of their contact with pollinator. There was large sediment amyloplast found in sectioned tissue of style. In addition to this action of gravity, phototropic response was also observed at lesser degree, while the gravitational cue was removed by the 3D-clinorotation of the plant. In contrast to azalea, pistil of lily flower senses light in order to determine the direction of bending. Lily, Lilium cv. 'Casablanca', tepals open horizontally or slightly inclined downward. After its anthesis, pistil and stamen start to bend upward by light. Gravity induced no tropic response at all, evidenced by the experiment conducted under dark. Sediment amyloplast was not found in lily style. Phototropic response of pistil and stamen in lily was activated by blue light even at lower energy density. On the other hand, red light was not effective to induce the tropic response even with substantial energy density. This action spectrum of light agreed with those for the phototropism shown in coleoptile of monocotyledonous plants. Because the tropism of style was not hindered at removal of stigma, reception site for incident light is neither restricted to stigma nor its close vicinity, but distributes through style. The process of lily pistil elongation was analyzed in details to identify the site of its initiation and propagation of bending movement through the anthesis period. Elongation started at basal part of pistil and propagated towards its top after opening of perianth. Steep bending occurred at the basal zone of pistil as long as differential incidence of light was given at its part. Elongation and bending of filament of stamen in lily differed from those of style in several points. After perianth opened, filaments deployed and spread out from the central axis of flower. Distinctive elongation of filament developed at a zone close to anther. It will be discussed how such regulation made by either gravity or light improves the degree of adaptation for those plants during entomophilous pollination.

A LEAFY co-regulator encoded by UNUSUAL FLORAL ORGANS.

PubMed

Lee, I; Wolfe, D S; Nilsson, O; Weigel, D

1997-02-01

. Development of petals and stamens in Arabidopsis flowers requires the function of the organ-identity gene APETALA3 (AP3), whose RNA is expressed specifically in petal and stamen primordia. AP3 expression is positively regulated by the meristem-identity gene LEAFY (LFY), which is expressed ubiquitously in young flowers. It is unknown how the transition from ubiquitous expression of LFY to region-specific expression of AP3 is made. It has previously been proposed for Antirrhinum that another gene, FIMBRIATA (FIM), mediates between the LFY and AP3 orthologs, with the three genes acting in a simple regulatory hierarchy. FIM is activated later than the LFY ortholog, and its expression is more restricted than that of the LFY ortholog. . We have tested whether the model proposed for Antirrhinum applies to Arabidopsis, by creating transgenic plants in which the FIM ortholog UNUSUAL FLORAL ORGANS (UFO) was expressed constitutively from the promoter of the cauliflower mosaic virus 35S gene. In 35S::UFO flowers, AP3 was expressed precociously and ectopically, confirming that UFO is an upstream regulator of AP3. However, 35S::UFO could not restore petal and stamen development in lfy mutants, indicating that UFO can only function in the presence of LFY activity. The failure of 35S::UFO to rescue lfy mutants is consistent with our observation that UFO expression levels are not markedly changed in lfy mutants. . We conclude that UFO is not a simple mediator between meristem- and organ-identity genes, but is likely to be a partially dispensable co-regulator that acts together with LFY. The interplay between LFY and UFO provides a paradigm for how a global regulator such as LFY activates selected target genes only in restricted regions within its expression domain.

The genetics of reproductive organ morphology in two Petunia species with contrasting pollination syndromes.

PubMed

Hermann, Katrin; Klahre, Ulrich; Venail, Julien; Brandenburg, Anna; Kuhlemeier, Cris

2015-05-01

Switches between pollination syndromes have happened frequently during angiosperm evolution. Using QTL mapping and reciprocal introgressions, we show that changes in reproductive organ morphology have a simple genetic basis. In animal-pollinated plants, flowers have evolved to optimize pollination efficiency by different pollinator guilds and hence reproductive success. The two Petunia species, P. axillaris and P. exserta, display pollination syndromes adapted to moth or hummingbird pollination. For the floral traits color and scent, genetic loci of large phenotypic effect have been well documented. However, such large-effect loci may be typical for shifts in simple biochemical traits, whereas the evolution of morphological traits may involve multiple mutations of small phenotypic effect. Here, we performed a quantitative trait locus (QTL) analysis of floral morphology, followed by an in-depth study of pistil and stamen morphology and the introgression of individual QTL into reciprocal parental backgrounds. Two QTLs, on chromosomes II and V, are sufficient to explain the interspecific difference in pistil and stamen length. Since most of the difference in organ length is caused by differences in cell number, genes underlying these QTLs are likely to be involved in cell cycle regulation. Interestingly, conservation of the locus on chromosome II in a different P. axillaris subspecies suggests that the evolution of organ elongation was initiated on chromosome II in adaptation to different pollinators. We recently showed that QTLs for pistil and stamen length on chromosome II are tightly linked to QTLs for petal color and volatile emission. Linkage of multiple traits will enable major phenotypic change within a few generations in hybridizing populations. Thus, the genomic architecture of pollination syndromes in Petunia allows for rapid responses to changing pollinator availability.

Molecular evolution and patterns of duplication in the SEP/AGL6-like lineage of the Zingiberales: a proposed mechanism for floral diversification.

PubMed

Yockteng, Roxana; Almeida, Ana M R; Morioka, Kelsie; Alvarez-Buylla, Elena R; Specht, Chelsea D

2013-11-01

The diversity of floral forms in the plant order Zingiberales has evolved through alterations in floral organ morphology. One striking alteration is the shift from fertile, filamentous stamens to sterile, laminar (petaloid) organs in the stamen whorls, attributed to specific pollination syndromes. Here, we examine the role of the SEPALLATA (SEP) genes, known to be important in regulatory networks underlying floral development and organ identity, in the evolution of development of the diverse floral organs phenotypes in the Zingiberales. Phylogenetic analyses show that the SEP-like genes have undergone several duplication events giving rise to multiple copies. Selection tests on the SEP-like genes indicate that the two copies of SEP3 have mostly evolved under balancing selection, probably due to strong functional restrictions as a result of their critical role in floral organ specification. In contrast, the two LOFSEP copies have undergone differential positive selection, indicating neofunctionalization. Reverse transcriptase-polymerase chain reaction, gene expression from RNA-seq data, and in situ hybridization analyses show that the recovered genes have differential expression patterns across the various whorls and organ types found in the Zingiberales. Our data also suggest that AGL6, sister to the SEP-like genes, may play an important role in stamen morphology in the Zingiberales. Thus, the SEP-like genes are likely to be involved in some of the unique morphogenetic patterns of floral organ development found among this diverse order of tropical monocots. This work contributes to a growing body of knowledge focused on understanding the role of gene duplications and the evolution of entire gene networks in the evolution of flower development.

Mutagenic interactions between X-rays and two promutagens, o-phenylenediamine and N-nitrosodimethylamine, in the stamen hairs of Tradescantia clone BNL 4430.

PubMed

Xiao, L Z; Ichikawa, S

1998-03-16

Mutagenic interactions between X-rays and two promutagens, o-phenylenediamine (PDA) and N-nitrosodimethylamine (DMN), were studied in the stamen hairs of Tradescantia clone BNL 4430, a blue/pink heterozygote. The young inflorescence-bearing shoots with roots of this clone cultivated in a nutrient solution circulating growth chamber were used as tester plants. After determining dose-response curves for X-rays. PDA and DMN, combined treatments with PDA or DMN and X-rays were conducted, exposing acutely to X-rays 20 h before starting, at the midpoint of, or 20 h after completing the PDA or DMN treatments for 4 h. Clear synergistic effects in inducing somatic pink mutations were detected when X-rays were irradiated before the PDA or DMN treatments, resembling those confirmed earlier between maleic hydrazide (MH) and X-rays. On the contrary, clear antagonistic effects were observed when X-rays were given after the PDA or DMN treatments, also resembling those between MH and X-rays. When X-rayed at the midpoint of the PDA or DMN treatments, merely additive and synergistic effects were observed, respectively, differing from the antagonistic effects between MH and X-rays. The mutagenic synergisms detected were considered to be the results of interactions between DNA strand breaks (and the resultant chromosome breaks) induced by X-rays and those by PDA or DMN, whereas the mutagenic antagonisms observed were presumed to be due to X-ray-caused inhibition of the activation of PDA and DMN in the stamen-hair cells. The time periods required for penetrations into floral tissues and/or activations into mutagens seem different among PDA, DMN and MH. Copyright 1998 Elsevier Science B.V.

Timing of pollen release and stigma receptivity period of Piper vicosanum: New insights into sexual reproduction of the genus.

PubMed

Valentin-Silva, Adriano; Coelho, Victor Peçanha de Miranda; Ventrella, Marília Contin; Vieira, Milene Faria

2015-04-01

Dichogamy is a common characteristic among angiosperms, including Piper species. In this genus, the tiny flowers are morphologically similar and have an asynchronous stamen development. However, there is no information on the duration of stigma receptivity and whether it overlaps with pollen release. To better understand mechanisms of floral function in Piper vicosanum, we provide a detailed characterization of the timing of pollen release from the four stamens and the period of stigma receptivity and exposure mode of the receptive areas. We investigated plants of a natural population in a semideciduous seasonal forest (Viçosa, Minas Gerais State, southeastern Brazil), based on chemical tests, light microscopy, and scanning electron microscopy analyses. Incomplete protogyny-a mechanism that favors outcrossing-was recorded. The period of stigma receptivity was long (14 d), and the sequential exposure and senescence of stigmatic papillae occurred gradually and in a basipetal direction. Pollen release began 2-6 d after the beginning of the pistillate phase, with an average pollen viability of 87.7%, during the bisexual flower phase. Pollen was released for up to 6 d and occurred in one stamen at a time. The fruit set observed in tests of self-pollination indicated self-compatibility. The gradual and sequential exposure of stigmatic papillae in P. vicosanum flowers is described here as the mechanism for the long duration of receptivity. Anther development and pollen release were also sequential. These findings are yet unreported reproductive characteristics of the genus and offer new perspectives for future studies on the floral biology of other Piper species. © 2015 Botanical Society of America, Inc.

Effects of abscisic acid on ethylene biosynthesis and perception in Hibiscus rosa-sinensis L. flower development

PubMed Central

Trivellini, Alice; Ferrante, Antonio; Vernieri, Paolo; Serra, Giovanni

2011-01-01

The effect of the complex relationship between ethylene and abscisic acid (ABA) on flower development and senescence in Hibiscus rosa-sinensis L. was investigated. Ethylene biosynthetic (HrsACS and HrsACO) and receptor (HrsETR and HrsERS) genes were isolated and their expression evaluated in three different floral tissues (petals, style–stigma plus stamens, and ovaries) of detached buds and open flowers. This was achieved through treatment with 0.1 mM 1-aminocyclopropane-1-carboxylic acid (ACC) solution, 500 nl l−1 methylcyclopropene (1-MCP), and 0.1 mM ABA solution. Treatment with ACC and 1-MCP confirmed that flower senescence in hibiscus is ethylene dependent, and treatment with exogenous ABA suggested that ABA may play a role in this process. The 1-MCP impeded petal in-rolling and decreased ABA content in detached open flowers after 9 h. This was preceded by an earlier and sequential increase in ABA content in 1-MCP-treated petals and style–stigma plus stamens between 1 h and 6 h. ACC treatment markedly accelerated flower senescence and increased ethylene production after 6 h and 9 h, particularly in style–stigma plus stamens. Ethylene evolution was positively correlated in these floral tissues with the induction of the gene expression of ethylene biosynthetic and receptor genes. Finally, ABA negatively affected the ethylene biosynthetic pathway and tissue sensitivity in all flower tissues. Transcript abundance of HrsACS, HrsACO, HrsETR, and HrsERS was reduced by exogenous ABA treatment. This research underlines the regulatory effect of ABA on the ethylene biosynthetic and perception machinery at a physiological and molecular level when inhibitors or promoters of senescence are exogenously applied. PMID:21841180

Activation of the Arabidopsis B class homeotic genes by APETALA1.

PubMed

Ng, M; Yanofsky, M F

2001-04-01

Proper development of petals and stamens in Arabidopsis flowers requires the activities of APETALA3 (AP3) and PISTILLATA (PI), whose transcripts can be detected in the petal and stamen primordia. Localized expression of AP3 and PI requires the activities of at least three genes: APETALA1 (AP1), LEAFY (LFY), and UNUSUAL FLORAL ORGANS (UFO). It has been proposed that UFO provides spatial cues and that LFY specifies competence for AP3 and PI expression in the developing flower. To understand the epistatic relationship among AP1, LFY, and UFO in regulating AP3 and PI expression, we generated two versions of AP1 that have strong transcriptional activation potential. Genetic and molecular analyses of transgenic plants expressing these activated AP1 proteins show that the endogenous AP1 protein acts largely as a transcriptional activator in vivo and that AP1 specifies petals by regulating the spatial domains of AP3 and PI expression through UFO.

Ectopic expression of pMADS3 in transgenic petunia phenocopies the petunia blind mutant.

PubMed Central

Tsuchimoto, S; van der Krol, A R; Chua, N H

1993-01-01

We cloned a MADS-box gene, pMADS3, from Petunia hybrida, which shows high sequence homology to the Arabidopsis AGAMOUS and Antirrhinum PLENA. pMADS3 is expressed exclusively in stamens and carpels of wild-type petunia plants. In the petunia mutant blind, which shows homeotic conversions of corolla limbs into antheroid structures with pollen grains and small parts of sepals into carpelloid tissue, pMADS3 is expressed in all floral organs as well as in leaves. Ectopic expression of pMADS3 in transgenic petunia leads to phenocopies of the blind mutant, i.e., the formation of antheroid structures on limbs and carpelloid tissue on sepals. Transgenic tobacco plants that overexpress pMADS3 exhibit an even more severe phenotype, with the sepals forming a carpel-like structure encasing the interior floral organs. Our results identify BLIND as a negative regulator of pMADS3, which specifies stamens and carpels during petunia flower development. PMID:8104573

Overexpression of a novel chrysanthemum SUPERMAN-like gene in tobacco affects lateral bud outgrowth and flower organ development.

PubMed

Liu, Qing-Lin; Xu, Ke-Dong; Ma, Nan; Zhao, Liang-Jun; Xi, Lin

2014-04-01

Previous studies have shown that the SUP genes play important roles in flower development and plant growth and morphogenesis. In this study, we isolated and characterized a SUPERMAN-like gene DgSZFP from chrysanthemum. DgSZFP contains one conserved Cys2/His2-type zinc finger motifs in the N-terminal region and an EAR-box in C-terminus. Its expression was significantly higher in nodes, flower buds, disc stamens, and petals than in the other tissues. Overexpression of DgSZFP in tobacco resulted in enhanced branching, reduced plant height, increased the width of petal tubes, produced the staminoid petals and petaloid stamens in flowers, and enhanced the seed weight and size. In addition, DgSZFP-overexpression tobacco plants accumulated high concentrations of cytokinin and chlorophyll. These results suggest that DgSZFP may be the candidate gene for regulating branching and floral organ development in chrysanthemum. Crown Copyright © 2014. Published by Elsevier Masson SAS. All rights reserved.

The evolution of floral biology in basal angiosperms

PubMed Central

Endress, Peter K.

2010-01-01

In basal angiosperms (including ANITA grade, magnoliids, Choranthaceae, Ceratophyllaceae) almost all bisexual flowers are dichogamous (with male and female functions more or less separated in time), and nearly 100 per cent of those are protogynous (with female function before male function). Movements of floral parts and differential early abscission of stamens in the male phase are variously associated with protogyny. Evolution of synchronous dichogamy based on the day/night rhythm and anthesis lasting 2 days is common. In a few clades in Magnoliales and Laurales heterodichogamy has also evolved. Beetles, flies and thrips are the major pollinators, with various degrees of specialization up to large beetles and special flies in some large-flowered Nymphaeaceae, Magnoliaceae, Annonaceae and Aristolochiaceae. Unusual structural specializations are involved in floral biological adaptations (calyptras, inner staminodes, synandria and food bodies, and secretory structures on tepals, stamens and staminodes). Numerous specializations that are common in monocots and eudicots are absent in basal angiosperms. Several families are poorly known in their floral biology. PMID:20047868

Master Regulatory Genes, Auxin Levels, and Sexual Organogeneses in the Dioecious Plant Mercurialis annua

PubMed Central

Hamdi, Saïd; Teller, Gerard; Louis, Jean-Paul

1987-01-01

In Mercurialis annua L. (2n = 16) genes for sex determination are considered as major regulator genes controlling stamen and ovary development and sexual phenotypes. After stamen induction, sterility determinants control sporogenous tissue and pollen formation. Moreover, exogenous auxins are able to induce male flowers on female plants. In order to verify if sex and sterility genes have an effect on indole-3-acetic acid (IAA) contents of these plants, various wild or genetically constructed strains were assayed. The IAA levels of their apices were determined by HPLC followed by gas chromatography, selected ion monitoring, mass spectrometry. Results show that high auxin levels are linked to male phenotypes. The genes inducing maleness and the determinants of restored male fertility appear to control and modulate the IAA content. Close correspondence between the number of these dominant genes and IAA levels was established. A final hypothesis about the control of sexual specialization by phytohormones induced by the presence of these genes is discussed. Images Fig. 4 PMID:16665709

Multilocus genotyping of a ‘Candidatus Phytoplasma aurantifolia’-related strain associated with cauliflower phyllody disease in China

USDA-ARS?s Scientific Manuscript database

A new cauliflower disease characterized by formation of leaf-like inflorescences and malformed flowers occurred in a seed production filed located in Yunnan, a southwest province of China. In the diseased plants, floral organs in three inner whorls (petals, carpels, and stamens) were under-develope...

Tamarix chinensis Lour.: saltcedar or five-stamen tamarisk

Treesearch

Wayne D. Shepperd

2008-01-01

Saltcedar (Tamarix chinensis (Lour.)) and smallflower tamarisk (T. parviflora DC.) hybridize in the Southwest (Baum 1967; Horton and Campbell 1974) and are deciduous, pentamerous tamarisks that are both commonly referred to as saltcedar. Saltcedar is a native of Eurasia that has naturalized in the southwestern United States within the last century. It was introduced...

Assessment of the genotoxicity of 137Cs radiation using Vicia-micronucleus, Tradescantia-micronucleus and Tradescantia-stamen-hair mutation bioassays.

PubMed

Minouflet, Marion; Ayrault, Sophie; Badot, Pierre-Marie; Cotelle, Sylvie; Ferard, Jean-François

2005-01-01

Since the middle of the 20th century, ionizing radiations from radioactive isotopes including 137Cs have been investigated to determine their genotoxic impact on living organisms. The present study was designed to compare the effectiveness of three plant bioassays to assess DNA damage induced by low doses of 137Cs: Vicia-micronucleus test (Vicia-MCN), Tradescantia-micronucleus test (Trad-MCN) and Tradescantia-stamen-hair mutation test (Trad-SH) were used. Vicia faba (broad bean) and Tradescantia clone 4430 (spiderwort) were exposed to 137Cs according to different scenarios: external and internal (contamination) irradiations. Experiments were conducted with various levels of radioactivity in solution or in soil, using solid or liquid 137Cs sources. The three bioassays showed different sensitivities to the treatments. Trad-MCN appeared to be the most sensitive test (significative response from 1.5 kBq/200 ml after 30 h of contamination). Moreover, at comparable doses, internal irradiations led to larger effects for the three bioassays. These bioassays are effective tests for assessing the genotoxic effects of radioactive 137Cs pollution.

Floral and Inflorescence Morphology and Ontogeny in Beta vulgaris, with Special Emphasis on the Ovary Position

PubMed Central

Olvera, Hilda Flores; Smets, Erik; Vrijdaghs, Alexander

2008-01-01

Background and Aims In spite of recent phylogenetic analyses for the Chenopodiaceae–Amaranthaceae complex, some morphological characters are not unambiguously interpreted, which raises homology questions. Therefore, ontogenetic investigations, emphasizing on ‘bracteoles’ in Atripliceae and flowers in Chenopodioideae, were conducted. This first paper presents original ontogenetic observations in Beta vulgaris, which was chosen as a reference species for further comparative investigation because of its unclarified phylogenetic position and its flowers with a (semi-)inferior ovary, whereas all other Chenopodiaceae–Amaranthaceae have hypogynous flowers. Methods Inflorescences and flowers were examined using scanning electron microscopy and light microscopy. Key Results Floral development starts from an inflorescence unit primordium subtended by a lateral bract. This primordium develops into a determinate axis on which two opposite lateral flowers originate, each subtended by a bracteole. On a flower primordium, first five tepal primordia appear, followed by five opposite stamen primordia. Simultaneously, a convex floral apex appears, which differentiates into an annular ovary primordium with three stigma primordia, surrounding a central, single ovule. A floral tube, which raises the outer floral whorls, envelops the ovary, resulting in a semi-inferior ovary at mature stage. Similarly, a stamen tube is formed, raising the insertion points of the stamens, and forming a staminal ring, which does not contain stomata. During floral development, the calyces of the terminal flower and of one of the lateral flowers often fuse, forming a compound fruit structure. Conclusions In Beta vulgaris, the inflorescence is compound, consisting of an indeterminate main axis with many elementary dichasia as inflorescence units, of which the terminal flower and one lateral flower fuse at a later stage. Floral parts develop starting from the outer whorl towards the gynoecium. Because of the formation of an epigynous hypanthium, the ovary becomes semi-inferior in the course of floral development. PMID:18694878

Analysis of the APETALA3- and PISTILLATA-like genes in Hedyosmum orientale (Chloranthaceae) provides insight into the evolution of the floral homeotic B-function in angiosperms

PubMed Central

Liu, Shujun; Sun, Yonghua; Du, Xiaoqiu; Xu, Qijiang; Wu, Feng; Meng, Zheng

2013-01-01

Background and Aims According to the floral ABC model, B-function genes appear to play a key role in the origin and diversification of the perianth during the evolution of angiosperms. The basal angiosperm Hedyosmum orientale (Chloranthaceae) has unisexual inflorescences associated with a seemingly primitive reproductive morphology and a reduced perianth structure in female flowers. The aim of this study was to investigate the nature of the perianth and the evolutionary state of the B-function programme in this species. Methods A series of experiments were conducted to characterize B-gene homologues isolated from H. orientale, including scanning electron microscopy to observe the development of floral organs, phylogenetic analysis to reconstruct gene evolutionary history, reverse transcription–PCR, quantitative real-time PCR and in situ hybridization to identify gene expression patterns, the yeast two-hybrid assay to explore protein dimerization affinities, and transgenic analyses in Arabidopsis thaliana to determine activities of the encoded proteins. Key Results The expression of HoAP3 genes was restricted to stamens, whereas HoPI genes were broadly expressed in all floral organs. HoAP3 was able to partially restore the stamen but not petal identity in Arabidopsis ap3-3 mutants. In contrast, HoPI could rescue aspects of both stamen and petal development in Arabidopsis pi-1 mutants. When the complete C-terminal sequence of HoPI was deleted, however, no or weak transgenic phenotypes were observed and homodimerization capability was completely abolished. Conclusions The results suggest that Hedyosmum AP3-like genes have an ancestral function in specifying male reproductive organs, and that the activity of the encoded PI-like proteins is highly conserved between Hedyosmum and Arabidopsis. Moreover, there is evidence that the C-terminal region is important for the function of HoPI. Our findings indicate that the development of the proposed perianth in Hedyosmum does not rely on the B homeotic function. PMID:23956161

The corona of the daffodil Narcissus bulbocodium is distinct from the orthodox floral whorls.

USDA-ARS?s Scientific Manuscript database

The structural homology of the daffodil corona has remained a source of confusion throughout the history of botany. Over the years it has been separately referred to as a modified petal stipule, stamen and tepal. Here we provide new insights from anatomy and molecular studies to clarify the early de...

Two similar but distinct second intron fragments from tobacco AGAMOUS homologs confer identical floral organ-specific expression sufficient for generating complete sterility in plants

USDA-ARS?s Scientific Manuscript database

The carpel- and stamen-specific AtAGIP promoter derived from the Arabidopsis AGAMOUS (AG) second intron/enhancer is ideal for engineering complete sterility, but it is highly host-specific. To ascertain that a chimeric promoter with similar tissue specificity can be created for species other than A...

Synergistic effects of N-ethyl-N-nitrosourea (an alkylating agent with a low Swain-Scott substrate constant) and X-rays in the stamen hairs of Tradescantia clone BNL 4430.

PubMed

Shima, N; Ichikawa, S

1997-01-01

The mutagenic interaction between N-ethyl-N-nitrosourea (ENU) and X-rays was tested in the stamen hairs of Tradescantia clone BNL 4430, a blue/pink heterozygote. ENU, a monofunctional alkylating agent with a low Swain-Scott substrate constant (s) of 0.26, exhibited a strong cytotoxicity. ENU-induced somatic pink mutation frequency per 10(4) hair-cell divisions increased with increasing ENU dose, with a slope of 1.243 on a log-log graph, the slope value being similar to that for X-ray-induced mutation frequency. Three out of five combined treatments with ENU and X-rays produced mutation frequencies significantly higher than those expected from the additive effects of the two mutagens. Clear synergistic effects were detected when relatively higher X-ray doses were applied, resembling those confirmed earlier between methyl methanesulfonate (MMS) and X-rays, although the s value for ENU is very much smaller than that (0.88) for MMS. It is therefore concluded that mutagenic interactions between alkylating agents and X-rays do not have any clear relationship with the s values.

The ASK1 gene regulates development and interacts with the UFO gene to control floral organ identity in Arabidopsis.

PubMed

Zhao, D; Yang, M; Solava, J; Ma, H

1999-09-01

Normal flower development likely requires both specific and general regulators. We have isolated an Arabidopsis mutant ask1-1 (for -Arabidopsis skp1-like1-1), which exhibits defects in both vegetative and reproductive development. In the ask1-1mutant, rosette leaf growth is reduced, resulting in smaller than normal rosette leaves, and internodes in the floral stem are shorter than normal. Examination of cell sizes in these organs indicates that cell expansion is normal in the mutant, but cell number is reduced. In the mutant, the numbers of petals and stamens are reduced, and many flowers have one or more petals with a reduced size. In addition, all mutant flowers have short stamen filaments. Furthermore, petal/stamen chimeric organs are found in many flowers. These results indicate that the ASK1 gene affects the size of vegetative and floral organs. The ask1 floral phenotype resembles somewhat that of the Arabidopsis ufo mutants in that both genes affect whorls 2 and 3. We therefore tested for possible interactions between ASK1 and UFO by analyzing the phenotypes of ufo-2 ask1-1 double mutant plants. In these plants, vegetative development is similar to that of the ask1-1 single mutant, whereas the floral defects are more severe than those in either single mutant. Interior to the first whorl, the double mutant flowers have more sepals or sepal-like organs than are found in ufo-2, and less petals than ask1-1. Our results suggest that ASK1 interacts with UFO to control floral organ identity in whorls 2 and 3. This is very intriguing because ASK1 is very similar in sequence to the yeast SKP1 protein and UFO contains an F-box, a motif known to interact with SKP1 in yeast. Although the precise mechanism of ASK1 and UFO action is unknown, our results support the hypothesis that these two proteins physically interact in vivo. Copyright 1999 Wiley-Liss, Inc.

Unveiling the osmophores of Philodendron adamantinum (Araceae) as a means to understanding interactions with pollinators.

PubMed

Gonçalves-Souza, Patrícia; Schlindwein, Clemens; Dötterl, Stefan; Paiva, Elder Antônio Sousa

2017-03-01

Araceae species pollinated by nocturnal Cyclocephalini beetles attract their pollinators by inflorescence scents. In Philodendron , despite the intense odour, the osmophores exhibit no definite morphological identity, making them difficult to locate. This may explain why structural studies of the scent-releasing tissue are not available so far. Several approaches were employed for locating and understanding the osmophores of Philodendron adamantinum . A sensory test allowed other analyses to be restricted to fertile and sterile stamens as odour production sites. Stamens were studied under light and electron microscopy. Dynamic headspace and gas chromatography-mass spectrometry were used to collect and analyse scents from different zones of the inflorescence. The epidermal cells of the distal portion of fertile stamens and staminodes are papillose and, similar to the parenchyma cells of this region, have dense cytoplasm and large nuclei. In these cells, the composition of organelles is compatible with secretory activity, especially the great number of mitochondria and plastids. In this portion, lipid droplets that are consumed concomitantly with the release of odour were observed. Quantitative scent analyses revealed that the scent, with a predominance of dihydro-β-ionone, is mainly emitted by the fertile and sterile staminate zones of the spadix. An amorphous substance in the stomata pores indicates that the components are secreted and volatilized outside of the osmophore under thermogenic heat. Despite the difficulty in locating osmophores in the absence of morphological identity and inefficiency of neutral red staining, the osmophores of P. adamantinum have some features expected for these structures. The results indicate a functional link between thermogenesis and volatilization of osmophore secretions to produce olfactory signals for attracting specialized beetle pollinators. These first experimental data about the precise location of osmophores in Philodendron will stimulate studies in related species that will allow future comparison and the establishment of patterns of functional morphology. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

The M locus and ethylene-controlled sex determination in andromonoecious cucumber plants.

PubMed

Yamasaki, S; Fujii, N; Matsuura, S; Mizusawa, H; Takahashi, H

2001-06-01

Sex determination in cucumber (Cucumis sativus L.) plants is genetically controlled by the F and M loci. These loci interact to produce three different sexual phenotypes: gynoecious (M-F-), monoecious (M-ff), and andromonoecious (mmff). Gynoecious cucumber plants produce more ethylene than do monoecious plants. We found that the levels of ethylene production and the accumulation of CS-ACS2 mRNA in andromonoecious cucumber plants did not differ from those in monoecious plants and were lower than the levels measured in gynoecious plants. Ethylene inhibited stamen development in gynoecious cucumbers but not in andromonoecious ones. Furthermore, ethylene caused substantial increases in the accumulation of CS-ETR2, CS-ERS, and CS-ACS2 mRNA in monoecious and gynoecious cucumber plants, but not in andromonoecious one. In addition, the inhibitory effect of ethylene on hypocotyl elongation in andromonoecious cucumber plants was less than that in monoecious and gynoecious plants. These results suggest that ethylene responses in andromonoecious cucumber plants are reduced from those in monoecious and gynoecious plants. This is the first evidence that ethylene signals may influence the product of the M locus and thus inhibit stamen development in cucumber. The andromonoecious line provides novel material for studying the function of the M locus during sex determination in flowering cucumbers.

Down-Regulation of TM29, a Tomato SEPALLATA Homolog, Causes Parthenocarpic Fruit Development and Floral Reversion1

PubMed Central

Ampomah-Dwamena, Charles; Morris, Bret A.; Sutherland, Paul; Veit, Bruce; Yao, Jia-Long

2002-01-01

We have characterized the tomato (Lycopersicon esculentum Mill.) MADS box gene TM29 that shared a high amino acid sequence homology to the Arabidopsis SEP1, 2, and 3 (SEPALLATA1, 2, and 3) genes. TM29 showed similar expression profiles to SEP1, with accumulation of mRNA in the primordia of all four whorls of floral organs. In addition, TM29 mRNA was detected in inflorescence and vegetative meristems. To understand TM29 function, we produced transgenic tomato plants in which TM29 expression was down-regulated by either cosuppression or antisense techniques. These transgenic plants produced aberrant flowers with morphogenetic alterations in the organs of the inner three whorls. Petals and stamens were green rather than yellow, suggesting a partial conversion to a sepalloid identity. Stamens and ovaries were infertile, with the later developing into parthenocarpic fruit. Ectopic shoots with partially developed leaves and secondary flowers emerged from the fruit. These shoots resembled the primary transgenic flowers and continued to produce parthenocarpic fruit and additional ectopic shoots. Based on the temporal and spatial expression pattern and transgenic phenotypes, we propose that TM29 functions in floral organ development, fruit development, and maintenance of floral meristem identity in tomato. PMID:12376628

Cloning of a MADS box gene (GhMADS3) from cotton and analysis of its homeotic role in transgenic tobacco.

PubMed

Guo, Yulong; Zhu, Qinlong; Zheng, Shangyong; Li, Mingyang

2007-06-01

A MADS box gene (GhMADS3) was cloned from cotton (Gossypium hirsutum L.) based on EST sequences. The predicted protein sequence of GhMADS3 showed 85%, 73%, and 62% identity with Theobroma cacao TcAG, Antirrhinum majus FAR, and Arabidopsis thaliana AG, respectively, and was grouped with AG homologues when the full length sequences excluding N-extensions were compared. GhMADS3 expressed in the wild type cotton flower primarily in stamens and carpels, which was comparable to AG in Arabidopsis. However, it was not expressed in floral buds of a homeotic cotton variant chv1. Ectopic expression of GhMADS3 in tobacco (Nicotiana tabacum L.) resulted in flowers with sepal-to-carpel and petal-to-stamen transformation. The carpelloid first whorl organs, with stigmatic tissue on their upper edges, had a white appearance when compared with the dark green color of the wild type sepals. At times, long filaments were observed at the fusion site of the first carpelloid oranges. The second whorl organs in staminoid were usually smaller than the wild type and the color was changed from pink to white. These results suggest that GhMADS3 has a homeotic role in flower development.

Early floral development of Heliconia latispatha (Heliconiaceae), a key taxon for understanding the evolution of flower development in the Zingiberales.

PubMed

Kirchoff, Bruce K; Lagomarsino, Laura P; Newman, Winnell H; Bartlett, Madelaine E; Specht, Chelsea D

2009-03-01

We present new comparative data on early floral development of Heliconia latispatha, an ecologically and horticulturally important tropical plant within the order Zingiberales. Modification of the six members of two androecial whorls is characteristic of Zingiberales, with a reduction in number of fertile stamen from five or six in the banana families (Musaceae, Strelitziaceae, Lowiaceae, and Heliconiaceae) to one in Costaceae and Zingiberaceae and one-half in Marantaceae and Cannaceae. The remaining five infertile stamens in these later four families (the ginger families) are petaloid, and in Costaceae and Zingiberaceae fuse together to form a novel structure, the labellum. Within this developmental sequence, Heliconiaceae share with the ginger families the possession of an antisepalous staminode, a synapomorphy that has been used to place Heliconiaceae as sister to the ginger family clade. Here, we use epi-illumination light microscopy and reconstruction of serial sections to investigate the ontogeny of the Heliconia flower with emphasis on the ontogeny of the staminode. We compare floral development in Heliconia with that previously described for other species of Zingiberales. A comparison of floral structure and development across Zingiberales is presented to better understand the evolution of the flower in this charismatic group of tropical plants.

Loss of YABBY2-Like Gene Expression May Underlie the Evolution of the Laminar Style in Canna and Contribute to Floral Morphological Diversity in the Zingiberales.

PubMed

Morioka, Kelsie; Yockteng, Roxana; Almeida, Ana M R; Specht, Chelsea D

2015-01-01

The Zingiberales is an order of tropical monocots that exhibits diverse floral morphologies. The evolution of petaloid, laminar stamens, staminodes, and styles contributes to this diversity. The laminar style is a derived trait in the family Cannaceae and plays an important role in pollination as its surface is used for secondary pollen presentation. Previous work in the Zingiberales has implicated YABBY2-like genes, which function in promoting laminar outgrowth, in the evolution of stamen morphology. Here, we investigate the evolution and expression of Zingiberales YABBY2-like genes in order to understand the evolution of the laminar style in Canna. Phylogenetic analyses show that multiple duplication events have occurred in this gene lineage prior to the diversification of the Zingiberales. Reverse transcription-PCR in Canna, Costus, and Musa reveals differential expression across floral organs, taxa, and gene copies, and a role for YABBY2-like genes in the evolution of the laminar style is proposed. Selection tests indicate that almost all sites in conserved domains are under purifying selection, consistent with their functional relevance, and a motif unique to monocot YABBY2-like genes is identified. These results contribute to our understanding of the molecular mechanisms underlying the evolution of floral morphologies.

Loss of YABBY2-Like Gene Expression May Underlie the Evolution of the Laminar Style in Canna and Contribute to Floral Morphological Diversity in the Zingiberales

PubMed Central

Morioka, Kelsie; Yockteng, Roxana; Almeida, Ana M. R.; Specht, Chelsea D.

2015-01-01

The Zingiberales is an order of tropical monocots that exhibits diverse floral morphologies. The evolution of petaloid, laminar stamens, staminodes, and styles contributes to this diversity. The laminar style is a derived trait in the family Cannaceae and plays an important role in pollination as its surface is used for secondary pollen presentation. Previous work in the Zingiberales has implicated YABBY2-like genes, which function in promoting laminar outgrowth, in the evolution of stamen morphology. Here, we investigate the evolution and expression of Zingiberales YABBY2-like genes in order to understand the evolution of the laminar style in Canna. Phylogenetic analyses show that multiple duplication events have occurred in this gene lineage prior to the diversification of the Zingiberales. Reverse transcription-PCR in Canna, Costus, and Musa reveals differential expression across floral organs, taxa, and gene copies, and a role for YABBY2-like genes in the evolution of the laminar style is proposed. Selection tests indicate that almost all sites in conserved domains are under purifying selection, consistent with their functional relevance, and a motif unique to monocot YABBY2-like genes is identified. These results contribute to our understanding of the molecular mechanisms underlying the evolution of floral morphologies. PMID:26734021

Genome-wide identification of physically clustered genes suggests chromatin-level co-regulation in male reproductive development in Arabidopsis thaliana

PubMed Central

Reimegård, Johan; Kundu, Snehangshu; Pendle, Ali; Irish, Vivian F.; Shaw, Peter

2017-01-01

Abstract Co-expression of physically linked genes occurs surprisingly frequently in eukaryotes. Such chromosomal clustering may confer a selective advantage as it enables coordinated gene regulation at the chromatin level. We studied the chromosomal organization of genes involved in male reproductive development in Arabidopsis thaliana. We developed an in-silico tool to identify physical clusters of co-regulated genes from gene expression data. We identified 17 clusters (96 genes) involved in stamen development and acting downstream of the transcriptional activator MS1 (MALE STERILITY 1), which contains a PHD domain associated with chromatin re-organization. The clusters exhibited little gene homology or promoter element similarity, and largely overlapped with reported repressive histone marks. Experiments on a subset of the clusters suggested a link between expression activation and chromatin conformation: qRT-PCR and mRNA in situ hybridization showed that the clustered genes were up-regulated within 48 h after MS1 induction; out of 14 chromatin-remodeling mutants studied, expression of clustered genes was consistently down-regulated only in hta9/hta11, previously associated with metabolic cluster activation; DNA fluorescence in situ hybridization confirmed that transcriptional activation of the clustered genes was correlated with open chromatin conformation. Stamen development thus appears to involve transcriptional activation of physically clustered genes through chromatin de-condensation. PMID:28175342

Epidermal jasmonate perception is sufficient for all aspects of jasmonate-mediated male fertility in Arabidopsis.

PubMed

Jewell, Jeremy B; Browse, John

2016-03-01

Jasmonate (JA) signaling is essential for several environmental responses and reproductive development in many plant species. In Arabidopsis thaliana, the most obvious phenotype of JA biosynthetic and perception mutants is profound sporophytic male sterility characterized by failure of stamen filament elongation, severe delay of anther dehiscence and pollen inviability. The site of action of JA in the context of reproductive development has been discussed, but the ideas have not been tested experimentally. To this end we used targeted expression of a COI1-YFP transgene in the coi1-1 mutant background. As COI1 is an essential component of the JA co-receptor complex, the null coi1-1 mutant is male sterile due to lack of JA perception. We show that expression of COI1-YFP in the epidermis of the stamen filament and anther in coi1 mutant plants is sufficient to rescue filament elongation, anther dehiscence and pollen viability. In contrast, filament expression alone or expression in the tapetum do not restore dehiscence and pollen viability. These results demonstrate that epidermal JA perception is sufficient for anther function and pollen viability, and suggest the presence of a JA-dependent non-autonomous signal produced in the anther epidermis to synchronize both anther dehiscence and pollen maturation. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

Sex determination in papaya.

PubMed

Ming, Ray; Yu, Qingyi; Moore, Paul H

2007-06-01

Sex determination is an intriguing system in trioecious papaya. Over the past seven decades various hypotheses, based on the knowledge and information available at the time, have been proposed to explain the genetics of the papaya's sex determination. These include a single gene with three alleles, a group of closely linked genes, a genic balance of sex chromosome over autosomes, classical XY chromosomes, and regulatory elements of the flower development pathway. Recent advancements in genomic technology make it possible to characterize the genomic region involved in sex determination at the molecular level. High density linkage mapping validated the hypothesis that predicted recombination suppression at the sex determination locus. Physical mapping and sample sequencing of the non-recombination region led to the conclusion that sex determination is controlled by a pair of primitive sex chromosomes with a small male-specific region (MSY) of the Y chromosome. We now postulate that two sex determination genes control the sex determination pathway. One, a feminizing or stamen suppressor gene, causes stamen abortion before or at flower inception while the other, a masculinizing or carpel suppressor gene, causes carpel abortion at a later flower developmental stage. Detailed physical mapping is beginning to reveal structural details about the sex determination region and sequencing is expected to uncover candidate sex determining genes. Cloning of the sex determination genes and understanding the sex determination process could have profound application in papaya production.

Starch Turnover and Metabolism during Flower and Early Embryo Development1[CC-BY

PubMed Central

Pazmino, Diana; Gagliardini, Valeria

2016-01-01

The accumulation of starch within photosynthetic tissues and within dedicated storage organs has been characterized extensively in many species, and a function in buffering carbon availability or in fueling later growth phases, respectively, has been proposed. However, developmentally regulated starch turnover within heterotrophic tissues other than dedicated storage organs is poorly characterized, and its function is not well understood. Here, we report on the characterization of starch turnover during flower, early embryo, and silique development in Arabidopsis (Arabidopsis thaliana) using a combined clearing-staining technique on whole-mount tissue. Besides the two previously documented waves of transient starch accumulation in the stamen envelope, occurring during meiosis and pollen mitosis I, we identified a novel, third wave of starch amylogenesis/amylolysis during the last stages of stamen development. To gain insights into the underlying molecular mechanisms, we analyzed publicly available microarray data, which revealed a developmentally coordinated expression of carbohydrate transport and metabolism genes during these waves of transient starch accumulation. Based on this analysis, we characterized starch dynamics in mutants affecting hexose phosphate metabolism and translocation, and identified the Glc-6-phosphate/phosphate antiporter GPT1 as the putative translocator of Glc-6-phosphate for starch biosynthesis in reproductive tissues. Based on these results, we propose a model of starch synthesis within the pollen grain and discuss the nutrient transport route feeding the embryo within the developing seed. PMID:27794100

Mutagenic synergism detected between dimethyl sulfate and X-rays but not found between N-methyl-N-nitrosourea and X-rays in the stamen hairs of Tradescantia clone BNL 4430.

PubMed

Shima, N; Ichikawa, S

1995-09-01

Mutagenic interactions with X-rays of two monofunctional alkylating agents, dimethyl sulfate (DMS) and N-methyl-N-nitrosourea (MNU), were studied in the stamen hairs of Tradescantia clone BNL 4430, a blue/pink heterozygote. The young inflorescence-bearing shoots with roots cultivated in the nutrient solution circulating growth chamber were used as tester plants. Synergism between two different mutagens was judged to have occurred when the mutation frequency observed after applying the two mutagens concurrently was statistically significantly higher than the mutation frequency expected from the additive effects of the two mutagens. Clear synergistic effects in inducing somatic pink mutations were detected with all combinations of doses of DMS and X-rays examined, even in a relatively low X-ray dose range (down to 299 mGy), resembling those confirmed earlier between ethyl methanesulfonate (EMS) and X-rays, but somewhat differing from the synergisms observed earlier between methyl methanesulfonate (MMS) and X-rays. On the other hand, no mutagenic synergism was detected between MNU and X-rays, even in a relatively high X-ray dose range (up to 862 mGy). The presence or absence of mutagenic synergisms of these alkylating agents with X-rays could be related to the action mechanism of each alkylating agent.

Flower Development as an Interplay between Dynamical Physical Fields and Genetic Networks

PubMed Central

Barrio, Rafael Ángel; Hernández-Machado, Aurora; Varea, C.; Romero-Arias, José Roberto; Álvarez-Buylla, Elena

2010-01-01

In this paper we propose a model to describe the mechanisms by which undifferentiated cells attain gene configurations underlying cell fate determination during morphogenesis. Despite the complicated mechanisms that surely intervene in this process, it is clear that the fundamental fact is that cells obtain spatial and temporal information that bias their destiny. Our main hypothesis assumes that there is at least one macroscopic field that breaks the symmetry of space at a given time. This field provides the information required for the process of cell differentiation to occur by being dynamically coupled to a signal transduction mechanism that, in turn, acts directly upon the gene regulatory network (GRN) underlying cell-fate decisions within cells. We illustrate and test our proposal with a GRN model grounded on experimental data for cell fate specification during organ formation in early Arabidopsis thaliana flower development. We show that our model is able to recover the multigene configurations characteristic of sepal, petal, stamen and carpel primordial cells arranged in concentric rings, in a similar pattern to that observed during actual floral organ determination. Such pattern is robust to alterations of the model parameters and simulated failures predict altered spatio-temporal patterns that mimic those described for several mutants. Furthermore, simulated alterations in the physical fields predict a pattern equivalent to that found in Lacandonia schismatica, the only flowering species with central stamens surrounded by carpels. PMID:21048956

Flower development as an interplay between dynamical physical fields and genetic networks.

PubMed

Barrio, Rafael Ángel; Hernández-Machado, Aurora; Varea, C; Romero-Arias, José Roberto; Alvarez-Buylla, Elena

2010-10-27

In this paper we propose a model to describe the mechanisms by which undifferentiated cells attain gene configurations underlying cell fate determination during morphogenesis. Despite the complicated mechanisms that surely intervene in this process, it is clear that the fundamental fact is that cells obtain spatial and temporal information that bias their destiny. Our main hypothesis assumes that there is at least one macroscopic field that breaks the symmetry of space at a given time. This field provides the information required for the process of cell differentiation to occur by being dynamically coupled to a signal transduction mechanism that, in turn, acts directly upon the gene regulatory network (GRN) underlying cell-fate decisions within cells. We illustrate and test our proposal with a GRN model grounded on experimental data for cell fate specification during organ formation in early Arabidopsis thaliana flower development. We show that our model is able to recover the multigene configurations characteristic of sepal, petal, stamen and carpel primordial cells arranged in concentric rings, in a similar pattern to that observed during actual floral organ determination. Such pattern is robust to alterations of the model parameters and simulated failures predict altered spatio-temporal patterns that mimic those described for several mutants. Furthermore, simulated alterations in the physical fields predict a pattern equivalent to that found in Lacandonia schismatica, the only flowering species with central stamens surrounded by carpels.

Stamina pistilloida: a new mutation induced in pea.

PubMed

Monti, L M; Devreux, M

1969-01-01

After diethylsulphate treatment of seeds of the pea variety 'Parvus', a new floral mutation was isolated in the second generation. This mutation, named stamina pistilloida, is characterized by a partial fusion of the androecium with the gynoecium; the two marginal stamens of the staminal column are transformed in rudimentary carpels more or less differentiated according to ecoclimatic conditions. The genetic analysis has shown the monogenic and recessive behaviour of the mutation (gene proposed stp) and its linkage with the gene oh in the chromosome II.

Simultaneous qualitative assessment and quantitative analysis of flavonoids in various tissues of lotus (Nelumbo nucifera) using high performance liquid chromatography coupled with triple quad mass spectrometry.

PubMed

Chen, Sha; Fang, Linchuan; Xi, Huifen; Guan, Le; Fang, Jinbao; Liu, Yanling; Wu, Benhong; Li, Shaohua

2012-04-29

Flavonoid composition and concentration were investigated in 12 different tissues of 'Ti-1' lotus (Nelumbo nucifera) by high performance liquid chromatography equipped with photodiode array detection tandem electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS(n)). A total of 20 flavonoids belonging to six groups (myricetin, quercetin, kaempferol, isohamnetin, diosmetin derivatives) were separated and identified. Myricetin 3-O-galactoside, myricetin 3-O-glucuronide, isorhamnetin 3-O-glucuronide and free aglycone diometin (3',5,7-trihydroxy-4'-methoxyflavone) were first reported in lotus. Flavonoid composition varied largely with tissue type, and diverse compounds (5-15) were found in leaf and flower stalks, flower pistils, seed coats and embryos. Flower tissues including flower petals, stamens, pistils, and, especially, reproductive tissue fruit coats had more flavonoid compounds (15-17) than leaves (12), while no flavonoids were detectable in seed kernels. The flavonoid content of seed embryos was high, 730.95 mg 100g(-1) DW (dry weight). As regards the other tissues, mature leaf pulp (771.79 mg 100 g(-1) FW (fresh weight)) and young leaves (650.67 mg 100 g(-1) FW) had higher total flavonoid amount than flower stamens (359.45 mg 100 g(-1) FW) and flower petals (342.97 mg 100g(-1) FW), while leaf stalks, flower stalks and seed coats had much less total flavonoid (less than 40 mg 100 g(-1) FW). Copyright © 2012 Elsevier B.V. All rights reserved.

A Matter of Contrast: Yellow Flower Colour Constrains Style Length in Crocus species.

PubMed

Lunau, Klaus; Konzmann, Sabine; Bossems, Jessica; Harpke, Doerte

2016-01-01

Most flowers display distinct colour patterns comprising two different areas. The peripheral large-area component of floral colour patterns attracts flower visitors from some distance and the central small-area component guides flower visitors towards landing sites. Whereas the peripheral colour is largely variable among species, the central colour, produced mostly by anthers and pollen or pollen mimicking floral guides, is predominantly yellow and UV-absorbing. This holds also for yellow flowers that regularly display a UV bull's eye pattern. Here we show that yellow-flowering Crocus species are a noticeable exception, since yellow-flowering Crocus species-being entirely UV-absorbing-exhibit low colour contrast between yellow reproductive organs and yellow tepals. The elongated yellow or orange-yellow style of Crocus flowers is a stamen-mimicking structure promoting cross-pollination by facilitating flower visitors' contact with the apical stigma before the flower visitors are touching the anthers. Since Crocus species possess either yellow, violet or white tepals, the colour contrast between the stamen-mimicking style and the tepals varies among species. In this study comprising 106 Crocus species, it was tested whether the style length of Crocus flowers is dependent on the corolla colour. The results show that members of the genus Crocus with yellow tepals have evolved independently up to twelve times in the genus Crocus and that yellow-flowering Crocus species possess shorter styles as compared to violet- and white-flowering ones. The manipulation of flower visitors by anther-mimicking elongated styles in Crocus flowers is discussed.

[Morphogenetic lability of reproductive structures in Ruppia maritima (Ruppiaceae, Alismatales): from two lateral flowers to a terminal flower].

PubMed

Lokk, I É; Sokolov, D D; Remizova, M V

2011-01-01

Flowers of Ruppia are normally arranged into an open two-flowered spike, but sometimes the two lateral flowers are congenitally united with each other and form a terminal flower-like structure. This developmental abnormality resembles those described in well-investigated mutants of model organisms of developmental genetics such as Arabidopsis Antirrhinum. A study of Ruppia allows investigating morphogenetic lability of this feature in natural populations. These data will be important for understanding evolutionary transitions between open and closed inflorescences. This paper presents first data on frequencies ofterminal flower-like structures in natural populations of Ruppia maritima and first observations of their development. Vascular supply of inflorescences with free and united flowers is compared for the first time. Strong differences in frequencies of occurrence of terminal flower-like structures among examined natural populations are revealed. Data on variation of organ numbers in flowers of plants from different populations allow hypothesizing that increased size of floral primordia is a factor that plays a role in their amalgamation into ajoint primordium of a terminal structure. Vascular system of inflorescences of R. maritima with united flowers is quite similar to the vascular system of a flower and nothing contradicts a hypothesis on terminal position ofthis structure. Transversally inserted stamens in inflorescences with united flowers are usually of inverted polarity. This appears to be the first documented example of an inversion of relative polarity of stamens and carpels in angiosperms.

Phylogenetics, biogeography, and staminal evolution in the tribe Mentheae (Lamiaceae).

PubMed

Drew, Bryan T; Sytsma, Kenneth J

2012-05-01

The mint family (Lamiaceae) is the sixth largest family of flowering plants, with the tribe Mentheae containing about a third of the species. We present a detailed perspective on the evolution of the tribe Mentheae based on a phylogenetic analysis of cpDNA and nrDNA that is the most comprehensive to date, a biogeographic set of analyses using a fossil-calibrated chronogram, and an examination of staminal evolution. Data from four cpDNA and two nrDNA markers representing all extant genera within the tribe Mentheae were analyzed using the programs BEAST, Lagrange, S-DIVA, and BayesTraits. BEAST was used to simultaneously estimate phylogeny and divergence times, Lagrange and S-DIVA were used for biogeographical reconstruction, and BayesTraits was used to infer staminal evolution within the tribe. Currently accepted subtribal delimitations are shown to be invalid and are updated. The Mentheae and all five of its subtribes have a Mediterranean origin and have dispersed to the New World multiple times. The vast majority of New World species of subtribe Menthinae are the product of a single dispersal event in the mid-late Miocene. At least four transitions from four stamens to two stamens have occurred within Mentheae, once in the subtribe Salviinae, once in the subtribe Lycopinae, and at least twice in the subtribe Menthinae. Worldwide cooling trends probably played a large role in the diversification and present day distribution of the tribe Mentheae. Additional work is needed to ascertain relationships within some Mentheae genera, especially in the subtribe Menthinae.

The use of Tradescantia and Vicia faba bioassays for the in situ detection of mutagens in an aquatic environment.

PubMed

Grant, W F; Lee, H G; Logan, D M; Salamone, M F

1992-11-01

Tests have shown plant bioassays to be excellent for mutagenicity studies. Most studies with plant bioassays, however, have been carried out either in the laboratory, or if, in situ, as monitors of atmospheric contaminants. The primary purpose of this study was to assess the utility of in situ plant mutagenicity bioassays in monitoring water contaminants. The assay systems tested were the Tradescantia stamen hair and micronucleus assays for the detection of gene mutations and chromosomal aberrations respectively, and the Vicia faba bioassay system which detects chromosomal aberrations in root tips. The assays were used to test the effluent from a pulp and paper mill located on the north shore of Lake Superior. Assays were performed in a creek containing raw effluent and in the bay of Lake Superior into which the creek emptied. All in situ treatments were carried out for 24 h. The effluent from the creek was heavy with pulp and debris which coated the plant cuttings and the Vicia faba seedlings and may have restricted the uptake from the effluent. In the creek, at test sites 11.5 km from the source, the effluent was toxic to the Vicia faba roots as evidenced by a reduction in the mitotic index. The data for the Tradescantia stamen hair assay in the creek were equivocal. The cuttings from the creek test sites and the air and water control sites appeared to have undergone a physiological delay. Within a day or two after the return to the laboratory, that is 6-8 days after testing, flowering almost ceased and did not fully resume until about day 35. This reduction in flowering was particularly severe with the cuttings from the effluent and air control sites, making it very difficult to interpret the results. In contrast, the Tradescantia micronucleus and Vicia faba chromosomal aberration data were unequivocal; each produced positive responses at both test sites relative to the air and water controls. The results obtained for the bay sites with all 3 assays were in agreement. In that section of the bay visibly contaminated by the creek effluent, increases in stamen hair mutants, micronuclei, and chromosome aberrations were measured. In general, there was a considerable reduction in the number of mutant events observed for the water samples brought back from the test sites and tested in the laboratory.(ABSTRACT TRUNCATED AT 400 WORDS)

Microscopy and bioinformatic analyses of lipid metabolism implicate a sporophytic signaling network supporting pollen development in Arabidopsis.

PubMed

Wang, Yixing; Wu, Hong; Yang, Ming

2008-07-01

The Arabidopsis sporophytic tapetum undergoes a programmed degeneration process to secrete lipid and other materials to support pollen development. However, the molecular mechanism regulating the degeneration process is unknown. To gain insight into this molecular mechanism, we first determined that the most critical period for tapetal secretion to support pollen development is from the vacuolate microspore stage to the early binucleate pollen stage. We then analyzed the expression of enzymes responsible for lipid biosynthesis and degradation with available in-silico data. The genes for these enzymes that are expressed in the stamen but not in the concurrent uninucleate microspore and binucleate pollen are of particular interest, as they presumably hold the clues to unique molecular processes in the sporophytic tissues compared to the gametophytic tissue. No gene for lipid biosynthesis but a single gene encoding a patatin-like protein likely for lipid mobilization was identified based on the selection criterion. A search for genes co-expressed with this gene identified additional genes encoding typical signal transduction components such as a leucine-rich repeat receptor kinase, an extra-large G-protein, other protein kinases, and transcription factors. In addition, proteases, cell wall degradation enzymes, and other proteins were also identified. These proteins thus may be components of a signaling network leading to degradation of a broad range of cellular components. Since a broad range of degradation activities is expected to occur only in the tapetal degeneration process at this stage in the stamen, it is further hypothesized that the signaling network acts in the tapetal degeneration process.

Exertional oxygen uptake kinetics: a stamen of stamina?

PubMed

Whipp, Brian J; Rossiter, H B; Ward, S A

2002-04-01

The fundamental pulmonary O(2) uptake (.VO(2)) response to moderate, constant-load exercise can be characterized as (d.VO(2)/dt)(tau)+Delta.VO(2) (t)=Delta.VO(2SS) where Delta.VO(2SS) is the steady-state response, and tau is the time constant, with the .VO(2) kinetics reflecting intramuscular O(2) uptake (.QO(2)) kinetics, to within 10%. The role of phosphocreatine (PCr) turnover in .QO(2) control can be explored using (31)P-MR spectroscopy, simultaneously with .VO(2). Although tau.VO(2) and tauPCr vary widely among subjects (approx. 20-65 s), they are not significantly different from each other, either at the on- or off-transient. A caveat to interpreting the "well-fit" exponential is that numerous units of similar Delta.VO(2SS) but with a wide tau distribution can also yield a .VO(2) response with an apparent single tau. This tau is, significantly, inversely correlated with lactate threshold and .VO(2max)(but is poorly predictive; a frail stamen, therefore), consistent with tau not characterizing a compartment with uniform kinetics. At higher intensities, the fundamental kinetics become supplemented with a slowly-developing phase, setting .VO(2)on a trajectory towards maximum .VO(2). This slow component is also demonstrable in Delta[PCr]: the decreased efficiency thereby reflecting a predominantly high phosphate-cost of force production rather than a high O(2)-cost of phosphate production. We also propose that the O(2)-deficit for the slow-component is more likely to reflect shifting Delta.VO(2SS) rather than a single one with a single tau.

In the interface of caesalpinioids and mimosoids: Comparative floral development elucidates shared characters in Dimorphandra mollis and Pentaclethra macroloba (Leguminosae).

PubMed

De Barros, Thais C; Pedersoli, Giseli D; Paulino, Juliana V; Teixeira, Simone P

2017-02-01

Pentaclethra and Dimorphandra (Leguminosae) have long been considered a possible enigmatic link between caesalpinioids and mimosoids because they both have an imbricate calyx and heteromorphic androecium, floral features that are rare among mimosoids but common among caesalpinioids. This study compared the developing flowers of Dimorphandra mollis and Pentaclethra macroloba to determine whether the shared floral conditions also have the same ontogenetic origin. Buds of different sizes and flowers were processed for surface (scanning electron microscopy) and histological (light microscopy) examination. The floral meristem initiates five sepal primordia in a modified helical order in both species. The median sagittal sepal is adaxial. The overlap of the sepals during elongation culminates with the formation of the imbricate calyx. Heteromorphic androecia arise in the intermediate stages of development. In P. macroloba , the fertile pollen-bearing stamens are antesepalous, robust and short, and the anthers carry a robust apical gland; the staminodes are long and white with a vestigial apical gland. In contrast, in D. mollis the fertile pollen-bearing stamens are antepetalous without glands and as long as the staminodes. The staminodes are thinner with an expanded apical region. The imbricate calyx and the heteromorphic androecium in the studied species originated via distinct pathways, favoring the hypothesis of homoplasy of these conditions. The pathways observed in P. macroloba are more similar to those observed in caesalpinioids than to those observed in mimosoids, indicating that although the floral development differs between the species studied, it supports the basal placement of Pentaclethra among mimosoids. © 2017 Botanical Society of America.

Characterization and Functional Analysis of Five MADS-Box B Class Genes Related to Floral Organ Identification in Tagetes erecta.

PubMed

Ai, Ye; Zhang, Chunling; Sun, Yalin; Wang, Weining; He, Yanhong; Bao, Manzhu

2017-01-01

According to the floral organ development ABC model, B class genes specify petal and stamen identification. In order to study the function of B class genes in flower development of Tagetes erecta, five MADS-box B class genes were identified and their expression and putative functions were studied. Sequence comparisons and phylogenetic analyses indicated that there were one PI-like gene-TePI, two euAP3-like genes-TeAP3-1 and TeAP3-2, and two TM6-like genes-TeTM6-1 and TeTM6-2 in T. erecta. Strong expression levels of these genes were detected in stamens of the disk florets, but little or no expression was detected in bracts, receptacles or vegetative organs. Yeast hybrid experiments of the B class proteins showed that TePI protein could form a homodimer and heterodimers with all the other four B class proteins TeAP3-1, TeAP3-2, TeTM6-1 and TeTM6-2. No homodimer or interaction was observed between the euAP3 and TM6 clade members. Over-expression of five B class genes of T. erecta in Nicotiana rotundifolia showed that only the transgenic plants of 35S::TePI showed altered floral morphology compared with the non-transgenic line. This study could contribute to the understanding of the function of B class genes in flower development of T. erecta, and provide a theoretical basis for further research to change floral organ structures and create new materials for plant breeding.

Somatic mutation frequencies in the stamen hairs of Tradescantia grown in soil samples from the Bikini Island.

PubMed

Ichikawa, S; Ishii, C

1991-02-01

Somatic pink mutation frequencies in the stamen hairs of Tradescantia BNL 02 clone grown for 76 days in two soil samples taken from the Bikini Island (where a hydrogen bomb explosion test had been conducted in 1954) were investigated. A significantly high mutation frequency (2.58 +/- 0.17 pink mutant events per 10(3) hairs or 1.34 +/- 0.09 pink mutant events per 10(4) hair-cell divisions) was observed for the plant grown in one of the two Bikini soil samples, as compared to the control plants (1.70 +/- 0.14 or 0.88 +/- 0.07, respectively) grown in the field soil of Saitama University. The soil sample which caused the significant increase in mutation frequency contained 6,880 +/- 330 mBq/g 137Cs, 62.5 +/- 4.4 mBq/g 60Co, and some other nuclides; a 150 microR/hr exposure rate being measured on the surface of the soil sample. The effective cumulative external exposures measured for the inflorescences of the plant grown in this soil sample averaged at most 60.8 mR, being too small to explain the significant elevation in mutation frequency observed. On the other hand, internal exposure due to uptake of radioactive nuclides was estimated to be 125 mrad (1.25 mGy) as an accumulated effective dose, mainly based on a gamma-spectrometrical analysis. However, it seemed highly likely that this value of internal exposure was a considerable underestimate, and the internal exposure was considered to be more significant than the external exposure.

Chemical composition of Tipuana tipu, a source for tropical honey bee products.

PubMed

dos Santos Pereira, Alberto; de Aquino Neto, Francisco Radler

2003-01-01

Tipuana tipu (Benth.) Kuntze is a tree from the leguminosae family (Papilionoideae) indigenous in Argentina and extensively used in urbanism, mainly in Southern Brazil. The epicuticular waxes of leaves and branch, and flower surface were studied by high temperature high resolution gas chromatography. Several compounds were characterized, among which the aliphatic alcohols were predominant in branch, leaves and receptacle. Alkanes were predominant only in the petals and the aliphatic acids were predominant in stamen. In branches and leaf epicuticular surfaces, six long chain wax esters series were characterized, as well as lupeol and b-amyrin hexadecanoates.

Somatic Embryogenesis in Horse Chestnut (Aesculus hippocastanum L.).

PubMed

Capuana, Maurizio

2016-01-01

Embryogenic cultures of horse chestnut (Aesculus hippocastanum L.) can be obtained from different organs and tissues. We describe here the induction from stamen filaments and the procedures applied for the successive phases of somatic embryo development and maturation. Embryogenic tissues are obtained on Murashige and Skoog medium containing 9.0 μM 2,4-dichlorophenoxyacetic acid. Somatic embryos develop after transfer to hormone-free medium enriched with glutamine. Maturation and germination of isolated embryos are achieved by transfer to medium containing polyethylene glycol 4000 and activated charcoal, successive desiccation treatment, and cold storage at 4 °C for 8 weeks.

[Natural history of flowers and gravity].

PubMed

Yamashita, Masamichi; Tomita-Yokotani, Kaori; Nakamura, Teruko

2004-06-01

Many flowers have coevolved with their pollinator animals. Gravity has been one of selection pressure for the evolution of flowers. Gravity rules morphology and other features of flowers in many aspects. Pair matching between the flower and its specific pollinator is one of factors that determine the fitness of both sides. Evolution of flower morphology and its molecular basis are reviewed briefly. Anemophilous flowers are also under the influence of gravity. Shape and other features of entomophilous flowers have been highly diversed. Gravitropic response and its mechanism are summarized. Recent findings on gravitropism and phototropism of pistils and stamens are presented in this article.

Heterotopic expression of class B floral homeotic genes supports a modified ABC model for tulip (Tulipa gesneriana).

PubMed

Kanno, Akira; Saeki, Hiroshi; Kameya, Toshiaki; Saedler, Heinz; Theissen, Günter

2003-07-01

In higher eudicotyledonous angiosperms the floral organs are typically arranged in four different whorls, containing sepals, petals, stamens and carpels. According to the ABC model, the identity of these organs is specified by floral homeotic genes of class A, A+B, B+C and C, respectively. In contrast to the sepal and petal whorls of eudicots, the perianths of many plants from the Liliaceae family have two outer whorls of almost identical petaloid organs, called tepals. To explain the Liliaceae flower morphology, van Tunen et al. (1993) proposed a modified ABC model, exemplified with tulip. According to this model, class B genes are not only expressed in whorls 2 and 3, but also in whorl 1. Thus the organs of both whorls 1 and 2 express class A plus class B genes and, therefore, get the same petaloid identity. To test this modified ABC model we have cloned and characterized putative class B genes from tulip. Two DEF- and one GLO-like gene were identified, named TGDEFA, TGDEFB and TGGLO. Northern hybridization analysis showed that all of these genes are expressed in whorls 1, 2 and 3 (outer and inner tepals and stamens), thus corroborating the modified ABC model. In addition, these experiments demonstrated that TGGLO is also weakly expressed in carpels, leaves, stems and bracts. Gel retardation assays revealed that TGGLO alone binds to DNA as a homodimer. In contrast, TGDEFA and TGDEFB cannot homodimerize, but make heterodimers with PI. Homodimerization of GLO-like protein has also been reported for lily, suggesting that this phenomenon is conserved within Liliaceae plants or even monocot species.

Promoter isolation and characterization of GhAO-like1, a Gossypium hirsutum gene similar to multicopper oxidases that is highly expressed in reproductive organs.

PubMed

Lambret-Frotté, Julia; Artico, Sinara; Muniz Nardeli, Sarah; Fonseca, Fernando; Brilhante Oliveira-Neto, Osmundo; Grossi-de-Sá, Maria Fatima; Alves-Ferreira, Marcio

2016-01-01

Cotton is one of the most economically important cultivated crops. It is the major source of natural fiber for the textile industry and an important target for genetic modification for both biotic stress and herbicide tolerance. Therefore, the characterization of genes and regulatory regions that might be useful for genetic transformation is indispensable. The isolation and characterization of new regulatory regions is of great importance to drive transgene expression in genetically modified crops. One of the major drawbacks in cotton production is pest damage; therefore, the most promising, cost-effective, and sustainable method for pest control is the development of genetically resistant cotton lines. Considering this scenario, our group isolated and characterized the promoter region of a MCO (multicopper oxidase) from Gossypium hirsutum, named GhAO-like1 (ascorbate oxidase-like1). The quantitative expression, together with the in vivo characterization of the promoter region reveals that GhAO-like1 has a flower- and fruit-specific expression pattern. The GUS activity is mainly observed in stamens, as expected considering that the GhAO-like1 regulatory sequence is enriched in cis elements, which have been characterized as a target of reproductive tissue specific transcription factors. Both histological and quantitative analyses in Arabidopsis thaliana have confirmed flower (mainly in stamens) and fruit expression of GhAO-like1. In the present paper, we isolated and characterized both in silico and in vivo the promoter region of the GhAO-like1 gene. The regulatory region of GhAO-like1 might be useful to confer tissue-specific expression in genetically modified plants.

Low temperature-induced DNA hypermethylation attenuates expression of RhAG, an AGAMOUS homolog, and increases petal number in rose (Rosa hybrida).

PubMed

Ma, Nan; Chen, Wen; Fan, Tiangang; Tian, Yaran; Zhang, Shuai; Zeng, Daxing; Li, Yonghong

2015-10-05

Flower development is central to angiosperm reproduction and is regulated by a broad range of endogenous and exogenous stimuli. It has been well documented that ambient temperature plays a key role in controlling flowering time; however, the mechanisms by which temperature regulates floral organ differentiation remain largely unknown. In this study, we show that low temperature treatment significantly increases petal number in rose (Rosa hybrida) through the promotion of stamen petaloidy. Quantitative RT-PCR analysis revealed that the expression pattern of RhAG, a rose homolog of the Arabidopsis thaliana AGAMOUS C-function gene, is associated with low temperature regulated flower development. Silencing of RhAG mimicked the impact of low temperature treatments on petal development by significantly increasing petal number through an increased production of petaloid stamens. In situ hybridization studies further revealed that low temperature restricts its spatial expression area. Analysis of DNA methylation level showed that low temperature treatment enhances the methylation level of the RhAG promoter, and a specific promoter region that was hypermethylated at CHH loci under low temperature conditions, was identified by bisulfite sequencing. This suggests that epigenetic DNA methylation contributes to the ambient temperature modulation of RhAG expression. Our results provide highlights in the role of RhAG gene in petal number determination and add a new layer of complexity in the regulation of floral organ development. We propose that RhAG plays an essential role in rose flower patterning by regulating petal development, and that low temperatures increase petal number, at least in part, by suppressing RhAG expression via enhancing DNA CHH hypermethylation of the RhAG promoter.

Pollinator scarcity drives the shift to delayed selfing in Himalayan mayapple Podophyllum hexandrum (Berberidaceae)

PubMed Central

Xiong, Ying-Ze; Fang, Qiang; Huang, Shuang-Quan

2013-01-01

Recent molecular phylogenetics have indicated that American mayapple (mainly self-incompatible, SI) and Himalayan mayapple, which was considered to be self-compatible (SC), are sister species with disjunct distribution between eastern Asia and eastern North America. We test a hypothesis that the persistence of this early spring flowering herb in the Himalayan region is attributable to the transition from SI to SC, the capacity for selfing in an unpredictable pollination environment. Pollinator observations were conducted in an alpine meadow with hundreds of Himalayan mayapple (Podophyllum hexandrum Royle) individuals over 2 years. To examine autogamy, seed set under different pollination treatments was compared. To clarify whether automatic self-pollination is achieved by movement of the pistil as a previous study suggested, we measured incline angles of the pistil and observed flower movement during anthesis using video. Floral visitors to the nectarless flowers were very rare, but solitary bees and honeybees could be potential pollinators. Seed set of bagged flowers was not significantly different from that of open-pollinated, self- or cross-pollinated flowers. However, removal of petals or stamens lowered seed yield. The angles of inclination of pistils did not change during the process of pollination. Automatic self-pollination was facilitated by petals closing and stamens moving simultaneously to contact the stigma. Stigmatic pollen load increased little during the day time, in contrast to a sharp increase when the flowers closed during the night-time. These observations indicated that Himalayan mayapple was SC and delayed self-pollination was facilitated by the movement of petals rather than the pistil. Compared with SI American mayapple, no obvious inbreeding depression in SC Himalayan mayapple may contribute its existence in the uplifting zone. A scarcity of pollinators may have driven the shift to delayed selfing in P. hexandrum.

Within and between Whorls: Comparative Transcriptional Profiling of Aquilegia and Arabidopsis

PubMed Central

Voelckel, Claudia; Borevitz, Justin O.; Kramer, Elena M.; Hodges, Scott A.

2010-01-01

Background The genus Aquilegia is an emerging model system in plant evolutionary biology predominantly because of its wide variation in floral traits and associated floral ecology. The anatomy of the Aquilegia flower is also very distinct. There are two whorls of petaloid organs, the outer whorl of sepals and the second whorl of petals that form nectar spurs, as well as a recently evolved fifth whorl of staminodia inserted between stamens and carpels. Methodology/Principal Findings We designed an oligonucleotide microarray based on EST sequences from a mixed tissue, normalized cDNA library of an A. formosa x A. pubescens F2 population representing 17,246 unigenes. We then used this array to analyze floral gene expression in late pre-anthesis stage floral organs from a natural A. formosa population. In particular, we tested for gene expression patterns specific to each floral whorl and to combinations of whorls that correspond to traditional and modified ABC model groupings. Similar analyses were performed on gene expression data of Arabidopsis thaliana whorls previously obtained using the Ath1 gene chips (data available through The Arabidopsis Information Resource). Conclusions/Significance Our comparative gene expression analyses suggest that 1) petaloid sepals and petals of A. formosa share gene expression patterns more than either have organ-specific patterns, 2) petals of A. formosa and A. thaliana may be independently derived, 3) staminodia express B and C genes similar to stamens but the staminodium genetic program has also converged on aspects of the carpel program and 4) staminodia have unique up-regulation of regulatory genes and genes that have been implicated with defense against microbial infection and herbivory. Our study also highlights the value of comparative gene expression profiling and the Aquilegia microarray in particular for the study of floral evolution and ecology. PMID:20352114

Floral structure and ontogeny of Syndiclis (Lauraceae)

PubMed Central

Zeng, Gang; Liu, Bing; Ferguson, David K.; Rohwer, Jens G.

2017-01-01

Generic delimitation in the Beilschmiedia group of the Lauraceae remains ambiguous because flowering specimens of a few genera with confined distribution are poorly represented in herbaria, and a few floral characters important for taxonomy are still poorly known. Syndiclis is sporadically distributed in southwestern China, and is represented in the herbaria by only a few flowering specimens. We conducted field investigations to collect floral materials of four species and observed structures and ontogeny of the tiny flowers using both light microscopy (LM) and scanning electron microscopy (SEM). The results show that the genus Syndiclis possesses flowers with huge variation in both merosity and organ number. Flowers of the genus are dimerous, trimerous, or tetramerous, or have mixed merosity with monomerous and dimerous, or dimerous and trimerous, or trimerous and tetramerous whorls. The number of staminodes ranges from two to eight, depending on floral merosity, and on how many stamens of the third androecial whorl are reduced to staminodes. The staminodes of the fourth androecial whorl are comparable to the staminodes in Potameia, but the staminodes of the third androecial whorl of Syndiclis are relatively larger than the staminodes in Potameia. They are erect or curved inwards, covering the ovary. The anthers are usually two-locular, but rarely one-locular or three-locular. Each stamen of the third androecial whorl bears two conspicuous and enlarged glands at the base. The lability of floral merosity and organ number of Syndiclis may have been caused by changes of pollination system and loss of special selective pressures that are present in most Lauraceous plants with fixed floral organ number. This study furthers our understanding of variation and evolution of a few important characters of the Beilschmiedia group and provides essential data for a revised generic classification of the group. PMID:29028818

Floral development and floral phyllotaxis in Anaxagorea (Annonaceae).

PubMed

Endress, Peter K; Armstrong, Joseph E

2011-10-01

Background and Aims Anaxagorea is the phylogenetically basalmost genus in the large tropical Annonaceae (custard apple family) of Magnoliales, but its floral structure is unknown in many respects. The aim of this study is to analyse evolutionarily interesting floral features in comparison with other genera of the Annonaceae and the sister family Eupomatiaceae. Methods Live flowers of Anaxagorea crassipetala were examined in the field with vital staining, liquid-fixed material was studied with scanning electron microscopy, and microtome section series were studied with light microscopy. In addition, herbarium material of two other Anaxagorea species was cursorily studied with the dissecting microscope. Key Results Floral phyllotaxis in Anaxagorea is regularly whorled (with complex whorls) as in all other Annonaceae with a low or medium number of floral organs studied so far (in those with numerous stamens and carpels, phyllotaxis becoming irregular in the androecium and gynoecium). The carpels are completely plicate as in almost all other Annonaceae. In these features Anaxagorea differs sharply from the sister family Eupomatiaceae, which has spiral floral phyllotaxis and ascidiate carpels. Flat stamens and the presence of inner staminodes differ from most other Annonaceae and may be plesiomorphic in Anaxagorea. However, the inner staminodes appear to be non-secretory in most Anaxagorea species, which differs from inner staminodes in other families of Magnoliales (Eupomatiaceae, Degeneriacae, Himantandraceae), which are secretory. Conclusions Floral phyllotaxis in Anaxagorea shows that there is no signature of a basal spiral pattern in Annonaceae and that complex whorls are an apomorphy not just for a part of the family but for the family in its entirety, and irregular phyllotaxis is derived. This and the presence of completely plicate carpels in Anaxagorea makes the family homogeneous and distinguishes it from the closest relatives in Magnoliales.

Floral development and floral phyllotaxis in Anaxagorea (Annonaceae)

PubMed Central

Endress, Peter K.; Armstrong, Joseph E.

2011-01-01

Background and Aims Anaxagorea is the phylogenetically basalmost genus in the large tropical Annonaceae (custard apple family) of Magnoliales, but its floral structure is unknown in many respects. The aim of this study is to analyse evolutionarily interesting floral features in comparison with other genera of the Annonaceae and the sister family Eupomatiaceae. Methods Live flowers of Anaxagorea crassipetala were examined in the field with vital staining, liquid-fixed material was studied with scanning electron microscopy, and microtome section series were studied with light microscopy. In addition, herbarium material of two other Anaxagorea species was cursorily studied with the dissecting microscope. Key Results Floral phyllotaxis in Anaxagorea is regularly whorled (with complex whorls) as in all other Annonaceae with a low or medium number of floral organs studied so far (in those with numerous stamens and carpels, phyllotaxis becoming irregular in the androecium and gynoecium). The carpels are completely plicate as in almost all other Annonaceae. In these features Anaxagorea differs sharply from the sister family Eupomatiaceae, which has spiral floral phyllotaxis and ascidiate carpels. Flat stamens and the presence of inner staminodes differ from most other Annonaceae and may be plesiomorphic in Anaxagorea. However, the inner staminodes appear to be non-secretory in most Anaxagorea species, which differs from inner staminodes in other families of Magnoliales (Eupomatiaceae, Degeneriacae, Himantandraceae), which are secretory. Conclusions Floral phyllotaxis in Anaxagorea shows that there is no signature of a basal spiral pattern in Annonaceae and that complex whorls are an apomorphy not just for a part of the family but for the family in its entirety, and irregular phyllotaxis is derived. This and the presence of completely plicate carpels in Anaxagorea makes the family homogeneous and distinguishes it from the closest relatives in Magnoliales. PMID:21821626

The Ethylene Biosynthesis Gene CitACS4 Regulates Monoecy/Andromonoecy in Watermelon (Citrullus lanatus)

PubMed Central

Manzano, Susana; Aguado, Encarnación; Martínez, Cecilia; Megías, Zoraida; García, Alicia; Jamilena, Manuel

2016-01-01

Monoecious and andromonoecious cultivars of watermelon are characterised by the production of male and female flower or male and hermaphrodite flowers, respectively. The segregation analysis in the offspring of crosses between monoecious and andromonoecious lines has demonstrated that this trait is controlled by a single gene pair, being the monoecious allele M semi-dominant to the andromonoecious allele A. The two studied F1 hybrids (MA) had a predominantly monoecious phenotype since both produced not only female flowers, but also bisexual flowers with incomplete stamens, and hermaphrodite flowers with pollen. Given that in other cucurbit species andromonoecy is conferred by mutations in the ethylene biosynthesis genes CmACS7, CsACS2 and CpACS27A we have cloned and characterised CitACS4, the watermelon gene showing the highest similarity with the formers. CitACS4 encoded for a type ACS type III enzyme that is predominantly expressed in pistillate flowers of watermelon. In the andromonoecious line we have detected a missense mutation in a very conserved residue of CitACS4 (C364W) that cosegregates with the andromonoecious phenotype in two independent F2 populations, concomitantly with a reduction in ethylene production in the floral buds that will develop as hermaphrodite flowers. The gene does not however co-segregates with other sex expression traits regulated by ethylene in this species, including pistillate flowering transition and the number of pistillate flowers per plant. These data indicate that CitAC4 is likely to be involved in the biosynthesis of the ethylene required for stamen arrest during the development of female flowers. The C364W mutation would reduce the production of ethylene in pistillate floral buds, promoting the conversion of female into hermaphrodite flowers, and therefore of monoecy into andromonoecy. PMID:27149159

Flower-predominant expression of a gene encoding a novel class I chitinase in rice (Oryza sativa L.).

PubMed

Takakura, Y; Ito, T; Saito, H; Inoue, T; Komari, T; Kuwata, S

2000-04-01

A flower-predominant cDNA for a gene, termed OsChia 1;175, was isolated from a cDNA library of rice pistils. Northern blot and RT-PCR analyses revealed that the OsChia 1;175 gene is highly expressed in floral organs (pistils, stamens and lodicules at the heading stage) but not or at an extremely low level in vegetative organs. OsChia 1;175 encodes a protein that consists of 340 amino acid residues, and the putative mature protein shows 52% to 63% amino acid identity to class I chitinases of rice or other plants. The phylogenetic tree shows that the OsChia 1;175 protein is a new type of plant class I chitinase in rice. The expression of OsChia 1;175 in vegetative organs is not induced by several chemicals, UV, and wounding. The soluble putative mature OsChia 1;175 protein expressed in Escherichia coli exhibited chitinase activity in the assay with colloidal chitin as a substrate. Genomic Southern analysis revealed that the OsChia 1;175 gene was organized as a low-copy gene family. The rice genomic library was screened and a genome clone corresponding to OsChia 1;175 was isolated. The transcription start sites of the OsChia 1;175 gene were mapped by primer extension analysis. The 1.2 kb putative promoter region of the OsChia 1;175 gene was fused to the GUS (beta-glucuronidase) gene, and this chimeric gene was introduced to rice by Agrobacterium-mediated transformation. The flower-predominant gene expression was identified also in the transgenic rice plants. The high promoter activity was detected in the stigmas, styles, stamens and lodicules in transgenic plants. The possible functions of OsChia 1;175 are discussed.

Unique morphological changes in plant pathogenic phytoplasma-infected petunia flowers are related to transcriptional regulation of floral homeotic genes in an organ-specific manner.

PubMed

Himeno, Misako; Neriya, Yutaro; Minato, Nami; Miura, Chihiro; Sugawara, Kyoko; Ishii, Yoshiko; Yamaji, Yasuyuki; Kakizawa, Shigeyuki; Oshima, Kenro; Namba, Shigetou

2011-09-01

Abnormal flowers are often induced by infection of certain plant pathogens, e.g. phytoplasma, but the molecular mechanisms underlying these malformations have remained poorly understood. Here, we show that infection with OY-W phytoplasma (Candidatus Phytoplasma asteris, onion yellows phytoplasma strain, line OY-W) affects the expression of the floral homeotic genes of petunia plants in an organ-specific manner. Upon infection with OY-W phytoplasma, floral morphological changes, including conversion to leaf-like structures, were observed in sepals, petals and pistils, but not in stamens. As the expression levels of homeotic genes differ greatly between floral organs, we examined the expression levels of homeotic genes in each floral organ infected by OY-W phytoplasma, compared with healthy plants. The expression levels of several homeotic genes required for organ development, such as PFG, PhGLO1 and FBP7, were significantly downregulated by the phytoplasma infection in floral organs, except the stamens, suggesting that the unique morphological changes caused by the phytoplasma infection might result from the significant decrease in expression of some crucial homeotic genes. Moreover, the expression levels of TER, ALF and DOT genes, which are known to participate in floral meristem identity, were significantly downregulated in the phytoplasma-infected petunia meristems, implying that phytoplasma would affect an upstream signaling pathway of floral meristem identity. Our results suggest that phytoplasma infection may have complex effects on floral development, resulting in the unique phenotypes that were clearly distinct from the mutant flower phenotypes produced by the knock-out or the overexpression of certain homeotic genes. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

Floral ontogeny and gene protein localization rules out euanthial interpretation of reproductive units in Lepironia (Cyperaceae, Mapanioideae, Chrysitricheae)

PubMed Central

Prychid, C. J.; Bruhl, J. J.

2013-01-01

Background and Aims In the sedge subfamily Mapanioideae there are considerable discrepancies between the standard trimerous monocot floral architecture expected and the complex floral and inflorescence morphologies seen. Decades of debate about whether the basic reproductive units are single flowers or pseudanthia have not resolved the question. This paper evaluates current knowledge about Mapaniid reproductive structures and presents an ontogenetic study of the Mapaniid genus Lepironia with the first floral protein expression maps for the family, localizing the products of the APETALA1/FRUITFULL-like (AP1/FUL) MADS-box genes with the aim of shedding light on this conundrum. Methods A range of reproductive developmental stages, from spikelet primordia through to infructescence material, were processed for anatomical and immunohistochemical analyses. Key Results The basic reproductive unit is subtended by a bract and possesses two prophyll-like structures, the first organs to be initiated on the primordium, which grow rapidly, enclosing two whorls of initiating leaf-like structures with intervening stamens and a central gynoecium, formed from an annular primordium. The subtending bract and prophyll-like structures possess very different morphologies from that of the internal leaf-like structures and do not show AP1/FUL-like protein localization, which is otherwise strongly localized in the internal leaf-like structures, stamens and gynoecia. Conclusions Results support the synanthial hypothesis as the evolutionary origin of the reproductive unit. Thus, the basic reproductive unit in Lepironia is an extremely condensed pseudanthium, of staminate flowers surrounding a central terminal pistillate female flower. Early in development the reproductive unit becomes enclosed by a split-prophyll, with the whole structure subtended by a bract. PMID:23723258

Oldest fossil flowers of hamamelidaceous affinity, from the Late Cretaceous of New Jersey.

PubMed Central

Crepet, W L; Nixon, K C; Friis, E M; Freudenstein, J V

1992-01-01

Exceptionally well-preserved staminate inflorescences, pistillate inflorescences, and detached stamens with important phylogenetic and paleoecological implications have been discovered from the Turonian (ca. 88.5-90.4 million years B.P.) Raritan Formation of New Jersey. The fossils have a combination of floral and pollen characters found in various genera of modern entomophilous and anemophilous Hamamelidaceae and anemophilous Platanus (Platanaceae). The floral characters of the fossils, including a sepal cup, staminal tube, and apparently nectariferous staminodes, indicate that this taxon was probably insect pollinated. The juxtaposition of character complexes in an extinct taxon from disparate modern taxa provides an interesting phylogenetic perspective on the origins of Hamamelidaceae and is a striking example of a fossil that is a mosaic of familial level characters relative to modern taxa. Of even broader interest, however, is the occurrence of staminodal nectaries that have structural characters intermediate between the fossil's functional stamens and modern hamamelidaceous petals. This transitional staminode morphology in the context of the other fossil characters suggests a staminodal origin of petals in the hamamelid-rosid lineage. This hypothesis is supported by the apparent staminode position within the fossil flowers where petals are found in modern genera. The character complex of morphologically transitional staminodes, a staminal tube, and sepal cup can be viewed as prehypanthial, lacking only fusion of the staminal tube to the sepal cup. The appearance of the character complex embodied in these flowers during the late mid-Cretaceous may signal the early stages of the relationship between specialized pollinators, such as bees, and the hamamelid-rosid-asterid lineage of angiosperms, arguably one of the most important events in angiosperm radiation. Images PMID:11607328

Staminal Evolution in the Genus Salvia (Lamiaceae): Molecular Phylogenetic Evidence for Multiple Origins of the Staminal Lever

PubMed Central

Walker, Jay B.; Sytsma, Kenneth J.

2007-01-01

Background and Aims The genus Salvia has traditionally included any member of the tribe Mentheae (Lamiaceae) with only two stamens and with each stamen expressing an elongate connective. The recent demonstration of the non-monophyly of the genus presents interesting implications for staminal evolution in the tribe Mentheae. In the context of a molecular phylogeny, the staminal morphology of the various lineages of Salvia and related genera is characterized and an evolutionary interpretation of staminal variation within the tribe Mentheae is presented. Methods Two molecular analyses are presented in order to investigate phylogenetic relationships in the tribe Mentheae and the genus Salvia. The first presents a tribal survey of the Mentheae and the second concentrates on Salvia and related genera. Schematic sketches are presented for the staminal morphology of each major lineage of Salvia and related genera. Key Results These analyses suggest an independent origin of the staminal elongate connective on at least three different occasions within the tribe Mentheae, each time with a distinct morphology. Each independent origin of the lever mechanism shows a similar progression of staminal change from slight elongation of the connective tissue separating two fertile thecae to abortion of the posterior thecae and fusion of adjacent posterior thecae. A monophyletic lineage within the Mentheae is characterized consisting of the genera Lepechinia, Melissa, Salvia, Dorystaechas, Meriandra, Zhumeria, Perovskia and Rosmarinus. Conclusions Based on these results the following are characterized: (1) the independent origin of the staminal lever mechanism on at least three different occasions in Salvia, (2) that Salvia is clearly polyphyletic, with five other genera intercalated within it, and (3) staminal evolution has proceeded in different ways in each of the three lineages of Salvia but has resulted in remarkably similar staminal morphologies. PMID:16926227

Environmental responses of the FT/TFL1 gene family and their involvement in flower induction in Fragaria × ananassa.

PubMed

Nakano, Yoshihiro; Higuchi, Yohei; Yoshida, Yuichi; Hisamatsu, Tamotsu

2015-04-01

Flowering time control is important for fruit production in Fragaria × ananassa. The flowering inhibition pathway has been extensively elucidated in the woodland strawberry, Fragaria vesca, whereas the factors involved in its promotion remain unclear. In this study, we investigated the environmental responses of F. × ananassa FT and TFL1-like genes, which are considered key floral promoters and repressors in many plants, respectively. A putative floral promoter, FaFT3, was up-regulated in the shoot tip under short-day and/or low growth temperature, in accordance with the result that these treatments promoted flowering. FaFT3 mRNA accumulated before induction of a floral meristem identity gene, FaAP1. FaFT2, a counterpart of FvFT2, expressed in the flower bud of F. vesca, was not induced in the shoot tip differentiating sepal or stamen, suggesting that this gene works at a later stage than stamen formation. In F. vesca, FvFT1 transmits the long-day signal perceived in the leaves to the shoot tip, and induces the potent floral inhibitor FvTFL1. FaFT1 was expressed in the leaves under long-day conditions in F. × ananassa. Expression of FaTFL1 was higher in the shoot tip under long-day than short-day conditions. Independent of day-length, FaTFL1 expression was higher under high temperature than low temperature conditions. These results suggest that FaFT3 induction by short-day or low temperature stimuli is a key step for flowering initiation. As in F. vesca, F. × ananassa floral inhibition pathways depend on FaTFL1 regulation by day-length via FaFT1, and by temperature. Copyright © 2015 Elsevier GmbH. All rights reserved.

orf260cra, a novel mitochondrial gene, is associated with the homeotic transformation of stamens into pistil-like structures (pistillody) in alloplasmic wheat.

PubMed

Zhu, Ye; Saraike, Tatsunori; Yamamoto, Yuko; Hagita, Hiroko; Takumi, Shigeo; Murai, Koji

2008-11-01

Homeotic transformation of stamens into pistil-like structures (pistillody) can occur in cytoplasmic substitution (alloplasmic) lines of bread wheat (Triticum aestivum) that have the cytoplasm of the related species, Aegilops crassa. Previously we showed that pistillody results from altered patterns of expression of class B MADS-box genes mediated by mitochondrial gene(s) in the Ae. crassa cytoplasm. The wheat cultivar Chinese Spring does not show pistillody when Ae. crassa cytoplasm is introduced. The absence of an effect is due to a single dominant gene (designated Rfd1) located on the long arm of chromosome 7B. To identify the mitochondrial gene involved in pistillody induction, we performed a subtraction analysis using cDNAs derived from young spikes of a pistillody line and a normal line. We found that mitochondrial cDNA clone R04 was abundant in the young spikes of the pistillody line but was down-regulated in the normal line that carried nuclear Rfd1. Sequencing of the full-length cDNA corresponding to clone R04 showed that two genes were present, cox I (cytochrome c oxidase subunit I) and orf260(cra). orf260(cra) shows high sequence similarity to orf256, the T. timopheevii mitochondrial gene responsible for cytoplasmic male sterility (CMS). orf260(cra) was also present in the cytoplasms of Ae. juvenalis and Ae. vavilovii, which induce pistillody, but not in the cytoplasms of other species not associated with pistillody. Furthermore, Western blot analysis revealed that the ORF260cra protein was more abundant in the pistillody line than in the normal line. We suggest therefore that orf260(cra) is associated with pistillody induction.

Oldest fossil flowers of hamamelidaceous affinity, from the Late Cretaceous of New Jersey.

PubMed

Crepet, W L; Nixon, K C; Friis, E M; Freudenstein, J V

1992-10-01

Exceptionally well-preserved staminate inflorescences, pistillate inflorescences, and detached stamens with important phylogenetic and paleoecological implications have been discovered from the Turonian (ca. 88.5-90.4 million years B.P.) Raritan Formation of New Jersey. The fossils have a combination of floral and pollen characters found in various genera of modern entomophilous and anemophilous Hamamelidaceae and anemophilous Platanus (Platanaceae). The floral characters of the fossils, including a sepal cup, staminal tube, and apparently nectariferous staminodes, indicate that this taxon was probably insect pollinated. The juxtaposition of character complexes in an extinct taxon from disparate modern taxa provides an interesting phylogenetic perspective on the origins of Hamamelidaceae and is a striking example of a fossil that is a mosaic of familial level characters relative to modern taxa. Of even broader interest, however, is the occurrence of staminodal nectaries that have structural characters intermediate between the fossil's functional stamens and modern hamamelidaceous petals. This transitional staminode morphology in the context of the other fossil characters suggests a staminodal origin of petals in the hamamelid-rosid lineage. This hypothesis is supported by the apparent staminode position within the fossil flowers where petals are found in modern genera. The character complex of morphologically transitional staminodes, a staminal tube, and sepal cup can be viewed as prehypanthial, lacking only fusion of the staminal tube to the sepal cup. The appearance of the character complex embodied in these flowers during the late mid-Cretaceous may signal the early stages of the relationship between specialized pollinators, such as bees, and the hamamelid-rosid-asterid lineage of angiosperms, arguably one of the most important events in angiosperm radiation.

Characterization and classification of one new cytoplasmic male sterility (CMS) line based on morphological, cytological and molecular markers in non-heading Chinese cabbage (Brassica rapa L.).

PubMed

Heng, Shuangping; Shi, Dianyi; Hu, Zhenhua; Huang, Tao; Li, Jinping; Liu, Liyan; Xia, Chunxiu; Yuan, Zhenzhen; Xu, Yuejin; Fu, Tingdong; Wan, Zhengjie

2015-09-01

A new non-heading Chinese cabbage CMS line M119A was characterized and specific molecular markers were developed to classify different CMS types. One new non-heading Chinese cabbage (Brassica rapa L.) cytoplasmic male sterile (CMS) line M119A was obtained by interspecific crosses between the recently discovered hau CMS line of Brassica juncea and B. rapa. Furthermore, the line was characterized and compared with other five isonuclear-alloplasmic CMS lines. The M119A line produced six stamens without pollen and only two stamen fused together in fewer flowers. Tissue section indicated that anther abortion in M119A may have occurred during differentiation of the archesporial cells without pollen sac. All the six CMS lines were grouped into three types based on the presence of three PCR fragments of 825, 465 and 772 bp amplified with different mitochondrial genes specific primers. The 825-bp fragment was amplified both in 09-10A and H201A using the specific primer pair P-orf224-atp6, and showed 100 % identity with the mitochondrial gene of pol CMS. The 465-bp fragment was amplified in 30A and 105A using the primer pair P-orf138 and shared 100 % identity with the mitochondrial gene of ogu CMS. The 772-bp fragment was amplified in M119A and H203A using the primer pair P-orf288 and showed 100 % identity with the mitochondrial gene of hau CMS. Therefore, these markers could efficiently distinguish different types of isonuclear-alloplasmic CMS lines of non-heading Chinese cabbage, which were useful for improving the efficiency of cross-breeding and heterosis utilization in cruciferous vegetables.

Floral morphology and anatomy of Ophiocaryon, a paedomorphic genus of Sabiaceae.

PubMed

Thaowetsuwan, P; Honorio Coronado, E N; Ronse De Craene, L P

2017-11-10

Ophiocaryon is a lesser known genus in Sabiaceae. This study examines flowers of six Ophiocaryon species in comparison with Meliosmaalba, to identify taxonomically informative characters for understanding relationships within the family Sabiaceae, to imply previously unknown pollination mechanisms of Ophiocaryon, and to contribute to the placement of Sabiaceae within the early-diverging eudicots. Floral morphology and anatomy of six Ophiocaryon species and M. alba were studied and described using scanning electron microscopy, clearing techniques and resin sectioning. Novel characters of Ophiocaryon were identified, e.g. conical cells on petals, different kinds of orbicules in anthers, stomata on nectary appendage tips and ovary, two distinct surface patterns on stamens and ovary, tanniferous cell layers in the ovary wall, and acorn-shaped unitegmic ovules with very short integuments. Comparison of floral characters between Ophiocaryon and Meliosma found that the calyx, corolla, androecium and gynoecium of Ophiocaryon resemble an undeveloped state of the latter taxon, reflecting a paedomorphic regression of the flower of Ophiocaryon. The flower morphology and anatomy of Ophiocaryon was compared with its putative sister species M. alba, but no clear shared derived characters could be detected. Moreover, the findings of scent, presence of conical cells on petals and a nectary suggest flowers are pollinated by small insects with a secondary pollen presentation on the cupula of fertile stamens. We found that Ophiocaryon may be derived from ancestors that were similar to extant Meliosma in their flower structure and pollination mechanism. However, the lack of shared derived characters between Ophiocaryon and its phylogenetic sister group M. alba is puzzling and requires further investigations on the diversity of the latter species. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Influence of plant size on female-biased sex allocation in a single-flowered, nectarless herb

PubMed Central

Xiong, Ying-Ze; Xie, Meng; Huang, Shuang-Quan

2016-01-01

Relative allocation to female and male function in hermaphroditic species often departs from strict equisexuality. Increased femaleness with plant size in animal-pollinated species has been proposed in theory and demonstrated in empirical studies. However, such size-dependent sex allocation (SDS) has not been observed in some insect-pollinated species, throwing doubt on the generalization of SDS, that large plants have decelerated male function investment. Himalayan mayapple Podophyllum hexandrum (Berberidaceae) produces a single terminal flower and no nectar, providing a simple system for studying SDS without the confounding effects of flower number and nectar production. To investigate the SDS in P. hexandrum, plant size, biomass of floral organs (stamens, pistils and petals) and gamete production (pollen and ovule number) were measured in four populations in Yunnan Province, northwest China. Isometric allocation to female and male function with plant size was found in two populations, but the prediction of SDS was supported in the other two populations. Using pollen and ovule production as the allocation currency, allocation to female and male function was isometric in all studied populations. Resources allocated to attractive (petals) and sexual (pistils and stamens) structures did not show a significantly disproportionate increase with plant size in three of the four studied populations. The general pattern of isometric allocation to female and male function and to attractive and sexual structures could be attributed to the species being capable of automatic self-pollination, related to low pollen loss, minor deleterious effect of selfing and low importance of attractive structures. However, in further studies, careful consideration should be given to the different currencies used to estimate sex allocation. PMID:26602988

Ectopic expression of the HAM59 gene causes homeotic transformations of reproductive organs in sunflower (Helianthus annuus L.).

PubMed

Shulga, O A; Neskorodov, Ya B; Shchennikova, A V; Gaponenko, A K; Skryabin, K G

2015-01-01

The function of the HAM59 MADS-box gene in sunflower (Helianthus annuus L.) was studied to clarify homeotic C activity in the Asteraceae plant family. For the first time, transgenic sunflower plants with a modified pattern of HAM59 expression were obtained. It was shown that the HAM59 MADS-box transcription factor did mediate C activity in sunflower. In particular, it participated in termination of the floral meristem, repression of the cadastral function of A-activity, and together with other C-type sunflower protein HAM45-in the specification of the identity of stamens and pistils.

Two new desert Eschscholzia (Papaveraceae) from southwestern North America.

PubMed

Still, Shannon M

2014-01-01

Two new species of Eschscholzia are described. Both are found in the deserts of California and one extends outside the state boundary into Arizona. Eschscholzia androuxii Still, sp. nov. is found mainly in and around Joshua Tree National Park in Riverside and San Bernardino counties. Eschscholzia papastillii Still, sp. nov. is found from the northern Mojave south through Joshua Tree National Park to central Imperial County. Both are annuals found in coarse, sandy soil and have yellow flowers typical of desert Eschscholzia. Eschscholzia papastillii has an expanded receptacular rim similar to that of Eschscholzia californica. Eschscholzia androuxii has anthocyanin bands around the stamen filaments.

[Comparison of the botanic morphology and blooming characteristics of four cultivars of rose].

PubMed

Wang, Kang-cai; Tang, Xiao-qing; Sheng, Min-li; Xu, Xiao-lan; Fang, Zhen

2004-05-01

To establish identifying method for further development and utilization by studying botanic morphology and blooming characteristics of four varieties of roses in Jiangsu province. Flower-bud and flower-form were observed by dissection and plant modality and blooming process were investigated. The flower form and plant modality was obviously different among the 4 varieties of roses. The process of differentiation of flower-bud could be divided into five stages: the transformation of nutritive growth cone, the occurrence and development of sepal, formation of petal primordium, formation of pistil and stamen. The blooming process was made up of flower-bud period, display-petal period, initiating blooming period, blooming period, withering period and corresponding biological marks.

Laser capture microdissection to study flower morphogenesis

NASA Astrophysics Data System (ADS)

Pawełkowicz, Magdalena Ewa; Skarzyńska, Agnieszka; Kowalczuk, Cezary; PlÄ der, Wojciech; Przybecki, Zbigniew

2017-08-01

Laser Capture Microdissection (LCM) is a sample preparation microscopic method that enables isolation of an interesting cell or cells population from human, animal or plant tissue. This technique allows for obtaining pure sample from heterogeneous mixture. From isolated cells, it is possible to obtain the appropriate quality material used for genomic research in transcriptomics, proteomics and metabolomics. We used LCM method to study flower morphogenesis and specific bud's organ organization and development. The genes expression level in developing flower buds of male (B10) and female (2gg) lines were analyzed with qPCR. The expression was checked for stamen and carpel primordia obtained with LCM and for whole flower buds at successive stages of growth.

AN INDUCED MULTIPLE CARPEL MUTATION IN BREAD WHEAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatia, C.R.; Swaminathan, M.S.

>Mutants showing partical or complete transformation of stamens into carpels or carpet-like structures were recorded in M/sub 2/ progenies, following irradiation of dry seeds with 16 R rads of x rays and following treatment with BETA particles from S/sup 35/, in bread wheat variety H 167. The multiple carpel mutation has a low and variable expression. It appears to be recessive to normal. Seed setting was poor in bagged spikes of the mutant plants but reasonably good seed set was obtained under conditions of open pollination. Not more than one functional carpel was found in any flower and this wasmore » always the normal carpel. (auth)« less

Two new fossil flowers of magnoliid affinity from the Late Cretaceous of New Jersey.

PubMed

Crepet, W L; Nixon, K C

1998-09-01

Two taxa of cupulate magnoliid fossil flowers, Cronquistiflora and Detrusandra, are described from the Late Cretaceous (Turonian, ∼90 million years before present [MYBP]) Raritan (or lower Magothy) Formation of New Jersey. The fossil taxa are represented by flowers at various stages of development, associated fragments of cup-shaped floral receptacles with attached anthers, and isolated anthers. Both taxa have laminar stamens with adaxial thecae and valvate dehiscence. Pollen is boat-shaped and foveolate in anthers associated with Cronquistiflora and spherical with reticulate ornamentation in Detrusandra. Cup-shaped receptacles are externally bracteose in both taxa. The receptacle of Cronquistiflora is broader than the campanulate one of Detrusandra. Cronquistiflora also has more carpels (∼50 in a spiral vs. ∼5 in a whorl or tight spiral). In Detrusandra the carpels are surrounded by dorsiventrally flattened structures (pistillodes?) that are remote from the attachment of the stamens near the distal rim of the receptacular cupule. Detrusandra stigmas are rounded and bilobed, while those of Cronquistiflora, although bilateral in symmetry, are somewhat peltate. The fossil taxa share prominent characters with extant cupulate magnoliids (e.g., Eupomatia, Calycanthus), but also share characters with other magnoliids including Winteraceae. These fossils represent taxa that are character mosaics relative to currently recognized families. Inclusion of these fossils in existing data matrices and ensuing phylogenetic analyses effect changes in tree topologies consistent with their mosaicism relative to modern taxa. But such analyses do not definitively demonstrate the affinities of the fossils other than illustrating that these fossils are generalized magnoliids. Additional analysis of modern and fossil magnoliids is necessary to fully appreciate the phylogenetic significance and positions of these fossil taxa. However, the results of the phylogenetic analyses do introduce the possibility that extinct taxa of Magnoliales with cupulate floral receptacles were transitional between basal angiosperms and those with tricolpate pollen. The fossils provide insights into the timing of evolution of character complexes now associated with coleopteran pollination.

Floral heterochrony promotes flexibility of reproductive strategies in the morphologically homogeneous genus Eugenia (Myrtaceae).

PubMed

Vasconcelos, Thais N C; Lucas, Eve J; Faria, Jair E Q; Prenner, Gerhard

2018-01-25

Comparative floral ontogeny represents a valuable tool to understand angiosperm evolution. Such an approach may elucidate subtle changes in development that discretely modify floral architecture and underlie reproductive lability in groups with superficial homogeneous morphology. This study presents a comparative survey of floral development in Eugenia (Myrtaceae), one of the largest genera of angiosperms, and shows how previously undocumented ontogenetic trends help to explain the evolution of its megadiversity in contrast to its apparent flower uniformity. Using scanning electron microscopy, selected steps of the floral ontogeny of a model species (Eugenia punicifolia) are described and compared with 20 further species representing all ten major clades in the Eugenia phylogenetic tree. Additional floral trait data are contrasted for correlation analysis and character reconstructions performed against the Myrtaceae phylogenetic tree. Eugenia flowers show similar organ arrangement patterns: radially symmetrical, (most commonly) tetramerous flowers with variable numbers of stamens and ovules. Despite a similar general organization, heterochrony is evident from size differences between tissues and structures at similar developmental stages. These differences underlie variable levels of investment in protection, subtle modifications to symmetry, herkogamic effects and independent androecium and gynoecium variation, producing a wide spectrum of floral display and contributing to fluctuations in fitness. During Eugenia's bud development, the hypanthium (as defined here) is completely covered by stamen primordia, unusual in other Myrtaceae. This is the likely plesiomorphic state for Myrteae and may have represented a key evolutionary novelty in the tribe. Floral evolution in Eugenia depends on heterochronic patterns rather than changes in complexity to promote flexibility in floral strategies. The successful early establishment of Myrteae, previously mainly linked to the key innovation of fleshy fruit, may also have benefitted from changes in flower structure. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The effect of temperature on reproduction in the summer and winter annual Arabidopsis thaliana ecotypes Bur and Cvi

PubMed Central

Huang, Ziyue; Footitt, Steven; Finch-Savage, William E.

2014-01-01

Background and Aims Seed yield and dormancy status are key components of species fitness that are influenced by the maternal environment, in particular temperature. Responses to environmental conditions can differ between ecotypes of the same species. Therefore, to investigate the effect of maternal environment on seed production, this study compared two contrasting Arabidopsis thaliana ecotypes, Cape Verdi Isle (Cvi) and Burren (Bur). Cvi is adapted to a hot dry climate and Bur to a cool damp climate, and they exhibit winter and summer annual phenotypes, respectively. Methods Bur and Cvi plants were grown in reciprocal controlled environments that simulated their native environments. Reproductive development, seed production and subsequent germination behaviour were investigated. Measurements included: pollen viability, the development of floral structure, and germination at 10 and 25 °C in the light to determine dormancy status. Floral development was further investigated by applying gibberellins (GAs) to alter the pistil:stamen ratio. Key Results Temperature during seed development determined seed dormancy status. In addition, seed yield was greatly reduced by higher temperature, especially in Bur (>90 %) compared with Cvi (approx. 50 %). The reproductive organs (i.e. stamens) of Bur plants were very sensitive to high temperature during early flowering. Viability of pollen was unaffected, but limited filament extension relative to that of the pistils resulted in failure to pollinate. Thus GA applied to flowers to enhance filament extension largely overcame the effect of high temperature on yield. Conclusions High temperature in the maternal environment reduced dormancy and negatively affected the final seed yield of both ecotypes; however, the extent of these responses differed, demonstrating natural variation. Reduced seed yield in Bur resulted from altered floral development not reduced pollen viability. Future higher temperatures will impact on seed performance, but the consequences may differ significantly between ecotypes of the same species. PMID:24573642

Exploratory monitoring of air pollutants for mutagenicity activity with the Tradescantia stamen hair system.

PubMed

Schairer, L A; Van't Hof, J; Hayes, C G; Burton, R M; de Serres, F J

1978-12-01

The Tradescantia genetic system developed by the late Dr. Arnold H. Sparrow for the study of effects of ionizing radiation is applicable to chemical mutagen detection. Early radiobiological data demonstrated that the stamen hairs were sensitive to as little as 0.25 rad of x-rays and that the number of cells showing a phenotypic change in pigmentation from blue to pink plateaus after approximately 21 days of chronic, low-level irradiation. Exposures to the air pollutants SO(2), NO(2), and O(3) and to vapors of mutagens such as 1,2-dibromoethane (DBE) and ethyl methanesulfonate (EMS) demonstrated the usefulness of the system as a detector of chemical mutagens. A significant number of phenotypic changes was observed following exposures to as little as 0.14 ppm of DBE. The maximum sensitivity of the system is obtained with long-term or chronic exposures because the response increases linearly in proportion to the duration of exposure up to 21 days. To monitor industrial sites for atmospheric mutagens a mobile laboratory was designed to support plant culture in the field. Environment-controlled growth chambers were installed in a trailer so that both ambient air fumigations and concurrent clean-air control exposures could be made. Sites monitored by the mobile laboratory were: Elizabeth, N. J.; Charleston, W. Va.; Birmingham, Ala.; Baton Rouge, La.; Houston, Tex.; Upland, Calif.; Magna, Utah; and Grand Canyon, Ariz. The latter site at Grand Canyon served as a clean air control study. Atmospheric contaminants from petroleum and chemical processing plants generated a significant number of phenotypic pigment changes that were 17 to 31% above the control levels; contaminants from steel and copper smelters, automotive combustion products and photochemical compounds were negative. Chemical analyses are underway to identify the atmospheric mutagens at the sites that showed a positive response.

Time to split Salvia s.l. (Lamiaceae) - New insights from Old World Salvia phylogeny.

PubMed

Will, Maria; Claßen-Bockhoff, Regine

2017-04-01

Salvia L. is widely known as the largest genus in the mint family. A morphological modification of the androecium (lever-like stamens) was used to support this genus. However, molecular data revealed that Salvia is polyphyletic. Since phylogenetic studies largely underrepresented Old World Salvia species, we filled this gap and combined new data with existing sequences. The aim of our study was the identification of well-supported clades that provide the basis for evolutionary and taxonomic conclusions. We included ITS data (internal transcribed spacer) from 220 Salvia species, 86 of which were sequenced for the first time. Additionally, the highly variable plastid marker rpl32-trnL was sequenced, providing new data for 100 Salvia species. These sequences were combined with the accessions available from GenBank. Old World Salvia is represented herein with 57% of its species. The two datasets were analyzed separately using BI and ML approaches. Our data confirm that Salvia is polyphyletic with four distinct evolutionary lineages (Clade I-IV), including five additional genera. The clades strongly reflect the geographical distribution, i.e., Clade IV (East Asia), Clade III (Southwest Asia to Northern Africa), and Clade II (America). The origin of Salvia s.s. (Clade I) is most likely Southwest Asia. A high degree of parallel character evolution was identified in most of the Old World sections. Based on our results, we reconstructed the evolution and biogeography of Salvia s.l. and propose to split this large group into six genera, each supported by geographical distribution, morphology, and karyology. Salvia s.l. is a polyphyletic group that was originally regarded as a genus because its species share a derived stamen structure. However, phylogenetic data clearly indicate that this floral trait and other morphological characters evolved in parallel. Our study illustrates that the combination of different data sets allows a comprehensive reconstruction of taxa and characteristic evolution, both of which are a precondition for future revision. Copyright © 2017 Elsevier Inc. All rights reserved.

Flower-like heads from flower-like meristems: pseudanthium development in Davidia involucrata (Nyssaceae).

PubMed

Claßen-Bockhoff, Regine; Arndt, Melanie

2018-05-01

Flower-like inflorescences (pseudanthia) have fascinated botanists for a long time. They are explained as condensed inflorescences implying that the pseudanthium develops from an inflorescence meristem (IM). However, recent developmental studies identified a new form of reproductive meristem, the floral unit meristem (FUM). It differs from IMs by lacking acropetal growth and shares fractionation, expansion and autonomous space filling with flower meristems (FM). The similarity among FUMs and FMs raises the question how far flower-like heads originate from flower-like meristems. In the present paper, pseudanthium development in Davidia involucrata is investigated using scanning electron microscopy. D. involucrata has pincushion-shaped heads composed of densely aggregated, perianthless flowers and associated with two large showy bracts. Early developmental stages show a huge naked FUM. The FMs appear almost simultaneously and lack subtending bracts. With ongoing FUM expansion new space is generated which is immediately used by further FM fractionation. The heads have only staminate flowers or are andromonoecious with staminate and a single perfect flower in oblique position. All FMs lack perianth structures and fractionate a variable number of stamen primordia. The perfect FM is much larger than the staminate FMs and forms a syncarpous gynoecium with inferior ovary. Pseudanthium development in D. involucrata confirms the morphogenetic similarity to FMs as to acropetal growth limitation, meristem expansion and fractionation. It thus should not be interpreted as a condensed inflorescence, but as a flower equivalent. Furthermore as the FUM develops inside a bud, its development is considered to be influenced by mechanical pressure. The oblique position of the perfect flower, the developmental delay of the proximal flowers, and the variable number of stamens which were observed in the pseudanthium development, can be caused by mechanical pressure. Next to the Asteraceae, D. involucrata offers a further example of a pseudanthium originating from a FUM. More knowledge on FUMs is still needed to understand diversification and evolution of flower-like inflorescences.

Isolation of the three grape sub-lineages of B-class MADS-box TM6, PISTILLATA and APETALA3 genes which are differentially expressed during flower and fruit development.

PubMed

Poupin, María Josefina; Federici, Fernán; Medina, Consuelo; Matus, José Tomás; Timmermann, Tania; Arce-Johnson, Patricio

2007-12-01

The B class of MADS-box floral homeotic genes specifies petal and stamen identity in angiosperms. While this group is one of the most studied in herbaceous plant species, it has remained largely uncharacterized in woody species such as grapevine. Although the B class PI/GLO and AP3/DEF clades have been extensively characterized in model species, the role of the TM6 subgroup within the AP3 clade is not completely understood, since it is absent in Arabidopsis thaliana. In this study, the coding regions of VvTM6 and VvAP3 and the genomic sequence of VvPI, were cloned. VvPI and AtPI were confirmed to be functional homologues by means of complementation of the pi Arabidopsis mutant. Expression analysis revealed that VvPI and VvAP3 transcripts are restricted almost exclusively to inflorescences, although VvPI was detected at low levels in leaves and roots. VvTM6 expresses throughout the plant, with higher levels in flowers and berries. A detailed chronological study of grape flower progression by light microscopy and temporal expression analysis throughout early and late developmental stages, revealed that VvPI expression increases during pollen maturation and decreases between the events of pollination and fertilization, before the cap fall. On the other hand, VvTM6 is expressed in the last stage of anther development. Specific expression of VvAP3 and VvPI was detected in petals and stamens within the flower, while VvTM6 was also expressed in carpels. Moreover, this work provides the first evidence for expression of a TM6-like gene throughout fruit growth and ripening. Even if these genes belong to the same genetic class they could act in different periods and/or tissues during reproductive organ development.

Gibberellic Acid: A Key Phytohormone for Spikelet Fertility in Rice Grain Production.

PubMed

Kwon, Choon-Tak; Paek, Nam-Chon

2016-05-23

The phytohormone gibberellic acid (GA) has essential signaling functions in multiple processes during plant development. In the "Green Revolution", breeders developed high-yield rice cultivars that exhibited both semi-dwarfism and altered GA responses, thus improving grain production. Most studies of GA have concentrated on germination and cell elongation, but GA also has a pivotal role in floral organ development, particularly in stamen/anther formation. In rice, GA signaling plays an important role in spikelet fertility; however, the molecular genetic and biochemical mechanisms of GA in male fertility remain largely unknown. Here, we review recent progress in understanding the network of GA signaling and its connection with spikelet fertility, which is tightly associated with grain productivity in cereal crops.

Grass flower development.

PubMed

Hirano, Hiro-Yuki; Tanaka, Wakana; Toriba, Taiyo

2014-01-01

Grasses bear unique flowers lacking obvious petals and sepals in special inflorescence units, the florets and the spikelet. Despite this, grass floral organs such as stamens and lodicules (petal homologs) are specified by ABC homeotic genes encoding MADS domain transcription factors, suggesting that the ABC model of eudicot flower development is largely applicable to grass flowers. However, some modifications need to be made for the model to fit grasses well: for example, a YABBY gene plays an important role in carpel specification. In addition, a number of genes are involved in the development of the lateral organs that constitute the spikelet. In this review, we discuss recent progress in elucidating the genes required for flower and spikelet development in grasses, together with those involved in fate determination of the spikelet and flower meristems.

Roles of jasmonate signalling in plant inflorescence and flower development.

PubMed

Yuan, Zheng; Zhang, Dabing

2015-10-01

Development of inflorescences and flowers in plants is controlled by the combined action of environmental and genetic signals. Investigations reveal that the phytohormone jasmonate (JA) plays a critical function in plant reproduction such as male fertility, sex determination and seed maturation. Here, we review recent progress on JA synthesis, signalling, the interplay between JAs and other hormones, and regulatory network of JA in controlling the development of inflorescence, flower and the male organ. The conserved and diversified roles of JAs in meristem transition and specification of flower organ identity and number, and multiple regulatory networks of JAs in stamen development are highlighted. Further, this review provides perspectives on future research endeavors to elucidate mechanisms underlying JAs homeostasis and transport during plant reproductive development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mutations induced in Tradescantia by small doses of X-rays and neutrons - Analysis of dose-response curves.

NASA Technical Reports Server (NTRS)

Sparrow, A. H.; Underbrink, A. G.; Rossi, H. H.

1972-01-01

Dose-response curves for pink somatic mutations in Tradescantia stamen hairs were analyzed after neutron and X-ray irradiation with doses ranging from a fraction of a rad to the region of saturation. The dose-effect relation for neutrons indicates a linear dependence from 0.01 to 8 rads; between 0.25 and 5 rads, a linear dependence is indicated for X-rays also. As a consequence the relative biological effectiveness reaches a constant value (about 50) at low doses. The observations are in good agreement with the predictions of the theory of dual radiation action and support its interpretation of the effects of radiation on higher organisms. The doubling dose of X-rays was found to be nearly 1 rad.

Floral development of Berberidopsis beckleri - can an additional species of the Berberidopsidaceae add evidence to floral evolution in the core eudicots?

PubMed

Ronse De Craene, Louis P

2017-03-01

Berberidopsis beckleri is one of three species of the family Berberidopsidaceae. The flower of Berberidopsis is unusual for core eudicots in being spiral with an undifferentiated perianth. In a previous study of the sister species B. corallina , it was suggested that Berberidopsidaceae represent a prototype for the origin of the bipartite perianth and pentamery in core eudicots. The floral development of B. beckleri was investigated with a scanning electron microscope and compared with previous studies on B. corallina and Aextoxicon punctatum of Berberidopsidales. Flowers are inserted at the end of short shoots, which are not distinguishable from a pedicel. The initiation of perianth parts is highly predictable and spiral with a divergence angle of 137·5°, in a progression of a variable number of bracts to weakly differentiated sepaloid and petaloid tepals. The androecium most often consists 11 stamens arising in a rapid sequence. Compared with B. corallina , the number of perianth parts and stamens is more variable and there is no evidence of an alternation of shorter and longer plastochrons leading to a whorled arrangement. However, the gynoecium is generally pentamerous and arises from five primordia. The carpels are laterally connected into massive intercarpellary ridges on which ovules are initiated. The position of Streptothamnus within Berberidopsidaceae is questioned. It is demonstrated that the floral development of Berberidopsis beckleri lies within a gradient from spiral flowers without perianth differentiation leading to flowers with differentiated sepals and petals. The arrangement of flowers in compact inflorescences in B. corallina and Aextoxicon leads to a more stabilized arrangement of organs in whorls. The inherent variability of the flower of Berberidopsis is well correlated with the limited canalization of flowers in taxa at the base of the core eudicots and could act as a prototype for the current eudicot floral Bauplan. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Flower Development and Perianth Identity Candidate Genes in the Basal Angiosperm Aristolochia fimbriata (Piperales: Aristolochiaceae)

PubMed Central

Pabón-Mora, Natalia; Suárez-Baron, Harold; Ambrose, Barbara A.; González, Favio

2015-01-01

Aristolochia fimbriata (Aristolochiaceae: Piperales) exhibits highly synorganized flowers with a single convoluted structure forming a petaloid perianth that surrounds the gynostemium, putatively formed by the congenital fusion between stamens and the upper portion of the carpels. Here we present the flower development and morphology of A. fimbriata, together with the expression of the key regulatory genes that participate in flower development, particularly those likely controlling perianth identity. A. fimbriata is a member of the magnoliids, and thus gene expression detected for all ABCE MADS-box genes in this taxon, can also help to elucidate patterns of gene expression prior the independent duplications of these genes in eudicots and monocots. Using both floral development and anatomy in combination with the isolation of MADS-box gene homologs, gene phylogenetic analyses and expression studies (both by reverse transcription PCR and in situ hybridization), we present hypotheses on floral organ identity genes involved in the formation of this bizarre flower. We found that most MADS-box genes were expressed in vegetative and reproductive tissues with the exception of AfimSEP2, AfimAGL6, and AfimSTK transcripts that are only found in flowers and capsules but are not detected in leaves. Two genes show ubiquitous expression; AfimFUL that is found in all floral organs at all developmental stages as well as in leaves and capsules, and AfimAG that has low expression in leaves and is found in all floral organs at all stages with a considerable reduction of expression in the limb of anthetic flowers. Our results indicate that expression of AfimFUL is indicative of pleiotropic roles and not of a perianth identity specific function. On the other hand, expression of B-class genes, AfimAP3 and AfimPI, suggests their conserved role in stamen identity and corroborates that the perianth is sepal and not petal-derived. Our data also postulates an AGL6 ortholog as a candidate gene for sepal identity in the Aristolochiaceae and provides testable hypothesis for a modified ABCE model in synorganized magnoliid flowers. PMID:26697047

Fusion within and between whorls of floral organs in Galipeinae (Rutaceae): structural features and evolutionary implications

PubMed Central

El Ottra, Juliana Hanna Leite; Pirani, José Rubens; Endress, Peter K.

2013-01-01

Background and Aims Most genera of the neotropical Galipeinae (tribe Galipeeae, Rutoideae) exhibit several forms and degrees of fusion between the floral organs, including the union of petals into an apparently sympetalous corolla, the joining of the stamens among themselves and to the corolla, and the partial to complete connation of carpels. Though these and others floral traits are currently used in the circumscription of species in Galipeinae, few studies have shown in detail in which way (postgenital or congenital) and to what extent these fusions occur. To elucidate these anatomical conditions, a structural study of the flowers of the Galipeinae species was carried out. Methods Flowers of six species from three genera of Galipeinae were studied in their morphology, anatomy and development with stereomicroscopy, light microscopy and scanning electron microscopy (SEM). Key Results The floral tube is formed by synorganization of stamens with petals in all species, and exhibits three main patterns: (1) Conchocarpus heterophyllus and C. minutiflorus have a floral tube formed by marginal coherence/adherence of petals and filaments due to interwining trichomes (postgenital connection); (2) Erythrochiton brasiliensis has a tube formed by congenital fusion of petals and filaments; and (3) Galipea jasminiflora and Conchocarpus macrophyllus have a tube formed distally with the first pattern, and proximally with the second pattern. Although floral tubes seem to be homologous within Galipeinae, this is not true at the level of the family: the floral tube of Correa (from an only distantly related clade of the family) is formed by postgenital union of the petals representing a convergent structure. The gynoecium of the studied species of Galipeinae shows a great variability in the extent of fusion of carpel flanks. Even though different structures for the mature gynoecium were found in each genus, all genera show postgenitally fused carpel apices, which is related to the formation of a compitum, as described earlier for other members of Rutaceae. Conclusions The degree and diversity of fusions of floral organs in Galipeinae is unique within the order Sapindales. A study of the amount of diversification of Galipeinae in South America and comparison with other clades of Rutaceae would be of interest. PMID:23463590

Characterization of TM8, a MADS-box gene expressed in tomato flowers.

PubMed

Daminato, Margherita; Masiero, Simona; Resentini, Francesca; Lovisetto, Alessandro; Casadoro, Giorgio

2014-11-30

The identity of flower organs is specified by various MIKC MADS-box transcription factors which act in a combinatorial manner. TM8 is a MADS-box gene that was isolated from the floral meristem of a tomato mutant more than twenty years ago, but is still poorly known from a functional point of view in spite of being present in both Angiosperms and Gymnosperms, with some species harbouring more than one copy of the gene. This study reports a characterization of TM8 that was carried out in transgenic tomato plants with altered expression of the gene. Tomato plants over-expressing either TM8 or a chimeric repressor form of the gene (TM8:SRDX) were prepared. In the TM8 up-regulated plants it was possible to observe anomalous stamens with poorly viable pollen and altered expression of several floral identity genes, among them B-, C- and E-function ones, while no apparent morphological modifications were visible in the other whorls. Oblong ovaries and fruits, that were also parthenocarpic, were obtained in the plants expressing the TM8:SRDX repressor gene. Such ovaries showed modified expression of various carpel-related genes. No apparent modifications could be seen in the other flower whorls. The latter plants had also epinastic leaves and malformed flower abscission zones. By using yeast two hybrid assays it was possible to show that TM8 was able to interact in yeast with MACROCALIX. The impact of the ectopically altered TM8 expression on the reproductive structures suggests that this gene plays some role in the development of the tomato flower. MACROCALYX, a putative A-function MADS-box gene, was expressed in all the four whorls of fully developed flowers, and showed quantitative variations that were opposite to those of TM8 in the anomalous stamens and ovaries. Since the TM8 protein interacted in vitro only with the A-function MADS-box protein MACROCALYX, it seems that for the correct differentiation of the tomato reproductive structures possible interactions between TM8 and MACROCALYX proteins might be important.

Overexpression of a flower-specific aerolysin-like protein from the dioecious plant Rumex acetosa alters flower development and induces male sterility in transgenic tobacco.

PubMed

Manzano, Susana; Megías, Zoraida; Martínez, Cecilia; García, Alicia; Aguado, Encarnación; Chileh, Tarik; López-Alonso, Diego; García-Maroto, Federico; Kejnovský, Eduard; Široký, Jiří; Kubát, Zdeněk; Králová, Tereza; Vyskot, Boris; Jamilena, Manuel

2017-01-01

Sex determination in Rumex acetosa, a dioecious plant with a complex XY 1 Y 2 sex chromosome system (females are XX and males are XY 1 Y 2 ), is not controlled by an active Y chromosome but depends on the ratio between the number of X chromosomes and autosomes. To gain insight into the molecular mechanisms of sex determination, we generated a subtracted cDNA library enriched in genes specifically or predominantly expressed in female floral buds in early stages of development, when sex determination mechanisms come into play. In the present paper, we report the molecular and functional characterization of FEM32, a gene encoding a protein that shares a common architecture with proteins in different plants, animals, bacteria and fungi of the aerolysin superfamily; many of these function as β pore-forming toxins. The expression analysis, assessed by northern blot, RT-PCR and in situ hybridization, demonstrates that this gene is specifically expressed in flowers in both early and late stages of development, although its transcripts accumulate much more in female flowers than in male flowers. The ectopic expression of FEM32 under both the constitutive promoter 35S and the flower-specific promoter AP3 in transgenic tobacco showed no obvious alteration in vegetative development but was able to alter floral organ growth and pollen fertility. The 35S::FEM32 and AP3::FEM32 transgenic lines showed a reduction in stamen development and pollen viability, as well as a diminution in fruit set, fruit development and seed production. Compared with other floral organs, pistil development was, however, enhanced in plants overexpressing FEM32. According to these effects, it is likely that FEM32 functions in Rumex by arresting stamen and pollen development during female flower development. The aerolysin-like pore-forming proteins of eukaryotes are mainly involved in defence mechanisms against bacteria, fungi and insects and are also involved in apoptosis and programmed cell death (PCD), a mechanism that could explain the role of FEM32 in Rumex sex determination. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

[Morphology, anatomy and floral biology of Cabralea canjerana (Vell.) Mart. (Meliaceae)].

PubMed

Moscheta, Ismar S; de Souza, Luiz A; Mourão, Káthia S; da Rosa, Sônia M

2002-01-01

Cabralea canjerana (Vell.) Mart. is a tree that occurs frequently in secondary forests of Maringá, Paraná, Brazil and presents a valuable wood. Its flowering time occurs from August to October and the anthesis occurs during the night. Its flowers are visited by Lepidoptera-Noctuidae. The flowers are unisexual and solitary or arranged in panicles. The perianth presents a papillose epidermis with striate cuticle and a parenchymatic mesophyll. Ten stamens constitute the androecium and are arranged in a staminal tube with anthers. The anthers present epidermis, endothecium, two median layers and secretory tapetum with binucleate cells. The semi-inferior ovary presents anatropous, bitegmic and crassinucleate ovules. The nectaries are located in the base of the ovary and staminal tube and they present papillose epidermis with stomata and secretory parenchyma with a conspicuous phloematic tissue.

Two new species of endemic Ecuadorean Amaryllidaceae (Asparagales, Amaryllidaceae, Amarylloideae, Eucharideae)

PubMed Central

Meerow, Alan W.; Jost, Lou; Oleas, Nora

2015-01-01

Abstract New species of the genera Stenomesson and Eucharis (Amaryllidaceae) are described from Ecuador. Stenomesson ecuadorense is the second species of the genus reported from that country, and the only endemic one. It is related to Stenomesson miniatum and Stenomesson campanulatum, both from Peru, with which it shares orange flower color and the fusion of the staminal corona to the perianth tube. It differs from Stenomesson miniatum by the non-urceolate perianth, from Stenomesson campanulatum by its shorter stamens and longer perianth, and from both by its lower montane, cloud forest habitat. Eucharis ruthiana, found in the vicinity of Zamora, is related to Eucharis moorei from which it differs by the narrower leaves and tepals; short, deeply cleft staminal corona; the long teeth on either side of the free filaments; the narrowly subulate, incurved free filaments; and the shorter style. The green mature fruit and campanulate floral morphology place it in Eucharis subg. Heterocharis. PMID:25931969

Tropism in azalea and lily flowers

NASA Astrophysics Data System (ADS)

Shimizu, M.; Tomita-Yokotani, K.; Nakamura, T.; Yamashita, M.

Tropic responses were examined in azalea Rhododendrom pulchrum and lily Lilium cv. 'Casablanca' flowers. Orientation of the flowers in these two species depicts several up/down characteristics, such as angle of the corolla opening, alignment or configuration of a specific petal at the top, plus direction in the curved tip of the pistil and stamen. Gravity was found to be the prime factor, with light as a secondary signal that determines gravitropism in the pistil of the azalea. Within the azalea, sedimented amyloplasts were observed throughout the cells along the inner layers below the epidermis. In lily flowers, no sedimented amyloplasts were found in style cells, and phototropic responses caused upward bending of the pistil. Responses of lily pistils to monochromatic light were consistent with the action spectrum for phototropism in the shoots of monocotyledonous plants. We discuss how these features may increase the fitness for pollination in these two species.

Characterization of PsMPK2, the first C1 subgroup MAP kinase from pea (Pisum sativum L.).

PubMed

Ortiz-Masia, Dolores; Perez-Amador, Miguel A; Carbonell, Pablo; Aniento, Fernando; Carbonell, Juan; Marcote, Maria J

2008-05-01

Mitogen-activated protein kinase (MAPK) cascades play a key role in plant growth and development as well as in biotic and abiotic stress responses. They are classified according to their sequence homology into four major groups (A-D). A large amount of information about MAPKs in groups A and B is available but few data of the C group have been reported. In this study, a C1 subgroup MAP kinase cDNA, PsMPK2, was isolated from Pisum sativum. PsMPK2 is expressed in vegetative (root and leaf) and reproductive (stamen, pistil and fruit) organs. Expression of PsMPK2 in Arabidopsis thaliana shows that mechanical injury and other stress signals as abscisic acid, jasmonic acid and hydrogen peroxide increase its kinase activity, extending previous results indicating that C1 subgroup MAPKs may be involved in the response to stress.

Effect of free fall on higher plants.

NASA Technical Reports Server (NTRS)

Gordon, S. A.

1973-01-01

The influence of exposure to the free-fall state on the orientation, morphogenesis, physiology, and radiation response of higher plants is briefly summarized. It is proposed that the duration of the space-flight experiments has been to brief to permit meaningful effects of free fall on general biochemistry, growth, and development to appear. However, two types of significant effect did occur. The first is on differential growth - i.e., tropism and epinasty - resulting from the absence of a normal geostimulus. For these phenomena it is suggested that ground-based experiments with the clinostat would suffice to mimic the effect of the free-fall state. The second is an apparent interaction between the radiation response and some flight condition, yielding an enhanced microspore abortion, a disturbed spindle function, and a stunting of stamen hairs. It is suggested that this apparent interaction may be derived from a shift in the rhythm of the cell cycle, induced by the free fall.

The ancestral flower of angiosperms and its early diversification

PubMed Central

Sauquet, Hervé; von Balthazar, Maria; Magallón, Susana; Doyle, James A.; Endress, Peter K.; Bailes, Emily J.; Barroso de Morais, Erica; Bull-Hereñu, Kester; Carrive, Laetitia; Chartier, Marion; Chomicki, Guillaume; Coiro, Mario; Cornette, Raphaël; El Ottra, Juliana H. L.; Epicoco, Cyril; Foster, Charles S. P.; Jabbour, Florian; Haevermans, Agathe; Haevermans, Thomas; Hernández, Rebeca; Little, Stefan A.; Löfstrand, Stefan; Luna, Javier A.; Massoni, Julien; Nadot, Sophie; Pamperl, Susanne; Prieu, Charlotte; Reyes, Elisabeth; dos Santos, Patrícia; Schoonderwoerd, Kristel M.; Sontag, Susanne; Soulebeau, Anaëlle; Staedler, Yannick; Tschan, Georg F.; Wing-Sze Leung, Amy; Schönenberger, Jürg

2017-01-01

Recent advances in molecular phylogenetics and a series of important palaeobotanical discoveries have revolutionized our understanding of angiosperm diversification. Yet, the origin and early evolution of their most characteristic feature, the flower, remains poorly understood. In particular, the structure of the ancestral flower of all living angiosperms is still uncertain. Here we report model-based reconstructions for ancestral flowers at the deepest nodes in the phylogeny of angiosperms, using the largest data set of floral traits ever assembled. We reconstruct the ancestral angiosperm flower as bisexual and radially symmetric, with more than two whorls of three separate perianth organs each (undifferentiated tepals), more than two whorls of three separate stamens each, and more than five spirally arranged separate carpels. Although uncertainty remains for some of the characters, our reconstruction allows us to propose a new plausible scenario for the early diversification of flowers, leading to new testable hypotheses for future research on angiosperms. PMID:28763051

Oberholzeria (Fabaceae subfam. Faboideae), a New Monotypic Legume Genus from Namibia

PubMed Central

Swanepoel, Wessel; le Roux, M. Marianne; Wojciechowski, Martin F.; van Wyk, Abraham E.

2015-01-01

Oberholzeria etendekaensis, a succulent biennial or short-lived perennial shrublet is described as a new species, and a new monotypic genus. Discovered in 2012, it is a rare species known only from a single locality in the Kaokoveld Centre of Plant Endemism, north-western Namibia. Phylogenetic analyses of molecular sequence data from the plastid matK gene resolves Oberholzeria as the sister group to the Genisteae clade while data from the nuclear rDNA ITS region showed that it is sister to a clade comprising both the Crotalarieae and Genisteae clades. Morphological characters diagnostic of the new genus include: 1) succulent stems with woody remains; 2) pinnately trifoliolate, fleshy leaves; 3) monadelphous stamens in a sheath that is fused above; 4) dimorphic anthers with five long, basifixed anthers alternating with five short, dorsifixed anthers, and 5) pendent, membranous, one-seeded, laterally flattened, slightly inflated but indehiscent fruits. PMID:25816251

Oberholzeria (Fabaceae subfam. Faboideae), a new monotypic legume genus from Namibia.

PubMed

Swanepoel, Wessel; le Roux, M Marianne; Wojciechowski, Martin F; van Wyk, Abraham E

2015-01-01

Oberholzeria etendekaensis, a succulent biennial or short-lived perennial shrublet is described as a new species, and a new monotypic genus. Discovered in 2012, it is a rare species known only from a single locality in the Kaokoveld Centre of Plant Endemism, north-western Namibia. Phylogenetic analyses of molecular sequence data from the plastid matK gene resolves Oberholzeria as the sister group to the Genisteae clade while data from the nuclear rDNA ITS region showed that it is sister to a clade comprising both the Crotalarieae and Genisteae clades. Morphological characters diagnostic of the new genus include: 1) succulent stems with woody remains; 2) pinnately trifoliolate, fleshy leaves; 3) monadelphous stamens in a sheath that is fused above; 4) dimorphic anthers with five long, basifixed anthers alternating with five short, dorsifixed anthers, and 5) pendent, membranous, one-seeded, laterally flattened, slightly inflated but indehiscent fruits.

Evaluation of saffron (Crocus sativus L.) adulteration with plant adulterants by (1)H NMR metabolite fingerprinting.

PubMed

Petrakis, Eleftherios A; Cagliani, Laura R; Polissiou, Moschos G; Consonni, Roberto

2015-04-15

In the present work, a preliminary study for the detection of adulterated saffron and the identification of the adulterant used by means of (1)H NMR and chemometrics is reported. Authentic Greek saffron and four typical plant-derived materials utilised as bulking agents in saffron, i.e., Crocus sativus stamens, safflower, turmeric, and gardenia were investigated. A two-step approach, relied on the application of both OPLS-DA and O2PLS-DA models to the (1)H NMR data, was adopted to perform authentication and prediction of authentic and adulterated saffron. Taking into account the deficiency of established methodologies to detect saffron adulteration with plant adulterants, the method developed resulted reliable in assessing the type of adulteration and could be viable for dealing with extensive saffron frauds at a minimum level of 20% (w/w). Copyright © 2014 Elsevier Ltd. All rights reserved.

[Floral structure of two species of Trachycarpea (Arecaceae)].

PubMed

Guevara, Lorena I; Jáuregui, Damelis J; Stauffer, Fred W

2014-09-01

Copernicia and Washingtonia are two genera of the Trachycarpeae for which no subtribal classification has been proposed, mainly because of the lack of resolution in phylogenetic studies. Morphology and anatomy of flowers whithin Coryphoideae have proven useful for taxa delimitation and supporting relationships among their members. A description of the morphological and anatomical structure of flowers of C. tectorum and W. filifera is presented in order to explore reproductive characters that may clarify their classification within the subfamily and to contribute with floral biology studies. Flowers of cultivated specimens of both taxa and developing fruits of C. tectorum were fixed in FAA, dissected for morphological analysis, and parafin-embedded flowers and fruits were serially sectioned for obtaining permanent slides, using conventional techniques and safranin-fast green staining. All procedures were carried out in the Laboratory of Morpho-Anatomy, Agronomy Faculty of the Universidad Central de Venezuela (UCV). Both species have hermaphroditic flowers. C. tectorum flowers have a thick and pubescent perianth, six stamens with filaments forming a tube fused to the corolla, with rounded projections and an acute apex where the anthers are inserted. W. filifera flowers have an irregularly dentate calyx, and a shortly acuminate corolla, six stamens united by their filaments to the corolla which at the same time are briefly fused to the gynoecium. Cells with druse crystals in the staminal tube are reported for C. tectorum. Only one of the carpels of the gynoecium of C. tectorum develops at fruit stage, and a layer of abundant raphide cells forming a crustaceous endocarp in mature fruits, was found. W. filifera presents the perianth mesophyll with few layers of thick walled cells and schlerenchymatic tissue, gynoecium with apically fused carpels in the ventral region of ovary, free at the base and the apex of the style, where the ventral sutures are opened. C. tectorum has a ventral hypodermis in the petals made of large and thick walled cells, gynoecium with apically fused carpels in the ovary, free and adpressed basally, style-stigma completely fused, and stylar transmission channel absent distally. Distinct stylar canals in C. tectorum, united distally in W. filifera confirm the close relationship between these species and subtribe Livistoninae. Also, some floral morpho-anatomical similarities (e.g. fleshy calyx base and a hypodermis with thickened cell walls in petals) were found between C. tectorum and Pritchardia, supporting the affinities between both genera.

Gene Duplication and Transference of Function in the paleoAP3 Lineage of Floral Organ Identity Genes

PubMed Central

Galimba, Kelsey D.; Martínez-Gómez, Jesús; Di Stilio, Verónica S.

2018-01-01

The floral organ identity gene APETALA3 (AP3) is a MADS-box transcription factor involved in stamen and petal identity that belongs to the B-class of the ABC model of flower development. Thalictrum (Ranunculaceae), an emerging model in the non-core eudicots, has AP3 homologs derived from both ancient and recent gene duplications. Prior work has shown that petals have been lost repeatedly and independently in Ranunculaceae in correlation with the loss of a specific AP3 paralog, and Thalictrum represents one of these instances. The main goal of this study was to conduct a functional analysis of the three AP3 orthologs present in Thalictrum thalictroides, representing the paleoAP3 gene lineage, to determine the degree of redundancy versus divergence after gene duplication. Because Thalictrum lacks petals, and has lost the petal-specific AP3, we also asked whether heterotopic expression of the remaining AP3 genes contributes to the partial transference of petal function to the first whorl found in insect-pollinated species. To address these questions, we undertook functional characterization by virus-induced gene silencing (VIGS), protein–protein interaction and binding site analyses. Our results illustrate partial redundancy among Thalictrum AP3s, with deep conservation of B-class function in stamen identity and a novel role in ectopic petaloidy of sepals. Certain aspects of petal function of the lost AP3 locus have apparently been transferred to the other paralogs. A novel result is that the protein products interact not only with each other, but also as homodimers. Evidence presented here also suggests that expression of the different ThtAP3 paralogs is tightly integrated, with an apparent disruption of B function homeostasis upon silencing of one of the paralogs that codes for a truncated protein. To explain this result, we propose two testable alternative scenarios: that the truncated protein is a dominant negative mutant or that there is a compensational response as part of a back-up circuit. The evidence for promiscuous protein–protein interactions via yeast two-hybrid combined with the detection of AP3 specific binding motifs in all B-class gene promoters provide partial support for these hypotheses. PMID:29628932

Angiosperm phylogeny inferred from multiple genes as a tool for comparative biology.

PubMed

Soltis, P S; Soltis, D E; Chase, M W

1999-11-25

Comparative biology requires a firm phylogenetic foundation to uncover and understand patterns of diversification and evaluate hypotheses of the processes responsible for these patterns. In the angiosperms, studies of diversification in floral form, stamen organization, reproductive biology, photosynthetic pathway, nitrogen-fixing symbioses and life histories have relied on either explicit or implied phylogenetic trees. Furthermore, to understand the evolution of specific genes and gene families, evaluate the extent of conservation of plant genomes and make proper sense of the huge volume of molecular genetic data available for model organisms such as Arabidopsis, Antirrhinum, maize, rice and wheat, a phylogenetic perspective is necessary. Here we report the results of parsimony analyses of DNA sequences of the plastid genes rbcL and atpB and the nuclear 18S rDNA for 560 species of angiosperms and seven non-flowering seed plants and show a well-resolved and well-supported phylogenetic tree for the angiosperms for use in comparative biology.

Flexibility contra Stiffness: The Phragmoplast as a Physical Barrier for Beads But Not for Vesicles[OA

PubMed Central

Esseling-Ozdoba, Agnieszka; Kik, Richard A.; van Lammeren, André A.M.; Kleijn, J. Mieke; Emons, Anne Mie C.

2010-01-01

In plant cells, Golgi vesicles are transported to the division plane to fuse with each other, forming the cell plate, the initial membrane-bordered cell wall separating daughter cells. Vesicles, but not organelles, move through the phragmoplast, which consists of two opposing cylinders of microtubules and actin filaments, interlaced with endoplasmic reticulum membrane. To study physical aspects of this transport/inhibition process, we microinjected fluorescent synthetic 1,2-dioleoyl-sn-glycero-3-phospho-rac-1-glycerol (DOPG) vesicles and polystyrene beads into Tradescantia virginiana stamen hair cells. The phragmoplast was nonselective for DOPG vesicles of a size up to 150 nm in diameter but was a physical barrier for polystyrene beads having a diameter of 20 and 40 nm and also when beads were coated with the same DOPG membrane. We conclude that stiffness is a parameter for vesicle transit through the phragmoplast and discuss that cytoskeleton configurations can physically block such transit. PMID:19939943

The wheat transcription factor, TabHLH39, improves tolerance to multiple abiotic stressors in transgenic plants.

PubMed

Zhai, Yiqian; Zhang, Lichao; Xia, Chuan; Fu, Silu; Zhao, Guangyao; Jia, Jizeng; Kong, Xiuying

2016-05-13

Although bHLH transcription factors play important roles regulating plant development and abiotic stress response and tolerance, few functional studies have been performed in wheat. In this study, we isolated and characterized a bHLH gene, TabHLH39, from wheat. The TabHLH39 gene is located on wheat chromosome 5DL, and the protein localized to the nucleus and activated transcription. TabHLH39 showed variable expression in roots, stems, leaves, glumes, pistils and stamens and was induced by polyethylene glycol, salt and cold treatments. Further analysis revealed that TabHLH39 overexpression in Arabidopsis significantly enhanced tolerance to drought, salt and freezing stress during the seedling stage, which was also demonstrated by enhanced abiotic stress-response gene expression and changes to several physiological indices. Therefore, TabHLH39 has potential in transgenic breeding applications to improve abiotic stress tolerance in crops. Copyright © 2016 Elsevier Inc. All rights reserved.

UFO: an Arabidopsis gene involved in both floral meristem and floral organ development.

PubMed

Levin, J Z; Meyerowitz, E M

1995-05-01

We describe the role of the UNUSUAL FLORAL ORGANS (UFO) gene in Arabidopsis floral development based on a genetic and molecular characterization of the phenotypes of nine ufo alleles. UFO is required for the proper identity of the floral meristem and acts in three different aspects of the process that distinguishes flowers from shoots. UFO is involved in establishing the whorled pattern of floral organs, controlling the determinacy of the floral meristem, and activating the APETALA3 and PISTILLATA genes required for petal and stamen identity. In many respects, UFO acts in a manner similar to LEAFY, but the ufo mutant phenotype also suggests an additional role for UFO in defining boundaries within the floral primordia or controlling cell proliferation during floral organ growth. Finally, genetic interactions that prevent flower formation and lead to the generation of filamentous structures implicate UFO as a member of a new, large, and diverse class of genes in Arabidopsis necessary for flower formation.

Genotoxicity of Water Contaminants from the Basin of Lake Sevan, Armenia Evaluated by the Comet Assay in Gibel Carp (Carassius auratus gibelio) and Tradescantia Bioassays.

PubMed

Simonyan, Anna; Gabrielyan, Barduch; Minasyan, Seyran; Hovhannisyan, Galina; Aroutiounian, Rouben

2016-03-01

Combination of bioassays and chemical analysis was applied to determine the genotoxic/mutagenic contamination in four different sites of the basin of Lake Sevan in Armenia. Water genotoxicity was evaluated using the single cell gel electrophoresis technique (comet assay) in erythrocytes of gibel carp (Carassius auratus gibelio), Tradescantia micronucleus (Trad-MCN) and Tradescantia stamen hair mutation (Trad-SHM) assays. Significant inter-site differences in the levels of water genotoxicity according to fish and Trad-MCN bioassays have been revealed. Two groups of locations with lower (south-southwest of the village Shorzha and Peninsula of Lake Sevan) and higher (estuaries of Gavaraget and Dzknaget rivers) levels of water genotoxicity were distinguished. Correlation analysis support the hypothesis that the observed genetic alterations in fish and plant may be a manifestation of the effects of water contamination by nitrate ions, Si, Al, Fe, Mn and Cu. Increase of DNA damage in fish also correlated with content of total phosphorus.

Developmental Regulation of a Plasma Membrane Arabinogalactan Protein Epitope in Oilseed Rape Flowers.

PubMed Central

Pennell, RI; Janniche, L; Kjellbom, P; Scofield, GN; Peart, JM; Roberts, K

1991-01-01

We have identified and characterized the temporal and spatial regulation of a plasma membrane arabinogalactan protein epitope during development of the aerial parts of oilseed rape using the monoclonal antibody JIM8. The JIM8 epitope is expressed by the first cells of the embryo and by certain cells in the sexual organs of flowers. During embryogenesis, the JIM8 epitope ceases to be expressed by the embryo proper but is still found in the suspensor. During differentiation of the stamens and carpels, expression of the JIM8 epitope progresses from one cell type to another, ultimately specifying the endothecium and sperm cells, the nucellar epidermis, synergid cells, and the egg cell. This complex temporal sequence demonstrates rapid turnover of the JIM8 epitope. There is no direct evidence for any cell-inductive process in plant development. However, if cell-cell interactions exist in plants and participate in flower development, the JIM8 epitope may be a marker for one set of them. PMID:12324592

The mechanics of pollination by wind: is anemophily aeroelastically optimized for reproduction?

NASA Astrophysics Data System (ADS)

Timerman, David; Greene, David F.; Ackerman, Josef D.; Urzay, Javier

2011-11-01

Approximately 10 percent of plant species rely on wind for pollination (anemophily). These include many taxa of economic importance: e.g. cultigens such as wheat and maize; species like grasses and ragweed that trigger allergies; and the conifers, our most important species for the forest industry in the mid- latitudes. It has often been assumed that anemophily is an inefficient mechanism compared to animal pollination (zoophily), but very little is known about the forces and micromechanics that deliver pollen grains into wind streams. Here we ask a fundamental question: is anemophily optimized for pollen shedding? In this talk, we focus on an as-yet rudimentary theory of turbulence- initiated pollen shed that models the pollen-bearing stamen as an aeroelastic oscillator. Ongoing experiments with anemophilous and zoophilous flowers excited by shakers are analyzed to extract values of damping ratios, adhesion forces and flexural rigidities. Finally, the anatomical differences between anemophilous and zoophilous species are evaluated using a dimensionless number that measures the ratio of adhesion to aeroleastic forces.

Pollen dispersal by catapult: Experiments of Lyman J. Briggs on the flower of mountain laurel

USGS Publications Warehouse

Nimmo, John R.; Hermann, Paula M.; Kirkham, M.B.; Landa, Edward R.

2014-01-01

The flower of Kalmia latifolia L. employs a catapult mechanism that flings its pollen to considerable distances. Physicist Lyman J. Briggs investigated this phenomenon in the 1950s after retiring as longtime director of the National Bureau of Standards, attempting to explain how hydromechanical effects inside the flower’s stamen could make it possible. Briggs’s unfinished manuscript implies that liquid under negative pressure generates stress, which, superimposed on the stress generated from the flower’s growth habit, results in force adequate to propel the pollen as observed. With new data and biophysical understanding to supplement Briggs’s experimental results and research notes, we show that his postulated negative-pressure mechanism did not play the exclusive and crucial role that he credited to it, though his revisited investigation sheds light on various related processes. Important issues concerning the development and reproductive function of Kalmia flowers remain unresolved, highlighting the need for further biophysical advances.

Cytological characterization of anther development in Panax ginseng Meyer.

PubMed

Kim, Yu-Jin; Jang, Moon-Gi; Zhu, Lu; Silva, Jeniffer; Zhu, Xiaolei; Sukweenadhi, Johan; Kwon, Woo-Saeng; Yang, Deok-Chun; Zhang, Dabing

2016-07-01

Ginseng (Panax ginseng), a valued medicinal herb, is a slow-growing plant that flowers after 3 years of growth with the formation of a solitary terminal umbel inflorescence. However, little is known about cytological events during ginseng reproduction, such as the development of the male organ, the stamen. To better understand the mechanism controlling ginseng male reproductive development, here, we investigated the inflorescence and flower structure of ginseng. Moreover, we performed cytological analysis of anther morphogenesis and showed the common and specialized cytological events including the formation of four concentric cell layers surrounding male reproductive cells followed by subsequent cell differentiation and degeneration of tapetal cells, as well as the formation of mature pollen grains via meiosis and mitosis during ginseng anther development. Particularly, our transverse section and microscopic observations showed that the ginseng tapetal layer exhibits obvious nonsynchronous cell division evidenced by the observation of one or two tapetal layers frequently observed in one anther lobe, suggesting the unique control of cell division. To facilitate the future study on ginseng male reproduction, we grouped the anther development into 10 developmental stages according to the characterized cytological events.

Superior microwave absorption properties of ultralight reduced graphene oxide/black phosphorus aerogel.

PubMed

Hao, Chunxue; Wang, Bochong; Wen, Fusheng; Mu, Congpu; Xiang, Jianyong; Li, Lei; Liu, Zhongyuan

2018-06-08

Through a facile self-assembled process, an ultralight reduced graphene oxide/black phosphorus (rGO/BP) composite aerogel was successfully fabricated. The BP nanosheets were homogeneously distributed throughout the rGO 3D framework, and the interfaces between rGO and BP possessed four kinds of interconnections, such as wrapping, wearing, bridging and weak linking. As an ultralight composite, the rGO/BP aerogel could easily stand on the stamen of a flower. Compared with pure rGO aerogel, the rGO/BP composite aerogel exhibited enhanced microwave absorption ability. The minimum reflection loss value of -46.9 dB with a thickness of 2.53 mm was obtained, and a wide absorption band of 6.1 GHz (RL < -10 dB) was achieved. The superior microwave absorption property was demonstrated to stem from the interfacial polarization loss mechanism in which the multiform interface interactions between the rGO skeleton and BP nanosheets played critical roles. The rGO/BP aerogel has great potential to be used as an ultralight microwave absorber.

The F-box-containing protein UFO and AGAMOUS participate in antagonistic pathways governing early petal development in Arabidopsis.

PubMed

Durfee, Tim; Roe, Judith L; Sessions, R Allen; Inouye, Carla; Serikawa, Kyle; Feldmann, Kenneth A; Weigel, Detlef; Zambryski, Patricia C

2003-07-08

The UNUSUAL FLORAL ORGANS (UFO) gene is required for multiple processes in the developing Arabidopsis flower, including the proper patterning and identity of both petals and stamens. The gene encodes an F-box-containing protein, UFO, which interacts physically and genetically with the Skp1 homolog, ASK1. In this report, we describe four ufo alleles characterized by the absence of petals, which uncover another role for UFO in promoting second whorl development. This UFO-dependent pathway is required regardless of the second whorl organ to be formed, arguing that it affects a basic process acting in parallel with those establishing organ identity. However, the pathway is dispensable in the absence of AGAMOUS (AG), a known inhibitor of petal development. In situ hybridization results argue that AG is not transcribed in the petal region, suggesting that it acts non-cell-autonomously to inhibit second whorl development in ufo mutants. These results are combined into a genetic model explaining early second whorl initiation/proliferation, in which UFO functions to inhibit an AG-dependent activity.

A null mutation in the first enzyme of flavonoid biosynthesis does not affect male fertility in Arabidopsis.

PubMed Central

Burbulis, I E; Iacobucci, M; Shirley, B W

1996-01-01

Flavonoids are a major class of secondary metabolites that serves a multitude of functions in higher plants, including a recently discovered role in male fertility. Surprisingly, Arabidopsis plants deficient in flavonoid biosynthesis appear to be fully fertile. Using RNA gel blot analysis and polymerase chain reaction-based assays, we have shown that a mutation at the 3' splice acceptor site in the Arabidopsis chalcone synthase gene completely disrupts synthesis of the active form of the enzyme. We also confirmed that this enzyme, which catalyzes the first step of flavonoid biosynthesis, is encoded by a single-copy gene. HPLC analysis of whole flowers and stamens was used to show that plants homozygous for the splice site mutation are completely devoid of flavonoids. This work provides compelling evidence that despite the high levels of these compounds in the pollen of most plant species, flavonoids are not universally required for fertility. The role of flavonoids in plant reproduction may therefore offer an example of convergent functional evolution in secondary metabolism. PMID:8672888

Co-option of the polarity gene network shapes filament morphology in angiosperms

PubMed Central

de Almeida, Ana Maria Rocha; Yockteng, Roxana; Schnable, James; Alvarez-Buylla, Elena R.; Freeling, Michael; Specht, Chelsea D.

2014-01-01

The molecular genetic mechanisms underlying abaxial-adaxial polarity in plants have been studied as a property of lateral and flattened organs, such as leaves. In leaves, laminar expansion occurs as a result of balanced abaxial-adaxial gene expression. Over- or under- expression of either abaxializing or adaxializing genes inhibits laminar growth, resulting in a mutant radialized phenotype. Here, we show that co-option of the abaxial-adaxial polarity gene network plays a role in the evolution of stamen filament morphology in angiosperms. RNA-Seq data from species bearing laminar (flattened) or radial (cylindrical) filaments demonstrates that species with laminar filaments exhibit balanced expression of abaxial-adaxial (ab-ad) genes, while overexpression of a YABBY gene is found in species with radial filaments. This result suggests that unbalanced expression of ab-ad genes results in inhibition of laminar outgrowth, leading to a radially symmetric structure as found in many angiosperm filaments. We anticipate that co-option of the polarity gene network is a fundamental mechanism shaping many aspects of plant morphology during angiosperm evolution. PMID:25168962

Co-option of the polarity gene network shapes filament morphology in angiosperms.

PubMed

de Almeida, Ana Maria Rocha; Yockteng, Roxana; Schnable, James; Alvarez-Buylla, Elena R; Freeling, Michael; Specht, Chelsea D

2014-08-29

The molecular genetic mechanisms underlying abaxial-adaxial polarity in plants have been studied as a property of lateral and flattened organs, such as leaves. In leaves, laminar expansion occurs as a result of balanced abaxial-adaxial gene expression. Over- or under- expression of either abaxializing or adaxializing genes inhibits laminar growth, resulting in a mutant radialized phenotype. Here, we show that co-option of the abaxial-adaxial polarity gene network plays a role in the evolution of stamen filament morphology in angiosperms. RNA-Seq data from species bearing laminar (flattened) or radial (cylindrical) filaments demonstrates that species with laminar filaments exhibit balanced expression of abaxial-adaxial (ab-ad) genes, while overexpression of a YABBY gene is found in species with radial filaments. This result suggests that unbalanced expression of ab-ad genes results in inhibition of laminar outgrowth, leading to a radially symmetric structure as found in many angiosperm filaments. We anticipate that co-option of the polarity gene network is a fundamental mechanism shaping many aspects of plant morphology during angiosperm evolution.

Involvement of a banana MADS-box transcription factor gene in ethylene-induced fruit ripening.

PubMed

Liu, Juhua; Xu, Biyu; Hu, Lifang; Li, Meiying; Su, Wei; Wu, Jing; Yang, Jinghao; Jin, Zhiqiang

2009-01-01

To investigate the regulation of MADS-box genes in banana (Musa acuminata L. AAA group cv. Brazilian) fruit development and postharvest ripening, we isolated from banana fruit a MADS-box gene designated MuMADS1. Amino acid alignment indicated MuMADS1 belongs to the AGAMOUS subfamily, and phylogenetic analysis indicates that this gene is most similar to class D MADS-box genes. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed that MuMADS1 is expressed in the stamen and pistil of male and female flowers and in the rhizome, the vegetative reproductive organ of the banana plant. In preharvest banana fruit, MuMADS1 is likely expressed throughout banana fruit development. In postharvest banana ripening, MuMADS1 is associated with ethylene biosynthesis. Expression patterns of MuMADS1 during postharvest ripening as determined by real-time RT-PCR suggest that differential expression of MuMADS1 may not only be induced by ethylene biosynthesis associated with postharvest banana ripening, but also may be induced by exogenous ethylene.

Overexpression of AtAP1M3 regulates flowering time and floral development in Arabidopsis and effects key flowering-related genes in poplar.

PubMed

Chen, Zhong; Ye, Meixia; Su, Xiaoxing; Liao, Weihua; Ma, Huandi; Gao, Kai; Lei, Bingqi; An, Xinmin

2015-08-01

APETALA1 plays a crucial role in the transition from vegetative to reproductive phase and in floral development. In this study, to determine the effect of AP1 expression on flowering time and floral organ development, transgenic Arabidopsis and poplar overexpressing of AtAP1M3 (Arabidopsis AP1 mutant by dominant negative mutation) were generated. Transgenic Arabidopsis with e35Spro::AtAP1M3 displayed phenotypes with delayed-flowering compared to wild-type and flowers with abnormal sepals, petals and stamens. In addition, transgenic Arabidopsis plants exhibited reduced growth vigor compared to the wild-type plants. Ectopic expression of AtAP1M3 in poplar resulted in up- or down-regulation of some endogenous key flowering-related genes, including floral meristems identity gene LFY, B-class floral organ identity genes AP3 and PI, flowering pathway integrator FT1 and flower repressors TFL1 and SVP. These results suggest that AtAP1M3 regulates flowering time and floral development in plants.

Micromorphology and ultrastructure of the floral nectaries of Polemonium caeruleum L. (Polemoniaceae).

PubMed

Chwil, Mirosława; Chwil, Stanisław

2012-10-01

The Polemoniaceae family forms flowers diverse in the terms of pollination methods and nectar types. The micromorphology of the nectary surface and the tissue structures as well as the ultrastructure of the cells of the floral nectaries in Polemonium caeruleum L. were examined using light, scanning and transmission electron microscopy. A bowl-shaped nectary, detached from the ovary, grows at its base. Its contour shows folds with depressions in the places where the stamens grow, forming five-lobed disc (synapomorphic character). Nectar is secreted through modified anomocytic stomata, which are formed in the epidermis covering the tip and the lateral wall of the projection located between the staminal filaments. The undulate nectary consists of a single-layered epidermis and three to nine layers of parenchymal cells. The cells of the nectary contain a dense cytoplasm, numerous plastids with an osmophilic stroma and starch grains, well-developed endoplasmic reticulum, as well as a large number of mitochondria interacting with the Golgi bodies. The ultrastructure of nectary cells indicates the granulocrine secretion mechanism and diversified transport of nectar.

Tomato Flower Abnormalities Induced by Low Temperatures Are Associated with Changes of Expression of MADS-Box Genes1

PubMed Central

Lozano, Rafael; Angosto, Trinidad; Gómez, Pedro; Payán, Carmen; Capel, Juan; Huijser, Peter; Salinas, Julio; Martínez-Zapater, José M.

1998-01-01

Flower and fruit development in tomato (Lycopersicon esculentum Mill.) were severely affected when plants were grown at low temperatures, displaying homeotic and meristic transformations and alterations in the fusion pattern of the organs. Most of these homeotic transformations modified the identity of stamens and carpels, giving rise to intermediate organs. Complete homeotic transformations were rarely found and always affected organs of the reproductive whorls. Meristic transformations were also commonly observed in the reproductive whorls, which developed with an excessive number of organs. Scanning electron microscopy revealed that meristic transformations take place very early in the development of the flower and are related to a significant increase in the floral meristem size. However, homeotic transformations should occur later during the development of the organ primordia. Steady-state levels of transcripts corresponding to tomato MADS-box genes TM4, TM5, TM6, and TAG1 were greatly increased by low temperatures and could be related to these flower abnormalities. Moreover, in situ hybridization analyses showed that low temperatures also altered the stage-specific expression of TM4. PMID:9576778

Conservation and canalization of gene expression during angiosperm diversification accompany the origin and evolution of the flower

PubMed Central

Chanderbali, André S.; Yoo, Mi-Jeong; Zahn, Laura M.; Brockington, Samuel F.; Wall, P. Kerr; Gitzendanner, Matthew A.; Albert, Victor A.; Leebens-Mack, James; Altman, Naomi S.; Ma, Hong; dePamphilis, Claude W.; Soltis, Douglas E.; Soltis, Pamela S.

2010-01-01

The origin and rapid diversification of the angiosperms (Darwin's “Abominable Mystery”) has engaged generations of researchers. Here, we examine the floral genetic programs of phylogenetically pivotal angiosperms (water lily, avocado, California poppy, and Arabidopsis) and a nonflowering seed plant (a cycad) to obtain insight into the origin and subsequent evolution of the flower. Transcriptional cascades with broadly overlapping spatial domains, resembling the hypothesized ancestral gymnosperm program, are deployed across morphologically intergrading organs in water lily and avocado flowers. In contrast, spatially discrete transcriptional programs in distinct floral organs characterize the more recently derived angiosperm lineages represented by California poppy and Arabidopsis. Deep evolutionary conservation in the genetic programs of putatively homologous floral organs traces to those operating in gymnosperm reproductive cones. Female gymnosperm cones and angiosperm carpels share conserved genetic features, which may be associated with the ovule developmental program common to both organs. However, male gymnosperm cones share genetic features with both perianth (sterile attractive and protective) organs and stamens, supporting the evolutionary origin of the floral perianth from the male genetic program of seed plants. PMID:21149731

Conservation and canalization of gene expression during angiosperm diversification accompany the origin and evolution of the flower.

PubMed

Chanderbali, André S; Yoo, Mi-Jeong; Zahn, Laura M; Brockington, Samuel F; Wall, P Kerr; Gitzendanner, Matthew A; Albert, Victor A; Leebens-Mack, James; Altman, Naomi S; Ma, Hong; dePamphilis, Claude W; Soltis, Douglas E; Soltis, Pamela S

2010-12-28

The origin and rapid diversification of the angiosperms (Darwin's "Abominable Mystery") has engaged generations of researchers. Here, we examine the floral genetic programs of phylogenetically pivotal angiosperms (water lily, avocado, California poppy, and Arabidopsis) and a nonflowering seed plant (a cycad) to obtain insight into the origin and subsequent evolution of the flower. Transcriptional cascades with broadly overlapping spatial domains, resembling the hypothesized ancestral gymnosperm program, are deployed across morphologically intergrading organs in water lily and avocado flowers. In contrast, spatially discrete transcriptional programs in distinct floral organs characterize the more recently derived angiosperm lineages represented by California poppy and Arabidopsis. Deep evolutionary conservation in the genetic programs of putatively homologous floral organs traces to those operating in gymnosperm reproductive cones. Female gymnosperm cones and angiosperm carpels share conserved genetic features, which may be associated with the ovule developmental program common to both organs. However, male gymnosperm cones share genetic features with both perianth (sterile attractive and protective) organs and stamens, supporting the evolutionary origin of the floral perianth from the male genetic program of seed plants.

Two new species of Primulina (Gesneriaceae) from limestone karsts of China.

PubMed

Hong, Xin; Li, Zhong-Lin; Liu, Jia-Zhi; Zhou, Shou-Biao; Qin, Wei-Hua; Wen, Fang

2018-01-01

The limestone karst area of South China is a major biodiversity hotspot of global terrestrial biomes. During extensive field work on the Guangxi limestone formations, two unknown species of Gesneriaceae were collected. After conducting a comprehensive study of the literature and herbarium specimens, Primulina davidioides and P. hiemalis are recognized as two species new to science, and described and illustrated here. P. davidioides is morphologically close to P. lunglinensis based on the shape of the leaf and flower, but it can be easily distinguished by the shape of the bracts, corolla and stigma, indumentum of peduncles, pedicels and pistil and number of staminodes. P. hiemalis is closely relate to P. luzhaiensis in vegetative appearance, but differs in the shape of the calyx and stigma, number of bracts and staminodes, indumentum of the leaf blade and peduncle, and position of stamens in the corolla tube. Considering that not enough is known about their populations, it is proposed that their conservation statuses should currently be classed as data deficient (DD) according to the IUCN Red List Category and Criteria.

From flower to honey bouquet: possible markers for the botanical origin of Robinia honey.

PubMed

Aronne, Giovanna; Giovanetti, Manuela; Sacchi, Raffaele; De Micco, Veronica

2014-01-01

Flowers are complex structures devoted to pollinator attraction, through visual as well as chemical signals. As bees collect nectar on flowers to produce honey, some aspects of floral chemistry are transferred to honey, making chemical markers an important technique to identify the botanical and geographical origins of honey. We applied a new approach that considers the simultaneous analysis of different floral parts (petals, stamens + pistils, calyxes + nectarines, and nectar) and the corresponding unifloral honey. We collected fresh flowers of Robinia pseudoacacia L. (black locust), selected five samples of Robinia honey from different geographical origins, applied SPME-GC/MS for volatile analyses, and defined the chemical contribution added by different floral parts to the honey final bouquet. Our results show that honey blends products from nectar as well as other flower parts. Comparing honey and flower profiles, we detected compounds coming directly from flower parts but not present in the nectar, such as hotrienol and β-pinene. These may turn out to be of special interest when selecting floral markers for the botanical origin of honey.

Superior microwave absorption properties of ultralight reduced graphene oxide/black phosphorus aerogel

NASA Astrophysics Data System (ADS)

Hao, Chunxue; Wang, Bochong; Wen, Fusheng; Mu, Congpu; Xiang, Jianyong; Li, Lei; Liu, Zhongyuan

2018-06-01

Through a facile self-assembled process, an ultralight reduced graphene oxide/black phosphorus (rGO/BP) composite aerogel was successfully fabricated. The BP nanosheets were homogeneously distributed throughout the rGO 3D framework, and the interfaces between rGO and BP possessed four kinds of interconnections, such as wrapping, wearing, bridging and weak linking. As an ultralight composite, the rGO/BP aerogel could easily stand on the stamen of a flower. Compared with pure rGO aerogel, the rGO/BP composite aerogel exhibited enhanced microwave absorption ability. The minimum reflection loss value of ‑46.9 dB with a thickness of 2.53 mm was obtained, and a wide absorption band of 6.1 GHz (RL < ‑10 dB) was achieved. The superior microwave absorption property was demonstrated to stem from the interfacial polarization loss mechanism in which the multiform interface interactions between the rGO skeleton and BP nanosheets played critical roles. The rGO/BP aerogel has great potential to be used as an ultralight microwave absorber.

Jasmonate Hormone: Regulating Synthesis of Reduced Carbon Compounds in Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Browse, John

Our original interest in understanding the role of jasmonate (JA) in regulating the final stages of stamen and pollen development led to our discovery of the JAZ repressors, and the molecular mechanism of JA action is now a second important focus of our research. The specific goals for this grant period are to: 1. Investigate the generation and clearance of the hormone with emphasis on the regulation of the OPR3 enzyme and the hydrolysis of JA-Ile. 2. Use dominant-negative and overexpression constructs to explore the role of the MYC5 transcription factor in initiating and regulating JA responses. 3. Investigate specificmore » JAZ protein interactions that will help us to recognize and understand the extended network of processes, such as sulfur nutrition, that interface with JA signaling. The COI1 F-Box protein is a JA-Ile coreceptor and coi1 mutant plants lack JA responses. We have tested the possibility that sites of JA action can be probed by using tissue-specific promoters to drive expression of a COI1-YFP fusion protein in coi1 mutant plants deficient in stamen and pollen function. When we expressed COI1 behind a filament-specific promoter (from the DAD1 gene), filament elongation was restored but not anther dehiscence or pollen function. Three tapetum specific promoters, all failed to restore any of these three functions but, unexpectedly, a promoter active in the stomium and epidermal cells, restored both pollen function and anther dehiscence. Most importantly, our results demonstrate the power of promoter::COI1-YFP constructs in revealing the primary sites of JA-regulated gene expression that control developmental and other responses in neighboring tissues. We now plan to use this new tool to test current hypotheses about JA action in other organs of the plant. The MYC2, MYC3, and MYC4 proteins are the primary transcription factors initiating defense and root growth responses to JA signaling. However, transgenic plants overexpressing these proteins do not show any substantial reduction in shoot growth, even though they have increased expression of many JA-responsive genes. MYC5 is closely related to MYC2, MYC3, and MYC4 but has not previously been considered a candidate in JA signaling, in part because myc5 mutants exhibit no overt phenotype. However, when we overexpressed the MYC5 protein in wild-type Arabidopsis we got a surprising result. Whereas plants overexpressing MYC2 were similar in size to wild type, as observed previously, MYC5-OE plants were much smaller. This is an exciting discovery because it indicates that growth responses to JA may be controlled by a signaling pathway that is distinct from that pathway (or pathways) controlling secondary-product synthesis and defense.« less

Interactions among Genes Regulating Ovule Development in Arabidopsis Thaliana

PubMed Central

Baker, S. C.; Robinson-Beers, K.; Villanueva, J. M.; Gaiser, J. C.; Gasser, C. S.

1997-01-01

The INNER NO OUTER (INO) and AINTEGUMENTA (ANT) genes are essential for ovule integument development in Arabidopsis thaliana. Ovules of ino mutants initiate two integument primordia, but the outer integument primordium forms on the opposite side of the ovule from the normal location and undergoes no further development. The inner integument appears to develop normally, resulting in erect, unitegmic ovules that resemble those of gymnosperms. ino plants are partially fertile and produce seeds with altered surface topography, demonstrating a lineage dependence in development of the testa. ant mutations affect initiation of both integuments. The strongest of five new ant alleles we have isolated produces ovules that lack integuments and fail to complete megasporogenesis. ant mutations also affect flower development, resulting in narrow petals and the absence of one or both lateral stamens. Characterization of double mutants between ant, ino and other mutations affecting ovule development has enabled the construction of a model for genetic control of ovule development. This model proposes parallel independent regulatory pathways for a number of aspects of this process, a dependence on the presence of an inner integument for development of the embryo sac, and the existence of additional genes regulating ovule development. PMID:9093862

Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity

PubMed Central

O'Meara, Brian C.; Smith, Stacey D.; Armbruster, W. Scott; Harder, Lawrence D.; Hardy, Christopher R.; Hileman, Lena C.; Hufford, Larry; Litt, Amy; Magallón, Susana; Smith, Stephen A.; Stevens, Peter F.; Fenster, Charles B.; Diggle, Pamela K.

2016-01-01

Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years. PMID:27147092

Prunus pananensis (Rosaceae), a New Species from Pan'an of Central Zhejiang, China

PubMed Central

Chen, Huan; Zhou, Ying-Ying; Tang, Mei-Qin; Fu, Meng-Qi; Jin, Xiao-Feng

2013-01-01

Prunus pananensis Z. L. Chen, W. J. Chen & X. F. Jin, a new species of Rosaceae from central Zhejiang, China is described and illustrated. Micromorphological characters of the indumentum on young shoots, leaves, petioles and peduncles, including scanning electron microscope [SEM] images, are provided. This new species is morphologically similar to P. schneiderianae Koehne in having its young shoots, petioles and pedicels all densely villose, but differs in having bracts persistent, styles glabrous, stipules 8–9 mm long, stamens 28–30 of per flower, and drupes glabrous. The new species is also similar to P. discoidea (Yü & C. L. Li) Yü & C. L. Li ex Z. Wei & Y. B. Chang in having 2 or 3 flowers in an umbellate inflorescence, and bracts persistent and marginally glandular, but it differs in having young shoots and petioles densely covered with yellowish-brown villose trichomes; leaves rounded or slightly cordate at base, the mid-ribs and lateral veins abaxially densely covered with yellowish-brown villose trichomes; and hypanthium ca. 3 mm long, shorter than sepals. The atpB-rbcL and trnL-F intergenic chloroplast spacers are selected for identification of the new and its similar species. PMID:23349780

Preliminary study of effects of military obscurant smokes on flora and fauna during field and laboratory exposures. Final technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaeffer, D.J.; Lower, W.R.; Kapila, S.

1986-12-01

Since continued routine use of obscurant smokes could be detrimental to the native flora and fauna of training sites, a preliminary biological and chemical study of smokes was conducted to determine whether tests could be developed to demonstrate measurable changes in organisms exposed to smokes and to evaluate whether short exposures to smokes produced measurable changes in the organisms tested. Fog oil, hexachloroethane, and tank diesel smokes were tested. Tradescantia clones were examined for mutagenic effects indicated by micronuclei induction in developing pollen and pink somatic mutations in stamen hairs. Photosynthetic perturbations were measured in Tradescantia and Ambrosia dumosa usingmore » variable fluorescence induction. Animals were examined for sister chromatid exchanges and chromosome aberrations. It was found that all of the smokes tested exerted varying degrees of physiological and mutagenic effects in one or several of the assay systems at one or more of the exposure distances. These studies indicate that exposed ecological systems, or at least components of these systems, are at a higher risk than are control organisms for several types of damage attributed to obscurant smoke exposure.« less

Ovary-derived precursor gibberellin A9 is essential for female flower development in cucumber.

PubMed

Pimenta Lange, Maria João; Lange, Theo

2016-12-01

Gibberellins (GAs) are hormones that control many aspects of plant development, including flowering. It is well known that stamen is the source of GAs that regulate male and bisexual flower development. However, little is known about the role of GAs in female flower development. In cucumber, high levels of GA precursors are present in ovaries and high levels of bioactive GA 4 are identified in sepals/petals, reflecting the expression of GA 20-oxidase and 3-oxidase in these organs, respectively. Here, we show that the biologically inactive precursor GA 9 moves from ovaries to sepal/petal tissues where it is converted to the bioactive GA 4 necessary for female flower development. Transient expression of a catabolic GA 2-oxidase from pumpkin in cucumber ovaries decreases GA 9 and GA 4 levels and arrests the development of female flowers, and this can be restored by application of GA 9 to petals thus confirming its function. Given that bioactive GAs can promote sex reversion of female flowers, movement of biologically inactive precursors, instead of the hormone itself, might help to maintain floral organ identity, ensuring fruit and seed production. © 2016. Published by The Company of Biologists Ltd.

The Evolutionary History and Diverse Physiological Roles of the Grapevine Calcium-Dependent Protein Kinase Gene Family

PubMed Central

Chen, Fei; Fasoli, Marianna; Tornielli, Giovanni Battista; Dal Santo, Silvia; Pezzotti, Mario; Zhang, Liangsheng; Cai, Bin; Cheng, Zong-Ming

2013-01-01

Calcium-dependent protein kinases (CDPKs) are molecular switches that bind Ca2+, ATP, and protein substrates, acting as sensor relays and responders that convert Ca2+ signals, created by developmental processes and environmental stresses, into phosphorylation events. The precise functions of the CDPKs in grapevine (Vitis vinifera) are largely unknown. We therefore investigated the phylogenetic relationships and expression profiles of the 17 CDPK genes identified in the 12x grapevine genome sequence, resolving them into four subfamilies based on phylogenetic tree topology and gene structures. The origins of the CDPKs during grapevine evolution were characterized, involving 13 expansion events. Transcriptomic analysis using 54 tissues and developmental stages revealed three types of CDPK gene expression profiles: constitutive (housekeeping CDPKs), partitioned functions, and prevalent in pollen/stamen. We identified two duplicated CDPK genes that had evolved from housekeeping to pollen-prevalent functions and whose origin correlated with that of seed plants, suggesting neofunctionalization with an important role in pollen development and also potential value in the breeding of seedless varieties. We also found that CDPKs were involved in three abiotic stress signaling pathways and could therefore be used to investigate the crosstalk between stress responses. PMID:24324631

Flower Development

PubMed Central

Alvarez-Buylla, Elena R.; Benítez, Mariana; Corvera-Poiré, Adriana; Chaos Cador, Álvaro; de Folter, Stefan; Gamboa de Buen, Alicia; Garay-Arroyo, Adriana; García-Ponce, Berenice; Jaimes-Miranda, Fabiola; Pérez-Ruiz, Rigoberto V.; Piñeyro-Nelson, Alma; Sánchez-Corrales, Yara E.

2010-01-01

Flowers are the most complex structures of plants. Studies of Arabidopsis thaliana, which has typical eudicot flowers, have been fundamental in advancing the structural and molecular understanding of flower development. The main processes and stages of Arabidopsis flower development are summarized to provide a framework in which to interpret the detailed molecular genetic studies of genes assigned functions during flower development and is extended to recent genomics studies uncovering the key regulatory modules involved. Computational models have been used to study the concerted action and dynamics of the gene regulatory module that underlies patterning of the Arabidopsis inflorescence meristem and specification of the primordial cell types during early stages of flower development. This includes the gene combinations that specify sepal, petal, stamen and carpel identity, and genes that interact with them. As a dynamic gene regulatory network this module has been shown to converge to stable multigenic profiles that depend upon the overall network topology and are thus robust, which can explain the canalization of flower organ determination and the overall conservation of the basic flower plan among eudicots. Comparative and evolutionary approaches derived from Arabidopsis studies pave the way to studying the molecular basis of diverse floral morphologies. PMID:22303253

BnEPFL6, an EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) secreted peptide gene, is required for filament elongation in Brassica napus.

PubMed

Huang, Yi; Tao, Zhangsheng; Liu, Qiong; Wang, Xinfa; Yu, Jingyin; Liu, Guihua; Wang, Hanzhong

2014-07-01

Inflorescence architecture, pedicel length and stomata patterning in Arabidopsis thaliana are specified by inter-tissue communication mediated by ERECTA and its signaling ligands in the EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) family of secreted cysteine-rich peptides. Here, we identified and characterized BnEPFL6 from Brassica napus. Heterologous expression of this gene under the double enhanced CaMV promoter (D35S) in Arabidopsis resulted in shortened stamen filaments, filaments degradation, and reduced filament cell size that displayed down-regulated expression of AHK2, in which phenotypic variation of ahk2-1 mutant presented highly consistent with that of BnEPFL6 transgenic lines. Especially, the expression level of BnEPFL6 in the shortened filaments of four B. napus male sterile lines (98A, 86A, SA, and Z11A) was similar to that of BnEPFL6 in the transgenic Arabidopsis lines. The activity of pBnEPFL6.2::GUS was intensive in the filaments of transgenic lines. These observations reveal that BnEPFL6 plays an important role in filament elongation and may also affect organ morphology and floral organ specification via a BnEPFL6-mediated cascade.

Conserved and novel responses to cytokinin treatments during flower and fruit development in Brassica napus and Arabidopsis thaliana.

PubMed

Zuñiga-Mayo, Victor M; Baños-Bayardo, Cesar R; Díaz-Ramírez, David; Marsch-Martínez, Nayelli; de Folter, Stefan

2018-05-01

Hormones are an important component in the regulatory networks guiding plant development. Cytokinins are involved in different physiological and developmental processes in plants. In the model plant Arabidopsis thaliana, cytokinin application during gynoecium development produces conspicuous phenotypes. On the other hand, Brassica napus, also known as canola, is a crop plant belonging to the Brassicaceae family, as A. thaliana. This makes B. napus a good candidate to study whether the cytokinin responses observed in A. thaliana are conserved in the same plant family. Here, we observed that cytokinin treatment in B. napus affects different traits of flower and fruit development. It increases ovule and seed number, affects stamen filament elongation and anther maturation, and causes a conspicuous overgrowth of tissue in petals and gynoecia. Furthermore, cytokinin recovers replum development in both wild type B. napus and in the A. thaliana rpl ntt double mutant, in which no replum is visible. These results indicate both conserved and novel responses to cytokinin in B. napus. Moreover, in this species, some cytokinin-induced phenotypes are inherited to the next, untreated generation, suggesting that cytokinins may trigger epigenetic modifications.

Morphofunctional Traits and Pollination Mechanisms of Coronilla emerus L. Flowers (Fabaceae)

PubMed Central

Aronne, Giovanna; Giovanetti, Manuela; De Micco, Veronica

2012-01-01

It is accepted that the papilionaceous corolla of the Fabaceae evolved under the selective pressure of bee pollinators. Morphology and function of different parts of Coronilla emerus L. flowers were related to their role in the pollination mechanism. The corolla has a vexillum with red nectar lines, a keel hiding stamens and pistil, and two wing petals fasten to the keel with two notched folds. Pollinators land on the complex of keel and wings, trigger the protrusion of pollen and finally of the stigma from the keel tip. Data on pollen viability and stigma receptivity prove that flowers are proterandrous. The results of hand-pollination experiments confirmed that insects are fundamental to set seed. Interaction with pollinators allows not only the transport of pollen but also the rupture of the stigmatic cuticle, necessary to achieve both allogamy and autogamy. Field observations showed that Hymenoptera, Lepidoptera, and Diptera visited the flowers. Only some of the Hymenoptera landed on the flowers from the front and elicited pollination mechanisms. Most of the insects sucked the nectar from the back without any pollen transfer. Finally, morphological and functional characteristics of C. emerus flowers are discussed in terms of floral larceny and reduction in pollination efficiency. PMID:22666114

Multiple interactions amongst floral homeotic MADS box proteins.

PubMed Central

Davies, B; Egea-Cortines, M; de Andrade Silva, E; Saedler, H; Sommer, H

1996-01-01

Most known floral homeotic genes belong to the MADS box family and their products act in combination to specify floral organ identity by an unknown mechanism. We have used a yeast two-hybrid system to investigate the network of interactions between the Antirrhinum organ identity gene products. Selective heterodimerization is observed between MADS box factors. Exclusive interactions are detected between two factors, DEFICIENS (DEF) and GLOBOSA (GLO), previously known to heterodimerize and control development of petals and stamens. In contrast, a third factor, PLENA (PLE), which is required for reproductive organ development, can interact with the products of MADS box genes expressed at early, intermediate and late stages. We also demonstrate that heterodimerization of DEF and GLO requires the K box, a domain not found in non-plant MADS box factors, indicating that the plant MADS box factors may have different criteria for interaction. The association of PLENA and the temporally intermediate MADS box factors suggests that part of their function in mediating between the meristem and organ identity genes is accomplished through direct interaction. These data reveal an unexpectedly complex network of interactions between the factors controlling flower development and have implications for the determination of organ identity. Images PMID:8861961

Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity.

PubMed

O'Meara, Brian C; Smith, Stacey D; Armbruster, W Scott; Harder, Lawrence D; Hardy, Christopher R; Hileman, Lena C; Hufford, Larry; Litt, Amy; Magallón, Susana; Smith, Stephen A; Stevens, Peter F; Fenster, Charles B; Diggle, Pamela K

2016-05-11

Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years. © 2016 The Author(s).

Geraniales flowers revisited: evolutionary trends in floral nectaries

PubMed Central

Jeiter, Julius; Weigend, Maximilian; Hilger, Hartmut H.

2017-01-01

Background and Aims The detailed relationships in Geraniales in their current circumscription have only recently been clarified. The disparate floral morphologies and especially the nectaries of the corresponding group have consequently not previously been studied in a phylogenetic context. Methods The present study investigates floral and especially nectary morphology and structure for representatives of 12 of the 13 currently accepted genera in the five families of the Geraniales. Flowers were studied using light microscopy and scanning electron microscopy. Key Results The data demonstrate the derivation of even the most disparate floral morphologies from a basic pentamerous and pentacyclic organization, with an obdiplostemonous androecium and receptacular nectaries associated with the antesepalous stamens. Divergent morphologies are explained by modifications of merosity (tetramerous flowers), symmetry (several transitions to zygomorphic flowers) and elaboration of the nectaries into variously shaped outgrowths and appendages, especially in Francoaceae. The divergent development of nectar glands ultimately leads to either a reduction in their number (to one in some Geraniaceae and Melianthaceae) or their total loss (some Vivianiaceae). Conclusions Floral morphology of the Geraniales shows a high degree of similarity, despite the variation in overall floral appearance and nectary morphology. A hypothesis on the transformation of the nectaries within the Geraniales is presented. PMID:28025289

A molecular phylogenetic study of Graptopetalum (Crassulaceae) based on ETS, ITS, RPL16, and TRNL-F nucleotide sequences.

PubMed

Acevedo-Rosas, Raúl; Cameron, Kenneth; Sosa, Victoria; Pell, Susan

2004-07-01

Nuclear ETS and ITS, as well as plastid rpl16 and trnL-F DNA sequences were used to determine relationships among species of Graptopetalum (Crassulaceae) and closely related genera. Graptopetalum is member of a group of taxa restricted to North America, one of the centers of diversity of Crassulaceae; however, their phylogenetic relationships are not yet understood. Nineteen species of Graptopetalum and 24 species from nine other genera of Crassulaceae were sampled for use in three separate parsimony analyses: ITS alone, ETS alone, and a combined nuclear + plastid DNA analysis using all four gene regions. The ETS data set had the highest number of parsimony-informative sites, about 30% more than in ITS, but the most fully resolved tree resulted when the four DNA regions were combined. Only four subclades of the tree received moderate to strong bootstrap support, one of which includes all species of Graptopetalum having a single whorl of stamens. However, Graptopetalum is not monophyletic. Instead, Tacitus bellus and select species of Cremnophila, Sedum, and Echeveria are interspersed among species of Graptopetalum and show evidence of grouping according to geographical range of distribution more so than habit or floral morphology.

Stigmatic exudate in the Annonaceae: Pollinator reward, pollen germination medium or extragynoecial compitum?

PubMed Central

Lau, Jenny Y. Y.; Pang, Chun‐Chiu; Ramsden, Lawrence

2017-01-01

Abstract Although “dry‐type” stigmas are widely regarded as ancestral in angiosperms, the early‐divergent family Annonaceae has copious stigmatic exudate. We evaluate three putative functions for this exudate: as a nutritive reward for pollinators; as a pollen germination medium; and as an extragynoecial compitum that enables pollen tube growth between carpels. Stigmatic exudate is fructose dominated (72.2%), but with high levels of glucose and sucrose; the dominance of hexose sugars and the diversity of amino acids observed, including many that are essential for insects, support a nutritive role for pollinators. Sugar concentration in pre‐receptive flowers is high (28.2%), falling during the peak period of stigmatic receptivity (17.4%), and then rising again toward the end of the pistillate phase (32.9%). Pollen germination was highest in sugar concentrations <20%. Sugar concentrations during the peak pistillate phase therefore provide optimal osmolarity for pollen hydration and germination; subsequent changes in sugar concentration during anthesis reinforce protogyny (in which carpels mature before stamens), enabling the retention of concentrated exudate into the staminate phase as a pollinator food reward without the possibility of pollen germination. Intercarpellary growth of pollen tubes was confirmed: the exudate therefore also functions as a suprastylar extragynoecial compitum, overcoming the limitations of apocarpy. PMID:28880427

Gladiolus hybridus ABSCISIC ACID INSENSITIVE 5 (GhABI5) is an important transcription factor in ABA signaling that can enhance Gladiolus corm dormancy and Arabidopsis seed dormancy.

PubMed

Wu, Jian; Seng, Shanshan; Sui, Juanjuan; Vonapartis, Eliana; Luo, Xian; Gong, Benhe; Liu, Chen; Wu, Chenyu; Liu, Chao; Zhang, Fengqin; He, Junna; Yi, Mingfang

2015-01-01

The phytohormone abscisic acid (ABA) regulates plant development and is crucial for abiotic stress response. In this study, cold storage contributes to reducing endogenous ABA content, resulting in dormancy breaking of Gladiolus. The ABA inhibitor fluridone also promotes germination, suggesting that ABA is an important hormone that regulates corm dormancy. Here, we report the identification and functional characterization of the Gladiolus ABI5 homolog (GhABI5), which is a basic leucine zipper motif transcriptional factor (TF). GhABI5 is expressed in dormant vegetative organs (corm, cormel, and stolon) as well as in reproductive organs (stamen), and it is up-regulated by ABA or drought. Complementation analysis reveals that GhABI5 rescues the ABA insensitivity of abi5-3 during seed germination and induces the expression of downstream ABA response genes in Arabidopsis thaliana (EM1, EM6, and RD29B). Down-regulation of GhABI5 in dormant cormels via virus induced gene silence promotes sprouting and reduces the expression of downstream genes (GhLEA and GhRD29B). The results of this study reveal that GhABI5 regulates bud dormancy (vegetative organ) in Gladiolus in addition to its well-studied function in Arabidopsis seeds (reproductive organ).

History of yogurt and current patterns of consumption.

PubMed

Fisberg, Mauro; Machado, Rachel

2015-08-01

Yogurt has been a part of the human diet for several millennia and goes by many names throughout the world. The word "yogurt" is believed to have come from the Turkish word "yoğurmak," which means to thicken, coagulate, or curdle. While references to the health-promoting properties of yogurt date back to 6000 BC in Indian Ayurvedic scripts, it was not until the 20th century that Stamen Grigorov, a Bulgarian medical student, attributed the benefits to lactic acid bacteria. Today, most yogurt is fermented milk that is acidified with viable and well-defined bacteria (Lactobacillus bulgaricus and Streptococcus thermophiles). While patterns of yogurt consumption vary greatly from country to country, consumption is generally low. In the United States and Brazil, for example, only 6% of the population consume yogurt on a daily basis. Low consumption of yogurt represents a missed opportunity to contribute to a healthy lifestyle, as yogurt provides a good to excellent source of highly bioavailable protein and an excellent source of calcium as well as a source of probiotics that may provide a range of health benefits. © The Author(s) 2015. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Arabidopsis CALCINEURIN B-LIKE10 Functions Independently of the SOS Pathway during Reproductive Development in Saline Conditions1[OPEN

PubMed Central

Smith, Steven E.; Schumaker, Karen S.

2016-01-01

The accumulation of sodium in soil (saline conditions) negatively affects plant growth and development. The Salt Overly Sensitive (SOS) pathway in Arabidopsis (Arabidopsis thaliana) functions to remove sodium from the cytosol during vegetative development preventing its accumulation to toxic levels. In this pathway, the SOS3 and CALCINEURIN B-LIKE10 (CBL10) calcium sensors interact with the SOS2 protein kinase to activate sodium/proton exchange at the plasma membrane (SOS1) or vacuolar membrane. To determine if the same pathway functions during reproductive development in response to salt, fertility was analyzed in wild type and the SOS pathway mutants grown in saline conditions. In response to salt, CBL10 functions early in reproductive development before fertilization, while SOS1 functions mostly after fertilization when seed development begins. Neither SOS2 nor SOS3 function in reproductive development in response to salt. Loss of CBL10 function resulted in reduced anther dehiscence, shortened stamen filaments, and aborted pollen development. In addition, cbl10 mutant pistils could not sustain the growth of wild-type pollen tubes. These results suggest that CBL10 is critical for reproductive development in the presence of salt and that it functions in different pathways during vegetative and reproductive development. PMID:26979332

Redefining C and D in the petunia ABC.

PubMed

Heijmans, Klaas; Ament, Kai; Rijpkema, Anneke S; Zethof, Jan; Wolters-Arts, Mieke; Gerats, Tom; Vandenbussche, Michiel

2012-06-01

According to the ABC(DE) model for flower development, C-genes are required for stamen and carpel development and floral determinacy, and D-genes were proposed to play a unique role in ovule development. Both C- and D-genes belong to the AGAMOUS (AG) subfamily of MADS box transcription factors. We show that the petunia (Petunia hybrida) C-clade genes PETUNIA MADS BOX GENE3 and FLORAL BINDING PROTEIN6 (FBP6) largely overlap in function, both in floral organ identity specification and floral determinacy, unlike the pronounced subfunctionalization observed in Arabidopsis thaliana and snapdragon (Antirrhinum majus). Some specialization has also evolved, since FBP6 plays a unique role in the development of the style and stigma. Furthermore, we show that the D-genes FBP7 and FBP11 are not essential to confer ovule identity. Instead, this function is redundantly shared among all AG members. In turn, the D-genes also participate in floral determinacy. Gain-of-function analyses suggest the presence of a posttranscriptional C-repression mechanism in petunia, most likely not existing in Arabidopsis. Finally, we show that expression maintenance of the paleoAPETALA3-type B-gene TOMATO MADS BOX GENE6 depends on the activity of C-genes. Taken together, this demonstrates considerable variation in the molecular control of floral development between eudicot species.

Redefining C and D in the Petunia ABC[W

PubMed Central

Heijmans, Klaas; Ament, Kai; Rijpkema, Anneke S.; Zethof, Jan; Wolters-Arts, Mieke; Gerats, Tom; Vandenbussche, Michiel

2012-01-01

According to the ABC(DE) model for flower development, C-genes are required for stamen and carpel development and floral determinacy, and D-genes were proposed to play a unique role in ovule development. Both C- and D-genes belong to the AGAMOUS (AG) subfamily of MADS box transcription factors. We show that the petunia (Petunia hybrida) C-clade genes PETUNIA MADS BOX GENE3 and FLORAL BINDING PROTEIN6 (FBP6) largely overlap in function, both in floral organ identity specification and floral determinacy, unlike the pronounced subfunctionalization observed in Arabidopsis thaliana and snapdragon (Antirrhinum majus). Some specialization has also evolved, since FBP6 plays a unique role in the development of the style and stigma. Furthermore, we show that the D-genes FBP7 and FBP11 are not essential to confer ovule identity. Instead, this function is redundantly shared among all AG members. In turn, the D-genes also participate in floral determinacy. Gain-of-function analyses suggest the presence of a posttranscriptional C-repression mechanism in petunia, most likely not existing in Arabidopsis. Finally, we show that expression maintenance of the paleoAPETALA3-type B-gene TOMATO MADS BOX GENE6 depends on the activity of C-genes. Taken together, this demonstrates considerable variation in the molecular control of floral development between eudicot species. PMID:22706285

Evidence for the involvement of Globosa-like gene duplications and expression divergence in the evolution of floral morphology in the Zingiberales.

PubMed

Bartlett, Madelaine E; Specht, Chelsea D

2010-07-01

*The MADS box transcription factor family has long been identified as an important contributor to the control of floral development. It is often hypothesized that the evolution of floral development across angiosperms and within specific lineages may occur as a result of duplication, functional diversification, and changes in regulation of MADS box genes. Here we examine the role of Globosa (GLO)-like genes, members of the B-class MADS box gene lineage, in the evolution of floral development within the monocot order Zingiberales. *We assessed changes in perianth and stamen whorl morphology in a phylogenetic framework. We identified GLO homologs (ZinGLO1-4) from 50 Zingiberales species and investigated the evolution of this gene lineage. Expression of two GLO homologs was assessed in Costus spicatus and Musa basjoo. *Based on the phylogenetic data and expression results, we propose several family-specific losses and gains of GLO homologs that appear to be associated with key morphological changes. The GLO-like gene lineage has diversified concomitant with the evolution of the dimorphic perianth and the staminodial labellum. *Duplications and expression divergence within the GLO-like gene lineage may have played a role in floral diversification in the Zingiberales.

Floral biology of Tropaeolum majus L. and its relation with Astylus variegatus activity (Germar 1824).

PubMed

Silva, Maria Emilia P F; Mussury, Rosilda M; Vieira, Maria do Carmo; Alves Junior, Valter V; Pereira, Zefa V; Scalon, Silvana P Q

2011-12-01

Tropaeolum majus L. (nasturtium) is a culture popularly known by its medicinal, ornamental and culinary utility. This work aimed to evaluate the interaction between Astylus variegatus (Germar 1824) (Coleoptera: Melyridae) and the nasturtium flowers associated to the weeks of flourishing, in order to conceive the floral mechanims used by the species to attract A. variegatus. The insects collection was achieved with an entomologic net by the sweeping method, during the weekly flowering, at two hours, from 7am to 5pm. The studies of floral biology were carried out in twenty flowers by the analysis of measures and the arrangement of the floral parts. The nasturtium flower offers pollen and nectar to the insect as a compensation. However, it was observed that A. variegatus only collects pollen as a nutritious resource. Tropaeolum majus presents several flowers for each individual and, during the visits, A. variegatus walked throughout the interior of the flower, among the stamens and contacting the ventral region of its body, and while passing through the stigma it lodged the pollen. Sometimes, it uses the internal cavity for sheltering and mating. The visits occurred preferably on the second and fifth weeks of flourishing, with a populational fluctuation between 9am and 11am.

Exceptional inheritance of plastids via pollen in Nicotiana sylvestris with no detectable paternal mitochondrial DNA in the progeny.

PubMed

Thyssen, Gregory; Svab, Zora; Maliga, Pal

2012-10-01

Plastids and mitochondria, the DNA-containing cytoplasmic organelles, are maternally inherited in the majority of angiosperm species. Even in plants with strict maternal inheritance, exceptional paternal transmission of plastids has been observed. Our objective was to detect rare leakage of plastids via pollen in Nicotiana sylvestris and to determine if pollen transmission of plastids results in co-transmission of paternal mitochondria. As father plants, we used N. sylvestris plants with transgenic, selectable plastids and wild-type mitochondria. As mother plants, we used N. sylvestris plants with Nicotiana undulata cytoplasm, including the CMS-92 mitochondria that cause cytoplasmic male sterility (CMS) by homeotic transformation of the stamens. We report here exceptional paternal plastid DNA in approximately 0.002% of N. sylvestris seedlings. However, we did not detect paternal mitochondrial DNA in any of the six plastid-transmission lines, suggesting independent transmission of the cytoplasmic organelles via pollen. When we used fertile N. sylvestris as mothers, we obtained eight fertile plastid transmission lines, which did not transmit their plastids via pollen at higher frequencies than their fathers. We discuss the implications for transgene containment and plant evolutionary histories inferred from cytoplasmic phylogenies. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

Evolution of the staminode in a representative sample of Scrophularia and its role as nectar safeguard in three widespread species

NASA Astrophysics Data System (ADS)

Rodríguez-Riaño, Tomás; Valtueña, Francisco J.; López, Josefa; Navarro-Pérez, María Luisa; Pérez-Bote, José Luis; Ortega-Olivencia, Ana

2015-06-01

Approximately 30 % of the genera of Scrophulariaceae s.str. have a staminode, which is the remnant of a sterile stamen. However, there are no studies of the functionality or evolutionary pattern of staminodes in that family. This paper investigates three Scrophularia species with different staminode sizes to determine if the staminode safeguards nectar from dilution by rainwater and if it influences pollinator behavior. We also study staminode evolution and ancestral state reconstruction onto a phylogeny containing 71 species and subspecies with four different staminode developmental stages: tiny, large, enormous, and absent. The results showed that large staminodes did not hinder nectar collection or modify pollinator-visiting time but acted as a barrier to reduce rainwater entry. The latter reduced the dilution of nectar, which did not occur with tiny staminodes. The phylogenetic study revealed that the ancestral state in the genus corresponds with the presence of a large staminode vs. the tiny and enormous staminodes that are considered as derived. The complete disappearance of the staminode has occurred independently at least twice. Events occurred that increased or reduced the staminode size in one of the clades (Clade II), which includes species of sect. Caninae; most of these events occurred during the Pleistocene (0.6-2.7 Ma).

Flower, fruit phenology and flower traits in Cordia boissieri (Boraginaceae) from northeastern Mexico.

PubMed

Martínez-Adriano, Cristian Adrian; Jurado, Enrique; Flores, Joel; González-Rodríguez, Humberto; Cuéllar-Rodríguez, Gerardo

2016-01-01

We characterized variations in Cordia boissieri flowers and established if these variations occur between plants or between flowering events. Flowering and fruiting was measured for 256 plants. A GLM test was used to determine the relationship between flowering and fruit set processes and rainfall. We performed measurements of floral traits to detect variations within the population and between flowering events. The position of the anthers with respect to the ovary was determined in 1,500 flowers. Three out of four flowering events of >80% C. boissieri plants occurred after rainfall events. Only one flowering event occurred in a drought. Most plants flowered at least twice a year. The overlapping of flowering and fruiting only occurred after rainfall. Anthesis lasted three-to-five days, and there were two flower morphs. Half of the plants had longistylus and half had brevistylus flowers. Anacahuita flower in our study had 1-4 styles; 2-9 stamens; 6.5-41.5 mm long corolla; sepals from 4.5-29.5 mm in length; a total length from 15.5-59 mm; a corolla diameter from 10.5-77 mm. The nectar guide had a diameter from 5-30.5 mm; 4-9 lobes; and 5 distinguishable nectar guide colors. The highest variation of phenotypic expression was observed between plants.

Different cucumber CsYUC genes regulate response to abiotic stresses and flower development.

PubMed

Yan, Shuangshuang; Che, Gen; Ding, Lian; Chen, Zijing; Liu, Xiaofeng; Wang, Hongyin; Zhao, Wensheng; Ning, Kang; Zhao, Jianyu; Tesfamichael, Kiflom; Wang, Qian; Zhang, Xiaolan

2016-02-09

The phytohormone auxin is essential for plant growth and development, and YUCCA (YUC) proteins catalyze a rate-limiting step for endogenous auxin biosynthesis. Despite YUC family genes have been isolated from several species, systematic expression analyses of YUCs in response to abiotic stress are lacking, and little is known about the function of YUC homologs in agricultural crops. Cucumber (Cucumis sativus L.) is a world cultivated vegetable crop with great economical and nutritional value. In this study, we isolated 10 YUC family genes (CsYUCs) from cucumber and explored their expression pattern under four types of stress treatments. Our data showed that CsYUC8 and CsYUC9 were specifically upregulated to elevate the auxin level under high temperature. CsYUC10b was dramatically increased but CsYUC4 was repressed in response to low temperature. CsYUC10a and CsYUC11 act against the upregulation of CsYUC10b under salinity stress, suggesting that distinct YUC members participate in different stress response, and may even antagonize each other to maintain the proper auxin levels in cucumber. Further, CsYUC11 was specifically expressed in the male flower in cucumber, and enhanced tolerance to salinity stress and regulated pedicel and stamen development through auxin biosynthesis in Arabidopsis.

Botanical smuts and hermaphrodites: Lydia Becker, Darwin's botany, and education reform.

PubMed

Gianquitto, Tina

2013-06-01

In 1868, Lydia Becker (1827-1890), the renowned Manchester suffragist, announced in a talk before the British Association for the Advancement of Science that the mind had no sex. A year later, she presented original botanical research at the BAAS, contending that a parasitic fungus forced normally single-sex female flowers of Lychnis diurna to develop stamens and become hermaphroditic. This essay uncovers the complex relationship between Lydia Becker's botanical research and her stance on women's rights by investigating how her interest in evolutionary theory, as well as her correspondence with Charles Darwin, critically informed her reform agendas by providing her with a new vocabulary for advocating for equality. One of the facts that Becker took away from her work on Lychnis was that even supposedly fixed, dichotomous categories such as biological sex became unfocused under the evolutionary lens. The details of evolutionary theory, from specific arguments on structural adaptations to more encompassing theories on heredity (i.e., pangenesis), informed Becker's understanding of human physiology. At the same time, Becker's belief in the fundamental equality of the sexes enabled her to perceive the distinction between inherent, biological differences and culturally contingent ones. She applied biological principles to social constructs as she asked: Do analogous evolutionary forces act on humans?

Limitations of learning in the proboscis reflex of the flower visiting syrphid fly Eristalis tenax

PubMed Central

An, Lina; Donda, Miriam; Hohmann, Michele; Sermon, Leonie; Stegmanns, Vanessa

2018-01-01

Flower visiting Eristalis hoverflies feed on nectar and pollen and are known to rely on innate colour preferences. In addition to a preference for visiting yellow flowers, the flies possess an innate proboscis reflex elicited by chemical as well as yellow colour stimuli. In this study we show that the flies’ proboscis reflex is only triggered by yellow colour stimuli and not altered by conditioning to other colours. Neither in absolute nor in differential conditioning experiments the flies learned to associate other colours than yellow with reward. Even flies that experienced only blue nutrients during the first four days after hatching could not be trained to extend the proboscis towards other colours than yellow. The natural targets of the visually elicited proboscis reflex are yellow pollen and yellow anthers. One consequence of our findings is that flowers might advertise nectar and pollen rewards for Eristalis hoverflies by a yellow colour hue of nectar guides, nectaries, stamens or pollen. Alternatively, flowers might protect their pollen against Eristalis by displaying other pollen colours than yellow or direct flies by yellow pollen-mimicking floral guides towards nectar resources. Testing the proboscis extension of various hoverfly species in the field showed that only Eristalis hoverflies possess the proboscis reflex elicited by yellow colour hues. PMID:29558491

FLOOZY of petunia is a flavin mono-oxygenase-like protein required for the specification of leaf and flower architecture

PubMed Central

Tobeña-Santamaria, Rafael; Bliek, Mattijs; Ljung, Karin; Sandberg, Göran; Mol, Joseph N.M.; Souer, Erik; Koes, Ronald

2002-01-01

The mechanisms that determine the relative positions of floral organs, and thereby their numbers, is a poorly understood aspect of flower development. We isolated a petunia mutant, floozy (fzy), in which the formation of floral organ primordia in the outermost three floral whorls and one of the two bracts at the base of the flower is blocked at an early stage. In addition, fzy mutants fail to generate secondary veins in leaves and bracts and display a decreased apical dominance in the inflorescence. FZY encodes an enzyme with homology to flavin mono-oxygenases and appears to be the ortholog of YUCCA genes of Arabidopsis. FZY is expressed in young leafs and bracts and in developing flowers. In young floral meristems FZY is expressed in the center of the meristem dome and, later, expression becomes localized on the flanks of the initiating petal and stamen primordia and at several sites in maturing anthers and carpels. These findings indicate that FZY is involved in synthesizing a signaling compound that is required for floral organ initiation and specification of the vascularization pattern in leaves. Although fzy mutants contain normal auxin levels, ectopic expression of FZY results in excessive auxin accumulation, suggesting that the signaling compound is auxin. PMID:11914280

Distribution models and species discovery: the story of a new Solanum species from the Peruvian Andes

PubMed Central

Särkinen, Tiina; Gonzáles, Paúl; Knapp, Sandra

2013-01-01

Abstract A new species of Solanum sect. Solanum from Peru is described here. Solanum pseudoamericanum Särkinen, Gonzáles & S.Knapp sp. nov. is a member of the Morelloid clade of Solanum, and is characterized by the combination of mostly forked inflorescences, flowers with small stamens 2.5 mm long including the filament, and strongly exerted styles with capitate stigmas. The species was first thought to be restricted to the seasonally dry tropical forests of southern Peru along the dry valleys of Río Pampas and Río Apurímac. Results from species distribution modelling (SDM) analysis with climatic predictors identified further potential suitable habitat areas in northern and central Peru. These areas were visited during field work in 2013. A total of 17 new populations across the predicted distribution were discovered using the model-based sampling method, and five further collections were identified amongst herbarium loans. Although still endemic to Peru, Solanum pseudoamericanum is now known from across northern, central and southern Peru. Our study demonstrates the usefulness of SDM for predicting new occurrences of rare plants, especially in the Andes where collection densities are still low in many areas and where many new species remain to be discovered. PMID:24399901

Distribution models and species discovery: the story of a new Solanum species from the Peruvian Andes.

PubMed

Särkinen, Tiina; Gonzáles, Paúl; Knapp, Sandra

2013-01-01

A new species of Solanum sect. Solanum from Peru is described here. Solanum pseudoamericanum Särkinen, Gonzáles & S.Knapp sp. nov. is a member of the Morelloid clade of Solanum, and is characterized by the combination of mostly forked inflorescences, flowers with small stamens 2.5 mm long including the filament, and strongly exerted styles with capitate stigmas. The species was first thought to be restricted to the seasonally dry tropical forests of southern Peru along the dry valleys of Río Pampas and Río Apurímac. Results from species distribution modelling (SDM) analysis with climatic predictors identified further potential suitable habitat areas in northern and central Peru. These areas were visited during field work in 2013. A total of 17 new populations across the predicted distribution were discovered using the model-based sampling method, and five further collections were identified amongst herbarium loans. Although still endemic to Peru, Solanum pseudoamericanum is now known from across northern, central and southern Peru. Our study demonstrates the usefulness of SDM for predicting new occurrences of rare plants, especially in the Andes where collection densities are still low in many areas and where many new species remain to be discovered.

Grass meristems II: inflorescence architecture, flower development and meristem fate.

PubMed

Tanaka, Wakana; Pautler, Michael; Jackson, David; Hirano, Hiro-Yuki

2013-03-01

Plant development depends on the activity of various types of meristems that generate organs such as leaves and floral organs throughout the life cycle. Grass species produce complex inflorescences and unique flowers. The grass inflorescence is composed of different types of branches, including a specialized branch called a spikelet. The spikelet is a special unit of the inflorescence and forms one to several florets, depending on the species. In the floret, floral organs such as perianth organs, carpels and stamens are formed. In Arabidopsis, because the inflorescence meristem (IM) forms the floral meristems (FMs) directly on its flanks, the change of meristem fate is relatively simple. In contrast, in grasses, different types of meristem, such as the IM, the branch meristem (BM), the spikelet pair meristem (SPM) in some grasses, the spikelet meristem (SM) and the FM, are responsible for the elaboration of their complex inflorescences and flowers. Therefore, sequential changes of meristem fate are required, and a number of genes involved in the specification of the fate of each meristem have been identified. In this review, we focus on the following issues concerning the fate of the reproductive meristems in two grass species, maize (Zea mays) and rice (Oryza sativa): (i) meristem regulation during inflorescence development; (ii) specification and fate change of the BM and the SM; (iii) determinacy of the FM; and (iv) communication between the meristem and lateral organs.

Evolution of AGL6-like MADS Box Genes in Grasses (Poaceae): Ovule Expression Is Ancient and Palea Expression Is New[W][OA

PubMed Central

Reinheimer, Renata; Kellogg, Elizabeth A.

2009-01-01

AGAMOUS-like6 (AGL6) genes encode MIKC-type MADS box transcription factors and are closely related to SEPALLATA and AP1/FUL-like genes. Here, we focus on the molecular evolution and expression of the AGL6-like genes in grasses. We have found that AGL6-like genes are expressed in ovules, lodicules (second whorl floral organs), paleas (putative first whorl floral organs), and floral meristems. Each of these expression domains was acquired at a different time in evolution, indicating that each represents a distinct function of the gene product and that the AGL6-like genes are pleiotropic. Expression in the inner integument of the ovule appears to be an ancient expression pattern corresponding to the expression of the gene in the megasporangium and integument in gymnosperms. Expression in floral meristems appears to have been acquired in the angiosperms and expression in second whorl organs in monocots. Early in grass evolution, AGL6-like orthologs acquired a new expression domain in the palea. Stamen expression is variable. Most grasses have a single AGL6-like gene (orthologous to the rice [Oryza sativa] gene MADS6). However, rice and other species of Oryza have a second copy (orthologous to rice MADS17) that appears to be the result of an ancient duplication. PMID:19749151

Geraniales flowers revisited: evolutionary trends in floral nectaries.

PubMed

Jeiter, Julius; Weigend, Maximilian; Hilger, Hartmut H

2017-02-01

The detailed relationships in Geraniales in their current circumscription have only recently been clarified. The disparate floral morphologies and especially the nectaries of the corresponding group have consequently not previously been studied in a phylogenetic context. The present study investigates floral and especially nectary morphology and structure for representatives of 12 of the 13 currently accepted genera in the five families of the Geraniales. Flowers were studied using light microscopy and scanning electron microscopy. The data demonstrate the derivation of even the most disparate floral morphologies from a basic pentamerous and pentacyclic organization, with an obdiplostemonous androecium and receptacular nectaries associated with the antesepalous stamens. Divergent morphologies are explained by modifications of merosity (tetramerous flowers), symmetry (several transitions to zygomorphic flowers) and elaboration of the nectaries into variously shaped outgrowths and appendages, especially in Francoaceae. The divergent development of nectar glands ultimately leads to either a reduction in their number (to one in some Geraniaceae and Melianthaceae) or their total loss (some Vivianiaceae). Floral morphology of the Geraniales shows a high degree of similarity, despite the variation in overall floral appearance and nectary morphology. A hypothesis on the transformation of the nectaries within the Geraniales is presented. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Mutation in Torenia fournieri Lind. UFO homolog confers loss of TfLFY interaction and results in a petal to sepal transformation.

PubMed

Sasaki, Katsutomo; Yamaguchi, Hiroyasu; Aida, Ryutaro; Shikata, Masahito; Abe, Tomoko; Ohtsubo, Norihiro

2012-09-01

We identified a Torenia fournieri Lind. mutant (no. 252) that exhibited a sepaloid phenotype in which the second whorls were changed to sepal-like organs. This mutant had no stamens, and the floral organs consisted of sepals and carpels. Although the expression of a torenia class B MADS-box gene, GLOBOSA (TfGLO), was abolished in the 252 mutant, no mutation of TfGLO was found. Among torenia homologs such as APETALA1 (AP1), LEAFY (LFY), and UNUSUAL FLORAL ORGANS (UFO), which regulate expression of class B genes in Arabidopsis, only accumulation of the TfUFO transcript was diminished in the 252 mutant. Furthermore, a missense mutation was found in the coding region of the mutant TfUFO. Intact TfUFO complemented the mutant phenotype whereas mutated TfUFO did not; in addition, the transgenic phenotype of TfUFO-knockdown torenias coincided with the mutant phenotype. Yeast two-hybrid analysis revealed that the mutated TfUFO lost its ability to interact with TfLFY protein. In situ hybridization analysis indicated that the transcripts of TfUFO and TfLFY were partially accumulated in the same region. These results clearly demonstrate that the defect in TfUFO caused the sepaloid phenotype in the 252 mutant due to the loss of interaction with TfLFY. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

Effects of chemical smokes on flora and fauna under field and laboratory exposures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaeffer, D.J.; Novak, E.W.; Lower, W.R.

1987-06-01

Various types of obscurant smokes are used routinely in training by the U.S. Army. Because continued routine use of the smokes could be detrimental to the native flora and fauna at training sites, a preliminary biological and chemical field study of fogoil, hexachloroethane, and tank diesel smokes was conducted. Smoke plumes were sampled and chemically analyzed at distances of 15-150 m from the smoke source where Tradescantia clones 4430 and 03 and the native plant Ambrosia dumosa and the native rodent Dipodomys merriami were exposed for 30 min. In addition, Tradescantia clone 4430 was exposed to tank diesel in themore » laboratory at concentration levels equivalent to exposure at 15 and 50 m. Tradescantia clones were examined for mutagenic effects indicated by micronuclei induction in developing pollen and pink somatic mutations in stamen hairs. Photosynthetic perturbations were measured in Tradescantia and A. dumosa using variable fluorescence induction. Animals were examined for sister chromatid exchanges and chromosome aberrations. It was found that all of the smokes tested exerted varying degrees of physiological and mutagenic effects in one or more assay system at one or more exposure distance. The studies reported here indicate that exposed ecological systems, or at least components of these systems, are at a higher risk than are unexposed components (e.g., organisms) for several types of damage attributed to obscurant smoke exposure.« less

Modification of reproductive development in Arabidopsis thaliana under spaceflight conditions

NASA Technical Reports Server (NTRS)

Kuang, A.; Musgrave, M. E.; Matthews, S. W.

1996-01-01

Reproductive development in Arabidopsis thaliana (L.) Heynh. cv. Columbia plants was investigated under spaceflight conditions on shuttle mission STS-51. Plants launched just prior to initiation of the reproductive phase developed flowers and siliques during the 10-d flight. Approximately 500 flowers were produced in total by the 12 plants in both the ground control and spaceflight material, and there was no significant difference in the number of flowers in each size class. The flower buds and siliques of the spaceflight plants were not morphologically different from the ground controls. Pollen viability tests immediately post-flight using fluorescein diacetate indicated that about 35% of the pollen was viable in the spaceflight material. Light-microscopy observations on this material showed that the female gametophytes also had developed normally to maturity. However, siliques from the spaceflight plants contained empty, shrunken ovules, and no evidence of pollen transfer to stigmatic papillae was found by light microscopy immediately post-flight or by scanning electron microscopy on fixed material. Short stamen length and indehiscent anthers were observed in the spaceflight material, and a film-like substance inside the anther that connected to the tapetum appeared to restrict the release of pollen from the anthers. These observations indicate that given appropriate growing conditions, early reproductive development in A. thaliana can occur normally under spaceflight conditions. On STS-51, reproductive development aborted due to obstacles in pollination or fertilization.

Characterization of a purine permease family gene OsPUP7 involved in growth and development control in rice.

PubMed

Qi, Zhuyun; Xiong, Lizhong

2013-11-01

In this study, PUP-type cytokinin transporter genes were identified in rice (Oryza sativa L.). The Oryza sativa purine permease (OsPUP) family has 12 members that show similar predicted protein sequences with AtPUPs. To reveal the functions of OsPUP genes, we searched the T-DNA mutant library of rice and found one mutant for the member OsPUP7. The T-DNA insertion caused a new transcript that encodes a protein with 26 amino acids different from the native OsPUP7 at the C-terminus. The mutant showed multiple phenotypic changes including increased plant height, big seeds, and delayed flowering. The mutant also showed increased sensitivity to drought and salt stresses and treatments with kinetin and abscisic acid. OsPUP7 is expressed mainly in the vascular bundle, pistil, and stamens. The measurement of cytokinins (CKs) showed that CK content in the mutant spikelets accumulated higher than that in the wild type. Moreover, uptake experiment in the yeast fcy2 mutant suggested that OsPUP7 has the ability to transport caffeine, a CK derivative. Our results indicate that the PUP transport system also exists in rice, and OsPUP7 has an important role in the transport of CK, thus affecting developmental process and stress responses. © 2013 Institute of Botany, Chinese Academy of Sciences.

Molecular cloning and functional analysis of the FLOWERING LOCUS T (FT) homolog GhFT1 from Gossypium hirsutum.

PubMed

Guo, Danli; Li, Chao; Dong, Rui; Li, Xiaobo; Xiao, Xiangwen; Huang, Xianzhong

2015-06-01

FLOWERING LOCUS T (FT) encodes a member of the phosphatidylethanolamine-binding protein (PEBP) family that functions as the mobile floral signal, playing an important role in regulating the floral transition in angiosperms. We isolated an FT-homolog (GhFT1) from Gossypium hirsutum L. cultivar, Xinluzao 33 GhFT1 was predominantly expressed in stamens and sepals, and had a relatively higher expression level during the initiation stage of fiber development. GhFT1 mRNA displayed diurnal oscillations in both long-day and short-day condition, suggesting that the expression of this gene may be under the control of the circadian clock. Subcellular analysis revealed that GhFT1 protein located in the cytoplasm and nucleus. Ectopic expression of GhFT1 in transgenic arabidopsis plants resulted in early flowering compared with wild-type plants. In addition, ectopic expression of GhFT1 in arabidopsis ft-10 mutants partially rescued the extremely late flowering phenotype. Finally, several flowering related genes functioning downstream of AtFT were highly upregulated in the 35S::GhFT1 transgenic arabidopsis plants. In summary, GhFT1 is an FT-homologous gene in cotton that regulates flower transition similar to its orthologs in other plant species and thus it may be a candidate target for promoting early maturation in cotton breeding. © 2014 Institute of Botany, Chinese Academy of Sciences.

Restoring pollen fertility in transgenic male-sterile eggplant by Cre/loxp-mediated site-specific recombination system.

PubMed

Cao, Bihao; Huang, Zhiyin; Chen, Guoju; Lei, Jianjun

2010-04-01

This study was designed to control plant fertility by cell lethal gene Barnase expressing at specific developmental stage and in specific tissue of male organ under the control of Cre/loxP system, for heterosis breeding, producing hybrid seed of eggplant. The Barnase-coding region was flanked by loxP recognition sites for Cre-recombinase. The eggplant inbred/pure line ('E-38') was transformed with Cre gene and the inbred/pure line ('E-8') was transformed with the Barnase gene situated between loxp. The experiments were done separately, by means of Agrobacterium co-culture. Four T(0) -plants with the Barnase gene were obtained, all proved to be male-sterile and incapable of producing viable pollen. Flowers stamens were shorter, but the vegetative phenotype was similar to wild-type. Five T (0) -plants with the Cre gene developed well, blossomed out and set fruit normally. The crossing of male-sterile Barnase-plants with Cre expression transgenic eggplants resulted in site-specific excision with the male-sterile plants producing normal fruits. With the Barnase was excised, pollen fertility was fully restored in the hybrids. The phenotype of these restored plants was the same as that of the wild-type. Thus, the Barnase and Cre genes were capable of stable inheritance and expression in progenies of transgenic plants.

The petunia AGL6 gene has a SEPALLATA-like function in floral patterning.

PubMed

Rijpkema, Anneke S; Zethof, Jan; Gerats, Tom; Vandenbussche, Michiel

2009-10-01

SEPALLATA (SEP) MADS-box genes are required for the regulation of floral meristem determinacy and the specification of sepals, petals, stamens, carpels and ovules, specifically in angiosperms. The SEP subfamily is closely related to the AGAMOUS LIKE6 (AGL6) and SQUAMOSA (SQUA) subfamilies. So far, of these three groups only AGL6-like genes have been found in extant gymnosperms. AGL6 genes are more similar to SEP than to SQUA genes, both in sequence and in expression pattern. Despite the ancestry and wide distribution of AGL6-like MADS-box genes, not a single loss-of-function mutant exhibiting a clear phenotype has yet been reported; consequently the function of AGL6-like genes has remained elusive. Here, we characterize the Petunia hybrida AGL6 (PhAGL6, formerly called PETUNIA MADS BOX GENE4/pMADS4) gene, and show that it functions redundantly with the SEP genes FLORAL BINDING PROTEIN2 (FBP2) and FBP5 in petal and anther development. Moreover, expression analysis suggests a function for PhAGL6 in ovary and ovule development. The PhAGL6 and FBP2 proteins interact in in vitro experiments overall with the same partners, indicating that the two proteins are biochemically quite similar. It will be interesting to determine the functions of AGL6-like genes of other species, especially those of gymnosperms.

Flower, fruit phenology and flower traits in Cordia boissieri (Boraginaceae) from northeastern Mexico

PubMed Central

Martínez-Adriano, Cristian Adrian; Flores, Joel; González-Rodríguez, Humberto; Cuéllar-Rodríguez, Gerardo

2016-01-01

We characterized variations in Cordia boissieri flowers and established if these variations occur between plants or between flowering events. Flowering and fruiting was measured for 256 plants. A GLM test was used to determine the relationship between flowering and fruit set processes and rainfall. We performed measurements of floral traits to detect variations within the population and between flowering events. The position of the anthers with respect to the ovary was determined in 1,500 flowers. Three out of four flowering events of >80% C. boissieri plants occurred after rainfall events. Only one flowering event occurred in a drought. Most plants flowered at least twice a year. The overlapping of flowering and fruiting only occurred after rainfall. Anthesis lasted three-to-five days, and there were two flower morphs. Half of the plants had longistylus and half had brevistylus flowers. Anacahuita flower in our study had 1–4 styles; 2–9 stamens; 6.5–41.5 mm long corolla; sepals from 4.5–29.5 mm in length; a total length from 15.5–59 mm; a corolla diameter from 10.5–77 mm. The nectar guide had a diameter from 5–30.5 mm; 4–9 lobes; and 5 distinguishable nectar guide colors. The highest variation of phenotypic expression was observed between plants. PMID:27231656

Gladiolus hybridus ABSCISIC ACID INSENSITIVE 5 (GhABI5) is an important transcription factor in ABA signaling that can enhance Gladiolus corm dormancy and Arabidopsis seed dormancy

PubMed Central

Wu, Jian; Seng, Shanshan; Sui, Juanjuan; Vonapartis, Eliana; Luo, Xian; Gong, Benhe; Liu, Chen; Wu, Chenyu; Liu, Chao; Zhang, Fengqin; He, Junna; Yi, Mingfang

2015-01-01

The phytohormone abscisic acid (ABA) regulates plant development and is crucial for abiotic stress response. In this study, cold storage contributes to reducing endogenous ABA content, resulting in dormancy breaking of Gladiolus. The ABA inhibitor fluridone also promotes germination, suggesting that ABA is an important hormone that regulates corm dormancy. Here, we report the identification and functional characterization of the Gladiolus ABI5 homolog (GhABI5), which is a basic leucine zipper motif transcriptional factor (TF). GhABI5 is expressed in dormant vegetative organs (corm, cormel, and stolon) as well as in reproductive organs (stamen), and it is up-regulated by ABA or drought. Complementation analysis reveals that GhABI5 rescues the ABA insensitivity of abi5-3 during seed germination and induces the expression of downstream ABA response genes in Arabidopsis thaliana (EM1, EM6, and RD29B). Down-regulation of GhABI5 in dormant cormels via virus induced gene silence promotes sprouting and reduces the expression of downstream genes (GhLEA and GhRD29B). The results of this study reveal that GhABI5 regulates bud dormancy (vegetative organ) in Gladiolus in addition to its well-studied function in Arabidopsis seeds (reproductive organ). PMID:26579187

Five pectinase gene expressions highly responding to heat stress in rice floral organs revealed by RNA-seq analysis.

PubMed

Wu, Liquan; Taohua, Zhou; Gui, Wenbin; Xu, Lisen; Li, Juan; Ding, YanFeng

2015-07-31

Heat stress hurts rice, and floral organs are mostly sensitive to heat stress. We aimed to unravel molecular responses to heat stress in rice floral organs using Illumina/Solexa sequencing technology for addressing the increasing concern of globle warming. At meiophase of the pollen mother cell (pulvinus flat), the plants were stressed for 3 d at 38 C, and RNA was extracted from the stressed pistil and stamen for RNA-Seq sequencing to build the heat stress transcriptom library. A total of 7178 defferentially expressed genes (DEGs) between the normal and heat stress libraries were significant, 61% up-regulated and 39% down-regulated. The 7178 DEGs were significantly classified to 34 gene ontology (GO) categories, and 11 of the GO categories were significantly enriched. The GO:0016787 for hydrolase activity of molecular function was mostly enriched with the least probability, and included 11 DEGs named Hy1 - Hy11. Expression levels of five DEGs, Hy4 - Hy6 and Hy9 - Hy10 for starch and sucrose metablism via pectinase, increased 12 - 14 times in response to the heat stress. Further investigation of the five DEGs for pectin metabolism and association with reported heat responsive genes may help develop a molecular strategy to remedy heat damage in rice. Copyright © 2015 Elsevier Inc. All rights reserved.

Genome-Wide Identification and Expression Profiling of ATP-Binding Cassette (ABC) Transporter Gene Family in Pineapple (Ananas comosus (L.) Merr.) Reveal the Role of AcABCG38 in Pollen Development

PubMed Central

Chen, Piaojuan; Li, Yi; Zhao, Lihua; Hou, Zhimin; Yan, Maokai; Hu, Bingyan; Liu, Yanhui; Azam, Syed Muhammad; Zhang, Ziyan; Rahman, Zia ur; Liu, Liping; Qin, Yuan

2017-01-01

Pineapple (Ananas comosus L.) cultivation commonly relies on asexual reproduction which is easily impeded by many factors in agriculture production. Sexual reproduction might be a novel approach to improve the pineapple planting. However, genes controlling pineapple sexual reproduction are still remain elusive. In different organisms a conserved superfamily proteins known as ATP binding cassette (ABC) participate in various biological processes. Whereas, till today the ABC gene family has not been identified in pineapple. Here 100 ABC genes were identified in the pineapple genome and grouped into eight subfamilies (5 ABCAs, 20 ABCBs, 16 ABCCs, 2 ABCDs, one ABCEs, 5 ABCFs, 42 ABCGs and 9 ABCIs). Gene expression profiling revealed the dynamic expression pattern of ABC gene family in various tissues and different developmental stages. AcABCA5, AcABCB6, AcABCC4, AcABCC7, AcABCC9, AcABCG26, AcABCG38 and AcABCG42 exhibited preferential expression in ovule and stamen. Over-expression of AcABCG38 in the Arabidopsis double mutant abcg1-2abcg16-2 partially restored its pollen abortion defects, indicating that AcABCG38 plays important roles in pollen development. Our study on ABC gene family in pineapple provides useful information for developing sexual pineapple plantation which could be utilized to improve pineapple agricultural production. PMID:29312399

Genome-Wide Identification and Expression Profiling of ATP-Binding Cassette (ABC) Transporter Gene Family in Pineapple (Ananas comosus (L.) Merr.) Reveal the Role of AcABCG38 in Pollen Development.

PubMed

Chen, Piaojuan; Li, Yi; Zhao, Lihua; Hou, Zhimin; Yan, Maokai; Hu, Bingyan; Liu, Yanhui; Azam, Syed Muhammad; Zhang, Ziyan; Rahman, Zia Ur; Liu, Liping; Qin, Yuan

2017-01-01

Pineapple ( Ananas comosus L .) cultivation commonly relies on asexual reproduction which is easily impeded by many factors in agriculture production. Sexual reproduction might be a novel approach to improve the pineapple planting. However, genes controlling pineapple sexual reproduction are still remain elusive. In different organisms a conserved superfamily proteins known as ATP binding cassette (ABC) participate in various biological processes. Whereas, till today the ABC gene family has not been identified in pineapple. Here 100 ABC genes were identified in the pineapple genome and grouped into eight subfamilies (5 ABCAs , 20 ABCB s, 16 ABCCs , 2 ABCDs , one ABCEs , 5 ABCFs , 42 ABCGs and 9 ABCIs ). Gene expression profiling revealed the dynamic expression pattern of ABC gene family in various tissues and different developmental stages. AcABCA5, AcABCB6, AcABCC4 , AcABCC7 , AcABCC9 , AcABCG26 , AcABCG38 and AcABCG42 exhibited preferential expression in ovule and stamen. Over-expression of AcABCG38 in the Arabidopsis double mutant abcg1-2abcg16-2 partially restored its pollen abortion defects, indicating that AcABCG38 plays important roles in pollen development. Our study on ABC gene family in pineapple provides useful information for developing sexual pineapple plantation which could be utilized to improve pineapple agricultural production.

Intra-plant floral variation in Cleome viscosa L. and its possible significance in breeding system.

PubMed

Saroop, Shveta; Kaul, Veenu

2015-07-01

Cleome viscosa L., an annual rainy season weed, is cosmopolitan in distribution. Two naturally growing populations of C. viscosa from Jammu, J & K, India have been studied for floral variation at an intra-plant level and its possible role in its life cycle. Plants of both the populations bear flowers which exhibit tremendous intra-plant variation in size (large and small) and sex (hermaphrodite, staminate and pistillate). The average number of flowers per plant varied significantly and so did their structural and functional details. Greater propensity, however, was towards hermaphroditism at both plant and flower levels. The large and small sized flowers differed in their morphology and reproductive features; the former were significantly larger than the latter. Anthesis, anther dehiscence and stigma receptivity were coupled in all flower types. This functional aspect along with the structural proximity between stamens at two lengths and pistil further facilitated self-pollination. However, conspicuous floral display attracted diverse pollinator fauna (Apis dorsata, Halictus albescens, Nomia curvipes and N. elliotii) which in turn mediated cross pollination. Nevertheless, each floral type contributed towards plant's fitness in its own way. Hermaphrodite flowers exhibited both self and cross pollination and assured survival by setting fruits and seeds with the large sized counterparts more productive. All these floral variations seemed to impart flexibility to the pollination system and provide fitness over the short flowering season.

Divergence of the Floral A-Function between an Asterid and a Rosid Species[OPEN

PubMed Central

Heijmans, Klaas; Rozier, Frédérique; Zethof, Jan; Chamot, Sophy

2017-01-01

The ABC model is widely used as a genetic framework for understanding floral development and evolution. In this model, the A-function is required for the development of sepals and petals and to antagonize the C-function in the outer floral whorls. In the rosid species Arabidopsis thaliana, the AP2-type AP2 transcription factor represents a major A-function protein, but how the A-function is encoded in other species is not well understood. Here, we show that in the asterid species petunia (Petunia hybrida), AP2B/BLIND ENHANCER (BEN) confines the C-function to the inner petunia floral whorls, in parallel with the microRNA BLIND. BEN belongs to the TOE-type AP2 gene family, members of which control flowering time in Arabidopsis. In turn, we demonstrate that the petunia AP2-type REPRESSOR OF B-FUNCTION (ROB) genes repress the B-function (but not the C-function) in the first floral whorl, together with BEN. We propose a combinatorial model for patterning the B- and C-functions, leading to the homeotic conversion of sepals into petals, carpels, or stamens, depending on the genetic context. Combined with earlier results, our findings suggest that the molecular mechanisms controlling the spatial restriction of the floral organ identity genes are more diverse than the well-conserved B and C floral organ identity functions. PMID:28646074

Petal-specific subfunctionalization of an APETALA3 paralog in the Ranunculales and its implications for petal evolution.

PubMed

Sharma, Bharti; Guo, Chunce; Kong, Hongzhi; Kramer, Elena M

2011-08-01

• The petals of the lower eudicot family Ranunculaceae are thought to have been derived many times independently from stamens. However, investigation of the genetic basis of their identity has suggested an alternative hypothesis: that they share a commonly inherited petal identity program. This theory is based on the fact that an ancient paralogous lineage of APETALA3 (AP3) in the Ranunculaceae appears to have a conserved, petal-specific expression pattern. • Here, we have used a combination of approaches, including RNAi, comparative gene expression and molecular evolutionary studies, to understand the function of this petal-specific AP3 lineage. • Functional analysis of the Aquilegia locus AqAP3-3 has demonstrated that the paralog is required for petal identity with little contribution to the identity of the other floral organs. Expanded expression studies and analyses of molecular evolutionary patterns provide further evidence that orthologs of AqAP3-3 are primarily expressed in petals and are under higher purifying selection across the family than the other AP3 paralogs. • Taken together, these findings suggest that the AqAP3-3 lineage underwent progressive subfunctionalization within the order Ranunculales, ultimately yielding a specific role in petal identity that has probably been conserved, in stark contrast with the multiple independent origins predicted by botanical theories. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Effects of chemical smokes on flora and fauna under field and laboratory exposures.

PubMed

Schaeffer, D J; Novak, E W; Lower, W R; Yanders, A; Kapila, S; Wang, R

1987-06-01

Various types of obscurant smokes are used routinely in training by the U.S. Army. Because continued routine use of the smokes could be detrimental to the native flora and fauna at training sites, a preliminary biological and chemical field study of fogoil, hexachloroethane, and tank diesel smokes was conducted. Smoke plumes were sampled and chemically analyzed at distances of 15-150 m from the smoke source where Tradescantia clones 4430 and 03 and the native plant Ambrosia dumosa and the native rodent Dipodomys merriami were exposed for 30 min. In addition, Tradescantia clone 4430 was exposed to tank diesel in the laboratory at concentration levels equivalent to exposure at 15 and 50 m. Tradescantia clones were examined for mutagenic effects indicated by micronuclei induction in developing pollen and pink somatic mutations in stamen hairs. Photosynthetic perturbations were measured in Tradescantia and A. dumosa using variable fluorescence induction. Animals were examined for sister chromatid exchanges and chromosome aberrations. It was found that all of the smokes tested exerted varying degrees of physiological and mutagenic effects in one or more assay system at one or more exposure distance. The studies reported here indicate that exposed ecological systems, or at least components of these systems, are at a higher risk than are unexposed components (e.g., organisms) for several types of damage attributed to obscurant smoke exposure.

The evolutionary history of Mimosa (Leguminosae): toward a phylogeny of the sensitive plants.

PubMed

Simon, Marcelo F; Grether, Rosaura; de Queiroz, Luciano P; Särkinen, Tiina E; Dutra, Valquíria F; Hughes, Colin E

2011-07-01

Large genera provide remarkable opportunities to investigate patterns of morphological evolution and historical biogeography in plants. A molecular phylogeny of the species-rich and morphologically and ecologically diverse genus Mimosa was generated to evaluate its infrageneric classification, reconstruct the evolution of a set of morphological characters, and establish the relationships of Old World species to the rest of the genus. We used trnD-trnT plastid sequences for 259 species of Mimosa (ca. 50% of the total) to reconstruct the phylogeny of the genus. Six morphological characters (petiolar nectary, inflorescence type, number of stamens, number of petals, pollen type, and seismonasty) were optimized onto the molecular tree. Mimosa was recovered as a monophyletic clade nested within the Piptadenia group and includes the former members of Schrankia, corroborating transfer of that genus to Mimosa. Although we found good support for several infrageneric groups, only one section (Mimadenia) was recovered as monophyletic. All but one of the morphological characters analyzed showed high levels of homoplasy. High levels of geographic structure were found, with species from the same area tending to group together in the phylogeny. Old World species of Mimosa form a monophyletic clade deeply nested within New World groups, indicating recent (6-10 Ma) long-distance dispersal. Although based on a single plastid region, our results establish a preliminary phylogenetic framework for Mimosa that can be used to infer patterns of morphological evolution and relationships and which provides pointers toward a revised infrageneric classification.

Divergence of the Floral A-Function between an Asterid and a Rosid Species.

PubMed

Morel, Patrice; Heijmans, Klaas; Rozier, Frédérique; Zethof, Jan; Chamot, Sophy; Bento, Suzanne Rodrigues; Vialette-Guiraud, Aurélie; Chambrier, Pierre; Trehin, Christophe; Vandenbussche, Michiel

2017-07-01

The ABC model is widely used as a genetic framework for understanding floral development and evolution. In this model, the A-function is required for the development of sepals and petals and to antagonize the C-function in the outer floral whorls. In the rosid species Arabidopsis thaliana , the AP2-type AP2 transcription factor represents a major A-function protein, but how the A-function is encoded in other species is not well understood. Here, we show that in the asterid species petunia ( Petunia hybrida ), AP2B/BLIND ENHANCER ( BEN ) confines the C-function to the inner petunia floral whorls, in parallel with the microRNA BLIND BEN belongs to the TOE-type AP2 gene family, members of which control flowering time in Arabidopsis. In turn, we demonstrate that the petunia AP2-type REPRESSOR OF B-FUNCTION ( ROB ) genes repress the B-function (but not the C-function) in the first floral whorl, together with BEN We propose a combinatorial model for patterning the B- and C-functions, leading to the homeotic conversion of sepals into petals, carpels, or stamens, depending on the genetic context. Combined with earlier results, our findings suggest that the molecular mechanisms controlling the spatial restriction of the floral organ identity genes are more diverse than the well-conserved B and C floral organ identity functions. © 2017 American Society of Plant Biologists. All rights reserved.

Airborne soil particulates as vehicles for Salmonella contamination of tomatoes.

PubMed

Kumar, Govindaraj Dev; Williams, Robert C; Al Qublan, Hamzeh M; Sriranganathan, Nammalwar; Boyer, Renee R; Eifert, Joseph D

2017-02-21

The presence of dust is ubiquitous in the produce growing environment and its deposition on edible crops could occur. The potential of wind-distributed soil particulate to serve as a vehicle for S. Newport transfer to tomato blossoms and consequently, to fruits, was explored. Blossoms were challenged with previously autoclaved soil containing S. Newport (9.39log CFU/g) by brushing and airborne transfer. One hundred percent of blossoms brushed with S. Newport-contaminated soil tested positive for presence of the pathogen one week after contact (P<0.0001). Compressed air was used to simulate wind currents and direct soil particulates towards blossoms. Airborne soil particulates resulted in contamination of 29% of the blossoms with S. Newport one week after contact. Biophotonic imaging of blossoms post-contact with bioluminescent S. Newport-contaminated airborne soil particulates revealed transfer of the pathogen on petal, stamen and pedicel structures. Both fruits and calyxes that developed from blossoms contaminated with airborne soil particulates were positive for presence of S. Newport in both fruit (66.6%) and calyx (77.7%). Presence of S. Newport in surface-sterilized fruit and calyx tissue tested indicated internalization of the pathogen. These results show that airborne soil particulates could serve as a vehicle for Salmonella. Hence, Salmonella contaminated dust and soil particulate dispersion could contribute to pathogen contamination of fruit, indicating an omnipresent yet relatively unexplored contamination route. Copyright © 2016 Elsevier B.V. All rights reserved.

Wind of change: new insights on the ecology and evolution of pollination and mating in wind-pollinated plants.

PubMed

Friedman, Jannice; Barrett, Spencer C H

2009-06-01

The rich literature that characterizes the field of pollination biology has focused largely on animal-pollinated plants. At least 10 % of angiosperms are wind pollinated, and this mode of pollination has evolved on multiple occasions among unrelated lineages, and hence this discrepancy in research interest is surprising. Here, the evolution and functional ecology of pollination and mating in wind-pollinated plants are discussed, a theoretical framework for modelling the selection of wind pollination is outlined, and pollen capture and the occurrence of pollen limitation in diverse wind-pollinated herbs are investigated experimentally. Wind pollination may commonly evolve to provide reproductive assurance when pollinators are scarce. Evidence is presented that pollen limitation in wind-pollinated plants may not be as common as it is in animal-pollinated species. The studies of pollen capture in wind-pollinated herbs demonstrate that pollen transfer efficiency is not substantially lower than in animal-pollinated plants as is often assumed. These findings challenge the explanation that the evolution of few ovules in wind-pollinated flowers is associated with low pollen loads. Floral and inflorescence architecture is crucial to pollination and mating because of the aerodynamics of wind pollination. Evidence is provided for the importance of plant height, floral position, and stamen and stigma characteristics in promoting effective pollen dispersal and capture. Finally, it is proposed that geitonogamous selfing may alleviate pollen limitation in many wind-pollinated plants with unisexual flowers.

Ethylene responsive factor ERF110 mediates ethylene-regulated transcription of a sex determination-related orthologous gene in two Cucumis species.

PubMed

Tao, Qianyi; Niu, Huanhuan; Wang, Zhongyuan; Zhang, Wenhui; Wang, Hu; Wang, Shenhao; Zhang, Xian; Li, Zheng

2018-05-25

In plants, unisexual flowers derived from developmental sex determination form separate stamens and pistils that facilitate cross pollination. In cucumber and melon, ethylene plays a key role in sex determination. Six sex determination-related genes have been identified in ethylene biosynthesis in these Cucumis species. The interactions among these genes are thought to involve ethylene signaling; however, the underlying mechanism of regulation remains unknown. In this study, hormone treatment and qPCR assays were used to confirm expression of these sex determination-related genes in cucumber and melon is ethylene sensitive. RNA-Seq analysis subsequently helped identify the ethylene responsive factor (ERF) gene, CsERF110, related to ethylene signaling and sex determination. CsERF110 and its melon ortholog, CmERF110, shared a conserved AP2/ERF domain and showed ethylene-sensitive expression. Yeast one-hybrid and ChIP-PCR assays further indicated that CsERF110 bound to at least two sites in the promoter fragment of CsACS11, while transient transformation analysis showed that CsERF110 and CmERF110 enhance CsACS11 and CmACS11 promoter activity, respectively. Taken together, these findings suggest that CsERF110 and CmERF110 respond to ethylene signaling, mediating ethylene-regulated transcription of CsACS11 and CmACS11 in cucumber and melon, respectively. Furthermore, the mechanism involved in its regulation is thought to be conserved in these two Cucumis species.

ASYMMETRIC LEAVES1 regulates abscission zone placement in Arabidopsis flowers

PubMed Central

2014-01-01

Background The sepals, petals and stamens of Arabidopsis flowers detach via abscission zones formed at their boundaries with the underlying receptacle. The ASYMMETRIC LEAVES1 (AS1) MYB transcription factor plays a critical role in setting boundaries between newly formed leaf primordia and the shoot meristem. By repressing expression of a set of KNOTTED1-LIKE HOMEODOMAIN (KNOX) genes from developing leaf primordia, AS1 and its partner ASYMMETRIC LEAVES2 allow the patterning and differentiation of leaves to proceed. Here we show a unique role for AS1 in establishing the positions of the sepal and petal abscission zones in Arabidopsis flowers. Results In as1 mutant flowers, the sepal abscission zones are displaced into inverted V-shaped positions, leaving behind triangular stubs of tissue when the organs abscise. Movement of the petal abscission zones is also apparent. Abscission of the medial sepals is delayed in as1 flowers; loss of chlorophyll in the senescing sepals contrasts with proximal zones that remain green. AS1 has previously been shown to restrict expression of the KNOX gene, BREVIPEDICELLUS (BP), from the sepals. We show here that loss of BP activity in as1 flowers is sufficient to restore the positions of the sepal and petal abscission zones, the sepal-receptacle boundary of the medial sepals and the timing of their abscission. Conclusions Our results indicate that AS1 activity is critical for the proper placement of the floral organ abscission zones, and influences the timing of organ shedding. PMID:25038814

Chromosomal aberrations and delays in cell progression induced by x-rays in Tradescantia clone 02 meristems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geard, C.R.

1983-01-01

In root meristems of Tradescantia clone 02 (developed by Sparrow and his colleagues for mutation studies), X-rays interfere with the progression of cells through the cell cycle and induce chromosomal aberrations in a dose-dependent manner consistent with linear-quadratic kinetics. Sequential mitotic cell accumulations after irradiation indicate that sensitivity to aberration induction is probably greatest in cells from late S to early G2, with chromatid interchanges the most frequent aberration type and all aberrations consistent with initiation from the interaction between two lesions. The ratio of the coefficients in the linear (..cap alpha..) and the quadratic (..beta..) terms (..cap alpha../..beta..) ismore » equal to the dose average of specific energy produced by individual particles in the site where interaction takes place. The ratio ..cap alpha../..beta.. for chromosomal aberrations is similar to that previously found for X-ray-induced mutation in Tradescantia stamen hairs, supporting the proposal that radiation-induced mutational events are due to chromosomal aberrations with interaction distances of about 1..mu..m. Abrahamson and co-workers have noted that both ..cap alpha../..beta.. ratios appear to be related to nuclear target size and are similar for chromosomal and mutational endpoints in the same organism. These findings support this concept; however, it is apparent that any situation which diminishes yield at high doses (e.g., mitotic delay) will probably affect the ..beta.. component. 23 references, 5 figures, 2 tables.« less

Chromosomal aberrations and delays in cell progression induced by x-rays in Tradescantia clone 02 meristems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geard, C.R.

1983-01-01

In root meristems of Tradescantia clone 02 (developed by Sparrow and his colleagues for mutation studies), X-rays interfere with the progression of cells through the cell cycle and induce chromosomal aberrations in a dose-dependent manner consistent with linear-quadratic kinetics. Sequential mitotic cell accumulations after irradiation indicate that sensitivity to aberrration induction is probably greatest in cells from late S to early G2, with chromatid interchanges the most frequent aberration type and all aberrations consistent with intiation from the interaction between two lesions. The ratio of the coefficients in the linear (..cap alpha..) and the quadratic (..beta..) terms (..cap alpha../..beta..) ismore » equal to the dose average of specific energy produced by individual particles in the site where interaction takes place. The ratio ..cap alpha../..beta.. for chromosomal aberrations is similar to that previously found for X-ray-induced mutation in Tradescantia stamen hairs, supporting the proposal that radiation-induced mutational events are due to chromosomal aberrations with interaction distances of about 1 ..mu..m. Abrahmson and co-workers have noted that both ..cap alpha../..beta.. ratios appear to be related to nuclear target size and are similar for chromosomal and mutational endpoints in the same organism. These findings support this concept; however, it is apparent that any situation which diminishes yield at high doses (e.g., mitotic delay) will primarily affect the ..beta.. component, resulting in low assessments of interaction site diameters.« less

JAGGED Controls Arabidopsis Petal Growth and Shape by Interacting with a Divergent Polarity Field

PubMed Central

Sauret-Güeto, Susanna; Schiessl, Katharina; Bangham, Andrew; Sablowski, Robert; Coen, Enrico

2013-01-01

A flowering plant generates many different organs such as leaves, petals, and stamens, each with a particular function and shape. These types of organ are thought to represent variations on a common underlying developmental program. However, it is unclear how this program is modulated under different selective constraints to generate the diversity of forms observed. Here we address this problem by analysing the development of Arabidopsis petals and comparing the results to models of leaf development. We show that petal development involves a divergent polarity field with growth rates perpendicular to local polarity increasing towards the distal end of the petal. The hypothesis is supported by the observed pattern of clones induced at various stages of development and by analysis of polarity markers, which show a divergent pattern. We also show that JAGGED (JAG) has a key role in promoting distal enhancement of growth rates and influences the extent of the divergent polarity field. Furthermore, we reveal links between the polarity field and auxin function: auxin-responsive markers such as DR5 have a broader distribution along the distal petal margin, consistent with the broad distal organiser of polarity, and PETAL LOSS (PTL), which has been implicated in the control of auxin dynamics during petal initiation, is directly repressed by JAG. By comparing these results with those from studies on leaf development, we show how simple modifications of an underlying developmental system may generate distinct forms, providing flexibility for the evolution of different organ functions. PMID:23653565

An Activated Form of UFO Alters Leaf Development and Produces Ectopic Floral and Inflorescence Meristems

PubMed Central

Risseeuw, Eddy; Venglat, Prakash; Xiang, Daoquan; Komendant, Kristina; Daskalchuk, Tim; Babic, Vivijan; Crosby, William; Datla, Raju

2013-01-01

Plants are unique in their ability to continuously produce new meristems and organ primordia. In Arabidopsis, the transcription factor LEAFY (LFY) functions as a master regulator of a gene network that is important for floral meristem and organ specification. UNUSUAL FLORAL ORGANS (UFO) is a co-activator of LEAFY and is required for proper activation of APETALA3 in the floral meristem during the specification of stamens and petals. The ufo mutants display defects in other parts of the flower and the inflorescence, suggestive of additional roles. Here we show that the normal determinacy of the developing Arabidopsis leaves is affected by the expression of a gain-of-function UFO fusion protein with the VP16 transcriptional activator domain. In these lines, the rosette and cauline leaf primordia exhibit reiterated serration, and upon flowering produce ectopic meristems that develop into flowers, bract leaves and inflorescences. These striking phenotypes reveal that developing leaves maintain the competency to initiate flower and inflorescence programs. Furthermore, the gain-of-function phenotypes are dependent on LFY and the SEPALLATA (SEP) MADS-box transcription factors, indicative of their functional interactions with UFO. The findings of this study also suggest that UFO promotes the establishment of the lateral meristems and primordia in the peripheral zone of the apical and floral meristems by enhancing the activity of LFY. These novel phenotypes along with the mutant phenotypes of UFO orthologs in other plant species suggest a broader function for UFO in plants. PMID:24376756

An activated form of UFO alters leaf development and produces ectopic floral and inflorescence meristems.

PubMed

Risseeuw, Eddy; Venglat, Prakash; Xiang, Daoquan; Komendant, Kristina; Daskalchuk, Tim; Babic, Vivijan; Crosby, William; Datla, Raju

2013-01-01

Plants are unique in their ability to continuously produce new meristems and organ primordia. In Arabidopsis, the transcription factor LEAFY (LFY) functions as a master regulator of a gene network that is important for floral meristem and organ specification. UNUSUAL FLORAL ORGANS (UFO) is a co-activator of LEAFY and is required for proper activation of APETALA3 in the floral meristem during the specification of stamens and petals. The ufo mutants display defects in other parts of the flower and the inflorescence, suggestive of additional roles. Here we show that the normal determinacy of the developing Arabidopsis leaves is affected by the expression of a gain-of-function UFO fusion protein with the VP16 transcriptional activator domain. In these lines, the rosette and cauline leaf primordia exhibit reiterated serration, and upon flowering produce ectopic meristems that develop into flowers, bract leaves and inflorescences. These striking phenotypes reveal that developing leaves maintain the competency to initiate flower and inflorescence programs. Furthermore, the gain-of-function phenotypes are dependent on LFY and the SEPALLATA (SEP) MADS-box transcription factors, indicative of their functional interactions with UFO. The findings of this study also suggest that UFO promotes the establishment of the lateral meristems and primordia in the peripheral zone of the apical and floral meristems by enhancing the activity of LFY. These novel phenotypes along with the mutant phenotypes of UFO orthologs in other plant species suggest a broader function for UFO in plants.

Total variation based image deconvolution for extended depth-of-field microscopy images

NASA Astrophysics Data System (ADS)

Hausser, F.; Beckers, I.; Gierlak, M.; Kahraman, O.

2015-03-01

One approach for a detailed understanding of dynamical cellular processes during drug delivery is the use of functionalized biocompatible nanoparticles and fluorescent markers. An appropriate imaging system has to detect these moving particles so as whole cell volumes in real time with high lateral resolution in a range of a few 100 nm. In a previous study Extended depth-of-field microscopy (EDF-microscopy) has been applied to fluorescent beads and tradiscantia stamen hair cells and the concept of real-time imaging has been proved in different microscopic modes. In principle a phase retardation system like a programmable space light modulator or a static waveplate is incorporated in the light path and modulates the wavefront of light. Hence the focal ellipsoid is smeared out and images seem to be blurred in a first step. An image restoration by deconvolution using the known point-spread-function (PSF) of the optical system is necessary to achieve sharp microscopic images of an extended depth-of-field. This work is focused on the investigation and optimization of deconvolution algorithms to solve this restoration problem satisfactorily. This inverse problem is challenging due to presence of Poisson distributed noise and Gaussian noise, and since the PSF used for deconvolution exactly fits in just one plane within the object. We use non-linear Total Variation based image restoration techniques, where different types of noise can be treated properly. Various algorithms are evaluated for artificially generated 3D images as well as for fluorescence measurements of BPAE cells.

SEP-class genes in Prunus mume and their likely role in floral organ development.

PubMed

Zhou, Yuzhen; Xu, Zongda; Yong, Xue; Ahmad, Sagheer; Yang, Weiru; Cheng, Tangren; Wang, Jia; Zhang, Qixiang

2017-01-13

Flower phylogenetics and genetically controlled development have been revolutionised during the last two decades. However, some of these evolutionary aspects are still debatable. MADS-box genes are known to play essential role in specifying the floral organogenesis and differentiation in numerous model plants like Petunia hybrida, Arabidopsis thaliana and Antirrhinum majus. SEPALLATA (SEP) genes, belonging to the MADS-box gene family, are members of the ABCDE and quartet models of floral organ development and play a vital role in flower development. However, few studies of the genes in Prunus mume have yet been conducted. In this study, we cloned four PmSEPs and investigated their phylogenetic relationship with other species. Expression pattern analyses and yeast two-hybrid assays of these four genes indicated their involvement in the floral organogenesis with PmSEP4 specifically related to specification of the prolificated flowers in P. mume. It was observed that the flower meristem was specified by PmSEP1 and PmSEP4, the sepal by PmSEP1 and PmSEP4, petals by PmSEP2 and PmSEP3, stamens by PmSEP2 and PmSEP3 and pistils by PmSEP2 and PmSEP3. With the above in mind, flower development in P. mume might be due to an expression of SEP genes. Our findings can provide a foundation for further investigations of the transcriptional factors governing flower development, their molecular mechanisms and genetic basis.

Phylogeny determines flower size-dependent sex allocation at flowering in a hermaphroditic family.

PubMed

Teixido, A L; Guzmán, B; Staggemeier, V G; Valladares, F

2017-11-01

In animal-pollinated hermaphroditic plants, optimal floral allocation determines relative investment into sexes, which is ultimately dependent on flower size. Larger flowers disproportionally increase maleness whereas smaller and less rewarding flowers favour female function. Although floral traits are considered strongly conserved, phylogenetic relationships in the interspecific patterns of resource allocation to floral sex remain overlooked. We investigated these patterns in Cistaceae, a hermaphroditic family. We reconstructed phylogenetic relationships among Cistaceae species and quantified phylogenetic signal for flower size, dry mass and nutrient allocation to floral structures in 23 Mediterranean species using Blomberg's K-statistic. Lastly, phylogenetically-controlled correlational and regression analyses were applied to examine flower size-based allometry in resource allocation to floral structures. Sepals received the highest dry mass allocation, followed by petals, whereas sexual structures increased nutrient allocation. Flower size and resource allocation to floral structures, except for carpels, showed a strong phylogenetic signal. Larger-flowered species allometrically allocated more resources to maleness, by increasing allocation to corollas and stamens. Our results suggest a major role of phylogeny in determining interspecific changes in flower size and subsequent floral sex allocation. This implies that flower size balances the male-female function over the evolutionary history of Cistaceae. While allometric resource investment in maleness is inherited across species diversification, allocation to the female function seems a labile trait that varies among closely related species that have diversified into different ecological niches. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

Flexibility of resource allocation in a hermaphroditic-gynomonoecious herb through deployment of female and male resources in perfect flowers.

PubMed

Mamut, Jannathan; Xiong, Ying-Ze; Tan, Dun-Yan; Huang, Shuang-Quan

2017-03-01

It has been hypothesized that two flower types permit flexible allocation of resources to female and male functions, yet empirical evidence for the sex-allocation hypothesis remains scarce in gynomonoecious species. To characterize resource allocation to pistillate and perfect flowers and allocation of perfect flowers between gynomonoecious and hermaphroditic individuals, we examined the flexibility and whether female-biased allocation increases with plant size in the hermaphroditic-gynomonoecious herb Eremurus anisopterus . Frequency of gynomonoecious individuals, flower production, and plant size were investigated in different populations. Floral allocation was compared among the three flower types of E. anisopterus . Frequency of gynomonoecious plants varied from 2-17% in nine populations. Only larger plants produced female flowers at the bottom of racemes. Both female and perfect flower production tended to increase proportionately with plant size in gynomonoecious individuals. Female flowers did not produce less biomass than perfect flowers from hermaphroditic or gynomonoecious plants. However, both female and perfect flowers from gynomonoecious individuals had lighter stamen mass, but larger pistil mass, than perfect flowers from hermaphrodites. Although the prediction of an increase in female flower number with plant size was not observed in E. anisopterus , the flexibility of sex allocation in gynomonoecious species was confirmed in that gynomonoecious individuals had a female-biased floral allocation compared to hermaphroditic individuals. Such comparisons of gynomonoecious to hermaphroditic individuals permit us to unveil a sexual adjustment strategy: flexibility of sexual investments within plants. © 2017 Botanical Society of America.

Testing the influence of gravity on flower symmetry in five Saxifraga species.

PubMed

Koethe, Sebastian; Bloemer, Judith; Lunau, Klaus

2017-04-01

Flower symmetry is considered a species-specific trait and is categorized in asymmetry, actinomorphic symmetry, bisymmetry and zygomorphic symmetry. Here we report on the intra-individual variation of flower symmetry in the genus Saxifraga and the influence of light, gravity and intrinsic factors on the development of flower symmetry. We tested five species-Saxifraga cuneifolia, Saxifraga imparilis, Saxifraga rotundifolia, Saxifraga stolonifera and Saxifraga umbrosa-concerning six flower parameters-angles between petals, petal length, petal pigmentation, angular position of carpels, movement of stamens and (only for S. imparilis and S. stolonifera) the length of the two lower elongated petals in regard to their position towards the stem. Specimens of all species were tested on a vertical clinostat as a gravity compensator, on a horizontal clinostat as a light incidence compensator and on a stationary control. The results show that the angle of incident light has no apparent impact on flower symmetry, whereas gravity affects the angular position of petals in S. cuneifolia and S. umbrosa and the petal colouration in S. rotundifolia. In S. cuneifolia and S. umbrosa, the absence of directional gravity resulted in the development of actinomorphic flowers, whereas the corresponding control flowers were zygomorphic. The development of flowers in S. rotundifolia was not altered by this treatment. The length of the two elongated petals in S. stolonifera and S. imparilis was not affected by gravity, but rather was determined by position of the flower within the inflorescence and resulted in asymmetrical flowers.

BraLTP1, a Lipid Transfer Protein Gene Involved in Epicuticular Wax Deposition, Cell Proliferation and Flower Development in Brassica napus

PubMed Central

Liu, Fang; Xiong, Xiaojuan; Wu, Lei; Fu, Donghui; Hayward, Alice; Zeng, Xinhua; Cao, Yinglong; Wu, Yuhua; Li, Yunjing; Wu, Gang

2014-01-01

Plant non-specific lipid transfer proteins (nsLTPs) constitute large multigene families that possess complex physiological functions, many of which remain unclear. This study isolated and characterized the function of a lipid transfer protein gene, BraLTP1 from Brassica rapa, in the important oilseed crops Brassica napus. BraLTP1 encodes a predicted secretory protein, in the little known VI Class of nsLTP families. Overexpression of BnaLTP1 in B. napus caused abnormal green coloration and reduced wax deposition on leaves and detailed wax analysis revealed 17–80% reduction in various major wax components, which resulted in significant water-loss relative to wild type. BnaLTP1 overexpressing leaves exhibited morphological disfiguration and abaxially curled leaf edges, and leaf cross-sections revealed cell overproliferation that was correlated to increased cytokinin levels (tZ, tZR, iP, and iPR) in leaves and high expression of the cytokinin biosynthsis gene IPT3. BnaLTP1-overexpressing plants also displayed morphological disfiguration of flowers, with early-onset and elongated carpel development and outwardly curled stamen. This was consistent with altered expression of a a number of ABC model genes related to flower development. Together, these results suggest that BraLTP1 is a new nsLTP gene involved in wax production or deposition, with additional direct or indirect effects on cell division and flower development. PMID:25314222

Two euAGAMOUS Genes Control C-Function in Medicago truncatula

PubMed Central

Gómez-Mena, Concepción; Constantin, Gabriela D.; Wen, Jiangqi; Mysore, Kirankumar S.; Lund, Ole S.; Johansen, Elisabeth; Beltrán, José Pío; Cañas, Luis A.

2014-01-01

C-function MADS-box transcription factors belong to the AGAMOUS (AG) lineage and specify both stamen and carpel identity and floral meristem determinacy. In core eudicots, the AG lineage is further divided into two branches, the euAG and PLE lineages. Functional analyses across flowering plants strongly support the idea that duplicated AG lineage genes have different degrees of subfunctionalization of the C-function. The legume Medicago truncatula contains three C-lineage genes in its genome: two euAG genes (MtAGa and MtAGb) and one PLENA-like gene (MtSHP). This species is therefore a good experimental system to study the effects of gene duplication within the AG subfamily. We have studied the respective functions of each euAG genes in M. truncatula employing expression analyses and reverse genetic approaches. Our results show that the M. truncatula euAG- and PLENA-like genes are an example of subfunctionalization as a result of a change in expression pattern. MtAGa and MtAGb are the only genes showing a full C-function activity, concomitant with their ancestral expression profile, early in the floral meristem, and in the third and fourth floral whorls during floral development. In contrast, MtSHP expression appears late during floral development suggesting it does not contribute significantly to the C-function. Furthermore, the redundant MtAGa and MtAGb paralogs have been retained which provides the overall dosage required to specify the C-function in M. truncatula. PMID:25105497

Adaptor protein complex 2-mediated endocytosis is crucial for male reproductive organ development in Arabidopsis.

PubMed

Kim, Soo Youn; Xu, Zheng-Yi; Song, Kyungyoung; Kim, Dae Heon; Kang, Hyangju; Reichardt, Ilka; Sohn, Eun Ju; Friml, Jirí; Juergens, Gerd; Hwang, Inhwan

2013-08-01

Fertilization in flowering plants requires the temporal and spatial coordination of many developmental processes, including pollen production, anther dehiscence, ovule production, and pollen tube elongation. However, it remains elusive as to how this coordination occurs during reproduction. Here, we present evidence that endocytosis, involving heterotetrameric adaptor protein complex 2 (AP-2), plays a crucial role in fertilization. An Arabidopsis thaliana mutant ap2m displays multiple defects in pollen production and viability, as well as elongation of staminal filaments and pollen tubes, all of which are pivotal processes needed for fertilization. Of these abnormalities, the defects in elongation of staminal filaments and pollen tubes were partially rescued by exogenous auxin. Moreover, DR5rev:GFP (for green fluorescent protein) expression was greatly reduced in filaments and anthers in ap2m mutant plants. At the cellular level, ap2m mutants displayed defects in both endocytosis of N-(3-triethylammonium-propyl)-4-(4-diethylaminophenylhexatrienyl) pyridinium dibromide, a lypophilic dye used as an endocytosis marker, and polar localization of auxin-efflux carrier PIN FORMED2 (PIN2) in the stamen filaments. Moreover, these defects were phenocopied by treatment with Tyrphostin A23, an inhibitor of endocytosis. Based on these results, we propose that AP-2-dependent endocytosis plays a crucial role in coordinating the multiple developmental aspects of male reproductive organs by modulating cellular auxin level through the regulation of the amount and polarity of PINs.

Adaptor Protein Complex 2–Mediated Endocytosis Is Crucial for Male Reproductive Organ Development in Arabidopsis[W

PubMed Central

Kim, Soo Youn; Xu, Zheng-Yi; Song, Kyungyoung; Kim, Dae Heon; Kang, Hyangju; Reichardt, Ilka; Sohn, Eun Ju; Friml, Jiří; Juergens, Gerd; Hwang, Inhwan

2013-01-01

Fertilization in flowering plants requires the temporal and spatial coordination of many developmental processes, including pollen production, anther dehiscence, ovule production, and pollen tube elongation. However, it remains elusive as to how this coordination occurs during reproduction. Here, we present evidence that endocytosis, involving heterotetrameric adaptor protein complex 2 (AP-2), plays a crucial role in fertilization. An Arabidopsis thaliana mutant ap2m displays multiple defects in pollen production and viability, as well as elongation of staminal filaments and pollen tubes, all of which are pivotal processes needed for fertilization. Of these abnormalities, the defects in elongation of staminal filaments and pollen tubes were partially rescued by exogenous auxin. Moreover, DR5rev:GFP (for green fluorescent protein) expression was greatly reduced in filaments and anthers in ap2m mutant plants. At the cellular level, ap2m mutants displayed defects in both endocytosis of N-(3-triethylammonium-propyl)-4-(4-diethylaminophenylhexatrienyl) pyridinium dibromide, a lypophilic dye used as an endocytosis marker, and polar localization of auxin-efflux carrier PIN FORMED2 (PIN2) in the stamen filaments. Moreover, these defects were phenocopied by treatment with Tyrphostin A23, an inhibitor of endocytosis. Based on these results, we propose that AP-2–dependent endocytosis plays a crucial role in coordinating the multiple developmental aspects of male reproductive organs by modulating cellular auxin level through the regulation of the amount and polarity of PINs. PMID:23975898

Young inflorescence-bearing shoots with roots of Tradescantia clone BNL 4430 cultivated in nutrient solution circulating systems: an alternative to potted plants and cuttings for mutagenicity tests.

PubMed

Shima, N; Xiao, L Z; Sakuramoto, F; Ichikawa, S

1997-12-12

The use of young inflorescence-bearing shoots with roots of Tradescantia clone BNL 4430 cultivated in a nutrient solution circulating (NSC) growth chamber was tested and developed as an alternative method for using Tradescantia plants in mutagenicity testings. The NSC growth chamber was designed for our requirements, based on trial cultivations of the shoots with roots in its smaller-sized prototype. The nutrient solution used was a 1/2500 Hyponex solution. The characteristics of this clone, i.e., many new shoots constantly emerging from the basal nodes one after another and its short height favorable for early flowering, made it possible to prepare many young inflorescence-bearing shoots with roots at one time. A simplified NSC cultivation system could also be developed at a lower cost, and by using it together with the NSC growth chamber, recycling of untreated materials was established for supplying steadily enough amounts of young inflorescence-bearing shoots with roots for mutagenicity testings. Compared with traditional methods of using potted plants or cuttings, the new method exhibited more stable flower production, better stamen-hair growth and a significantly lower spontaneous (background) mutation frequency, and could produce more inflorescences per space. The use of such young inflorescence-bearing shoots with roots was therefore judged to be satisfactory to serve as a new mutagenicity test system alternating with potted plants and cuttings.

Floral traits and pollination ecology of European Arum hybrids.

PubMed

Chartier, Marion; Liagre, Suzanne; Weiss-Schneeweiss, Hanna; Kolano, Bozena; Bessière, Jean-Marie; Schönenberger, Jürg; Gibernau, Marc

2016-02-01

Hybridisation is common in plants and can affect the genetic diversity and ecology of sympatric parental populations. Hybrids may resemble the parental species in their ecology, leading to competition and/or gene introgression; alternatively, they may diverge from the parental phenotypes, possibly leading to the colonisation of new ecological niches and to speciation. Here, we describe inflorescence morphology, ploidy levels, pollinator attractive scents, and pollinator guilds of natural hybrids of Arum italicum and A. maculatum (Araceae) from a site with sympatric parental populations in southern France to determine how these traits affect the hybrid pollination ecology. Hybrids were characterised by inflorescences with a size and a number of flowers more similar to A. italicum than to A. maculatum. In most cases, hybrid stamens were purple, as in A. maculatum, and spadix appendices yellow, as in A. italicum. Hybrid floral scent was closer to that of A. italicum, but shared some compounds with A. maculatum and comprised unique compounds. Also, the pollinator guild of the hybrids was similar to that of A. italicum. Nevertheless, the hybrids attracted a high proportion of individuals of the main pollinator of A. maculatum. We discuss the effects of hybridisation in sympatric parental zones in which hybrids exhibit low levels of reproductive success, the establishment of reproductive barriers between parental species, the role of the composition of floral attractive scents in the differential attraction of pollinators and in the competition between hybrids and their parental species, and the potential of hybridisation to give rise to new independent lineages.

Conservation and divergence of plant LHP1 protein sequences and expression patterns in angiosperms and gymnosperms.

PubMed

Guan, Hexin; Zheng, Zhengui; Grey, Paris H; Li, Yuhua; Oppenheimer, David G

2011-05-01

Floral transition is a critical and strictly regulated developmental process in plants. Mutations in Arabidopsis LIKE HETEROCHROMATIN PROTEIN 1 (AtLHP1)/TERMINAL FLOWER 2 (TFL2) result in early and terminal flowers. Little is known about the gene expression, function and evolution of plant LHP1 homologs, except for Arabidopsis LHP1. In this study, the conservation and divergence of plant LHP1 protein sequences was analyzed by sequence alignments and phylogeny. LHP1 expression patterns were compared among taxa that occupy pivotal phylogenetic positions. Several relatively conserved new motifs/regions were identified among LHP1 homologs. Phylogeny of plant LHP1 proteins agreed with established angiosperm relationships. In situ hybridization unveiled conserved expression of plant LHP1 in the axillary bud/tiller, vascular bundles, developing stamens, and carpels. Unlike AtLHP1, cucumber CsLHP1-2, sugarcane SoLHP1 and maize ZmLHP1, rice OsLHP1 is not expressed in the shoot apical meristem (SAM) and the OsLHP1 transcript level is consistently low in shoots. "Unequal crossover" might have contributed to the divergence in the N-terminal and hinge region lengths of LHP1 homologs. We propose an "insertion-deletion" model for soybean (Glycine max L.) GmLHP1s evolution. Plant LHP1 homologs are more conserved than previously expected, and may favor vegetative meristem identity and primordia formation. OsLHP1 may not function in rice SAM during floral induction.

The DAL10 gene from Norway spruce (Picea abies) belongs to a potentially gymnosperm-specific subclass of MADS-box genes and is specifically active in seed cones and pollen cones.

PubMed

Carlsbecker, Annelie; Sundström, Jens; Tandre, Karolina; Englund, Marie; Kvarnheden, Anders; Johanson, Urban; Engström, Peter

2003-01-01

Transcription factors encoded by different members of the MADS-box gene family have evolved central roles in the regulation of reproductive organ development in the flowering plants, the angiosperms. Development of the stamens and carpels, the pollen- and seed-bearing organs, involves the B- and C-organ-identity MADS-box genes. B- and C-type gene orthologs with activities specifically in developing pollen- and seed-bearing organs are also present in the distantly related gymnosperms: the conifers and the gnetophytes. We now report on the characterization of DAL10, a novel MADS-box gene from the conifer Norway spruce, which unlike the B- and C-type conifer genes shows no distinct orthology relationship to any angiosperm gene or clade in phylogenetic analyses. Like the B- and C-type genes, it is active specifically in developing pollen cones and seed cones. In situ RNA localization experiments show DAL10 to be expressed in the cone axis, which carry the microsporophylls of the young pollen cone. In contrast, in the seed cone it is expressed both in the cone axis and in the bracts, which subtend the ovuliferous scales. Expression data and the phenotype of transgenic Arabidopsis plants expressing DAL10 suggest that the gene may act upstream to or in concert with the B- and C-type genes in the establishment of reproductive identity of developing cones.

Different ontogenetic processes promote dicliny in Ficus L. (Moraceae)

NASA Astrophysics Data System (ADS)

Basso-Alves, João Paulo; Pereira, Rodrigo Augusto Santinelo; Peng, Yang-Qiong; Teixeira, Simone Pádua

2014-05-01

The absence of reproductive organs in flowers may ontogenetically arise from inception or by abortion during development. Ficus L., a species-rich genus of angiosperms, is an interesting model for floral developmental studies because of the diversity of sexual systems it contains. This study compares the floral morphology of Ficus citrifolia (monoecious), Ficus religiosa (monoecious), Ficus racemosa (secondarily monoecious), and Ficus hispida (gynodioecious) across development to establish the ontogenetic pathways that result in diclinous flowers. Figs were collected at various developmental stages and were prepared for surface (scanning electron microscopy) and histological (light microscopy) analyses. Dicliny in Ficus is defined by stamen absence from inception in pistillate flowers and either pistil absence from inception (F. citrifolia, F. racemosa and F. religiosa) or by abortion (F. hispida) in staminate flowers. The perianth is formed by a single whorl of sepals, as found in other families related to Moraceae. The gynoecium is tubular during development, a condition that may be related with pseudomonomery. The staminate and neutral flowers in F. hispida develop by similar mechanisms. The diversity in the sexual systems in Ficus results from combinations of different floral morphs (dicliny), which originate from both previously established ontogenetic mechanisms (loss of reproductive organ function by abortion or from inception). These mechanisms act independently of phylogenetic proximity or mechanisms of sex system evolution in Ficus. Other aspects of floral development observed in Ficus are discussed in relation to their systematic position and reproductive biology.

Involvement of ethylene in sex expression and female flower development in watermelon (Citrullus lanatus).

PubMed

Manzano, Susana; Martínez, Cecilia; García, Juan Manuel; Megías, Zoraida; Jamilena, Manuel

2014-12-01

Although it is known that ethylene has a masculinizing effect on watermelon, the specific role of this hormone in sex expression and flower development has not been analyzed in depth. By using different approaches the present work demonstrates that ethylene regulates differentially two sex-related developmental processes: sexual expression, i.e. the earliness and the number of female flowers per plant, and the development of individual floral buds. Ethylene production in the shoot apex as well as in male, female and bisexual flowers demonstrated that the female flower requires much more ethylene than the male one to develop, and that bisexual flowers result from a decrease in ethylene production in the female floral bud. The occurrence of bisexual flowers was found to be associated with elevated temperatures in the greenhouse, concomitantly with a reduction of ethylene production in the shoot apex. External treatments with ethephon and AVG, and the use of Cucurbita rootstocks with different ethylene production and sensitivity, confirmed that, as occurs in other cucurbit species, ethylene is required to arrest the development of stamens in the female flower. Nevertheless, in watermelon ethylene inhibits the transition from male to female flowering and reduces the number of pistillate flowers per plant, which runs contrary to findings in other cucurbit species. The use of Cucurbita rootstocks with elevated ethylene production delayed the production of female flowers but reduced the number of bisexual flowers, which is associated with a reduced fruit set and altered fruit shape.

Testing the influence of gravity on flower symmetry in five Saxifraga species

NASA Astrophysics Data System (ADS)

Koethe, Sebastian; Bloemer, Judith; Lunau, Klaus

2017-04-01

Flower symmetry is considered a species-specific trait and is categorized in asymmetry, actinomorphic symmetry, bisymmetry and zygomorphic symmetry. Here we report on the intra-individual variation of flower symmetry in the genus Saxifraga and the influence of light, gravity and intrinsic factors on the development of flower symmetry. We tested five species— Saxifraga cuneifolia, Saxifraga imparilis, Saxifraga rotundifolia, Saxifraga stolonifera and Saxifraga umbrosa—concerning six flower parameters—angles between petals, petal length, petal pigmentation, angular position of carpels, movement of stamens and (only for S. imparilis and S. stolonifera) the length of the two lower elongated petals in regard to their position towards the stem. Specimens of all species were tested on a vertical clinostat as a gravity compensator, on a horizontal clinostat as a light incidence compensator and on a stationary control. The results show that the angle of incident light has no apparent impact on flower symmetry, whereas gravity affects the angular position of petals in S. cuneifolia and S. umbrosa and the petal colouration in S. rotundifolia. In S. cuneifolia and S. umbrosa, the absence of directional gravity resulted in the development of actinomorphic flowers, whereas the corresponding control flowers were zygomorphic. The development of flowers in S. rotundifolia was not altered by this treatment. The length of the two elongated petals in S. stolonifera and S. imparilis was not affected by gravity, but rather was determined by position of the flower within the inflorescence and resulted in asymmetrical flowers.

Physical Interaction of Floral Organs Controls Petal Morphogenesis in Arabidopsis1[W][OA

PubMed Central

Takeda, Seiji; Iwasaki, Akira; Matsumoto, Noritaka; Uemura, Tomohiro; Tatematsu, Kiyoshi; Okada, Kiyotaka

2013-01-01

Flowering plants bear beautiful flowers to attract pollinators. Petals are the most variable organs in flowering plants, with their color, fragrance, and shape. In Arabidopsis (Arabidopsis thaliana), petal primordia arise at a similar time to stamen primordia and elongate at later stages through the narrow space between anthers and sepals. Although many of the genes involved in regulating petal identity and primordia growth are known, the molecular mechanism for the later elongation process remains unknown. We found a mutant, folded petals1 (fop1), in which normal petal development is inhibited during their growth through the narrow space between sepals and anthers, resulting in formation of folded petals at maturation. During elongation, the fop1 petals contact the sepal surface at several sites. The conical-shaped petal epidermal cells are flattened in the fop1 mutant, as if they had been pressed from the top. Surgical or genetic removal of sepals in young buds restores the regular growth of petals, suggesting that narrow space within a bud is the cause of petal folding in the fop1 mutant. FOP1 encodes a member of the bifunctional wax ester synthase/diacylglycerol acyltransferase family, WSD11, which is expressed in elongating petals and localized to the plasma membrane. These results suggest that the FOP1/WSD11 products synthesized in the petal epidermis may act as a lubricant, enabling uninhibited growth of the petals as they extend between the sepals and the anthers. PMID:23314942

Wind of change: new insights on the ecology and evolution of pollination and mating in wind-pollinated plants

PubMed Central

Friedman, Jannice; Barrett, Spencer C. H.

2009-01-01

Background The rich literature that characterizes the field of pollination biology has focused largely on animal-pollinated plants. At least 10 % of angiosperms are wind pollinated, and this mode of pollination has evolved on multiple occasions among unrelated lineages, and hence this discrepancy in research interest is surprising. Here, the evolution and functional ecology of pollination and mating in wind-pollinated plants are discussed, a theoretical framework for modelling the selection of wind pollination is outlined, and pollen capture and the occurrence of pollen limitation in diverse wind-pollinated herbs are investigated experimentally. Scope and Conclusions Wind pollination may commonly evolve to provide reproductive assurance when pollinators are scarce. Evidence is presented that pollen limitation in wind-pollinated plants may not be as common as it is in animal-pollinated species. The studies of pollen capture in wind-pollinated herbs demonstrate that pollen transfer efficiency is not substantially lower than in animal-pollinated plants as is often assumed. These findings challenge the explanation that the evolution of few ovules in wind-pollinated flowers is associated with low pollen loads. Floral and inflorescence architecture is crucial to pollination and mating because of the aerodynamics of wind pollination. Evidence is provided for the importance of plant height, floral position, and stamen and stigma characteristics in promoting effective pollen dispersal and capture. Finally, it is proposed that geitonogamous selfing may alleviate pollen limitation in many wind-pollinated plants with unisexual flowers. PMID:19218583

Comparative transcriptomics among floral organs of the basal eudicot Eschscholzia californica as reference for floral evolutionary developmental studies

PubMed Central

2010-01-01

Background Molecular genetic studies of floral development have concentrated on several core eudicots and grasses (monocots), which have canalized floral forms. Basal eudicots possess a wider range of floral morphologies than the core eudicots and grasses and can serve as an evolutionary link between core eudicots and monocots, and provide a reference for studies of other basal angiosperms. Recent advances in genomics have enabled researchers to profile gene activities during floral development, primarily in the eudicot Arabidopsis thaliana and the monocots rice and maize. However, our understanding of floral developmental processes among the basal eudicots remains limited. Results Using a recently generated expressed sequence tag (EST) set, we have designed an oligonucleotide microarray for the basal eudicot Eschscholzia californica (California poppy). We performed microarray experiments with an interwoven-loop design in order to characterize the E. californica floral transcriptome and to identify differentially expressed genes in flower buds with pre-meiotic and meiotic cells, four floral organs at pre-anthesis stages (sepals, petals, stamens and carpels), developing fruits, and leaves. Conclusions Our results provide a foundation for comparative gene expression studies between eudicots and basal angiosperms. We identified whorl-specific gene expression patterns in E. californica and examined the floral expression of several gene families. Interestingly, most E. californica homologs of Arabidopsis genes important for flower development, except for genes encoding MADS-box transcription factors, show different expression patterns between the two species. Our comparative transcriptomics study highlights the unique evolutionary position of E. californica compared with basal angiosperms and core eudicots. PMID:20950453

Genotoxicity of leachates from a landfill using three bioassays.

PubMed

Cabrera, G L; Rodriguez, D M

1999-05-19

In the city of Queretaro, around 500 tons of solid wastes are produced everyday and are deposited in a landfill. This is the result of social and economic activities of human beings or from their normal physiological functions. As a result of rain, leachates are produced, which, if not handled and treated correctly, may pollute the underground water. Among the bioassays developed for the detection of mutagenicity in environmental pollutants, plant systems have been proven to be sensitive, cheap, and effective. The purpose of this study was to determine the presence of genotoxic agents in the leachates of the landfill of the city using three bioassays: Tradescantia-micronucleus (Trad-MCN), Tradescantia stamen hair mutations (Trad-SHM) and Allium root anaphase aberrations (AL-RAA) and make a comparison of the results in the three assays. Leachates were sampled during both the dry and rainy seasons. Plant cuttings of Tradescantia or the roots of Allium were treated by submerging them in the leachates. Three replicates of each sample were analyzed in each of the three bioassays. As expected the samples of leachates collected during the dry season showed a higher genotoxicity than those collected during the rainy season. In conclusion, there are substances present in the leachates capable of inducing genotoxicity in the plant assays. On the other hand, the plant assays showed different degrees of sensitivity: the more sensitive was the Trad-MCN bioassay and the less sensitive the Trad-SHM assay. Therefore, when analyzing environmental pollutants it is recommended to use a battery of bioassays. Copyright 1999 Elsevier Science B.V.

Genotoxicity of the extracts from the compost of the organic and the total municipal garbage using three plant bioassays.

PubMed

Cabrera, G L; Rodriguez, D M; Maruri, A B

1999-05-19

The production of compost is one of the alternatives for the disposal of non-hazardous solid wastes. Compost is used in agriculture and gardening as fertilizer. In the State of Queretaro, Mexico, there is a project to produce compost from the municipal garbage which could be used as a fertilizer. The presence of mutagenic compounds in the compost could be a major disadvantage for the selection of this alternative. For the above reason, this study was initiated as a pilot project to determine the potential mutagenic activity in the compost using three plant bioassays: Tradescantia-micronucleus (Trad-MCN), Tradescantia stamen hair mutations (Trad-SHM) and Allium root anaphase aberrations (AL-RAA). Compost was produced using both aerobic and anaerobic processes from either organic waste (from the residential area) or from the total components of the municipal garbage. Extractions from the compost were done using distilled water and organic solvents and shaking the sample for about 12 h under relatively low temperatures (15-20 degrees C). Plant cuttings of Tradescantia or the roots of Allium were treated by submerging them in the extracts. Three replicates of each sample were analyzed in each one of the three bioassays. As expected the samples of compost from the total garbage showed a higher genetoxicity than those from organic waste. In conclusion, there are some substances present in the compost capable of inducing genotoxicity in the plant assays and therefore there must be some restrictions for its use as a fertilizer. Copyright 1999 Elsevier Science B.V.

Flowering after disaster: Early Danian buckthorn (Rhamnaceae) flowers and leaves from Patagonia

PubMed Central

Gandolfo, Maria A.; Iglesias, Ari; Wilf, Peter

2017-01-01

Southern-Hemisphere terrestrial communities from the early Paleocene are poorly known, but recent work on Danian plant fossils from the Salamanca Formation in Chubut Province, Argentina are providing critical data on earliest Paleocene floras. The fossils described here come from a site in the Salamanca Formation dating to ca. 1 million years or less after the end-Cretaceous extinction event; they are the first fossil flowers reported from the Danian of South America, and possible the entire Southern Hemisphere. They are compressions and impressions in flat-laminated light gray shale, and they belong to the family Rhamnaceae (buckthorns). Flowers of Notiantha grandensis gen. et sp. nov. are pentamerous, with distinctly keeled calyx lobes projecting from the hypanthium, clawed and cucullate emarginate petals, antepetalous stamens, and a pentagonal floral disk that fills the hypanthium. Their phylogenetic position was evaluated using a molecular scaffold approach combined with morphological data. Results indicate that the flowers are most like those of extant ziziphoid Rhamnaceae. The associated leaves, assigned to Suessenia grandensis gen. et sp. nov. are simple and ovate, with serrate margins and three acrodromous basal veins. They conform to the distinctive leaves of some extant Rhamnaceae in the ziziphoid and ampelozizyphoid clades. These fossils provide the first unequivocal megafossil evidence of Rhamnaceae in the Southern Hemisphere, demonstrating that Rhamnaceae expanded beyond the tropics by the earliest Paleocene. Given previous reports of rhamnaceous pollen in the late Paleogene and Neogene of Antarctica and southern Australia, this new occurrence increases the possibility of high-latitude dispersal of this family between South America and Australia via Antarctica during the Cenozoic. PMID:28489895

Comparative Transcriptome Analysis between Gynoecious and Monoecious Plants Identifies Regulatory Networks Controlling Sex Determination in Jatropha curcas

PubMed Central

Chen, Mao-Sheng; Pan, Bang-Zhen; Fu, Qiantang; Tao, Yan-Bin; Martínez-Herrera, Jorge; Niu, Longjian; Ni, Jun; Dong, Yuling; Zhao, Mei-Li; Xu, Zeng-Fu

2017-01-01

Most germplasms of the biofuel plant Jatropha curcas are monoecious. A gynoecious genotype of J. curcas was found, whose male flowers are aborted at early stage of inflorescence development. To investigate the regulatory mechanism of transition from monoecious to gynoecious plants, a comparative transcriptome analysis between gynoecious and monoecious inflorescences were performed. A total of 3,749 genes differentially expressed in two developmental stages of inflorescences were identified. Among them, 32 genes were involved in floral development, and 70 in phytohormone biosynthesis and signaling pathways. Six genes homologous to KNOTTED1-LIKE HOMEOBOX GENE 6 (KNAT6), MYC2, SHI-RELATED SEQUENCE 5 (SRS5), SHORT VEGETATIVE PHASE (SVP), TERMINAL FLOWER 1 (TFL1), and TASSELSEED2 (TS2), which control floral development, were considered as candidate regulators that may be involved in sex differentiation in J. curcas. Abscisic acid, auxin, gibberellin, and jasmonate biosynthesis were lower, whereas cytokinin biosynthesis was higher in gynoecious than that in monoecious inflorescences. Moreover, the exogenous application of gibberellic acid (GA3) promoted perianth development in male flowers and partly prevented pistil development in female flowers to generate neutral flowers in gynoecious inflorescences. The arrest of stamen primordium at early development stage probably causes the abortion of male flowers to generate gynoecious individuals. These results suggest that some floral development genes and phytohormone signaling pathways orchestrate the process of sex determination in J. curcas. Our study provides a basic framework for the regulation networks of sex determination in J. curcas and will be helpful for elucidating the evolution of the plant reproductive system. PMID:28144243

Comparative Transcriptome Analysis between Gynoecious and Monoecious Plants Identifies Regulatory Networks Controlling Sex Determination in Jatropha curcas.

PubMed

Chen, Mao-Sheng; Pan, Bang-Zhen; Fu, Qiantang; Tao, Yan-Bin; Martínez-Herrera, Jorge; Niu, Longjian; Ni, Jun; Dong, Yuling; Zhao, Mei-Li; Xu, Zeng-Fu

2016-01-01

Most germplasms of the biofuel plant Jatropha curcas are monoecious. A gynoecious genotype of J. curcas was found, whose male flowers are aborted at early stage of inflorescence development. To investigate the regulatory mechanism of transition from monoecious to gynoecious plants, a comparative transcriptome analysis between gynoecious and monoecious inflorescences were performed. A total of 3,749 genes differentially expressed in two developmental stages of inflorescences were identified. Among them, 32 genes were involved in floral development, and 70 in phytohormone biosynthesis and signaling pathways. Six genes homologous to KNOTTED1-LIKE HOMEOBOX GENE 6 ( KNAT6 ), MYC2 , SHI-RELATED SEQUENCE 5 ( SRS5 ), SHORT VEGETATIVE PHASE ( SVP ), TERMINAL FLOWER 1 ( TFL1 ), and TASSELSEED2 ( TS2 ), which control floral development, were considered as candidate regulators that may be involved in sex differentiation in J. curcas . Abscisic acid, auxin, gibberellin, and jasmonate biosynthesis were lower, whereas cytokinin biosynthesis was higher in gynoecious than that in monoecious inflorescences. Moreover, the exogenous application of gibberellic acid (GA 3 ) promoted perianth development in male flowers and partly prevented pistil development in female flowers to generate neutral flowers in gynoecious inflorescences. The arrest of stamen primordium at early development stage probably causes the abortion of male flowers to generate gynoecious individuals. These results suggest that some floral development genes and phytohormone signaling pathways orchestrate the process of sex determination in J. curcas . Our study provides a basic framework for the regulation networks of sex determination in J. curcas and will be helpful for elucidating the evolution of the plant reproductive system.

Phylogeny of Celastraceae subfamily Hippocrateoideae inferred from morphological characters and nuclear and plastid loci.

PubMed

Coughenour, Jennifer M; Simmons, Mark P; Lombardi, Julio A; Yakobson, Kendra; Archer, Robert H

2011-05-01

The phylogeny of Celastraceae subfamily Hippocrateoideae (∼ 100 species and 19 genera in the Old and New World tropics) was inferred using morphological characters together with plastid (matK, trnL-F) and nuclear (ITS and 26S rDNA) genes. The subfamily is easily recognized by the synapomorphies of transversely flattened, deeply lobed capsules and seeds with membranous basal wings or narrow stipes together with bisexual, 5-merous flowers that generally have an extrastaminal disk and three stamens. Hippocrateoideae, like Salacioideae, are inferred to have an Old World origin. The narrow stipes of Neotropical species that are water-dispersed are inferred to be derived within the subfamily from ancestral species with wind-dispersed winged seeds. Helictonema, a monotypic genus endemic to tropical Africa, has a small, white, spongy aril that is located at the base of the seed wing and appears to be unique within Hippocrateoideae. Our inference that Helictonema is sister to the remaining members of the subfamily, considered in the context of Sarawakodendron being sister to Salacioideae, suggests that small arils and capsular fruit were primitive within both subfamilies. The aril became dramatically enlarged within Salacioideae, in which the fruits are berries, and lost entirely within Hippocrateoideae, in which the fruits are transversely flattened capsules. All five Old World taxa of Prionostemma and all eight currently recognized species within Simirestis are transferred to Pristimera, one South African variety of Pristimera is raised to species level, and all three taxa in Pristimera subgenus Trochantha are transferred to the new genus Trochantha. Copyright © 2011 Elsevier Inc. All rights reserved.

Structure-function relationships in highly modified shoots of cactaceae.

PubMed

Mauseth, James D

2006-11-01

Cacti are extremely diverse structurally and ecologically, and so modified as to be intimidating to many biologists. Yet all have the same organization as most dicots, none differs fundamentally from Arabidopsis or other model plants. This review explains cactus shoot structure, discusses relationships between structure, ecology, development and evolution, and indicates areas where research on cacti is necessary to test general theories of morphogenesis. Cactus leaves are diverse; all cacti have foliage leaves; many intermediate stages in evolutionary reduction of leaves are still present; floral shoots often have large, complex leaves whereas vegetative shoots have microscopic leaves. Spines are modified bud scales, some secrete sugar as extra-floral nectaries. Many cacti have juvenile/adult phases in which the flowering adult phase (a cephalium) differs greatly from the juvenile; in some, one side of a shoot becomes adult, all other sides continue to grow as the juvenile phase. Flowers are inverted: the exterior of a cactus 'flower' is a hollow vegetative shoot with internodes, nodes, leaves and spines, whereas floral organs occur inside, with petals physically above stamens. Many cacti have cortical bundles vascularizing the cortex, however broad it evolves to be, thus keeping surface tissues alive. Great width results in great weight of weak parenchymatous shoots, correlated with reduced branching. Reduced numbers of shoot apices is compensated by great increases in number of meristematic cells within individual SAMs. Ribs and tubercles allow shoots to swell without tearing during wet seasons. Shoot epidermis and cortex cells live and function for decades then convert to cork cambium. Many modifications permit water storage within cactus wood itself, adjacent to vessels.

Bad math in Linnaeus' Philosophia Botanica.

PubMed

Podani, János; Szilágyi, András

2016-09-01

In Philosophia Botanica (1751), Carolus Linnaeus (1707-1778) presented a calculation of the number of plant genera that may be distinguished based on his taxonomic concepts. In order to derive that number, he relied upon the organs of fructification, which represent the flower and the fruit, by selecting over 30 elements from them, and then assuming that each could vary by four dimensions. However, while Linnaeus was good in counting stamens and pistils, he and many of his followers who edited or translated Philosophia Botanica were less careful, basing their calculations of the number of possible genera on flawed assumptions, or even introducing basic arithmetic errors. Furthermore, although mathematics was quite advanced in the eighteenth century, the gap between combinatorial and botanical thinking was too deep, preventing Linnaeus to seek a reasonable solution to the problem he raised. The authors demonstrate this by a historical analysis of 15 editions of Philosophia Botanica, plus many references to it, and conclude that the desired number almost always appeared in error during the past 265 years. The German botanist J. G. Gleditsch (1714-1786) was the most successful with respect to Linnaeus' original intention. Elementary mathematics demonstrates that if Linnaeus' assumptions were taken seriously, then the possible number of genera would be astronomical. The practice he followed in Genera Plantarum (1754) shows, however, that the fructification dimensions served as a universal set for Linnaeus from which he chose only the relevant ones for describing a particular genus empirically. Based on the corrections and modifications implemented in reworked editions, we suggest an evolutionary network for the historical and modern versions or translations of Philosophia Botanica.

The miR172 target TOE3 represses AGAMOUS expression during Arabidopsis floral patterning.

PubMed

Jung, Jae-Hoon; Lee, Sangmin; Yun, Ju; Lee, Minyoung; Park, Chung-Mo

2014-02-01

microRNA172 (miR172) regulates phase transition and floral patterning in Arabidopsis by repressing targets that encode the APETALA2 (AP2) and AP2-like transcription factors. The miR172-mediated repression of the AP2 gene restricts AGAMOUS (AG) expression. In addition, most miR172 targets, including AP2, redundantly act as floral repressors, and the overexpression of the target genes causes delayed flowering. However, how miR172 targets other than AP2 regulate both of the developmental processes remains unclear. Here, we demonstrate that miR172-mediated repression of the TARGET OF EAT 3 (TOE3) gene is critical for floral patterning in Arabidopsis. Transgenic plants that overexpress a miR172-resistant TOE3 gene (rTOE3-ox) exhibit indeterminate flowers with numerous stamens and carpelloid organs, which is consistent with previous observations in transgenic plants that overexpress a miR172-resistant AP2 gene. TOE3 binds to the second intron of the AG gene. Accordingly, AG expression is significantly reduced in rTOE3-ox plants. TOE3 also interacts with AP2 in the nucleus. Given the major role of AP2 in floral patterning, miR172 likely regulates TOE3 in floral patterning, at least in part via AP2. In addition, a miR156 target SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 3 directly activates TOE3 expression, revealing a novel signaling interaction between miR156 and miR172 in floral patterning. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Expression of HtKNOT1, a class I KNOX gene, overlaps cell layers and development compartments of differentiating cells in stems and flowers of Helianthus tuberosus.

PubMed

Michelotti, V; Giorgetti, L; Geri, C; Cionini, G; Pugliesi, C; Fambrini, M

2007-10-01

In plant, post-embryonic development relies on the activities of indeterminate cell populations termed meristems, spatially clustered cell lineages, wherein a subset divides indeterminately. For correct growth, the plant must maintain a constant flow of cells through the meristem, where the input of dividing pluripotent cells offsets the output of differentiating cells. KNOTTED1-like homeobox (KNOX) genes are expressed in specific patterns in the plant meristems and play important roles in maintaining meristematic cell identity. We have analyzed the expression pattern of HtKNOT1, a class I KNOX gene of Helianthus tuberosus, in stems, inflorescence meristems, floral meristems and floral organs. HtKNOT1 is expressed in cambial cells, phloem cells and xylematic parenchyma within apical stem internodes, while in basal internodes HtKNOT1 expression was restricted to the presumptive initials and recently derived phloem cells. In the reproductive phase, HtKNOT1 mRNAs were detected in both the inflorescence and floral meristems as well within lateral organ primordia (i.e. floral bracts, petals, stamens and carpels). In more differentiated flowers, the expression of HtKNOT1 was restricted to developing ovules and pollen mother cells. HtKNOT1 may play a dual role being required to maintain the meristem initials as well as initiating differentiation and/or conferring new cell identity. In particular, it is possible that HtKNOT1 cooperates at floral level with additional factors that more specifically control floral organs and pollen development in H. tuberosus.

Expression of Selected Ginkgo biloba Heat Shock Protein Genes After Cold Treatment Could Be Induced by Other Abiotic Stress

PubMed Central

Cao, Fuliang; Cheng, Hua; Cheng, Shuiyuan; Li, Linling; Xu, Feng; Yu, Wanwen; Yuan, Honghui

2012-01-01

Heat shock proteins (HSPs) play various stress-protective roles in plants. In this study, three HSP genes were isolated from a suppression subtractive hybridization (SSH) cDNA library of Ginkgo biloba leaves treated with cold stress. Based on the molecular weight, the three genes were designated GbHSP16.8, GbHSP17 and GbHSP70. The full length of the three genes were predicted to encode three polypeptide chains containing 149 amino acids (Aa), 152 Aa, and 657 Aa, and their corresponding molecular weights were predicted as follows: 16.67 kDa, 17.39 kDa, and 71.81 kDa respectively. The three genes exhibited distinctive expression patterns in different organs or development stages. GbHSP16.8 and GbHSP70 showed high expression levels in leaves and a low level in gynoecia, GbHSP17 showed a higher transcription in stamens and lower level in fruit. This result indicates that GbHSP16.8 and GbHSP70 may play important roles in Ginkgo leaf development and photosynthesis, and GbHSP17 may play a positive role in pollen maturation. All three GbHSPs were up-regulated under cold stress, whereas extreme heat stress only caused up-regulation of GbHSP70, UV-B treatment resulted in up-regulation of GbHSP16.8 and GbHSP17, wounding treatment resulted in up-regulation of GbHSP16.8 and GbHSP70, and abscisic acid (ABA) treatment caused up-regulation of GbHSP70 primarily. PMID:22754330

The R2R3MYB VvMYBPA1 from grape reprograms the phenylpropanoid pathway in tobacco flowers.

PubMed

Passeri, Valentina; Martens, Stefan; Carvalho, Elisabete; Bianchet, Chantal; Damiani, Francesco; Paolocci, Francesco

2017-08-01

This work shows that, in tobacco, the ectopic expression of VvMYBPA1 , a grape regulator of proanthocyanidin biosynthesis, up- or down-regulates different branches of the phenylproanoid pathway, in a structure-specific fashion. Proanthocyanidins are flavonoids of paramount importance for animal and human diet. Research interest increasingly tilts towards generating crops enriched with these health-promoting compounds. Flavonoids synthesis is regulated by the MBW transcriptional complex, made of R2R3MYB, bHLH and WD40 proteins, with the MYB components liable for channeling the complex towards specific branches of the pathway. Hence, using tobacco as a model, here, we tested if the ectopic expression of the proanthocyanidin regulator VvMYBPA1 from grape induces the biosynthesis of these compounds in not-naturally committed cells. Here, we show, via targeted transcriptomic and metabolic analyses of primary transgenic lines and their progeny, that VvMYBPA1 alters the phenylpropanoid pathway in tobacco floral organs, in a structure-specific fashion. We also report that a modest VvMYBPA1 expression is sufficient to induce the expression of both proanthocyanidin-specific and early genes of the phenylpropanoid pathway. Consequently, proanthocyanidins and chlorogenic acids are induced or de novo synthetised in floral limbs, tubes and stamens. Other phenylpropanoid branches are conversely induced or depleted according to the floral structure. Our study documents a novel and distinct function of VvMYBPA1 with respect to other MYBs regulating proanthocyanidins. Present findings may have major implications in designing strategies for enriching crops with health-promoting compounds.

Transcriptome analysis of reproductive-stage Arabidopsis plants exposed gamma-ray irradiation at various doses.

PubMed

Hwang, Sun-Goo; Kim, Dong Sub; Kim, Jin-Baek; Hwang, Jung Eun; Park, Hyun Mi; Kim, Jin Hyuk; Jang, Cheol Seong

2016-08-01

Gamma rays (GR) induce significant changes in the structure and expression of genes involved in the regulation of diverse biochemical and physiological processes. Arabidopsis plants exhibit different growth and development patterns in response to exposure to GR. The effects on gene expression of different radiation doses of GR (100 and 800 Gy) administered to Arabidopsis plants were examined at the reproductive stage. We irradiated 26-day-old plants with three replications [developmental stages 5.1-6.0, according to Boyes et al. ( 2001 )] using a GR irradiator (60 Co, ca. 150 TBq capacity, Atomic Energy of Canada Limited, Ontario, Canada) at the Korea Atomic Energy Research Institute. Plants were treated with 100, 200, 300, 400, 800, 1200, 1600, or 2000 Gy, and the doses were made from varying the distance to the source. We conducted a high-throughput screening analysis and detected 883 GR-responsive genes that showed significant changes; these were involved in several putative metabolic pathways related to biotic stress. Additionally, five overrepresented cis-regulatory elements were identified in the 1-kb upstream regions of GR-responsive genes by using motif enrichment analysis. We also detected three GR-responsive genes associated with stamen development and confirmed their co-regulation with functionally interacting genes. This finding suggests that a network-based analysis is a viable approach to identify significant GR-responsive genes associated with the reproductive stage of Arabidopsis. Our results provide further insights into the complex biological systems involved in the response to different doses of GR in plants.

Cloning and Expression Analysis of a PISTILLATA Homologous Gene from Pineapple (Ananas comosus L. Merr)

PubMed Central

Lv, Ling-Ling; Duan, Jun; Xie, Jiang-Hui; Liu, Yu-Ge; Wei, Chang-Bin; Liu, Sheng-Hui; Zhang, Jian-Xia; Sun, Guang-Ming

2012-01-01

PISTILLATA (PI)-like genes are crucial regulators of flowering in angiosperms. A homologue of PI, designated as AcPI (Genbank accession number HQ717796), was isolated from pineapple cultivar Comte de Paris by reverse transcriptase polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The cDNA sequence of AcPI is 907 bp in length and contains an open reading frame of 594 bp, which encodes a protein of 197 amino acids. The molecular weight was 2.29 kDa and the isoelectric point was 9.28. The alignment showed that AcPI had a high identity with CsPIC2 (78.6%), AoPI (77.4%), OrcPI (75.7%) and HPI2 (72.4%). Quantitative real-time polymerase chain reaction (qRT-PCR) analyses in different tissues showed that the expression pattern of AcPI was different from the B-class genes in eudicots. AcPI was expressed in all the tissues investigated. The expression level was very low in fruit stems, bracts, leaves and sepals, high in petals and carpels, and moderate in apical meristems, flesh and stamens. The qRT-PCR analyses in different stages indicated that the expression of AcPI reached the highest level at 40 days after flower inducement, when the multiple fruit and floral organs were forming. It proved the important role of AcPI in floral organs and fruit development. The 35S::AcPI transgenic Arabidopsis plants flowered earlier and had more inflorescences or branches than wild type plants. PMID:22312303

Cloning and expression analysis of a PISTILLATA homologous gene from pineapple (Ananas comosus L. Merr).

PubMed

Lv, Ling-Ling; Duan, Jun; Xie, Jiang-Hui; Liu, Yu-Ge; Wei, Chang-Bin; Liu, Sheng-Hui; Zhang, Jian-Xia; Sun, Guang-Ming

2012-01-01

PISTILLATA (PI)-like genes are crucial regulators of flowering in angiosperms. A homologue of PI, designated as AcPI (Genbank accession number HQ717796), was isolated from pineapple cultivar Comte de Paris by reverse transcriptase polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The cDNA sequence of AcPI is 907 bp in length and contains an open reading frame of 594 bp, which encodes a protein of 197 amino acids. The molecular weight was 2.29 kDa and the isoelectric point was 9.28. The alignment showed that AcPI had a high identity with CsPIC2 (78.6%), AoPI (77.4%), OrcPI (75.7%) and HPI2 (72.4%). Quantitative real-time polymerase chain reaction (qRT-PCR) analyses in different tissues showed that the expression pattern of AcPI was different from the B-class genes in eudicots. AcPI was expressed in all the tissues investigated. The expression level was very low in fruit stems, bracts, leaves and sepals, high in petals and carpels, and moderate in apical meristems, flesh and stamens. The qRT-PCR analyses in different stages indicated that the expression of AcPI reached the highest level at 40 days after flower inducement, when the multiple fruit and floral organs were forming. It proved the important role of AcPI in floral organs and fruit development. The 35S::AcPI transgenic Arabidopsis plants flowered earlier and had more inflorescences or branches than wild type plants.

Why Africa matters: evolution of Old World Salvia (Lamiaceae) in Africa

PubMed Central

Will, Maria; Claßen-Bockhoff, Regine

2014-01-01

Background and Aims Salvia is the largest genus in Lamiaceae and it has recently been found to be non-monophyletic. Molecular data on Old World Salvia are largely lacking. In this study, we present data concerning Salvia in Africa. The focus is on the colonization of the continent, character evolution and the switch of pollination systems in the genus. Methods Maximum likelihood and Bayesian inference were used for phylogenetic reconstruction. Analyses were based on two nuclear markers [internal transcribed spacer (ITS) and external transcribed spacer (ETS)] and one plastid marker (rpl32-trnL). Sequence data were generated for 41 of the 62 African taxa (66 %). Mesquite was used to reconstruct ancestral character states for distribution, life form, calyx shape, stamen type and pollination syndrome. Key Results Salvia in Africa is non-monophyletic. Each of the five major regions in Africa, except Madagascar, was colonized at least twice, and floristic links between North African, south-west Asian and European species are strongly supported. The large radiation in Sub-Saharan Africa (23 species) can be traced back to dispersal from North Africa via East Africa to the Cape Region. Adaptation to bird pollination in southern Africa and Madagascar reflects parallel evolution. Conclusions The phenotypic diversity in African Salvia is associated with repeated introductions to the continent. Many important evolutionary processes, such as colonization, adaptation, parallelism and character transformation, are reflected in this comparatively small group. The data presented in this study can help to understand the evolution of Salvia sensu lato and other large genera. PMID:24966353

INCURVATA2 Encodes the Catalytic Subunit of DNA Polymerase α and Interacts with Genes Involved in Chromatin-Mediated Cellular Memory in Arabidopsis thaliana

PubMed Central

Barrero, José María; González-Bayón, Rebeca; del Pozo, Juan Carlos; Ponce, María Rosa; Micol, José Luis

2007-01-01

Cell type–specific gene expression patterns are maintained by the stable inheritance of transcriptional states through mitosis, requiring the action of multiprotein complexes that remodel chromatin structure. Genetic and molecular interactions between chromatin remodeling factors and components of the DNA replication machinery have been identified in Schizosaccharomyces pombe, indicating that some epigenetic marks are replicated simultaneously to DNA with the participation of the DNA replication complexes. This model of epigenetic inheritance might be extended to the plant kingdom, as we report here with the positional cloning and characterization of INCURVATA2 (ICU2), which encodes the putative catalytic subunit of the DNA polymerase α of Arabidopsis thaliana. The strong icu2-2 and icu2-3 insertional alleles caused fully penetrant zygotic lethality when homozygous and incompletely penetrant gametophytic lethality, probably because of loss of DNA polymerase activity. The weak icu2-1 allele carried a point mutation and caused early flowering, leaf incurvature, and homeotic transformations of sepals into carpels and of petals into stamens. Further genetic analyses indicated that ICU2 interacts with TERMINAL FLOWER2, the ortholog of HETEROCHROMATIN PROTEIN1 of animals and yeasts, and with the Polycomb group (PcG) gene CURLY LEAF. Another PcG gene, EMBRYONIC FLOWER2, was found to be epistatic to ICU2. Quantitative RT-PCR analyses indicated that a number of regulatory genes were derepressed in the icu2-1 mutant, including genes associated with flowering time, floral meristem, and floral organ identity. PMID:17873092

An Ethylene-Induced Regulatory Module Delays Flower Senescence by Regulating Cytokinin Content.

PubMed

Wu, Lin; Ma, Nan; Jia, Yangchao; Zhang, Yi; Feng, Ming; Jiang, Cai-Zhong; Ma, Chao; Gao, Junping

2017-01-01

In many plant species, including rose (Rosa hybrida), flower senescence is promoted by the gaseous hormone ethylene and inhibited by the cytokinin (CTK) class of hormones. However, the molecular mechanisms underlying these antagonistic effects are not well understood. In this study, we characterized the association between a pathogenesis-related PR-10 family gene from rose (RhPR10.1) and the hormonal regulation of flower senescence. Quantitative reverse transcription PCR analysis showed that RhPR10.1 was expressed at high levels during senescence in different floral organs, including petal, sepal, receptacle, stamen, and pistil, and that expression was induced by ethylene treatment. Silencing of RhPR10.1 expression in rose plants by virus-induced gene silencing accelerated flower senescence, which was accompanied by a higher ion leakage rate in the petals, as well as increased expression of the senescence marker gene RhSAG12 CTK content and the expression of three CTK signaling pathway genes were reduced in RhPR10.1-silenced plants, and the accelerated rate of petal senescence that was apparent in the RhPR10.1-silenced plants was restored to normal levels by CTK treatment. Finally, RhHB6, a homeodomain-Leu zipper I transcription factor, was observed to bind to the RhPR10.1 promoter, and silencing of its expression also promoted flower senescence. Our results reveal an ethylene-induced RhHB6-RhPR10.1 regulatory module that functions as a brake of ethylene-promoted senescence through increasing the CTK content. © 2017 American Society of Plant Biologists. All Rights Reserved.

Structure–Function Relationships in Highly Modified Shoots of Cactaceae

PubMed Central

MAUSETH, JAMES D.

2006-01-01

• Background and Aims Cacti are extremely diverse structurally and ecologically, and so modified as to be intimidating to many biologists. Yet all have the same organization as most dicots, none differs fundamentally from Arabidopsis or other model plants. This review explains cactus shoot structure, discusses relationships between structure, ecology, development and evolution, and indicates areas where research on cacti is necessary to test general theories of morphogenesis. • Scope Cactus leaves are diverse; all cacti have foliage leaves; many intermediate stages in evolutionary reduction of leaves are still present; floral shoots often have large, complex leaves whereas vegetative shoots have microscopic leaves. Spines are modified bud scales, some secrete sugar as extra-floral nectaries. Many cacti have juvenile/adult phases in which the flowering adult phase (a cephalium) differs greatly from the juvenile; in some, one side of a shoot becomes adult, all other sides continue to grow as the juvenile phase. Flowers are inverted: the exterior of a cactus ‘flower’ is a hollow vegetative shoot with internodes, nodes, leaves and spines, whereas floral organs occur inside, with petals physically above stamens. Many cacti have cortical bundles vascularizing the cortex, however broad it evolves to be, thus keeping surface tissues alive. Great width results in great weight of weak parenchymatous shoots, correlated with reduced branching. Reduced numbers of shoot apices is compensated by great increases in number of meristematic cells within individual SAMs. Ribs and tubercles allow shoots to swell without tearing during wet seasons. Shoot epidermis and cortex cells live and function for decades then convert to cork cambium. Many modifications permit water storage within cactus wood itself, adjacent to vessels. PMID:16820405

Wind-dragged corolla enhances self-pollination: a new mechanism of delayed self-pollination.

PubMed

Qu, Rongming; Li, Xiaojie; Luo, Yibo; Dong, Ming; Xu, Huanli; Chen, Xuan; Dafni, Amots

2007-12-01

Delayed self-pollination is a mechanism that allows animal-pollinated plants to outcross while ensuring seed production in the absence of pollinators. This study aims to explore a new mechanism of delayed self-pollination facilitated by wind-driven corolla abscission in Incarvillea sinensis var. sinensis. Floral morphology and development, and the process of delayed self-pollination were surveyed. Experiments dealing with pollinator and wind exclusion, pollination manipulations, and pollinator observations were conducted in the field. Delayed self-pollination occurs when the abscising corolla driven by wind drags the adherent epipetalous stamens, thus leading to contact of anthers with stigma in late anthesis. There is no dichogamy and self-incompatibility in this species. The significantly higher proportion of abscised corolla under natural conditions as compared with that in wind-excluding tents indicates the importance of wind in corolla abscission. When pollinators were excluded, corolla abscission significantly increased the number of pollen grains deposited on the stigma and, as a result, the fruit and seed set. Only half of the flowers in plots were visited by pollinators, and the fruit set of emasculated flowers was significantly lower than that of untreated flowers in open pollination. This species has a sensitive stigma, and its two open stigmatic lobes closed soon after being touched by a pollinator, but always reopened if no or only little pollen was deposited. This delayed self-pollination, which involved the movement of floral parts, the active participation of the wind and sensitive stigma, is quite different from that reported previously. This mechanism provides reproductive assurance for this species. The sensitive stigma contributes to ensuring seed production and reducing the interference of selfing with outcrossing. The pollination pattern, which combines actions by bees with indirect participation by wind, is also a new addition to ambophily.

A beta-galactosidase gene is expressed during mature fruit abscission of 'Valencia' orange (Citrus sinensis).

PubMed

Wu, Zhencai; Burns, Jacqueline K

2004-07-01

beta-galactosidases have been detected in a wide range of plants and are characterized by their ability to hydrolyse terminal non-reducing beta-D-galactosyl residues from beta-D-galactosides. These enzymes have been detected in a wide range of plant organs and tissues. In a search for differentially expressed genes during the abscission process in citrus, sequences encoding beta-galactosidase were identified. Three cDNA fragments of a beta-galactosidase gene were isolated from a cDNA subtraction library constructed from mature fruit abscission zones 48 h after the application of a mature fruit-specific abscission agent, 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole). Based on sequence information derived from these fragments, a full-length cDNA of 2847 nucleotides (GenBank accession number AY029198) encoding beta-galactosidase was isolated from mature fruit abscission zones by 5'- and 3'-RACE approaches. The beta-galactosidase cDNA encoded a protein of 737 amino acid residues with a calculated molecular weight of 82 kDa. The deduced protein was highly homologous to plant beta-galactosidases expressed in fruit ripening. Southern blot analysis demonstrated that at least two closely related beta-galactosidase genes were present in 'Valencia' orange. Temporal expression patterns in mature fruit abscission zones indicated beta-galactosidase mRNA was detected 48 h after treatment of CMN-pyrazole and ethephon in mature fruit abscission zones. beta-galactosidase transcripts were detected in leaf abscission zones only after ethephon application. The citrus beta-galactosidase was expressed in stamens and petals of fully opened flowers and young fruitlets. The results suggest that this beta-galactosidase may play a role during abscission as well as early growth and development processes in flowers and fruitlets.

Why Africa matters: evolution of Old World Salvia (Lamiaceae) in Africa.

PubMed

Will, Maria; Claßen-Bockhoff, Regine

2014-07-01

Salvia is the largest genus in Lamiaceae and it has recently been found to be non-monophyletic. Molecular data on Old World Salvia are largely lacking. In this study, we present data concerning Salvia in Africa. The focus is on the colonization of the continent, character evolution and the switch of pollination systems in the genus. Maximum likelihood and Bayesian inference were used for phylogenetic reconstruction. Analyses were based on two nuclear markers [internal transcribed spacer (ITS) and external transcribed spacer (ETS)] and one plastid marker (rpl32-trnL). Sequence data were generated for 41 of the 62 African taxa (66 %). Mesquite was used to reconstruct ancestral character states for distribution, life form, calyx shape, stamen type and pollination syndrome. Salvia in Africa is non-monophyletic. Each of the five major regions in Africa, except Madagascar, was colonized at least twice, and floristic links between North African, south-west Asian and European species are strongly supported. The large radiation in Sub-Saharan Africa (23 species) can be traced back to dispersal from North Africa via East Africa to the Cape Region. Adaptation to bird pollination in southern Africa and Madagascar reflects parallel evolution. The phenotypic diversity in African Salvia is associated with repeated introductions to the continent. Many important evolutionary processes, such as colonization, adaptation, parallelism and character transformation, are reflected in this comparatively small group. The data presented in this study can help to understand the evolution of Salvia sensu lato and other large genera. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Genotoxicity of soil from farmland irrigated with wastewater using three plant bioassays.

PubMed

Cabrera, G L; Rodriguez, D M

1999-05-19

Three well known plant bioassays, the Allium root chromosome aberration (AL-RAA) assay, the Tradescantia micronucleus (Trad-MCN) assay, and the Tradescantia stamen hair (Trad-SHM) mutation assay were validated in 1991 by the International Programme on Chemical Safety (IPCS) under the auspices of the World Health Organization, and the United Nations Environment Programme (UNEP). These plant bioassays have proven to be efficient tests for chemical screening and especially for in situ monitoring for genotoxicity of environmental pollutants. As a result of this validation study, standard protocols of these three plant bioassays were used by some of the 11 participating countries in the IPCS to carry on genotoxicity tests on air, water and soil as a follow up activity. In the city of Queretaro, Mexico, wastewater coming from both industrial and domestic sources and without any treatment is used to irrigate the farm crops, polluting the soil. Potentially the pollutants could reach the food chain. For the above reason, soil irrigated with wastewater was sampled and monitored for the presence of genotoxic agents using the above three bioassays. Extracts from soil samples were made using distilled water and organic solvents by shaking the sample for about 12 h under a relatively low temperature (15-20 degrees C). Plant cuttings of Tradescantia or the roots of Allium were treated by submerging them in the extracts. Three replicates of each sample were analyzed in each of the three bioassays. Extracts using DMSO, ethanol and distilled water tested positive in the three bioassays and there were no differences for the genotoxicity of the extracts with the different solvents. Copyright 1999 Elsevier Science B.V.

A novel role of BELL1-like homeobox genes, PENNYWISE and POUND-FOOLISH, in floral patterning.

PubMed

Yu, Lifeng; Patibanda, Varun; Smith, Harley M S

2009-02-01

Flowers are determinate shoots comprised of perianth and reproductive organs displayed in a whorled phyllotactic pattern. Floral organ identity genes display region-specific expression patterns in the developing flower. In Arabidopsis, floral organ identity genes are activated by LEAFY (LFY), which functions with region-specific co-regulators, UNUSUAL FLORAL ORGANS (UFO) and WUSCHEL (WUS), to up-regulate homeotic genes in specific whorls of the flower. PENNYWISE (PNY) and POUND-FOOLISH (PNF) are redundant functioning BELL1-like homeodomain proteins that are expressed in shoot and floral meristems. During flower development, PNY functions with a co-repressor complex to down-regulate the homeotic gene, AGAMOUS (AG), in the outer whorls of the flower. However, the function of PNY as well as PNF in regulating floral organ identity in the central whorls of the flower is not known. In this report, we show that combining mutations in PNY and PNF enhance the floral patterning phenotypes of weak and strong alleles of lfy, indicating that these BELL1-like homeodomain proteins play a role in the specification of petals, stamens and carpels during flower development. Expression studies show that PNY and PNF positively regulate the homeotic genes, APETALA3 and AG, in the inner whorls of the flower. Moreover, PNY and PNF function in parallel with LFY, UFO and WUS to regulate homeotic gene expression. Since PNY and PNF interact with the KNOTTED1-like homeodomain proteins, SHOOTMERISTEMLESS (STM) and KNOTTED-LIKE from ARABIDOPSIS THALIANA2 (KNAT2) that regulate floral development, we propose that PNY/PNF-STM and PNY/PNF-KNAT2 complexes function in the inner whorls to regulate flower patterning events.

The early inflorescence of Arabidopsis thaliana demonstrates positional effects in floral organ growth and meristem patterning.

PubMed

Plackett, Andrew R G; Powers, Stephen J; Phillips, Andy L; Wilson, Zoe A; Hedden, Peter; Thomas, Stephen G

2018-06-01

Linear modelling approaches detected significant gradients in organ growth and patterning across early flowers of the Arabidopsis inflorescence and uncovered evidence of new roles for gibberellin in floral development. Most flowering plants, including the genetic model Arabidopsis thaliana, produce multiple flowers in sequence from a reproductive shoot apex to form a flower spike (inflorescence). The development of individual flowers on an Arabidopsis inflorescence has typically been considered as highly stereotypical and uniform, but this assumption is contradicted by the existence of mutants with phenotypes visible in early flowers only. This phenomenon is demonstrated by mutants partially impaired in the biosynthesis of the phytohormone gibberellin (GA), in which floral organ growth is retarded in the first flowers to be produced but has recovered spontaneously by the 10th flower. We presently lack systematic data from multiple flowers across the Arabidopsis inflorescence to explain such changes. Using mutants of the GA 20-OXIDASE (GA20ox) GA biosynthesis gene family to manipulate endogenous GA levels, we investigated the dynamics of changing floral organ growth across the early Arabidopsis inflorescence (flowers 1-10). Modelling of floral organ lengths identified a significant, GA-independent gradient of increasing stamen length relative to the pistil in the wild-type inflorescence that was separable from other, GA-dependent effects. It was also found that the first flowers exhibited unstable organ patterning in contrast to later flowers and that this instability was prolonged by exogenous GA treatment. These findings indicate that the development of individual flowers is influenced by hitherto unknown factors acting across the inflorescence and also suggest novel functions for GA in floral patterning.

Functional diversification of duplicated CYC2 clade genes in regulation of inflorescence development in Gerbera hybrida (Asteraceae).

PubMed

Juntheikki-Palovaara, Inka; Tähtiharju, Sari; Lan, Tianying; Broholm, Suvi K; Rijpkema, Anneke S; Ruonala, Raili; Kale, Liga; Albert, Victor A; Teeri, Teemu H; Elomaa, Paula

2014-09-01

The complex inflorescences (capitula) of Asteraceae consist of different types of flowers. In Gerbera hybrida (gerbera), the peripheral ray flowers are bilaterally symmetrical and lack functional stamens while the central disc flowers are more radially symmetrical and hermaphroditic. Proteins of the CYC2 subclade of the CYC/TB1-like TCP domain transcription factors have been recruited several times independently for parallel evolution of bilaterally symmetrical flowers in various angiosperm plant lineages, and have also been shown to regulate flower-type identity in Asteraceae. The CYC2 subclade genes in gerbera show largely overlapping gene expression patterns. At the level of single flowers, their expression domain in petals shows a spatial shift from the dorsal pattern known so far in species with bilaterally symmetrical flowers, suggesting that this change in expression may have evolved after the origin of Asteraceae. Functional analysis indicates that GhCYC2, GhCYC3 and GhCYC4 mediate positional information at the proximal-distal axis of the inflorescence, leading to differentiation of ray flowers, but that they also regulate ray flower petal growth by affecting cell proliferation until the final size and shape of the petals is reached. Moreover, our data show functional diversification for the GhCYC5 gene. Ectopic activation of GhCYC5 increases flower density in the inflorescence, suggesting that GhCYC5 may promote the flower initiation rate during expansion of the capitulum. Our data thus indicate that modification of the ancestral network of TCP factors has, through gene duplications, led to the establishment of new expression domains and to functional diversification. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

The role of ABC genes in shaping perianth phenotype in the basal angiosperm Magnolia.

PubMed

Wróblewska, M; Dołzbłasz, A; Zagórska-Marek, B

2016-03-01

It is generally accepted that the genus Magnolia is characterised by an undifferentiated perianth, typically organised into three whorls of nearly identical tepals. In some species, however, we encountered interesting and significant perianth modifications. In Magnolia acuminata, M. liliiflora and M. stellata the perianth elements of the first whorl are visually different from the others. In M. stellata the additional, spirally arranged perianth elements are present above the first three whorls, which suggests that they have been formed within the domain of stamen primordia. In these three species, we analysed expression patterns of the key flower genes (AP1, AGL6, AP3, PI, AG) responsible for the identity of flower elements and correlated them with results of morphological and anatomical investigations. In all studied species the elements of the first whorl lacked the identity of petals (lack of AP3 and PI expression) but also that of leaves (presence of AGL6 expression), and this seems to prove their sepal character. The analysis of additional perianth elements of M. stellata, spirally arranged on the elongated floral axis, revealed overlapping and reduced activity of genes involved in specification of the identity of the perianth (AGL6) but also of generative parts (AG), even though no clear gradient of morphological changes could be observed. In conclusion, Magnolia genus is capable of forming, in some species, a perianth differentiated into a calyx (sepals) and corolla (petals). Spirally arranged, additional perianth elements of M. stellata, despite activity of AG falling basipetally, resemble petals. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

An organ-specific role for ethylene in rose petal expansion during dehydration and rehydration

PubMed Central

Liu, Daofeng; Liu, Xiaojing; Meng, Yonglu; Sun, Cuihui; Tang, Hongshu; Jiang, Yudong; Khan, Muhammad Ali; Xue, Jingqi; Ma, Nan; Gao, Junping

2013-01-01

Dehydration is a major factor resulting in huge loss from cut flowers during transportation. In the present study, dehydration inhibited petal cell expansion and resulted in irregular flowers in cut roses, mimicking ethylene-treated flowers. Among the five floral organs, dehydration substantially elevated ethylene production in the sepals, whilst rehydration caused rapid and elevated ethylene levels in the gynoecia and sepals. Among the five ethylene biosynthetic enzyme genes (RhACS1–5), expression of RhACS1 and RhACS2 was induced by dehydration and rehydration in the two floral organs. Silencing both RhACS1 and RhACS2 significantly suppressed dehydration- and rehydration-induced ethylene in the sepals and gynoecia. This weakened the inhibitory effect of dehydration on petal cell expansion. β-glucuronidase activity driven by both the RhACS1 and RhACS2 promoters was dramatically induced in the sepals, pistil, and stamens, but not in the petals of transgenic Arabidopsis. This further supports the organ-specific induction of these two genes. Among the five rose ethylene receptor genes (RhETR1–5), expression of RhETR3 was predominantly induced by dehydration and rehydration in the petals. RhETR3 silencing clearly aggravated the inhibitory effect of dehydration on petal cell expansion. However, no significant difference in the effect between RhETR3-silenced flowers and RhETR-genes-silenced flowers was observed. Furthermore, RhETR-genes silencing extensively altered the expression of 21 cell expansion-related downstream genes in response to ethylene. These results suggest that induction of ethylene biosynthesis by dehydration proceeds in an organ-specific manner, indicating that ethylene can function as a mediator in dehydration-caused inhibition of cell expansion in rose petals. PMID:23599274

Floral morphology and morphogenesis in Camptotheca (Nyssaceae), and its systematic significance.

PubMed

Gong, Jing-Zhi; Li, Qiu-Jie; Wang, Xi; Ma, Yue-Ping; Zhang, Xiao-Hui; Zhao, Liang; Chang, Zhao-Yang; Ronse De Craene, Louis

2018-03-22

Camptotheca is endemic to China and there are limited data about the breeding system and morphogenesis of the flowers. Camptotheca is thought to be related to Nyssa and Davidia in Nyssaceae, which has sometimes been included in Cornaceae. However, molecular phylogenetic studies confirmed the inclusion of Camptotheca in Nyssaceae and its exclusion from Cornaceae. The aim of this study was to reveal developmental features of the inflorescence and flowers in Camptotheca to compare with related taxa in Cornales. Inflorescences and flowers of Camptotheca acuminata at all developmental stages were collected and studied with a scanning electron microscope and stereo microscope. Camptotheca has botryoids which are composed of several capitate floral units (FUs) that are initiated acropetally. On each FU, flowers are grouped in dyads that are initiated acropetally. All floral organs are initiated centripetally. Calyx lobes are restricted to five teeth. The hypanthium, with five toothed calyx lobes, is adnate to the ovary. The five petals are free and valvate. Ten stamens are inserted in two whorls around the central depression, in which the style is immersed. Three carpels are initiated independently but the ovary is syncarpous and unilocular. The ovule is unitegmic and heterotropous. Inflorescences are functionally andromonoecious varying with the position of the FUs on the inflorescence system. Flowers on the upper FU often have robust styles and fully developed ovules. Flowers on the lower FU have undeveloped styles and aborted ovules, and the flowers on the middle FU are transitional. Camptotheca possesses several traits that unify it with Nyssa, Mastixia and Diplopanax. Inflorescence and floral characters support a close relationship with Nyssaceae and Mastixiaceae but a distant relationship with Cornus. Our results corroborate molecular inferences and support a separate family Nyssaceae.

Flower Development and Sex Determination between Male and Female Flowers in Vernicia fordii

PubMed Central

Mao, Yingji; Liu, Wenbo; Chen, Xue; Xu, Yang; Lu, Weili; Hou, Jinyan; Ni, Jun; Wang, Yuting; Wu, Lifang

2017-01-01

Vernicia fordii is a monoecious and diclinous species with male and female flowers on the same inflorescence. Low female to male flower ratio is one of the main reasons for low yield in this species. However, little is known of its floral development and sex determination. Here, according to the results of scanning electron microscopy and histological analysis, the floral development of V. fordii was divided into 12 stages and the first morphological divergence between the male and female flowers was found to occur at stage 7. The male flowers are always unisexual, but the female flowers present bisexual characteristics, with sterile stamen (staminode) restricted to pre-meiosis of mother sporogenous cells and cell death occurring at later development stages. To further elucidate the molecular mechanism underling sex determination at the divergence stage for male and female flowers, comparative transcriptome analysis was performed. In total, 56,065 unigenes were generated and 608 genes were differentially expressed between male and female flowers, among which 310 and 298 DEGs (differentially expressed genes) showed high expression levels in males and females, respectively. The transcriptome data showed that the sexual dimorphism of female flowers was affected by jasmonic acid, transcription factors, and some genes related to the floral meristem activity. Ten candidate genes showed consistent expression in the qRT-PCR validation and DEGs data. In this study, we provide developmental characterization and transcriptomic information for better understanding of the development of unisexual flowers and the regulatory networks underlying the mechanism of sex determination in V. fordii, which would be helpful in the molecular breeding of V. fordii to improve the yield output. PMID:28775735

The Quest for Molecular Regulation Underlying Unisexual Flower Development

PubMed Central

Sobral, Rómulo; Silva, Helena G.; Morais-Cecílio, Leonor; Costa, Maria M. R.

2016-01-01

The understanding of the molecular mechanisms responsible for the making of a unisexual flower has been a long-standing quest in plant biology. Plants with male and female flowers can be divided mainly into two categories: dioecious and monoecious, and both sexual systems co-exist in nature in ca of 10% of the angiosperms. The establishment of male and female traits has been extensively described in a hermaphroditic flower and requires the interplay of networks, directly and indirectly related to the floral organ identity genes including hormonal regulators, transcription factors, microRNAs, and chromatin-modifying proteins. Recent transcriptomic studies have been uncovering the molecular processes underlying the establishment of unisexual flowers and there are many parallelisms between monoecious, dioecious, and hermaphroditic individuals. Here, we review the paper entitled “Comparative transcriptomic analysis of male and female flowers of monoecious Quercus suber” published in 2014 in the Frontiers of Plant Science (volume 5 |Article 599) and discussed it in the context of recent studies with other dioecious and monoecious plants that utilized high-throughput platforms to obtain transcriptomic profiles of male and female unisexual flowers. In some unisexual flowers, the developmental programs that control organ initiation fail and male or female organs do not form, whereas in other species, organ initiation and development occur but they abort or arrest during different species-specific stages of differentiation. Therefore, a direct comparison of the pathways responsible for the establishment of unisexual flowers in different species are likely to reveal conserved modules of gene regulatory hubs involved in stamen or carpel development, as well as differences that reflect the different stages of development in which male and/or female organ arrest or loss-of-function occurs. PMID:26925078

Flower Development and Sex Determination between Male and Female Flowers in Vernicia fordii.

PubMed

Mao, Yingji; Liu, Wenbo; Chen, Xue; Xu, Yang; Lu, Weili; Hou, Jinyan; Ni, Jun; Wang, Yuting; Wu, Lifang

2017-01-01

Vernicia fordii is a monoecious and diclinous species with male and female flowers on the same inflorescence. Low female to male flower ratio is one of the main reasons for low yield in this species. However, little is known of its floral development and sex determination. Here, according to the results of scanning electron microscopy and histological analysis, the floral development of V. fordii was divided into 12 stages and the first morphological divergence between the male and female flowers was found to occur at stage 7. The male flowers are always unisexual, but the female flowers present bisexual characteristics, with sterile stamen (staminode) restricted to pre-meiosis of mother sporogenous cells and cell death occurring at later development stages. To further elucidate the molecular mechanism underling sex determination at the divergence stage for male and female flowers, comparative transcriptome analysis was performed. In total, 56,065 unigenes were generated and 608 genes were differentially expressed between male and female flowers, among which 310 and 298 DEGs (differentially expressed genes) showed high expression levels in males and females, respectively. The transcriptome data showed that the sexual dimorphism of female flowers was affected by jasmonic acid, transcription factors, and some genes related to the floral meristem activity. Ten candidate genes showed consistent expression in the qRT-PCR validation and DEGs data. In this study, we provide developmental characterization and transcriptomic information for better understanding of the development of unisexual flowers and the regulatory networks underlying the mechanism of sex determination in V. fordii , which would be helpful in the molecular breeding of V. fordii to improve the yield output.

Identification and Characterization of the MADS-Box Genes and Their Contribution to Flower Organ in Carnation (Dianthus caryophyllus L.)

PubMed Central

Zhang, Xiaoni; Wang, Qijian; Yang, Shaozong; Lin, Shengnan; Bao, Manzhu; Wu, Quanshu; Wang, Caiyun; Fu, Xiaopeng

2018-01-01

Dianthus is a large genus containing many species with high ornamental economic value. Extensive breeding strategies permitted an exploration of an improvement in the quality of cultivated carnation, particularly in flowers. However, little is known on the molecular mechanisms of flower development in carnation. Here, we report the identification and description of MADS-box genes in carnation (DcaMADS) with a focus on those involved in flower development and organ identity determination. In this study, 39 MADS-box genes were identified from the carnation genome and transcriptome by the phylogenetic analysis. These genes were categorized into four subgroups (30 MIKCc, two MIKC*, two Mα, and five Mγ). The MADS-box domain, gene structure, and conserved motif compositions of the carnation MADS genes were analysed. Meanwhile, the expression of DcaMADS genes were significantly different in stems, leaves, and flower buds. Further studies were carried out for exploring the expression of DcaMADS genes in individual flower organs, and some crucial DcaMADS genes correlated with their putative function were validated. Finally, a new expression pattern of DcaMADS genes in flower organs of carnation was provided: sepal (three class E genes and two class A genes), petal (two class B genes, two class E genes, and one SHORT VEGETATIVE PHASE (SVP)), stamen (two class B genes, two class E genes, and two class C), styles (two class E genes and two class C), and ovary (two class E genes, two class C, one AGAMOUS-LIKE 6 (AGL6), one SEEDSTICK (STK), one B sister, one SVP, and one Mα). This result proposes a model in floral organ identity of carnation and it may be helpful to further explore the molecular mechanism of flower organ identity in carnation. PMID:29617274

Identification and Characterization of the MADS-Box Genes and Their Contribution to Flower Organ in Carnation (Dianthus caryophyllus L.).

PubMed

Zhang, Xiaoni; Wang, Qijian; Yang, Shaozong; Lin, Shengnan; Bao, Manzhu; Bendahmane, Mohammed; Wu, Quanshu; Wang, Caiyun; Fu, Xiaopeng

2018-04-04

Dianthus is a large genus containing many species with high ornamental economic value. Extensive breeding strategies permitted an exploration of an improvement in the quality of cultivated carnation, particularly in flowers. However, little is known on the molecular mechanisms of flower development in carnation. Here, we report the identification and description of MADS-box genes in carnation ( DcaMADS ) with a focus on those involved in flower development and organ identity determination. In this study, 39 MADS-box genes were identified from the carnation genome and transcriptome by the phylogenetic analysis. These genes were categorized into four subgroups (30 MIKC c , two MIKC*, two Mα, and five Mγ). The MADS-box domain, gene structure, and conserved motif compositions of the carnation MADS genes were analysed. Meanwhile, the expression of DcaMADS genes were significantly different in stems, leaves, and flower buds. Further studies were carried out for exploring the expression of DcaMADS genes in individual flower organs, and some crucial DcaMADS genes correlated with their putative function were validated. Finally, a new expression pattern of DcaMADS genes in flower organs of carnation was provided: sepal (three class E genes and two class A genes), petal (two class B genes, two class E genes, and one SHORT VEGETATIVE PHASE ( SVP )), stamen (two class B genes, two class E genes, and two class C), styles (two class E genes and two class C), and ovary (two class E genes, two class C, one AGAMOUS-LIKE 6 ( AGL6 ), one SEEDSTICK ( STK ), one B sister , one SVP , and one Mα ). This result proposes a model in floral organ identity of carnation and it may be helpful to further explore the molecular mechanism of flower organ identity in carnation.

Moderate Increase of Mean Daily Temperature Adversely Affects Fruit Set of Lycopersicon esculentum by Disrupting Specific Physiological Processes in Male Reproductive Development

PubMed Central

SATO, S.; KAMIYAMA, M.; IWATA, T.; MAKITA, N.; FURUKAWA, H.; IKEDA, H.

2006-01-01

• Background and Aims Global warming is gaining significance as a threat to natural and managed ecosystems since temperature is one of the major environmental factors affecting plant productivity. Hence, the effects of moderate temperature increase on the growth and development of the tomato plant (Lycopersicon esculentum) were investigated. • Methods Plants were grown at 32/26 °C as a moderately elevated temperature stress (METS) treatment or at 28/22 °C (day/night temperatures) as a control with natural light conditions. Vegetative growth and reproductive development as well as sugar content and metabolism, proline content and translocation in the androecium were investigated. • Key Results METS did not cause a significant change in biomass, the number of flowers, or the number of pollen grains produced, but there was a significant decrease in the number of fruit set, pollen viability and the number of pollen grains released. Glucose and fructose contents in the androecium (i.e. all stamens from one flower) were generally higher in the control than METS, but sucrose was higher in METS. Coincidently, the mRNA transcript abundance of acid invertase in the androecium was decreased by METS. Proline contents in the androecium were almost the same in the control and METS, while the mRNA transcript level of proline transporter 1, which expresses specifically at the surface of microspores, was significantly decreased by METS. • Conclusions The research indicated that failure of tomato fruit set under a moderately increased temperature above optimal is due to the disruption of sugar metabolism and proline translocation during the narrow window of male reproductive development. PMID:16497700

Glandulocalyx upatoiensis, a fossil flower of Ericales (Actinidiaceae/Clethraceae) from the Late Cretaceous (Santonian) of Georgia, USA

PubMed Central

Schönenberger, Jürg; von Balthazar, Maria; Takahashi, Masamichi; Xiao, Xianghui; Crane, Peter R.; Herendeen, Patrick S.

2012-01-01

Background and Aims Ericales are a major group of extant asterid angiosperms that are well represented in the Late Cretaceous fossil record, mainly by flowers, fruits and seeds. Exceptionally well preserved fossil flowers, here described as Glandulocalyx upatoiensis gen. & sp. nov., from the Santonian of Georgia, USA, yield new detailed evidence of floral structure in one of these early members of Ericales and provide a secure basis for comparison with extant taxa. Methods The floral structure of several fossil specimens was studied by scanning electron microscopy (SEM), light microscopy of microtome thin sections and synchrotron-radiation X-ray tomographic microscopy (SRXTM). For direct comparisons with flowers of extant Ericales, selected floral features of Actinidiaceae and Clethraceae were studied with SEM. Key Results Flowers of G. upatoiensis have five sepals with quincuncial aestivation, five free petals with quincuncial aestivation, 20–28 stamens arranged in a single series, extrorse anther orientation in the bud, ventral anther attachment and a tricarpellate, syncarpous ovary with three free styles and numerous small ovules on axile, protruding-diffuse and pendant placentae. The calyx is characterized by a conspicuous indumentum of large, densely arranged, multicellular and possibly glandular trichomes. Conclusions Comparison with extant taxa provides clear evidence for a relationship with core Ericales comprised of the extant families Actinidiaceae, Roridulaceae, Sarraceniaceae, Clethraceae, Cyrillaceae and Ericaceae. Within this group, the most marked similarities are with extant Actinidiaceae and, to a lesser degree, with Clethraceae. More detailed analyses of the relationships of Glandulocalyx and other Ericales from the Late Cretaceous will require an improved understanding of the morphological features that diagnose particular extant groups defined on the basis of molecular data. PMID:22442339

Kalanchoe blossfeldiana plants expressing the Arabidopsis etr1-1 allele show reduced ethylene sensitivity.

PubMed

Sanikhani, Mohsen; Mibus, Heiko; Stummann, Bjarne M; Serek, Margrethe

2008-04-01

Transgenic Kalanchoe blossfeldiana Poelln. with reduced ethylene sensitivity in flowers was obtained by Agrobacterium tumefaciens-mediated transformation using the plasmid pBEO210 containing the mutant ethylene receptor gene etr1-1 from Arabidopsis thaliana under the control of the flower-specific fbp1-promoter from Petunia. Three ethylene-resistent T0 lines, 300, 324 and 331, were selected and analyzed for postharvest-performance and morphological characteristics. Line 324 was found to be infertile and only slightly less ethylene-sensitive than control-plants, but lines 300 and 331 had significantly increased ethylene-resistance and were fertile. These two lines were analyzed for copy-number of the etr1-1 gene by Southern blotting and were crossed with the ethylene-sensitive cultivar 'Celine' to create T1 progeny. Line 300 contains two T-DNA copies per nucleus, one of which is rearranged, and these are unlinked according to segregation data from the crossing to 'Celine' and PCR-analysis of progeny plants. For control plants all flowers were closed after 2 days at 2 microl l(-1 )ethylene, but for line 300 only 33% were closed after 10 days. Line 331 contains three T-DNA copies per nucleus and is more sensitive to ethylene than line 300. In the line 300 the etr1-1 gene was found by RT-PCR to be expressed in petals and stamens but not in carpels and sepals. Both lines 300 and 331, and their progeny, appear morphologically and physiologically identical to control plants except for the higher ethylene resistance. Line 300 and its progeny with only one T-DNA copy have very low ethylene sensitivity and may be useful in future breeding.

Characterization of the procera Tomato Mutant Shows Novel Functions of the SlDELLA Protein in the Control of Flower Morphology, Cell Division and Expansion, and the Auxin-Signaling Pathway during Fruit-Set and Development1[C][W

PubMed Central

Carrera, Esther; Ruiz-Rivero, Omar; Peres, Lazaro Eustaquio Pereira; Atares, Alejandro; Garcia-Martinez, Jose Luis

2012-01-01

procera (pro) is a tall tomato (Solanum lycopersicum) mutant carrying a point mutation in the GRAS region of the gene encoding SlDELLA, a repressor in the gibberellin (GA) signaling pathway. Consistent with the SlDELLA loss of function, pro plants display a GA-constitutive response phenotype, mimicking wild-type plants treated with GA3. The ovaries from both nonemasculated and emasculated pro flowers had very strong parthenocarpic capacity, associated with enhanced growth of preanthesis ovaries due to more and larger cells. pro parthenocarpy is facultative because seeded fruits were obtained by manual pollination. Most pro pistils had exserted stigmas, thus preventing self-pollination, similar to wild-type pistils treated with GA3 or auxins. However, Style2.1, a gene responsible for long styles in noncultivated tomato, may not control the enhanced style elongation of pro pistils, because its expression was not higher in pro styles and did not increase upon GA3 application. Interestingly, a high percentage of pro flowers had meristic alterations, with one additional petal, sepal, stamen, and carpel at each of the four whorls, respectively, thus unveiling a role of SlDELLA in flower organ development. Microarray analysis showed significant changes in the transcriptome of preanthesis pro ovaries compared with the wild type, indicating that the molecular mechanism underlying the parthenocarpic capacity of pro is complex and that it is mainly associated with changes in the expression of genes involved in GA and auxin pathways. Interestingly, it was found that GA activity modulates the expression of cell division and expansion genes and an auxin signaling gene (tomato AUXIN RESPONSE FACTOR7) during fruit-set. PMID:22942390

ULTRAPETALA1 encodes a SAND domain putative transcriptional regulator that controls shoot and floral meristem activity in Arabidopsis.

PubMed

Carles, Cristel C; Choffnes-Inada, Dan; Reville, Keira; Lertpiriyapong, Kvin; Fletcher, Jennifer C

2005-03-01

The higher-plant shoot apical meristem is a dynamic structure continuously producing cells that become incorporated into new leaves, stems and flowers. The maintenance of a constant flow of cells through the meristem depends on coordination of two antagonistic processes: self-renewal of the stem cell population and initiation of the lateral organs. This coordination is stringently controlled by gene networks that contain both positive and negative components. We have previously defined the ULTRAPETALA1 (ULT1) gene as a key negative regulator of cell accumulation in Arabidopsis shoot and floral meristems, because mutations in ULT1 cause the enlargement of inflorescence and floral meristems, the production of supernumerary flowers and floral organs, and a delay in floral meristem termination. Here, we show that ULT1 negatively regulates the size of the WUSCHEL (WUS)-expressing organizing center in inflorescence meristems. We have cloned the ULT1 gene and find that it encodes a small protein containing a B-box-like motif and a SAND domain, a DNA-binding motif previously reported only in animal transcription factors. ULT1 and its Arabidopsis paralog ULT2 define a novel small gene family in plants. ULT1 and ULT2 are expressed coordinately in embryonic shoot apical meristems, in inflorescence and floral meristems, and in developing stamens, carpels and ovules. Additionally, ULT1 is expressed in vegetative meristems and leaf primordia. ULT2 protein can compensate for mutant ULT1 protein when overexpressed in an ult1 background, indicating that the two genes may regulate a common set of targets during plant development. Downregulation of both ULT genes can lead to shoot apical meristem arrest shortly after germination, revealing a requirement for ULT activity in early development.

Conifer reproductive development involves B-type MADS-box genes with distinct and different activities in male organ primordia.

PubMed

Sundström, Jens; Engström, Peter

2002-07-01

The Norway spruce MADS-box genes DAL11, DAL12 and DAL13 are phylogenetically related to the angiosperm B-function MADS-box genes: genes that act together with A-function genes in specifying petal identity and with C-function genes in specifying stamen identity to floral organs. In this report we present evidence to suggest that the B-gene function in the specification of identity of the pollen-bearing organs has been conserved between conifers and angiosperms. Expression of DAL11 or DAL12 in transgenic Arabidopsis causes phenotypic changes which partly resemble those caused by ectopic expression of the endogenous B-genes. In similar experiments, flowers of Arabidopsis plants expressing DAL13 showed a different homeotic change in that they formed ectopic anthers in whorls one, two or four. We also demonstrate the capacity of the spruce gene products to form homodimers, and that DAL11 and DAL13 may form heterodimers with each other and with the Arabidopsis B-protein AP3, but not with PI, the second B-gene product in Arabidopsis. In situ hybridization experiments show that the conifer B-like genes are expressed specifically in developing pollen cones, but differ in both temporal and spatial distribution patterns. These results suggest that the B-function in conifers is dual and is separated into a meristem identity and an organ identity function, the latter function possibly being independent of an interaction with the C-function. Thus, even though an ancestral B-function may have acted in combination with C to specify micro- and megasporangia, the B-function has evolved differently in conifers and angiosperms.

Genomic Survey, Characterization, and Expression Profile Analysis of the SBP Genes in Pineapple (Ananas comosus L.).

PubMed

Ali, Hina; Liu, Yanhui; Azam, Syed Muhammad; Rahman, Zia Ur; Priyadarshani, S V G N; Li, Weimin; Huang, Xinyu; Hu, Bingyan; Xiong, Junjie; Ali, Umair; Qin, Yuan

2017-01-01

Gene expression is regulated by transcription factors, which play many significant developmental processes. SQUAMOSA promoter-binding proteins (SBP) perform a variety of regulatory functions in leaf, flower, and fruit development, plant architecture, and sporogenesis. 16 SBP genes were identified in pineapple and were divided into four groups on basis of phylogenetic analysis. Five paralogs in pineapple for SBP genes were identified with Ka/Ks ratio varied from 0.20 for AcSBP14 and AcSBP15 to 0.36 for AcSBP6 and AcSBP16 , respectively. 16 SBP genes were located on 12 chromosomes out of 25 pineapple chromosomes with highly conserved protein sequence structures. The isoionic points of SBP ranged from 6.05 to 9.57, while molecular weight varied from 22.7 to 121.9 kD. Expression profiles of SBP genes revealed that AcSBP7 and AcSBP15 (leaf), AcSBP13 , AcSBP12 , AcSBP8 , AcSBP16 , AcSBP9 , and AcSBP11 (sepal), AcSBP6 , AcSBP4 , and AcSBP10 (stamen), AcSBP14 , AcSBP1 , and AcSBP5 (fruit) while the rest of genes showed low expression in studied tissues. Four genes, that is, AcSBP11 , AcSBP6 , AcSBP4 , and AcSBP12 , were highly expressed at 4°C, while AcSBP16 were upregulated at 45°C. RNA-Seq was validated through qRT-PCR for some genes. Salt stress-induced expression of two genes, that is, AcSBP7 and AcSBP14 , while in drought stress, AcSBP12 and AcSBP15 were highly expressed. Our study lays a foundation for further gene function and expression studies of SBP genes in pineapple.

Genomic Survey, Characterization, and Expression Profile Analysis of the SBP Genes in Pineapple (Ananas comosus L.)

PubMed Central

Ali, Hina; Liu, Yanhui; Azam, Syed Muhammad; Rahman, Zia ur; Priyadarshani, S. V. G. N.; Li, Weimin; Huang, Xinyu; Hu, Bingyan; Xiong, Junjie; Ali, Umair

2017-01-01

Gene expression is regulated by transcription factors, which play many significant developmental processes. SQUAMOSA promoter-binding proteins (SBP) perform a variety of regulatory functions in leaf, flower, and fruit development, plant architecture, and sporogenesis. 16 SBP genes were identified in pineapple and were divided into four groups on basis of phylogenetic analysis. Five paralogs in pineapple for SBP genes were identified with Ka/Ks ratio varied from 0.20 for AcSBP14 and AcSBP15 to 0.36 for AcSBP6 and AcSBP16, respectively. 16 SBP genes were located on 12 chromosomes out of 25 pineapple chromosomes with highly conserved protein sequence structures. The isoionic points of SBP ranged from 6.05 to 9.57, while molecular weight varied from 22.7 to 121.9 kD. Expression profiles of SBP genes revealed that AcSBP7 and AcSBP15 (leaf), AcSBP13, AcSBP12, AcSBP8, AcSBP16, AcSBP9, and AcSBP11 (sepal), AcSBP6, AcSBP4, and AcSBP10 (stamen), AcSBP14, AcSBP1, and AcSBP5 (fruit) while the rest of genes showed low expression in studied tissues. Four genes, that is, AcSBP11, AcSBP6, AcSBP4, and AcSBP12, were highly expressed at 4°C, while AcSBP16 were upregulated at 45°C. RNA-Seq was validated through qRT-PCR for some genes. Salt stress-induced expression of two genes, that is, AcSBP7 and AcSBP14, while in drought stress, AcSBP12 and AcSBP15 were highly expressed. Our study lays a foundation for further gene function and expression studies of SBP genes in pineapple. PMID:29104869

The Role of Staminate Flowers in the Breeding System of Olea europaea (Oleaceae): an Andromonoecious, Wind‐pollinated Taxon

PubMed Central

CUEVAS, JULIÁN; POLITO, VITO S.

2004-01-01

• Background and Aims Andromonoecy, as a breeding system, has generated a considerable body of theory in terms of sexual selection, but extended records comparing the performance of pollen grains from staminate versus hermaphrodite flowers are still sparse. The objective in this study was to elucidate the role of staminate flowers in the andromonoecious breeding system of olive (Olea europaea). • Methods To determine the meaning of staminate flowers, an evaluation was made of resource allocation to, and phenology of, staminate and hermaphrodite flowers in the cultivar ‘Mission’, and a comparison was made of the male function between both kinds of flowers. • Key Results Dry weight of hermaphrodite flowers was 19 % greater than dry weight of staminate flowers arising in comparable positions of the panicle. This difference was mainly due to pistil and petal weight; there were no significant differences in stamen weight. There were no significant differences between staminate and hermaphrodite flowers in either amount of pollen per anther, or pollen quality as determined by pollen viability, germinability or ability to fertilize other flowers. There was no significant link between gender and time of anthesis. However, position of the flower within the panicle correlated with time of anthesis and gender. Flowers at the apex and at primary pedicels tended to be hermaphrodite and open earlier, whereas flowers arising in secondary pedicels were mainly staminate and were commonly the last to reach anthesis. • Conclusions It is proposed that the main advantage provided by production of staminate flowers in olive is to enhance male fitness by increasing pollen output at the whole plant level, although a relict function of attracting pollinators cannot be completely discarded. PMID:15037451

Transcriptome Profiling of Wheat Inflorescence Development from Spikelet Initiation to Floral Patterning Identified Stage-Specific Regulatory Genes1[OPEN

PubMed Central

Feng, Nan; Song, Gaoyuan; Guan, Jiantao; Chen, Kai; Jia, Meiling; Huang, Dehua; Wu, Jiajie; Zhang, Lichao; Kong, Xiuying; Geng, Shuaifeng

2017-01-01

Early reproductive development in cereals is crucial for final grain number per spike and hence the yield potential of the crop. To date, however, no systematic analyses of gene expression profiles during this important process have been conducted for common wheat (Triticum aestivum). Here, we studied the transcriptome profiles at four stages of early wheat reproductive development, from spikelet initiation to floral organ differentiation. K-means clustering and stage-specific transcript identification detected dynamically expressed homeologs of important transcription regulators in spikelet and floral meristems that may be involved in spikelet initiation, floret meristem specification, and floral organ patterning, as inferred from their homologs in model plants. Small RNA transcriptome sequencing discovered key microRNAs that were differentially expressed during wheat inflorescence development alongside their target genes, suggesting that miRNA-mediated regulatory mechanisms for floral development may be conserved in cereals and Arabidopsis. Our analysis was further substantiated by the functional characterization of the ARGONAUTE1d (AGO1d) gene, which was initially expressed in stamen primordia and later in the tapetum during anther maturation. In agreement with its stage-specific expression pattern, the loss of function of the predominantly expressed B homeolog of AGO1d in a tetraploid durum wheat mutant resulted in smaller anthers with more infertile pollens than the wild type and a reduced grain number per spike. Together, our work provides a first glimpse of the gene regulatory networks in wheat inflorescence development that may be pivotal for floral and grain development, highlighting potential targets for genetic manipulation to improve future wheat yields. PMID:28515146

A novel MADS-box gene subfamily with a sister-group relationship to class B floral homeotic genes.

PubMed

Becker, A; Kaufmann, K; Freialdenhoven, A; Vincent, C; Li, M-A; Saedler, H; Theissen, G

2002-02-01

Class B floral homeotic genes specify the identity of petals and stamens during the development of angiosperm flowers. Recently, putative orthologs of these genes have been identified in different gymnosperms. Together, these genes constitute a clade, termed B genes. Here we report that diverse seed plants also contain members of a hitherto unknown sister clade of the B genes, termed B(sister) (B(s)) genes. We have isolated members of the B(s) clade from the gymnosperm Gnetum gnemon, the monocotyledonous angiosperm Zea mays and the eudicots Arabidopsis thaliana and Antirrhinum majus. In addition, MADS-box genes from the basal angiosperm Asarum europaeum and the eudicot Petunia hybrida were identified as B(s) genes. Comprehensive expression studies revealed that B(s) genes are mainly transcribed in female reproductive organs (ovules and carpel walls). This is in clear contrast to the B genes, which are predominantly expressed in male reproductive organs (and in angiosperm petals). Our data suggest that the B(s) genes played an important role during the evolution of the reproductive structures in seed plants. The establishment of distinct B and B(s) gene lineages after duplication of an ancestral gene may have accompanied the evolution of male microsporophylls and female megasporophylls 400-300 million years ago. During flower evolution, expression of B(s) genes diversified, but the focus of expression remained in female reproductive organs. Our findings imply that a clade of highly conserved close relatives of class B floral homeotic genes has been completely overlooked until recently and awaits further evaluation of its developmental and evolutionary importance. Electronic supplementary material to this paper can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00438-001-0615-8.

Morphology of Nectaries and Biology of Nectar Production in the Distylous Species Fagopyrum esculentum

PubMed Central

Cawoy, Valerie; Kinet, Jean-Marie; Jacquemart, Anne-Laure

2008-01-01

Background and Aims The mechanisms of floral nectar production in buckwheat (Fagopyrum esculentum, Polygonaceae), a distylous pseudo-cereal, have received relatively little attention, prompting an investigation of the factors that regulate this process. The aim was to perform a refined study of the structures that secrete nectar and of the internal and external parameters influencing nectar volumes and sugar concentrations. Methods In order to control environmental parameters, plants were cultivated in growth rooms under controlled conditions. The structure of nectaries was studied based on histological sections from flowers and flower buds. Nectar was extracted using glass micropipettes and the sugar concentration was measured with a hand refractometer. Sugar concentration in the phloem sap was measured using the anthrone method. To test the influence of photosynthesis on nectar production, different light and defoliation treatments were applied. Key Results Unicellular trichomes were located in the epidermis at the ventral part of eight nectary glands situated on the flower receptacle alternately with stamens. Vascular bundles consisting of both phloem and xylem were identified at the boundary between a multilayered nectary parenchyma and a sub-nectary parenchyma with chloroplasts. A higher volume of nectar in thrum morphs was observed. No other difference was found in morphology or in sugar supply to inflorescences between morphs. Nectar secretion was strongly influenced by plant age and inflorescence position. Nectar volumes were higher in the upper inflorescences and during the flowering peak. Light had a dual role, (1) acting directly on reproductive structures to trigger flower opening, which conditions nectar secretion, and (2) stimulating photosynthetic activity, which regulates nectar accumulation in open flowers. Conclusions In buckwheat, nectar is secreted by trichomes and probably proceeds, at least in part, from phloem sap. Nectar secretion is strongly influenced by floral morph type, plant age, inflorescence position and light. PMID:18765442

Generation and characterization of tribenuron-methyl herbicide-resistant rapeseed (Brasscia napus) for hybrid seed production using chemically induced male sterility.

PubMed

Li, Haitao; Li, Juanjuan; Zhao, Bo; Wang, Jing; Yi, Licong; Liu, Chao; Wu, Jiangsheng; King, Graham J; Liu, Kede

2015-01-01

Identification and molecular analysis of four tribenuron-methyl resistant mutants in Brassica napus , which would be very useful in hybrid production using a Chemically induced male sterility system. Chemically induced male sterility (CIMS) systems dependent on chemical hybridization agents (CHAs) like tribenuron-methyl (TBM) represent an important approach for practical utilization of heterosis in rapeseed. However, when spraying the female parents with TBM to induce male sterility the male parents must be protected with a shield to avoid injury to the stamens, which would otherwise complicate the seed production protocol and increase the cost of hybrid seed production. Here we report the first proposed application of a herbicide-resistant cultivar in hybrid production, using a CIMS system based on identifying four TBM-resistant mutants in Brassica napus. Genetic analysis indicated that the TBM resistance was controlled by a single dominant nuclear gene. An in vitro enzyme activity assay for acetohydroxyacid synthase (AHAS) suggested that the herbicide resistance is caused by a gain-of-function mutation in a copy of AHAS genes. Comparative sequencing of the mutants and wild type BnaA.AHAS.a coding sequences identified a C-to-T transition at either position 535 or 536 from the translation start site, which resulted in a substitution of proline with serine or leucine at position 197 according to the Arabidopsis thaliana protein sequence. An allele-specific dCAPS marker developed from the C536T variation co-segregated with the herbicide resistance. Transgenic A. thaliana plants expressing BnaA.ahas3.a conferred herbicide resistance, which confirmed that the P197 substitution in BnaA.AHAS.a was responsible for the herbicide resistance. Moreover, the TBM-resistant lines maintain normal male fertility under TBM treatment and can be of practical value in hybrid seed production using CIMS.

Divergent Functions of orthologous NAC Transcription Factors in Wheat and Rice

PubMed Central

Distelfeld, Assaf; Pearce, Stephen P.; Avni, Raz; Scherer, Beatrice; Uauy, Cristobal; Piston, Fernando; Slade, Ann; Zhao, Rongrong; Dubcovsky, Jorge

2016-01-01

The wheat GPC-B1 gene located on chromosome 6B is an early regulator of senescence and affects remobilization of protein and minerals to the grain. GPC-B1 is a NAC transcription factor and has a paralogous copy on chromosome 2B in tetraploid wheat, GPC-B2. The closest rice homolog to both wheat GPC genes is Os07g37920 which is located on rice chromosome 2 and is colinear with GPC-B2. Since rice is a diploid species with a sequenced genome, we initiated the study of Os07g37920 to develop a simpler model to study senescence and mineral remobilization in cereals. We developed eleven independent RNA interference transgenic rice lines (Os07g37920-RNAi) and 10 over-expressing transgenic lines (Os07g37920-OE), but none of them showed differences in senescence. Transgenic Os07g37920-RNAi rice plants had reduced proportions of viable pollen grains and were male-sterile, but were able to produce seeds by cross pollination. Analysis of the flower morphology of the transgenic rice plants showed that anthers failed to dehisce. Transgenic Os07g37920-OE lines showed no sterility or anther dehiscence problems. Os07g37920 transcript levels were higher in stamens compared to leaves and significantly reduced in the transgenic Os07g37920-RNAi plants. Wheat GPC genes showed the opposite transcription profile (higher transcript levels in leaves than in flowers) and plants carrying knock-out mutations of all GPC-1 and GPC-2 genes exhibited delayed senescence but normal anther dehiscence and fertility. These results indicate a functional divergence of the homologous wheat and rice NAC genes and suggest the need for separate studies of the function and targets of these transcription factors in wheat and rice. PMID:22278768

Flower development and sex specification in wild grapevine.

PubMed

Ramos, Miguel Jesus Nunes; Coito, João Lucas; Silva, Helena Gomes; Cunha, Jorge; Costa, Maria Manuela Ribeiro; Rocheta, Margarida

2014-12-12

Wild plants of Vitis closely related to the cultivated grapevine (V. v. vinifera) are believed to have been first domesticated 10,000 years BC around the Caspian Sea. V. v. vinifera is hermaphrodite whereas V. v. sylvestris is a dioecious species. Male flowers show a reduced pistil without style or stigma and female flowers present reflexed stamens with infertile pollen. V. vinifera produce perfect flowers with all functional structures. The mechanism for flower sex determination and specification in grapevine is still unknown. To understand which genes are involved during the establishment of male, female and complete flowers, we analysed and compared the transcription profiles of four developmental stages of the three genders. We showed that sex determination is a late event during flower development and that the expression of genes from the ABCDE model is not directly correlated with the establishment of sexual dimorphism. We propose a temporal comprehensive model in which two mutations in two linked genes could be players in sex determination and indirectly establish the Vitis domestication process. Additionally, we also found clusters of genes differentially expressed between genders and between developmental stages that suggest a role involved in sex differentiation. Also, the detection of differentially transcribed regions that extended existing gene models (intergenic regions) between sexes suggests that they may account for some of the variation between the subspecies. There is no evidence of differences of expression levels in genes from the ABCDE model that could explain the shift from hermaphroditism to dioecy. We propose that sex specification occurs after floral organ identity has been established and therefore, sex determination genes might be having an effect downstream of the ABCDE model genes.For the first time a full transcriptomic analysis was performed in different flower developmental stages in the same individual. Our experimental approach enabled us to create a comprehensive catalogue of transcribed genes across developmental stages and genders that will contribute for future work in sex determination in seed plants.

From forgotten taxon to a missing link? The position of the genus Verhuellia (piperaceae) revealed by molecules.

PubMed

Wanke, S; Vanderschaeve, L; Mathieu, G; Neinhuis, C; Goetghebeur, P; Samain, M S

2007-06-01

The species-poor and little-studied genus Verhuellia has often been treated as a synonym of the genus Peperomia, downplaying its significance in the relationships and evolutionary aspects in Piperaceae and Piperales. The lack of knowledge concerning Verhuellia is largely due to its restricted distribution, poorly known collection localities, limited availability in herbaria and absence in botanical gardens and lack of material suitable for molecular phylogenetic studies until recently. Because Verhuellia has some of the most reduced flowers in Piperales, the reconstruction of floral evolution which shows strong trends towards reduction in all lineages needs to be revised. Verhuellia is included in a molecular phylogenetic analysis of Piperales (trnT-trnL-trnF and trnK/matK), based on nearly 6000 aligned characters and more than 1400 potentially parsimony-informative sites which were partly generated for the present study. Character states for stamen and carpel number are mapped on the combined molecular tree to reconstruct the ancestral states. The genus Peperomia is generally considered to have the most reduced flowers in Piperales but this study shows that this is only partially true. Verhuellia, with almost equally reduced flowers, is not part of or sister to Peperomia as expected, but is revealed as sister to all other Piperaceae in all analyses, putting character evolution in this family and in the perianthless Piperales in a different light. A robust phylogenetic analysis including all relevant taxa is presented as a framework for inferring patterns and processes of evolution in Piperales and Piperaceae. Verhuellia is a further example of how a molecular phylogenetic study can elucidate the relationships of an unplaced taxon. When more material becomes available, it will be possible to investigate character evolution in Piperales more thoroughly and to answer some evolutionary questions concerning Piperaceae.

Relationship between the species-representative phenotype and intraspecific variation in Ranunculaceae floral organ and Asteraceae flower numbers.

PubMed

Kitazawa, Miho S; Fujimoto, Koichi

2016-04-01

Phenotypic variation in floral morphologies contributes to speciation by testing various morphologies that might have higher adaptivity, leading eventually to phylogenetic diversity. Species diversity has been recognized, however, by modal morphologies where the variation is averaged out, so little is known about the relationship between the variation and the diversity. We analysed quantitatively the intraspecific variation of the organ numbers within flowers of Ranunculaceae, a family which branched near the monocot-eudicot separation, and the numbers of flowers within the capitula of Asteraceae, one of the most diverse families of eudicots. We used four elementary statistical quantities: mean, standard deviation (s.d.), degree of symmetry (skewness) and steepness (kurtosis). While these four quantities vary among populations, we found a common relationship between s.d. and the mean number of petals and sepals in Ranunculaceae and number of flowers per capitulum in Asteraceae. The s.d. is equal to the square root of the difference between the mean and specific number, showing robustness: for example, 3 in Ficaria sepals, 5 in Ranunculus petals and Anemone tepals, and 13 in Farfugium ray florets. This square-root relationship was not applicable to Eranthis petals which show little correlation between the s.d. and mean, and the stamens and carpels of Ranunculaceae whose s.d. is proportional to the mean. The specific values found in the square-root relationship provide a novel way to find the species-representative phenotype among varied morphologies. The representative phenotype is, in most cases, unique to the species or genus level, despite intraspecific differences of average phenotype among populations. The type of variation shown by the statistical quantities indicates not only the robustness of the morphologies but also how flowering plants changed during evolution among representative phenotypes that eventually led to phylogenetic diversification. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Relationship between the species-representative phenotype and intraspecific variation in Ranunculaceae floral organ and Asteraceae flower numbers

PubMed Central

Kitazawa, Miho S.; Fujimoto, Koichi

2016-01-01

Background and Aims Phenotypic variation in floral morphologies contributes to speciation by testing various morphologies that might have higher adaptivity, leading eventually to phylogenetic diversity. Species diversity has been recognized, however, by modal morphologies where the variation is averaged out, so little is known about the relationship between the variation and the diversity. Methods We analysed quantitatively the intraspecific variation of the organ numbers within flowers of Ranunculaceae, a family which branched near the monocot–eudicot separation, and the numbers of flowers within the capitula of Asteraceae, one of the most diverse families of eudicots. We used four elementary statistical quantities: mean, standard deviation (s.d.), degree of symmetry (skewness) and steepness (kurtosis). Key Results While these four quantities vary among populations, we found a common relationship between s.d. and the mean number of petals and sepals in Ranunculaceae and number of flowers per capitulum in Asteraceae. The s.d. is equal to the square root of the difference between the mean and specific number, showing robustness: for example, 3 in Ficaria sepals, 5 in Ranunculus petals and Anemone tepals, and 13 in Farfugium ray florets. This square-root relationship was not applicable to Eranthis petals which show little correlation between the s.d. and mean, and the stamens and carpels of Ranunculaceae whose s.d. is proportional to the mean. The specific values found in the square-root relationship provide a novel way to find the species-representative phenotype among varied morphologies. Conclusions The representative phenotype is, in most cases, unique to the species or genus level, despite intraspecific differences of average phenotype among populations. The type of variation shown by the statistical quantities indicates not only the robustness of the morphologies but also how flowering plants changed during evolution among representative phenotypes that eventually led to phylogenetic diversification. PMID:27052344

Reproductive biology and breeding system of Saraca asoca (Roxb.) De Wilde: a vulnerable medicinal plant.

PubMed

Smitha, G R; Thondaiman, V

2016-01-01

Ashoka ( Saraca asoca ) is a perennial, evergreen tree valued for its ornamental flowers and medicinal values. This species is classified as 'vulnerable' under IUCN list due to its dwindling population because of destructive harvesting from natural habitats. Therefore, conservation and multiplication of this species is need of the hour to utilize its astonishing medicinal uses eternally. Conservation approaches of any plant species require in-depth study of its reproductive biology, which is lacking in this species. The present study is the first detailed report on reproductive biology of S. asoca . This tree bears fragrant flowers in paniculate corymbose inflorescence from December end to May, with peak flowering during February-March. The fruits attain its maturity during last week of May-July. Seeds were dispersed from the pod to the tree premises upon complete maturity. The time of anthesis in this species is noticed in the early morning from 3.00 to 5.30 am, which coincided with anther dehiscence, stigma receptivity and insect activity. The length of the stamen and pistil points towards the pollination compatibility in both male and female parts. Pollen viability was maximum within 2 h of anthesis, which decreased thereafter and no pollens were viable after 6 h. The stigma was receptive at the time of anthesis and continued for 24 h. The tree produces bright colour attractive flowers, which changed from yellow/light orange to scarlet/red from the inception of buds to wilting. The bright color of the flowers attracted floral visitors/pollinators thereby facilitated the pollination in this species. The observations of the floral biology and breeding system indicated the cross pollination behaviour, which limited the production of selfed seeds and would help to maintain the sustainable levels of heterozygosity among the various populations. Considerable amount of seeds produced in this species indicated that the species is capable of sustaining its progenies in the natural populations. Polyembryony to an extent of 5% was also recorded in this species.

Reproductive biology characteristic of Jatropha curcas (Euphorbiaceae).

PubMed

Wang, Xiu-Rong; Ding, Gui-Jie

2012-12-01

Jatropha curcas belongs to family of Euphorbiaceae, and is an important biological tree species for diesel production. The current descriptions of the phenotypic traits for male and female flowers are not comprehensive and there have been no reports about the process of J. curcas from pollen germination on stigma to pollen tubes conducting fertilization after entering the ovary and ovule. To assess this, experiments were undertaken to study the reproductive biology characteristic of J. curcas in Guiyang Guizhou Province, China. Floral structure and pollen germination process were described in detail and the breeding system was determined. The results showed that flower of J. curcas was both unisexual and monoecious, with a flowering phase between April-November. Both female and male flowers have five petals in contorted arrangement and five calyxes in imbricated arrangement. Female flower originated from bisexual flower finally formed unisexual flowers as the stamen ceased growth in different period. The pistil had 3-5 styles, connected at base and separated into 3-5 stigmas on the top. Each stigma had 2-4 lobes. The styles were hollow. The pollen germinated on the surface of the stigma, is then transported via the vascular tissues, which was arranged in bundles, and finally channeled through the micropyle to enter the blastula. The pollen tube was shaped in a long uneven cylinder. The top end of it became swollen and formed a small round hole for the purpose of releasing sperm nuclei while the pollen tube itself was growing and extending. Estimation of out-crossing index and artificial pollination experiments indicated that J. curcas was capable of both self-pollination and cross-pollination. The germination speed of the pollen on the stigma did not differ so much between the one by self-pollination and the one by cross-pollination, and the pollen from the two different sources could both reach the ovary within one day. Both artificial pollination test and out-crossing index have indicated that: J. curcas has both self-pollination and cross-pollination systems.

The need to re-investigate the nature of homoplastic characters: an ontogenetic case study of the ‘bracteoles’ in Atripliceae (Chenopodiaceae)

PubMed Central

Flores-Olvera, Hilda; Vrijdaghs, Alexander; Ochoterena, Helga; Smets, Erik

2011-01-01

Background and Aims Within Chenopodioideae, Atripliceae have been distinguished by two bracteoles enveloping the female flowers/fruits, whereas in other tribes flowers are described as ebracteolate with persistent perianth. Molecular phylogenetic hypotheses suggest ‘bracteoles’ to be homoplastic. The origin of the bracteoles was explained by successive inflorescence reductions. Flower reduction was used to explain sex determination. Therefore, floral ontogeny was studied to evaluate the nature of the bracteoles and sex determination in Atripliceae. Methods Inflorescences of species of Atriplex, Chenopodium, Dysphania and Spinacia oleracea were investigated using light microscopy and scanning electron microscopy. Key Results The main axis of the inflorescence is indeterminate with elementary dichasia as lateral units. Flowers develop centripetally, with first the formation of a perianth primordium either from a ring primordium or from five individual tepal primordia fusing post-genitally. Subsequently, five stamen primordia originate, followed by the formation of an annular ovary primordium surrounding a central single ovule. Flowers are either initially hermaphroditic remaining bisexual and/or becoming functionally unisexual at later stages, or initially unisexual. In the studied species of Atriplex, female flowers are strictly female, except in A. hortensis. In Spinacia, female and male flowers are unisexual at all developmental stages. Female flowers of Atriplex and Spinacia are protected by two accrescent fused tepal lobes, whereas the other perianth members are absent. Conclusions In Atriplex and Spinacia modified structures around female flowers are not bracteoles, but two opposite accrescent tepal lobes, parts of a perianth persistent on the fruit. Flowers can achieve sexuality through many different combinations; they are initially hermaphroditic, subsequently developing into bisexual or functionally unisexual flowers, with the exception of Spinacia and strictly female flowers in Atriplex, which are unisexual from the earliest developmental stages. There may be a relationship between the formation of an annular perianth primordium and flexibility in floral sex determination. PMID:21852278

miRNAs involved in the development and differentiation of fertile and sterile flowers in Viburnum macrocephalum f. keteleeri.

PubMed

Li, Weixing; He, Zhichong; Zhang, Li; Lu, Zhaogeng; Xu, Jing; Cui, Jiawen; Wang, Li; Jin, Biao

2017-10-13

Sterile and fertile flowers are important evolutionary developmental phenotypes in angiosperm flowers. The development of floral organs, critical in angiosperm reproduction, is regulated by microRNAs (miRNAs). However, the mechanisms underpinning the miRNA regulation of the differentiation and development of sterile and fertile flowers remain unclear. Here, based on investigations of the morphological differences between fertile and sterile flowers, we used high-throughput sequencing to characterize the miRNAs in the differentiated floral organs of Viburnum macrocephalum f. keteleeri. We identified 49 known miRNAs and 67 novel miRNAs by small RNA (sRNA) sequencing and bioinformatics analysis, and 17 of these known and novel miRNA precursors were validated by polymerase chain reaction (PCR) and Sanger sequencing. Furthermore, by comparing the sequencing results of two sRNA libraries, we found that 30 known and 39 novel miRNA sequences were differentially expressed, and 35 were upregulated and 34 downregulated in sterile compared with fertile flowers. Combined with their predicted targets, the potential roles of miRNAs in V. macrocephalum f. keteleeri flowers include involvement in floral organogenesis, cell proliferation, hormonal pathways, and stress responses. miRNA precursors and targets were further validated by quantitative real-time PCR (qRT-PCR). Specifically, miR156a-5p, miR156g, and miR156j expression levels were significantly higher in fertile flowers than in sterile flowers, while SPL genes displayed the opposite expression pattern. Considering that the targets of miR156 are predicted to be SPL genes, we propose that miR156 may be involved in the regulation of stamen development in V. macrocephalum f. keteleeri. We identified miRNAs differentially expressed between fertile and sterile flowers in V. macrocephalum f. keteleeri and provided new insights into the important regulatory roles of miRNAs in the differentiation and development of fertile and sterile flowers.

Analysis of the Arabidopsis superman allelic series and the interactions with other genes demonstrate developmental robustness and joint specification of male-female boundary, flower meristem termination and carpel compartmentalization.

PubMed

Breuil-Broyer, Stéphanie; Trehin, Christophe; Morel, Patrice; Boltz, Véronique; Sun, Bo; Chambrier, Pierre; Ito, Toshiro; Negrutiu, Ioan

2016-04-01

SUPERMAN is a cadastral gene controlling the sexual boundary in the flower. The gene's functions and role in flower development and evolution have remained elusive. The analysis of a contrasting SUP allelic series (for which the names superman, superwoman and supersex have been coined) makes it possible to distinguish early vs. late regulatory processes at the flower meristem centre to which SUP is an important contributor. Their understanding is essential in further addressing evolutionary questions linking bisexuality and flower meristem homeostasis. Inter-allelic comparisons were carried out and SUP interactions with other boundary factors and flower meristem patterning and homeostasis regulators (such as CLV, WUS, PAN, CUC, KNU, AG, AP3/PI, CRC and SPT) have been evaluated at genetic, molecular, morphological and histological levels. Early SUP functions include mechanisms of male-female (sexual) boundary specification, flower mersitem termination and control of stamen number. A SUP-dependent flower meristem termination pathway is identified and analysed. Late SUP functions play a role in organ morphogenesis by controlling intra-whorl organ separation and carpel medial region formation. By integrating early and late SUP functions, and by analyzing in one single experiment a series of SUP genetic interactions, the concept of meristematic 'transference' (cascade) - a regulatory bridging process redundantly and sequentially co-ordinating the triggering and completion of flower meristem termination, and carpel margin meristem and placenta patterning - is proposed. Taken together, the results strongly support the view that SUP(-type) function(s) have been instrumental in resolving male/female gradients into sharp male and female identities (whorls, organs) and in enforcing flower homeostasis during evolution. This has probably been achieved by incorporating the meristem patterning system of the floral axis into the female/carpel programme. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Genetic Enhancer Analysis Reveals that FLORAL ORGAN NUMBER2 and OsMADS3 Co-operatively Regulate Maintenance and Determinacy of the Flower Meristem in Rice.

PubMed

Yasui, Yukiko; Tanaka, Wakana; Sakamoto, Tomoaki; Kurata, Tetsuya; Hirano, Hiro-Yuki

2017-05-01

Meristems such as the shoot apical meristem and flower meristem (FM) act as a reservoir of stem cells, which reproduce themselves and supply daughter cells for the differentiation of lateral organs. In Oryza sativa (rice), the FLORAL ORGAN NUMBER2 (FON2) gene, which is similar to Arabidopsis CLAVATA3, is involved in meristem maintenance. In fon2 mutants, the numbers of floral organs are increased due to an enlargement of the FM. To identify new factors regulating meristem maintenance in rice, we performed a genetic screening of mutants that enhanced the fon2 mutation, and found a mutant line (2B-424) in which pistil number was dramatically increased. By using a map-based approach and next-generation sequencing, we found that the line 2B-424 had a complete loss-of-function mutation (a large deletion) in OsMADS3, a class C MADS-box gene that is known to be involved in stamen specification. Disruption of OsMADS3 in the fon2 mutant by CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR-associated protein 9) technology caused a flower phenotype similar to that of 2B-424, confirming that the gene responsible for enhancement of fon2 was OsMADS3. Morphological analysis showed that the fon2 and osmads3 mutations synergistically affected pistil development and FM determinacy. We also found that whorl 3 was duplicated in mature flowers and the FM was enlarged at an early developmental stage in severe osmads3 single mutants. These findings suggest that OsMADS3 is involved not only in FM determinacy in late flower development but also in FM activity in early flower development. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Plant-environment interactions: Accumulation of hypericin in dark glands of Hypericum perforatum.

PubMed

Zobayed, S M A; Afreen, F; Goto, E; Kozai, T

2006-10-01

Hypericum perforatum is a perennial herbaceous plant and an extract from this plant has a significant antidepressant effect when administered to humans. The plant is characterized by its secretory glands, also known as dark glands, which are mainly visible on leaves and flowers. The current study evaluates the influence of several environmental factors and developmental stages of the plant on the accumulation and synthesis of hypericin and pseudohypericin (Hy-G), the major bioactive constituents, in H. perforatum plants. The appearance of dark glands on different parts of the plant, under several environmental conditions, was monitored by microscopy. Hy-G concentrations were quantified by high-performance liquid chromatography. A significant presence of dark glands accompanying the highest concentrations of Hy-G was observed in the stamen tissues more than in any other organ of H. perforatum. A linear relationship between the number of dark glands and net photosynthetic rate of the leaf and Hy-G concentration in the leaf tissue was also established. A very high concentration of Hy-G was measured in the dark-gland tissues, but in the tissues without any dark glands it was almost absent. The presence of emodin, a precursor of Hy-G, at a high concentration in the dark-gland tissues, and its absence in the surrounding tissues was also observed, suggesting that the site of biosynthesis of Hy-G is in the dark-gland cells. A significantly low concentration of Hy-G (occasionally non-detectable) was measured in the xylem sap of the stem tissues. The dark-gland tissues collected from leaves, stems or flowers contained similar concentrations of Hy-G. The concentration of Hy-G in various organs of H. perforatum plants is dependent on the number of dark glands, their size or area, not on the location of the dark glands on the plant. The study provides the first experimental evidence that Hy-G is synthesized and accumulates in dark glands.

Transcriptome analysis of Gossypium hirsutum flower buds infested by cotton boll weevil (Anthonomus grandis) larvae.

PubMed

Artico, Sinara; Ribeiro-Alves, Marcelo; Oliveira-Neto, Osmundo Brilhante; de Macedo, Leonardo Lima Pepino; Silveira, Sylvia; Grossi-de-Sa, Maria Fátima; Martinelli, Adriana Pinheiro; Alves-Ferreira, Marcio

2014-10-04

Cotton is a major fibre crop grown worldwide that suffers extensive damage from chewing insects, including the cotton boll weevil larvae (Anthonomus grandis). Transcriptome analysis was performed to understand the molecular interactions between Gossypium hirsutum L. and cotton boll weevil larvae. The Illumina HiSeq 2000 platform was used to sequence the transcriptome of cotton flower buds infested with boll weevil larvae. The analysis generated a total of 327,489,418 sequence reads that were aligned to the G. hirsutum reference transcriptome. The total number of expressed genes was over 21,697 per sample with an average length of 1,063 bp. The DEGseq analysis identified 443 differentially expressed genes (DEG) in cotton flower buds infected with boll weevil larvae. Among them, 402 (90.7%) were up-regulated, 41 (9.3%) were down-regulated and 432 (97.5%) were identified as orthologues of A. thaliana genes using Blastx. Mapman analysis of DEG indicated that many genes were involved in the biotic stress response spanning a range of functions, from a gene encoding a receptor-like kinase to genes involved in triggering defensive responses such as MAPK, transcription factors (WRKY and ERF) and signalling by ethylene (ET) and jasmonic acid (JA) hormones. Furthermore, the spatial expression pattern of 32 of the genes responsive to boll weevil larvae feeding was determined by "in situ" qPCR analysis from RNA isolated from two flower structures, the stamen and the carpel, by laser microdissection (LMD). A large number of cotton transcripts were significantly altered upon infestation by larvae. Among the changes in gene expression, we highlighted the transcription of receptors/sensors that recognise chitin or insect oral secretions; the altered regulation of transcripts encoding enzymes related to kinase cascades, transcription factors, Ca2+ influxes, and reactive oxygen species; and the modulation of transcripts encoding enzymes from phytohormone signalling pathways. These data will aid in the selection of target genes to genetically engineer cotton to control the cotton boll weevil.

Functional analysis reveals the possible role of the C-terminal sequences and PI motif in the function of lily (Lilium longiflorum) PISTILLATA (PI) orthologues

PubMed Central

Chen, Ming-Kun; Hsieh, Wen-Ping; Yang, Chang-Hsien

2012-01-01

Two lily (Lilium longiflorum) PISTILLATA (PI) genes, Lily MADS Box Gene 8 and 9 (LMADS8/9), were characterized. LMADS9 lacked 29 C-terminal amino acids including the PI motif that was present in LMADS8. Both LMADS8/9 mRNAs were prevalent in the first and second whorl tepals during all stages of development and were expressed in the stamen only in young flower buds. LMADS8/9 could both form homodimers, but the ability of LMADS8 homodimers to bind to CArG1 was relatively stronger than that of LMADS9 homodimers. 35S:LMADS8 completely, and 35S:LMADS9 only partially, rescued the second whorl petal formation and partially converted the first whorl sepal into a petal-like structure in Arabidopsis pi-1 mutants. Ectopic expression of LMADS8-C (with deletion of the 29 amino acids of the C-terminal sequence) or LMADS8-PI (with only the PI motif deleted) only partially rescued petal formation in pi mutants, which was similar to what was observed in 35S:LMADS9/pi plants. In contrast, 35:LMADS9+L8C (with the addition of the 29 amino acids of the LMADS8 C-terminal sequence) or 35S:LMADS9+L8PI (with the addition of the LMADS8 PI motif) demonstrated an increased ability to rescue petal formation in pi mutants, which was similar to what was observed in 35S:LMADS8/pi plants. Furthermore, ectopic expression of LMADS8-M (with the MADS domain truncated) generated more severe dominant negative phenotypes than those seen in 35S:LMADS9-M flowers. These results revealed that the 29 amino acids including the PI motif in the C-terminal region of the lily PI orthologue are valuable for its function in regulating perianth organ formation. PMID:22068145

Molecular cloning and characterization of three genes encoding dihydroflavonol-4-reductase from Ginkgo biloba in anthocyanin biosynthetic pathway.

PubMed

Hua, Cheng; Linling, Li; Shuiyuan, Cheng; Fuliang, Cao; Feng, Xu; Honghui, Yuan; Conghua, Wu

2013-01-01

Dihydroflavonol-4-reductase (DFR, EC1.1.1.219) catalyzes a key step late in the biosynthesis of anthocyanins, condensed tannins (proanthocyanidins), and other flavonoids important to plant survival and human nutrition. Three DFR cDNA clones (designated GbDFRs) were isolated from the gymnosperm Ginkgo biloba. The deduced GbDFR proteins showed high identities to other plant DFRs, which form three distinct DFR families. Southern blot analysis showed that the three GbDFRs each belong to a different DFR family. Phylogenetic tree analysis revealed that the GbDFRs share the same ancestor as other DFRs. The expression of the three recombinant GbDFRs in Escherichia coli showed that their actual protein sizes were in agreement with predictions from the cDNA sequences. The recombinant proteins were purified and their activity was analyzed; both GbDFR1 and GbDFR3 could catalyze dihydroquercetin conversion to leucocyanidin, while GbDFR2 catalyzed dihydrokaempferol conversion to leucopelargonidin. qRT-PCR showed that the GbDFRs were expressed in a tissue-specific manner, and transcript accumulation for the three genes was highest in young leaves and stamens. These transcription patterns were in good agreement with the pattern of anthocyanin accumulation in G.biloba. The expression profiles suggested that GbDFR1 and GbDFR2 are mainly involved in responses to plant hormones, environmental stress and damage. During the annual growth cycle, the GbDFRs were significantly correlated with anthocyanin accumulation in leaves. A fitted linear curve showed the best model for relating GbDFR2 and GbDFR3 with anthocyanin accumulation in leaves. GbDFR1 appears to be involved in environmental stress response, while GbDFR3 likely has primary functions in the synthesis of anthocyanins. These data revealed unexpected properties and differences in three DFR proteins from a single species.

Current trends and future directions in flower development research

PubMed Central

Scutt, Charlie P.; Vandenbussche, Michiel

2014-01-01

Flowers, the reproductive structures of the approximately 400 000 extant species of flowering plants, exist in a tremendous range of forms and sizes, mainly due to developmental differences involving the number, arrangement, size and form of the floral organs of which they consist. However, this tremendous diversity is underpinned by a surprisingly robust basic floral structure in which a central group of carpels forms on an axis of determinate growth, almost invariably surrounded by two successive zones containing stamens and perianth organs, respectively. Over the last 25 years, remarkable progress has been achieved in describing the molecular mechanisms that control almost all aspects of flower development, from the phase change that initiates flowering to the final production of fruits and seeds. However, this work has been performed almost exclusively in a small number of eudicot model species, chief among which is Arabidopsis thaliana. Studies of flower development must now be extended to a much wider phylogenetic range of flowering plants and, indeed, to their closest living relatives, the gymnosperms. Studies of further, more wide-ranging models should provide insights that, for various reasons, cannot be obtained by studying the major existing models alone. The use of further models should also help to explain how the first flowering plants evolved from an unknown, although presumably gymnosperm-like ancestor, and rapidly diversified to become the largest major plant group and to dominate the terrestrial flora. The benefits for society of a thorough understanding of flower development are self-evident, as human life depends to a large extent on flowering plants and on the fruits and seeds they produce. In this preface to the Special Issue, we introduce eleven articles on flower development, representing work in both established and further models, including gymnosperms. We also present some of our own views on current trends and future directions of the flower development field. PMID:25335868

Floral Morphogenesis: Stochastic Explorations of a Gene Network Epigenetic Landscape

PubMed Central

Aldana, Maximino; Benítez, Mariana; Cortes-Poza, Yuriria; Espinosa-Soto, Carlos; Hartasánchez, Diego A.; Lotto, R. Beau; Malkin, David; Escalera Santos, Gerardo J.; Padilla-Longoria, Pablo

2008-01-01

In contrast to the classical view of development as a preprogrammed and deterministic process, recent studies have demonstrated that stochastic perturbations of highly non-linear systems may underlie the emergence and stability of biological patterns. Herein, we address the question of whether noise contributes to the generation of the stereotypical temporal pattern in gene expression during flower development. We modeled the regulatory network of organ identity genes in the Arabidopsis thaliana flower as a stochastic system. This network has previously been shown to converge to ten fixed-point attractors, each with gene expression arrays that characterize inflorescence cells and primordial cells of sepals, petals, stamens, and carpels. The network used is binary, and the logical rules that govern its dynamics are grounded in experimental evidence. We introduced different levels of uncertainty in the updating rules of the network. Interestingly, for a level of noise of around 0.5–10%, the system exhibited a sequence of transitions among attractors that mimics the sequence of gene activation configurations observed in real flowers. We also implemented the gene regulatory network as a continuous system using the Glass model of differential equations, that can be considered as a first approximation of kinetic-reaction equations, but which are not necessarily equivalent to the Boolean model. Interestingly, the Glass dynamics recover a temporal sequence of attractors, that is qualitatively similar, although not identical, to that obtained using the Boolean model. Thus, time ordering in the emergence of cell-fate patterns is not an artifact of synchronous updating in the Boolean model. Therefore, our model provides a novel explanation for the emergence and robustness of the ubiquitous temporal pattern of floral organ specification. It also constitutes a new approach to understanding morphogenesis, providing predictions on the population dynamics of cells with different genetic configurations during development. PMID:18978941

Molecular Cloning and Characterization of Three Genes Encoding Dihydroflavonol-4-Reductase from Ginkgo biloba in Anthocyanin Biosynthetic Pathway

PubMed Central

Hua, Cheng; Linling, Li; Shuiyuan, Cheng; Fuliang, Cao; Feng, Xu; Honghui, Yuan; Conghua, Wu

2013-01-01

Dihydroflavonol-4-reductase (DFR, EC1.1.1.219) catalyzes a key step late in the biosynthesis of anthocyanins, condensed tannins (proanthocyanidins), and other flavonoids important to plant survival and human nutrition. Three DFR cDNA clones (designated GbDFRs) were isolated from the gymnosperm Ginkgo biloba. The deduced GbDFR proteins showed high identities to other plant DFRs, which form three distinct DFR families. Southern blot analysis showed that the three GbDFRs each belong to a different DFR family. Phylogenetic tree analysis revealed that the GbDFRs share the same ancestor as other DFRs. The expression of the three recombinant GbDFRs in Escherichia coli showed that their actual protein sizes were in agreement with predictions from the cDNA sequences. The recombinant proteins were purified and their activity was analyzed; both GbDFR1 and GbDFR3 could catalyze dihydroquercetin conversion to leucocyanidin, while GbDFR2 catalyzed dihydrokaempferol conversion to leucopelargonidin. qRT-PCR showed that the GbDFRs were expressed in a tissue-specific manner, and transcript accumulation for the three genes was highest in young leaves and stamens. These transcription patterns were in good agreement with the pattern of anthocyanin accumulation in G.biloba. The expression profiles suggested that GbDFR1 and GbDFR2 are mainly involved in responses to plant hormones, environmental stress and damage. During the annual growth cycle, the GbDFRs were significantly correlated with anthocyanin accumulation in leaves. A fitted linear curve showed the best model for relating GbDFR2 and GbDFR3 with anthocyanin accumulation in leaves. GbDFR1 appears to be involved in environmental stress response, while GbDFR3 likely has primary functions in the synthesis of anthocyanins. These data revealed unexpected properties and differences in three DFR proteins from a single species. PMID:23991027

Duplication and Whorl-Specific Down-Regulation of the Obligate AP3-PI Heterodimer Genes Explain the Origin of Paeonia lactiflora Plants with Spontaneous Corolla Mutation.

PubMed

Gong, Pichang; Ao, Xiang; Liu, Gaixiu; Cheng, Fangyun; He, Chaoying

2017-03-01

Herbaceous peony (Paeonia lactiflora) is a globally important ornamental plant. Spontaneous floral mutations occur frequently during cultivation, and are selected as a way to release new cultivars, but the underlying evolutionary developmental genetics remain largely elusive. Here, we investigated a collection of spontaneous corolla mutational plants (SCMPs) whose other floral organs were virtually unaffected. Unlike the corolla in normal plants (NPs) that withered soon after fertilization, the transformed corolla (petals) in SCMPs was greenish and persistent similar to the calyx (sepals). Epidermal cellular morphology of the SCMP corolla was also similar to that of calyx cells, further suggesting a sepaloid corolla in SCMPs. Ten floral MADS-box genes from these Paeonia plants were comparatively characterized with respect to sequence and expression. Codogenic sequence variation of these MADS-box genes was not linked to corolla changes in SCMPs. However, we found that both APETALA3 (AP3) and PISTILLATA (PI) lineages of B-class MADS-box genes were duplicated, and subsequent selective expression alterations of these genes were closely associated with the origin of SCMPs. AP3-PI obligate heterodimerization, essential for organ identity of corolla and stamens, was robustly detected. However, selective down-regulation of these duplicated genes might result in a reduction of this obligate heterodimer concentration in a corolla-specific manner, leading to the sepaloid corolla in SCMPs, thus representing a new sepaloid corolla model taking advantage of gene duplication. Our work suggests that modifying floral MADS-box genes could facilitate the breeding of novel cultivars with distinct floral morphology in ornamental plants, and also provides new insights into the functional evolution of the MADS-box genes in plants. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

[Morphology, anatomy, ontogeny and chemical composition of inflorescences volatile secondary metabolites of Lippia alba (Verbenaceae) at three stages of development].

PubMed

Parra-Garcés, María Isabel; Caroprese-Araque, José Fernando; Arrieta-Prieto, Dagoberto; Stashenko, Elena

2010-12-01

There is an increased interest to know and scientifically validate traditional knowledge of medicinal plants. Lippia alba belongs to Verbenaceae family and has been of interest, not only because of its worldwide extensive distribution, but also for its variable use as antiviral, bactericide, citostatic, analgesic and sedative. To study this, the morphology and ontogeny of Lippia alba inflorescences and the chemical composition of its volatile secondary metabolites were analyzed during three different stages of development. Plants were collected at the experimental crop field in CENIVAM, Bucaramanga, Colombia. The inflorescence's morphology and ontogeny, and the chemical composition of volatile secondary metabolites were analyzed using a stereoscopic microscope and chromatographic and spectroscopic techniques. Fresh material corresponding to each stage was fixed in F.A.A (formol, acetic acid and alcohol), included in paraffin and cutted in transversal and longitudinal sections. Sections were stained with safranine-fastgreen, photographed and decribed. The chemical composition of volatile secondary metabolites at each ontogenic stage, was extracted by solid phase micro-extraction in the headspace mode and analyzed by gas chromatography coupled to mass spectrometry. Stage I showed a meristematic mass of cells in vegetative apex and bracts, with an outline of floral whorls. In Stage III. the stamens were adnate, epipetals and didynamous, bicarpelar and syncarpic gynoecium, with superior ovary and decurrent stigma. The main secondary metabolites detected were the bicyclosesquiphellandrene followed by carvone, limonene and trans-beta-farnesene, that constituted the 78% of the total relative amounts of compounds. Other metabolites such as beta-copaene, gamma-amorphene and cis-beta-guaiene, were reported for the first time in this study. When compared to other studies, morphological differences reported in this study are possibly related to adaptation to environmental conditions or pollinators, which let us suggest that there is no specific ontogenic pattern. Similarly, the qualitative and quantitative variations in the detected compounds could be explained because one or more of them are used as precursors of others.

Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae).

PubMed

Wang, Shuai; Fu, Wen-Long; Du, Wei; Zhang, Qi; Li, Ya; Lyu, Yu-Shu; Wang, Xiao-Fan

2018-03-01

Floral nectaries are closely associated with biotic pollination, and the nectar produced by corolla nectaries is generally enclosed in floral structures. Although some Swertia spp. (Gentianaceae), including S. bimaculata , evolved a peculiar form of corolla nectaries (known as "gland patches") arranged in a conspicuous ring on the rotate corolla and that completely expose their nectar, little is known about the pollination of these plants. Two hypotheses were made concerning the possible effects of gland patches: visual attraction and visitor manipulation. The floral traits, mating system, and insect pollination of S. bimaculata were examined, and the pollination effects of gland patches were evaluated. A comparative study was made using Swertia kouitchensis , a species with fimbriate nectaries. Swertia bimaculata flowers were protandrous, with obvious stamen movement leading to herkogamy in the female phase and to a significant reduction in nectary-anther distance. The species is strongly entomophilous and facultatively xenogamous. The daily reward provided per flower decreased significantly after the male phase. The most effective pollinators were large dipterans, and the visiting proportion of Diptera was significantly higher in S. bimaculata than in S. kouitchensis . Most visitors performed "circling behavior" in S. bimaculata flowers. Removing or blocking the nectaries caused no reduction in visiting frequency but a significant reduction in visit duration, interrupting the circling behavior. The circling behavior was encouraged by nectar abundance and promoted pollen dispersal. Visitor species with small body size had little chance to contact the anthers or stigma, revealing a filtration effect exerted by the floral design. These results rejected the "visual attraction" hypothesis and supported the "visitor manipulation" hypothesis. The nectary whorl within a flower acted like a ring-shaped track that urged nectar foragers to circle on the corolla, making pollination in S. bimaculata flowers more orderly and selective than that in classically generalist flowers.

Analysis of the Arabidopsis superman allelic series and the interactions with other genes demonstrate developmental robustness and joint specification of male–female boundary, flower meristem termination and carpel compartmentalization

PubMed Central

Breuil-Broyer, Stéphanie; Trehin, Christophe; Morel, Patrice; Boltz, Véronique; Sun, Bo; Chambrier, Pierre; Ito, Toshiro; Negrutiu, Ioan

2016-01-01

Background and Aims SUPERMAN is a cadastral gene controlling the sexual boundary in the flower. The gene’s functions and role in flower development and evolution have remained elusive. The analysis of a contrasting SUP allelic series (for which the names superman, superwoman and supersex have been coined) makes it possible to distinguish early vs. late regulatory processes at the flower meristem centre to which SUP is an important contributor. Their understanding is essential in further addressing evolutionary questions linking bisexuality and flower meristem homeostasis. Methods Inter-allelic comparisons were carried out and SUP interactions with other boundary factors and flower meristem patterning and homeostasis regulators (such as CLV, WUS, PAN, CUC, KNU, AG, AP3/PI, CRC and SPT) have been evaluated at genetic, molecular, morphological and histological levels. Key Results Early SUP functions include mechanisms of male–female (sexual) boundary specification, flower mersitem termination and control of stamen number. A SUP-dependent flower meristem termination pathway is identified and analysed. Late SUP functions play a role in organ morphogenesis by controlling intra-whorl organ separation and carpel medial region formation. By integrating early and late SUP functions, and by analyzing in one single experiment a series of SUP genetic interactions, the concept of meristematic ‘transference’ (cascade) – a regulatory bridging process redundantly and sequentially co-ordinating the triggering and completion of flower meristem termination, and carpel margin meristem and placenta patterning – is proposed. Conclusions Taken together, the results strongly support the view that SUP(-type) function(s) have been instrumental in resolving male/female gradients into sharp male and female identities (whorls, organs) and in enforcing flower homeostasis during evolution. This has probably been achieved by incorporating the meristem patterning system of the floral axis into the female/carpel programme. PMID:27098089

Wind-Dragged Corolla Enhances Self-Pollination: A New Mechanism of Delayed Self-Pollination

PubMed Central

Qu, Rongming; Li, Xiaojie; Luo, Yibo; Dong, Ming; Xu, Huanli; Chen, Xuan; Dafni, Amots

2007-01-01

Background and Aims Delayed self-pollination is a mechanism that allows animal-pollinated plants to outcross while ensuring seed production in the absence of pollinators. This study aims to explore a new mechanism of delayed self-pollination facilitated by wind-driven corolla abscission in Incarvillea sinensis var. sinensis. Methods Floral morphology and development, and the process of delayed self-pollination were surveyed. Experiments dealing with pollinator and wind exclusion, pollination manipulations, and pollinator observations were conducted in the field. Key Results Delayed self-pollination occurs when the abscising corolla driven by wind drags the adherent epipetalous stamens, thus leading to contact of anthers with stigma in late anthesis. There is no dichogamy and self-incompatibility in this species. The significantly higher proportion of abscised corolla under natural conditions as compared with that in wind-excluding tents indicates the importance of wind in corolla abscission. When pollinators were excluded, corolla abscission significantly increased the number of pollen grains deposited on the stigma and, as a result, the fruit and seed set. Only half of the flowers in plots were visited by pollinators, and the fruit set of emasculated flowers was significantly lower than that of untreated flowers in open pollination. This species has a sensitive stigma, and its two open stigmatic lobes closed soon after being touched by a pollinator, but always reopened if no or only little pollen was deposited. Conclusions This delayed self-pollination, which involved the movement of floral parts, the active participation of the wind and sensitive stigma, is quite different from that reported previously. This mechanism provides reproductive assurance for this species. The sensitive stigma contributes to ensuring seed production and reducing the interference of selfing with outcrossing. The pollination pattern, which combines actions by bees with indirect participation by wind, is also a new addition to ambophily. PMID:17881336

Possible role of jasmonic acid in the regulation of floral induction, evocation and floral differentiation in Lemna minor L.

PubMed

Krajncic, B; Kristl, J; Janzekovic, I

2006-01-01

Jasmonic acid (JA) is implicated in a wide variety of developmental and physiological processes in plants. Here, we studied the effects of JA and the combination of JA and ethylenediamine-dio-hydroxyphenyl-acetic acid (EDDHA) on flowering in Lemna minor in axenical cultures. JA (0.475-47.5 nmol l(-1)) enhanced floral induction in L. minor under long-day (LD) conditions. Under the same conditions, at a concentration of 237.5 nmol l(-1), JA inhibited floral induction, and at a concentration of 475 nmol l(-1) it prevented floral induction. Under LD conditions with LD preculture, a combination of EDDHA (20,500 nmol l(-1)) and JA (47.5 nmol l(-1)) had a synergistic effect on the promotion of floral induction. Floral induction was enhanced to the greatest extent in experiments with LD precultures. Microscopic examination of microphotographs of histological sections showed that JA and, to an even greater extent, JA+EDDHA at optimal concentrations promote apical floral induction (evocation). Furthermore, JA, and to an even greater extent JA in combination with EDDHA in an optimal concentration, also promote flower differentiation, especially the development of stamens, as is evident from the microphotographs. The experimental results show that JA promotes floral induction in other species of Lemnaceae from various groups according to their photoperiodic response. The results support our hypothesis that, in addition to previously ascribed functions, JA may regulate floral induction, evocation and floral differentiation. Our hypothesis is supported also by the results obtained by quantitative determination of endogenous JA levels in L. minor at three growth stages. The levels of endogenous JA decreased from 389 ng JA g(-1) (fresh weight) of L. minor during the vegetative stage to 217 ng JA g(-1) during the evocation stage, and to 37.5 ng JA g(-1) during the flowering stage, which proves that JA is used for flowering.

Suppression of OsRAD51D results in defects in reproductive development in rice (Oryza sativa L.).

PubMed

Byun, Mi Young; Kim, Woo Taek

2014-07-01

The cellular roles of RAD51 paralogs in somatic and reproductive growth have been extensively described in a wide range of animal systems and, to a lesser extent, in Arabidopsis, a dicot model plant. Here, the OsRAD51D gene was identified and characterized in rice (Oryza sativa L.), a monocot model crop. In the rice genome, three alternative OsRAD51D mRNA splicing variants, OsRAD51D.1, OsRAD51D.2, and OsRAD51D.3, were predicted. Yeast two-hybrid studies, however, showed that only OsRAD51D.1 interacted with OsRAD51B and OsRAD51C paralogs, suggesting that OsRAD51D.1 is a functional OsRAD51D protein in rice. Loss-of-function osrad51d mutant rice plants displayed normal vegetative growth. However, the mutant plants were defective in reproductive growth, resulting in sterile flowers. Homozygous osrad51d mutant flowers exhibited impaired development of lemma and palea and contained unusual numbers of stamens and stigmas. During early meiosis, osrad51d pollen mother cells (PMCs) failed to form normal homologous chromosome pairings. In subsequent meiotic progression, mutant PMCs represented fragmented chromosomes. The osrad51d pollen cells contained numerous abnormal micro-nuclei that resulted in malfunctioning pollen. The abnormalities of heterozygous mutant and T2 Ubi:RNAi-OsRAD51D RNAi-knock-down transgenic plants were intermediate between those of wild type and homozygous mutant plants. The osrad51d and Ubi:RNAi-OsRAD51D plants contained longer telomeres compared with wild type plants, indicating that OsRAD51D is a negative factor for telomere lengthening. Overall, these results suggest that OsRAD51D plays a critical role in reproductive growth in rice. This essential function of OsRAD51D is distinct from Arabidopsis, in which AtRAD51D is not an essential factor for meiosis or reproductive development. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

An R2R3 MYB transcription factor determines red petal colour in an Actinidia (kiwifruit) hybrid population

PubMed Central

2013-01-01

Background Red colour in kiwifruit results from the presence of anthocyanin pigments. Their expression, however, is complex, and varies among genotypes, species, tissues and environments. An understanding of the biosynthesis, physiology and genetics of the anthocyanins involved, and the control of their expression in different tissues, is required. A complex, the MBW complex, consisting of R2R3-MYB and bHLH transcription factors together with a WD-repeat protein, activates anthocyanin 3-O-galactosyltransferase (F3GT1) to produce anthocyanins. We examined the expression and genetic control of anthocyanins in flowers of Actinidia hybrid families segregating for red and white petal colour. Results Four inter-related backcross families between Actinidia chinensis Planch. var. chinensis and Actinidia eriantha Benth. were identified that segregated 1:1 for red or white petal colour. Flower pigments consisted of five known anthocyanins (two delphinidin-based and three cyanidin-based) and three unknowns. Intensity and hue differed in red petals from pale pink to deep magenta, and while intensity of colour increased with total concentration of anthocyanin, no association was found between any particular anthocyanin data and hue. Real time qPCR demonstrated that an R2R3 MYB, MYB110a, was expressed at significant levels in red-petalled progeny, but not in individuals with white petals. A microsatellite marker was developed that identified alleles that segregated with red petal colour, but not with ovary, stamen filament, or fruit flesh colour in these families. The marker mapped to chromosome 10 in Actinidia. The white petal phenotype was complemented by syringing Agrobacterium tumefaciens carrying Actinidia 35S::MYB110a into the petal tissue. Red pigments developed in white petals both with, and without, co-transformation with Actinidia bHLH partners. MYB110a was shown to directly activate Actinidia F3GT1 in transient assays. Conclusions The transcription factor, MYB110a, regulates anthocyanin production in petals in this hybrid population, but not in other flower tissues or mature fruit. The identification of delphinidin-based anthocyanins in these flowers provides candidates for colour enhancement in novel fruits. PMID:23324587

Three endoplasmic reticulum-associated fatty acyl-coenzyme a reductases were involved in the production of primary alcohols in hexaploid wheat (Triticum aestivum L.).

PubMed

Chai, Guaiqiang; Li, Chunlian; Xu, Feng; Li, Yang; Shi, Xue; Wang, Yong; Wang, Zhonghua

2018-03-05

The cuticle covers the surface of the polysaccharide cell wall of leaf epidermal cells and forms an essential diffusion barrier between the plant and the environment. The cuticle is composed of cutin and wax. Cuticular wax plays an important role in the survival of plants by serving as the interface between plants and their biotic and abiotic environments, especially restricting nonstomatal water loss. Leaf cuticular waxes of hexaploid wheat at the seedling stage mainly consist of primary alcohols, aldehydes, fatty acids, alkane and esters. Primary alcohols account for more than 80% of the total wax load. Therefore, we cloned several genes encoding fatty acyl-coenzyme A reductases from wheat and analyzed their function in yeast and plants. We propose the potential use of these genes in wheat genetic breeding. We reported the cloning and characterization of three TaFARs, namely TaFAR6, TaFAR7 and TaFAR8, encoding fatty acyl-coenzyme A reductases (FAR) in wheat leaf cuticle. Expression analysis revealed that TaFAR6, TaFAR7 and TaFAR8 were expressed at the higher levels in the seedling leaf blades, and were expressed moderately or weakly in stamen, glumes, peduncle, flag leaf blade, sheath, spike, and pistil. The heterologous expression of three TaFARs in yeast (Saccharomyces cerevisiae) led to the production of C24:0 and C26:0 primary alcohols. Transgenic expression of the three TaFARs in tomato (Solanum lycopersicum) and rice (Oryza sativa) led to increased accumulation of C24:0-C30:0 primary alcohols. Transient expression of GFP protein-tagged TaFARs revealed that the three TaFAR proteins were localized to the endoplasmic reticulum (ER), the site of wax biosynthesis. The three TaFAR genes were transcriptionally induced by drought, cold, heat, powdery mildew (Blumeria graminis) infection, abscisic acid (ABA) and methyl jasmonate (MeJa) treatments. These results indicated that wheat TaFAR6, TaFAR7 and TaFAR8 are involved in biosynthesis of very-long-chain primary alcohols in hexaploid wheat and in response to multiple environmental stresses.

Flower-level developmental plasticity to nutrient availability in Datura stramonium: implications for the mating system.

PubMed

Camargo, Iván Darío; Nattero, Julieta; Careaga, Sonia A; Núñez-Farfán, Juan

2017-10-17

Studies of phenotypic plasticity in plants have mainly focused on (1) the effect of environmental variation on whole-plant traits related to the number of modules rather than on (2) the phenotypic consequences of environmental variation in traits of individual modules. Since environmental and developmental factors can produce changes in traits related to the mating system, this study used the second approach to investigate whether within-individual variation in herkogamy-related traits is affected by the environment during plant development in two populations of Datura stramonium , an annual herb with a hypothesized persistent mixed mating system, and to determine which morphological traits may promote self-fertilization. Full-sib families of two Mexican populations of D. stramonium , with contrasting ecological histories, were grown under low, mid and high nutrient availability to investigate the effects of genetic, environmental and within-plant flower position on flower size, corolla, stamen and pistil lengths, and herkogamy. Populations showed differences in familial variation, plasticity and familial differences in plasticity in most floral traits analysed. In one population (Ticumán), the effect of flower position on trait variation varied among families, whereas in the other (Pedregal) the effect of flower position interacted with the nutrient environment. Flower size varied with the position of flowers, but in the opposite direction between populations in low nutrients; a systematic within-plant trend of reduction in flower size, pistil length and herkogamy with flower position increased the probability of self-fertilization in the Pedregal population. Besides genetic variation in floral traits between and within populations, environmental variation affects phenotypic floral trait values at the whole-plant level, as well as among flower positions. The interaction between flower position and nutrient environment can affect the plant's mating system, and this differs between populations. Thus, reductions in herkogamy with flower positions may be expected in environments with either low pollinator abundance or low nutrients. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Current trends and future directions in flower development research.

PubMed

Scutt, Charlie P; Vandenbussche, Michiel

2014-11-01

Flowers, the reproductive structures of the approximately 400 000 extant species of flowering plants, exist in a tremendous range of forms and sizes, mainly due to developmental differences involving the number, arrangement, size and form of the floral organs of which they consist. However, this tremendous diversity is underpinned by a surprisingly robust basic floral structure in which a central group of carpels forms on an axis of determinate growth, almost invariably surrounded by two successive zones containing stamens and perianth organs, respectively. Over the last 25 years, remarkable progress has been achieved in describing the molecular mechanisms that control almost all aspects of flower development, from the phase change that initiates flowering to the final production of fruits and seeds. However, this work has been performed almost exclusively in a small number of eudicot model species, chief among which is Arabidopsis thaliana. Studies of flower development must now be extended to a much wider phylogenetic range of flowering plants and, indeed, to their closest living relatives, the gymnosperms. Studies of further, more wide-ranging models should provide insights that, for various reasons, cannot be obtained by studying the major existing models alone. The use of further models should also help to explain how the first flowering plants evolved from an unknown, although presumably gymnosperm-like ancestor, and rapidly diversified to become the largest major plant group and to dominate the terrestrial flora. The benefits for society of a thorough understanding of flower development are self-evident, as human life depends to a large extent on flowering plants and on the fruits and seeds they produce. In this preface to the Special Issue, we introduce eleven articles on flower development, representing work in both established and further models, including gymnosperms. We also present some of our own views on current trends and future directions of the flower development field. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

[Microscopic anatomy and volatile secondary metabolites at three stages of development of the inflorescences of Lantana camara (Verbenaceae)].

PubMed

Caroprese Araque, José Fernando; Parra Garcés, María Isabel; Arrieta Prieto, Dagoberto; Stashenko, Elena

2011-03-01

Plants of the Verbenaceae family, like L. camara, have called the attention of researchers, not only because of its high diversity and its distribution around the world, but also for its variable use as popular medicine to treat diseases like tetanus, rheumatism and malaria, and as bactericide and insecticide. To assess this, the morphology and ontogeny of the inflorescences of Lantana camara and the chemical composition of volatile secondary metabolites were analyzed at three different ontogeny stages. Plants were collected from the experimental crop area in CENIVAM, Bucaramanga, Colombia. Fresh inflorescence stages were established and analyzed using a stereoscopic microscope, fixed in FAA and included in parafine. Transversal and longitudinal 10 microm thick sections were prepared using a rotative microtome, safranine-fastgreen stained and were observed and photographed using a light microscope. The chemical composition of volatile secondary metabolites were analyzed for each stage. The analytes, obtained from 0.7 g of plant, were isolated by solid phase micro-extraction in the headspace mode (HS-SPME) and were placed in 20 ml vials. The components were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Stage I was microscopically characterized by an immature development in which the meristematic differentiation begins with a mass of cells. In Stage II, the morphogenetic movement gives way to the formation of the respective floral sexual structures, calyx and corolla. In Stage III, the different organs are conspicuous: four stamens epipetals and didynamous, monocarpelar, biloculate and globose gynoecium, upper ovary and lateral stigma; the flowers are hermaphroditic. The main secondary metabolites detected by GC-MS were bicyclosesquiphellandrene, E-beta-farnesene, E-beta-caryophyllene, gamma-muurolene + gamma-curcumene and alpha-zingiberene. Nevertheless, this study reports for the first time in plant species alpha-gurjunene, gamma-amorphene, alpha-muurolene, sesquithujene, alpha-trans-bergamotene and trans-cadina-1,4-diene. The diversity of compounds found can be only explained by the extraction methods employed, the developmental stages and section of the plant, the geographic conditions, collection time and the genetic constitution of the evaluated species.

Diagnostics, taxonomy, nomenclature and distribution of perennial Sesuvium (Aizoaceae) in Africa

PubMed Central

Sukhorukov, Alexander P.; Nilova, Maya V.; Erst, Andrey S.; Kushunina, Maria; Baider, Cláudia; Verloove, Filip; Salas-Pascual, Marcos; Belyaeva, Irina V.; Krinitsina, Anastasiya A.; Bruyns, Peter V.; Klak, Cornelia

2018-01-01

Abstract The taxonomy of perennial Sesuvium species in Africa has been poorly investigated until now. Previously five perennial species of Sesuvium were recognised in Africa (S. congense, S. crithmoides, S. mesembryanthemoides, S. portulacastrum, and S. sesuvioides). Based on the differing number of stamens, S. ayresii is accepted here as being distinct from S. portulacastrum. Field observations in Angola also led the authors to conclude that S. crystallinum and S. mesembryanthemoides are conspecific with S. crithmoides. A new subspecies, Sesuvium portulacastrum subsp. persoonii, is described from West Africa (Cape Verde, Gambia, Guinea-Bissau, Mauritania, Senegal). The molecular phylogeny indicates the position of S. portulacastrum subsp. persoonii within the “American lineage” as a part of the Sesuvium portulacastrum complex which needs further studies. A diagnostic key and taxonomic notes are provided for the six perennial species of Sesuvium found in Africa and recognised by the authors (S. ayresii, S. congense, S. crithmoides, S. portulacastrum subsp. portulacastrum, S. portulacastrum subsp. persoonii, S. verrucosum and the facultatively short-lived S. sesuvioides). The distribution of S. crithmoides, previously considered to be endemic to Angola, is now confirmed for the seashores of Republic of Congo and DR Congo. The American species S. verrucosum is reported for the first time for Africa (the Macaronesian islands: Cape Verde and the Canaries). It is locally naturalised in Gran Canaria, being a potentially invasive species. These findings as well as new records of S. verrucosum from Asia and the Pacific Islands confirm its proneness to transcontinental introduction. Lectotypes of S. brevifolium, S. crithmoides, S. crystallinum and S. mesembryanthemoides are selected. The seed micromorphology and anatomy of the perennial African species is studied. Compared to the seeds of some annual African Sesuvium investigated earlier, those of perennial species are smooth or slightly alveolate. The aril is one-layered and parenchymatous in all species and usually tightly covers the seed. The aril detachments from the seed coat that form a white stripe near the cotyledon area easily distinguish S. verrucosum from other species under study. PMID:29416411

Beetle pollination and flowering rhythm of Annona coriacea Mart. (Annonaceae) in Brazilian cerrado: Behavioral features of its principal pollinators.

PubMed

Costa, Marilza Silva; Silva, Ricardo José; Paulino-Neto, Hipólito Ferreira; Pereira, Mônica Josene Barbosa

2017-01-01

The conservation and sustainable management of Annona coriacea requires knowledge of its floral and reproductive biology, and of its main pollinators and their life cycles. In this work, we analyzed these aspects in detail. Floral biology was assessed by observing flowers from the beginning of anthesis to senescence. The visiting hours and behavior of floral visitors in the floral chamber were recorded, as were the sites of oviposition. Excavations were undertaken around specimens of A. coriacea to determine the location of immature pollinators. Anthesis was nocturnal, starting at sunset, and lasted for 52-56 h. The flowers were bisexual, protogynous and emitted a strong scent similar to the plant´s own ripe fruit. There was pronounced synchrony among all floral events (the period and duration of stigmatic receptivity, release of odor, pollen release and drooping flowers) in different individuals, but no synchrony in the same individuals. All of the flowers monitored were visited by beetle species of the genera Cyclocephala and Arriguttia. Beetles arrived at the flowers with their bodies covered in pollen and these pollen grains were transferred to the stigmata while foraging on nutritious tissues at the base of the petals. With dehiscence of the stamens and retention within the floral chamber, the bodies of the floral visitors were again covered with pollen which they carried to newly opened flowers, thus promoting the cycle of pollination. After leaving the flowers, female beetles often excavated holes in the soil to lay eggs. Larvae were found between the leaf litter and the first layer of soil under specimens of A. coriacea. Cyclocephala beetles were the main pollinators of A. coriacea, but Arriguttia brevissima was also considered a pollinator and is the first species of this genus to be observed in Annonaceae flowers. Annona coriacea was found to be self-compatible with a low reproductive efficiency in the area studied. The results of this investigation provide ecological data that should contribute to the conservation and economic exploitation of A. coriacea.

Emergence and patterning of the five cell types of the Zea mays anther locule

PubMed Central

Kelliher, Timothy; Walbot, Virginia

2011-01-01

One fundamental difference between plants and animals is the existence of a germ-line in animals and its absence in plants. In flowering plants the sexual organs (stamens and carpels) are composed almost entirely of somatic cells, a small subset of which switch to meiosis, however, the mechanism of meiotic cell fate acquisition is a long-standing botanical mystery. In the maize (Zea mays) anther microsporangium the somatic tissues consist of four concentric cell layers which surround and support reproductive cells as they progress through meiosis and pollen maturation. Male sterility, defined as the absence of viable pollen, is a common phenotype in flowering plants, and many male sterile mutants have defects in somatic and reproductive cell fate acquisition. However, without a robust model of anther cell fate acquisition based on careful observation of wild type anther ontogeny, interpretation of cell fate mutants is limited. To address this, the pattern of cell proliferation, expansion, and differentiation was tracked in three dimensions over thirty days of wild type (W23) anther development, using anthers stained with propidium iodide (PI) and/or 5-ethynyl-2′-deoxyuridine (EdU) (S-phase label) and imaged by confocal microscopy. The pervading lineage model of anther development claims that new cell layers are generated by coordinated, oriented cell divisions in transient precursor cell types. In reconstructing anther cell division patterns, however, we can only confirm this for the origin of the middle layer (ml) and tapetum, while young anther development appears more complex. We find that each anther cell type undergoes a burst of cell division after specification with a characteristic pattern of both cell expansion and division. Comparisons between two inbreds lines and between ab- and adaxial anther florets indicated near identity: anther development is highly canalized and synchronized. Three classical models of plant organ development are tested and ruled out; however, local clustering of developmental events was identified for several processes, including the first evidence for a direct relationship between the development of ml and tapetal cells. We speculate that small groups of ml and tapetum cells function as a developmental unit dedicated to the development of a single pollen grain. PMID:21070762

Beetle pollination and flowering rhythm of Annona coriacea Mart. (Annonaceae) in Brazilian cerrado: Behavioral features of its principal pollinators

PubMed Central

Pereira, Mônica Josene Barbosa

2017-01-01

The conservation and sustainable management of Annona coriacea requires knowledge of its floral and reproductive biology, and of its main pollinators and their life cycles. In this work, we analyzed these aspects in detail. Floral biology was assessed by observing flowers from the beginning of anthesis to senescence. The visiting hours and behavior of floral visitors in the floral chamber were recorded, as were the sites of oviposition. Excavations were undertaken around specimens of A. coriacea to determine the location of immature pollinators. Anthesis was nocturnal, starting at sunset, and lasted for 52–56 h. The flowers were bisexual, protogynous and emitted a strong scent similar to the plant´s own ripe fruit. There was pronounced synchrony among all floral events (the period and duration of stigmatic receptivity, release of odor, pollen release and drooping flowers) in different individuals, but no synchrony in the same individuals. All of the flowers monitored were visited by beetle species of the genera Cyclocephala and Arriguttia. Beetles arrived at the flowers with their bodies covered in pollen and these pollen grains were transferred to the stigmata while foraging on nutritious tissues at the base of the petals. With dehiscence of the stamens and retention within the floral chamber, the bodies of the floral visitors were again covered with pollen which they carried to newly opened flowers, thus promoting the cycle of pollination. After leaving the flowers, female beetles often excavated holes in the soil to lay eggs. Larvae were found between the leaf litter and the first layer of soil under specimens of A. coriacea. Cyclocephala beetles were the main pollinators of A. coriacea, but Arriguttia brevissima was also considered a pollinator and is the first species of this genus to be observed in Annonaceae flowers. Annona coriacea was found to be self-compatible with a low reproductive efficiency in the area studied. The results of this investigation provide ecological data that should contribute to the conservation and economic exploitation of A. coriacea. PMID:28152094

Positive selection on the K domain of the AGAMOUS protein in the Zingiberales suggests a mechanism for the evolution of androecial morphology.

PubMed

Almeida, Ana Maria R; Yockteng, Roxana; Otoni, Wagner C; Specht, Chelsea D

2015-01-01

The ABC model of flower development describes the molecular basis for specification of floral organ identity in model eudicots such as Arabidopsis and Antirrhinum. According to this model, expression of C-class genes is linked to stamen and gynoecium organ identity. The Zingiberales is an order of tropical monocots in which the evolution of floral morphology is characterized by a marked increase in petaloidy in the androecium. Petaloidy is a derived characteristic of the ginger families and seems to have arisen in the common ancestor of the ginger clade. We hypothesize that duplication of the C-class AGAMOUS (AG) gene followed by divergence of the duplicated AG copies during the diversification of the ginger clade lineages explains the evolution of petaloidy in the androecium. In order to address this hypothesis, we carried out phylogenetic analyses of the AG gene family across the Zingiberales and investigated patterns of gene expression within the androecium. Phylogenetic analysis supports a scenario in which Zingiberales-specific AG genes have undergone at least one round of duplication. Gene duplication was immediately followed by divergence of the retained copies. In particular, we detect positive selection in the third alpha-helix of the K domain of Zingiberales AGAMOUS copy 1 (ZinAG-1). A single fixed amino acid change is observed in ZinAG-1 within the ginger clade when compared to the banana grade. Expression analyses of AG and APETALA1/FRUITFULL (AP1/FUL) in Musa basjoo is similar to A- and C-class gene expressions in the Arabidopsis thaliana model, while Costus spicatus exhibits simultaneous expression of AG and AP1/FUL in most floral organs. We propose that this novel expression pattern could be correlated with the evolution of androecial petaloidy within the Zingiberales. Our results present an intricate story in which duplication of the AG lineage has lead to the retention of at least two diverged Zingiberales-specific copies, ZinAG-1 and Zingiberales AGAMOUS copy 2 (ZinAG-2). Positive selection on ZinAG-1 residues suggests a mechanism by which AG gene divergence may explain observed morphological changes in Zingiberales flowers. Expression data provides preliminary support for the proposed mechanism, although further studies are required to fully test this hypothesis.

Functional diversification of B MADS-box homeotic regulators of flower development: Adaptive evolution in protein-protein interaction domains after major gene duplication events.

PubMed

Hernández-Hernández, Tania; Martínez-Castilla, León Patricio; Alvarez-Buylla, Elena R

2007-02-01

B-class MADS-box genes have been shown to be the key regulators of petal and stamen specification in several eudicot model species such as Arabidopsis thaliana, Antirrhinum majus, and Petunia hybrida. Orthologs of these genes have been found across angiosperms and gymnosperms, and it is thought that the basic regulatory function of B proteins is conserved in seed plant lineages. The evolution of B genes is characterized by numerous duplications that might represent key elements fostering the functional diversification of duplicates with a deep impact on their role in the evolution of the floral developmental program. To evaluate this, we performed a rigorous statistical analysis with B gene sequences. Using maximum likelihood and Bayesian methods, we estimated molecular substitution rates and determined the selective regimes operating at each residue of B proteins. We implemented tests that rely on phylogenetic hypotheses and codon substitution models to detect significant differences in substitution rates (DSRs) and sites under positive adaptive selection (PS) in specific lineages before and after duplication events. With these methods, we identified several protein residues fixed by PS shortly after the origin of PISTILLATA-like and APETALA3-like lineages in angiosperms and shortly after the origin of the euAP3-like lineage in core eudicots, the 2 main B gene duplications. The residues inferred to have been fixed by positive selection lie mostly within the K domain of the protein, which is key to promote heterodimerization. Additionally, we used a likelihood method that accommodates DSRs among lineages to estimate duplication dates for AP3-PI and euAP3-TM6, calibrating with data from the fossil record. The dates obtained are consistent with angiosperm origins and diversification of core eudicots. Our results strongly suggest that novel multimer formation with other MADS proteins could have been crucial for the functional divergence of B MADS-box genes. We thus propose a mechanism of functional diversification and persistence of gene duplicates by the appearance of novel multimerization capabilities after duplications. Multimer formation in different combinations of regulatory proteins can be a mechanistic basis for the origin of novel regulatory functions and a gene regulatory mechanism for the appearance of morphological innovations.

Pleiotropic effects of the male sterile33 (ms33) mutation in Arabidopsis are associated with modifications in endogenous gibberellins, indole-3-acetic acid and abscisic acid.

PubMed

Fei, Houman; Zhang, Ruichuan; Pharis, Richard P; Sawhney, Vipen K

2004-08-01

Earlier, we reported that mutation in the Male Sterile33 (MS33) locus in Arabidopsis thaliana causes inhibition of stamen filament growth and a defect in the maturation of pollen grains [Fei and Sawhney (1999) Physiol Plant 105:165-170; Fei and Sawhney (2001) Can J Bot 79:118-129]. Here we report that the ms33 mutant has other pleiotropic effects, including aberrant growth of all floral organs and a delay in seed germination and in flowering time. These defects could be partially or completely restored by low temperature or by exogenous gibberellin A4 (GA4), which in all cases was more effective than GA3. Analysis of endogenous GAs showed that in wild type (WT) mature flowers GA4 was the major GA, and that relative to WT the ms33 flowers had low levels of the growth active GAs, GA1 and GA4, and very reduced levels of GA9, GA24 and GA15, precursors of GA4. This suggests that mutation in the MS33 gene may suppress the GA biosynthetic pathway that leads to GA4 via GA9 and the early 13-H C20 GAs. WT flowers also possessed a much higher level of indole-3-acetic acid (IAA), and a lower level of abscisic acid (ABA), relative to ms33 flowers. Low temperature induced partial restoration of male fertility in the ms33 flowers and this was associated with partial increase in GA4. In contrast, in WT flowers GA1 and GA4 were very much reduced by low temperature. Low temperature also had little effect on IAA or ABA levels of ms33 flowers, but did reduce (>2-fold) IAA levels in WT flowers. The double mutants, ms33 aba1-1 (an ABA-deficient mutant), and ms33 spy-3 (a GA signal transduction mutant) had flower phenotypes similar to ms33. Together, the data suggest that the developmental defects in the ms33 mutant are unrelated to ABA levels, but may be causally associated with reduced levels of IAA, GA1 and GA4, compared to WT flowers.

The involvement of InMIR167 in the regulation of expression of its target gene InARF8, and their participation in the vegetative and generative development of Ipomoea nil plants.

PubMed

Glazińska, Paulina; Wojciechowski, Waldemar; Wilmowicz, Emilia; Zienkiewicz, Agnieszka; Frankowski, Kamil; Kopcewicz, Jan

2014-02-15

The plant hormone auxin plays a critical role in regulating plant growth and development. Recent advances have been made that having improved our understanding of auxin response pathways, primarily by characterizing the genes encoding auxin response factors (ARFs) in Arabidopsis. In addition, the expression of some ARFs is regulated by microRNAs (miRNAs). In Arabidopsis thaliana, ARF6 and ARF8 are targeted by miR167, whereas ARF10, ARF16 and ARF17 are targeted by miR160. Nevertheless, little is known about any possible interactions between miRNAs and the auxin signaling pathway during plant development. In this study, we isolated the miR167 target gene InARF8 cDNA from the cotyledons of the short day plant (SDP) Ipomoea nil (named also Pharbitis nil). Additionally, the In-miR167 precursor was identified from the I. nil EST database and analyses of InARF8 mRNA, In-pre-miR167 and mature miR167 accumulation in the plant's vegetative and generative organs were performed. The identified cDNA of InARF8 contains a miR167 complementary sequence and shows significant similarity to ARF8 cDNAs of other plant species. The predicted amino acid sequence of InARF8 includes all of the characteristic domains for ARF family transcription factors (B3 DNA-binding domain, AUX/IAA-CTD and a glutamine-rich region). Quantitative RT-PCR reactions and in situ hybridization indicated that InARF8 was expressed primarily in the shoot apices, leaf primordia and hypocotyls of I. nil seedlings, as well as in flower pistils and petals. The InARF8 transcript level increased consistently during the entire period of pistil development, whereas in the stamens, the greatest transcriptional activity occurred only during the intensive elongation phase. Additionally, an expression analysis of both the precursor In-pre-miR167 molecules identified and mature miRNA was performed. We observed that, in most of the organs examined, the InARF8 expression pattern was opposite to that of MIR167, indicating that the gene's activity was regulated by mRNA cleavage. Our findings suggested that InARF8 and InMIR167 participated in the development of young tissues, especially the shoot apices and flower elements. The main function of MIR167 appears to be to regulate InARF8 organ localization. Copyright © 2013 Elsevier GmbH. All rights reserved.

Two early eudicot fossil flowers from the Kamikitaba assemblage (Coniacian, Late Cretaceous) in northeastern Japan

DOE PAGES

Takahashi, Masamichi; Herendeen, Patrick S.; Xiao, Xianghui

2017-05-11

Two new fossil taxa referable to the basal eudicot grade are described from the Kamikitaba locality (ca. 89 MYBP, early Coniacian: Late Cretaceous) in the Ashizawa Formation (Asamigawa Member) of Futaba Group in northeastern Japan. These charcoalified mesofossils exhibit well-preserved three-dimensional structure and were analyzed using synchrotron-radiation X-ray microtomography (SRXTM) at the Advanced Photon Source (APS) to document the composition and internal structure. Cathiaria japonica sp. nov. is represented by infructescence segments that consist of an axis bearing three to four fruits. The capsular fruits are sessile and dehiscent and consist of a gynoecium subtended by a bract. No perianthmore » parts are present. The gynoecium is monocarpellate containing two pendulous seeds. The carpel is ascidiate in the lower half and conduplicate in the upper part, style is deflected abaxially with a dorsiventral suture and a large, obliquely decurrent stigma. Pollen grains are tricolpate with a reticulate exine. The morphological features of Cathiaria are consistent with an assignment to the Buxaceae s. l. (including Didymelaceae). Archaeostella verticillata gen. et sp. nov. is represented by flowers that are small, actinomorphic, pedicellate, bisexual, semi-inferior, and multicarpellate. The floral receptacle is cup shaped with a perigynous perianth consisting of several tepals inserted around the rim. The androecium comprises ca. 120 stamens with clear differentiation into anther and filament. The anthers are basifixed and tetrasporangiate. The gynoecium consists of a whorl of ten conduplicate, laterally connate but distally distinct carpels with a conspicuous dorsal bulge, including a central cavity. The styles are short, becoming recurved with a ventrally decurrent stigma. The fruit type is a follicle. Seeds are ca. 10 per carpel, marginal, pendulous from the broad, oblique summit of the locule. Seeds are small, spindle-shaped, with a chalazal extension, Pollen grains are tricolpate with a reticulate exine pattern, suggesting a relationship to eudicots. The morphological features of Archaeostella indicate a possible relationship to Trochodendraceae in the basal grade of eudicots, although it is uncertain if the anther thecae open by longitudinal slits as in extant Trochodendron. The fossil currently provides the earliest record of the family and documents the presence of Trochodendraceae in eastern Eurasia during the middle part of the Late Cretaceous. Furthermore, the recovery of Cathiaria japonica and Archaeostella verticillata from the Kamikitaba locality suggests that the basal eudicot families Trochodendraceae and Buxaceae s. l. (including Didymelaceae) were differentiated and distributed in eastern Eurasia area during the Late Cretaceous.« less

Two early eudicot fossil flowers from the Kamikitaba assemblage (Coniacian, Late Cretaceous) in northeastern Japan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Masamichi; Herendeen, Patrick S.; Xiao, Xianghui

Two new fossil taxa referable to the basal eudicot grade are described from the Kamikitaba locality (ca. 89 MYBP, early Coniacian: Late Cretaceous) in the Ashizawa Formation (Asamigawa Member) of Futaba Group in northeastern Japan. These charcoalified mesofossils exhibit well-preserved three-dimensional structure and were analyzed using synchrotron-radiation X-ray microtomography (SRXTM) at the Advanced Photon Source (APS) to document the composition and internal structure. Cathiaria japonica sp. nov. is represented by infructescence segments that consist of an axis bearing three to four fruits. The capsular fruits are sessile and dehiscent and consist of a gynoecium subtended by a bract. No perianthmore » parts are present. The gynoecium is monocarpellate containing two pendulous seeds. The carpel is ascidiate in the lower half and conduplicate in the upper part, style is deflected abaxially with a dorsiventral suture and a large, obliquely decurrent stigma. Pollen grains are tricolpate with a reticulate exine. The morphological features of Cathiaria are consistent with an assignment to the Buxaceae s. l. (including Didymelaceae). Archaeostella verticillata gen. et sp. nov. is represented by flowers that are small, actinomorphic, pedicellate, bisexual, semi-inferior, and multicarpellate. The floral receptacle is cup shaped with a perigynous perianth consisting of several tepals inserted around the rim. The androecium comprises ca. 120 stamens with clear differentiation into anther and filament. The anthers are basifixed and tetrasporangiate. The gynoecium consists of a whorl of ten conduplicate, laterally connate but distally distinct carpels with a conspicuous dorsal bulge, including a central cavity. The styles are short, becoming recurved with a ventrally decurrent stigma. The fruit type is a follicle. Seeds are ca. 10 per carpel, marginal, pendulous from the broad, oblique summit of the locule. Seeds are small, spindle-shaped, with a chalazal extension, Pollen grains are tricolpate with a reticulate exine pattern, suggesting a relationship to eudicots. The morphological features of Archaeostella indicate a possible relationship to Trochodendraceae in the basal grade of eudicots, although it is uncertain if the anther thecae open by longitudinal slits as in extant Trochodendron. The fossil currently provides the earliest record of the family and documents the presence of Trochodendraceae in eastern Eurasia during the middle part of the Late Cretaceous. Furthermore, the recovery of Cathiaria japonica and Archaeostella verticillata from the Kamikitaba locality suggests that the basal eudicot families Trochodendraceae and Buxaceae s. l. (including Didymelaceae) were differentiated and distributed in eastern Eurasia area during the Late Cretaceous.« less

Stage- and tissue-expression of genes involved in the biosynthesis and signalling of ethylene in reproductive organs of damson plum (Prunus domestica L. subsp. insititia).

PubMed

Fernández-Otero, C I; de la Torre, F; Iglesias, R; Rodríguez-Gacio, M C; Matilla, A J

2007-01-01

In this work, four cDNA clones (Pd-ACS1,AJ890088; Pd-ETR1 and Pd-ERS1, AJ890092, AJ890091; and Pd-CTR1, AJ890089) encoding an ACC-synthase, two putative ethylene (ET) receptors, and a putative MAPKKK, respectively, were isolated and phylogenetically characterized in Prunus domestica L. subsp. insititia. Their expression was studied by real-time PCR during flower (closed, open and senescent) and fruit (early green, late green, maturation and ripening) development of damson plum, which is climateric. While two peaks of ET production were quantified at early green and ripening stages in whole fruits, the seed was not able to produce it during maturation and ripening stages. All studied genes were differentially expressed during flower and fruit development. In general, the level of transcripts of Pd-ACS1 was higher in fruits than in flowers. However, it was noteworthy that: (1) Pd-ACS1 expression was hardly detected in closed flowers and at low levels during early green stage; and fruit development provoked a notable differential expression in seeds, and pericarp; (2) the results of Pd-ACS1 expression during fruit development suggest a preponderant role of this gene from late green stage onward. The stamen was the only floral organ in which expression of both Pd-ETR1 and Pd-ERS1 receptor genes was not significantly altered during development; however, their expression decreased concomitantly with development of pistil (only floral organ to register a net ET production when fertilized) and during first days of ovary development (the highest ET production during all fruit development). Contrary to Pd-ERS1, the level of Pd-ETR1 mRNA was temporally quite similar in the seed. With regard Pd-ETR1, even its expression was very scarce during maturation of mesocarp, was stimulated during ripening. In the epicarp, Pd-ERS1 and Pd-ETR1 were low expressed during pit hardening increasing onward and decreasing during ripening. Pd-CTR1 expression was in the seed>mesocarp>epicarp. Spatial and temporal levels of Pd-ACS1, Pd-ETR1, Pd-ERS1 and Pd-CTR1 mRNAs described in this work demonstrate that the expression of these genes is not always constitutive and that control of its transcription may play an important role in regulating the development of reproductive organs of damson plum.

Positive selection and ancient duplications in the evolution of class B floral homeotic genes of orchids and grasses

PubMed Central

Mondragón-Palomino, Mariana; Hiese, Luisa; Härter, Andrea; Koch, Marcus A; Theißen, Günter

2009-01-01

Background Positive selection is recognized as the prevalence of nonsynonymous over synonymous substitutions in a gene. Models of the functional evolution of duplicated genes consider neofunctionalization as key to the retention of paralogues. For instance, duplicate transcription factors are specifically retained in plant and animal genomes and both positive selection and transcriptional divergence appear to have played a role in their diversification. However, the relative impact of these two factors has not been systematically evaluated. Class B MADS-box genes, comprising DEF-like and GLO-like genes, encode developmental transcription factors essential for establishment of perianth and male organ identity in the flowers of angiosperms. Here, we contrast the role of positive selection and the known divergence in expression patterns of genes encoding class B-like MADS-box transcription factors from monocots, with emphasis on the family Orchidaceae and the order Poales. Although in the monocots these two groups are highly diverse and have a strongly canalized floral morphology, there is no information on the role of positive selection in the evolution of their distinctive flower morphologies. Published research shows that in Poales, class B-like genes are expressed in stamens and in lodicules, the perianth organs whose identity might also be specified by class B-like genes, like the identity of the inner tepals of their lily-like relatives. In orchids, however, the number and pattern of expression of class B-like genes have greatly diverged. Results The DEF-like genes from Orchidaceae form four well-supported, ancient clades of orthologues. In contrast, orchid GLO-like genes form a single clade of ancient orthologues and recent paralogues. DEF-like genes from orchid clade 2 (OMADS3-like genes) are under less stringent purifying selection than the other orchid DEF-like and GLO-like genes. In comparison with orchids, purifying selection was less stringent in DEF-like and GLO-like genes from Poales. Most importantly, positive selection took place before the major organ reduction and losses in the floral axis that eventually yielded the zygomorphic grass floret. Conclusion In DEF-like genes of Poales, positive selection on the region mediating interactions with other proteins or DNA could have triggered the evolution of the regulatory mechanisms behind the development of grass-specific reproductive structures. Orchidaceae show a different trend, where gene duplication and transcriptional divergence appear to have played a major role in the canalization and modularization of perianth development. PMID:19383167

Potential of plant genetic systems for monitoring and screening mutagens

PubMed Central

Nilan, R. A.

1978-01-01

Plants have too long been ignored as useful screening and monitoring systems of environmental mutagens. However, there are about a dozen reliable, some even unique, plant genetic systems that can increase the scope and effectiveness of chemical and physical mutagen screening and monitoring procedures. Some of these should be included in the Tier II tests. Moreover, plants are the only systems now in use as monitors of genetic effects caused by polluted atmosphere and water and by pesticides. There are several major advantages of the plant test systems which relate to their reproductive nature, easy culture and growth habits that should be considered in mutagen screening and monitoring. In addition to these advantages, the major plant test systems exhibit numerous genetic and chromosome changes for determining the effects of mutagens. Some of these have not yet been detected in other nonmammalian and mammalian test systems, but probably occur in the human organism. Plants have played major roles in various aspects of mutagenesis research, primarily in mutagen screening (detection and verification of mutagenic activity), mutagen monitoring, and determining mutagen effects and mechanisms of mutagen action. They have played lesser roles in quantification of mutagenic activity and understanding the nature of induced mutations. Mutagen monitoring with plants, especially in situ on land or in water, will help determine potential genetic hazards of air and water pollutants and protect the genetic purity of crop plants and the purity of the food supply. The Tradescantia stamen-hair system is used in a mobile laboratory for determining the genetic effects of industrial and automobile pollution in a number of sites in the U.S.A. The fern is employed for monitoring genetic effects of water pollution in the Eastern states. The maize pollen system and certain weeds have monitored genetic effects of pesticides. Several other systems that have considerable value and should be developed and more widely used in mutagen monitoring and screening, especially for in situ monitoring, are discussed. Emphasis is placed on pollen systems in which changes in pollen structure, chemistry, and chromosomes can be scored for monitoring; and screening systems which can record low levels of genetic effects as well as provide information on the nature of induced mutations. The value of plant systems for monitoring and screening mutagens can be improved by: greater knowledge of plant cell processes at the molecular and ultrastructural levels; relating these processes to mutagen effects and plant cell responses; improving current systems for increased sensitivity, ease of detecting genetic and chromosome changes, recording of data (including automation), and for extending the range of genetic and chromosome end points; and designing and developing new systems with the aid of previous and current botanical and genetic knowledge. PMID:367768

Current understanding on Villosiclava virens, a unique flower-infecting fungus causing rice false smut disease.

PubMed

Fan, Jing; Yang, Juan; Wang, Yu-Qiu; Li, Guo-Bang; Li, Yan; Huang, Fu; Wang, Wen-Ming

2016-12-01

Villosiclava virens (Vv) is an ascomycete fungal pathogen that causes false smut disease in rice. Recent reports have revealed some interesting aspects of the enigmatic pathogen to address the question of why it specifically infects rice flowers and converts a grain into a false smut ball. Comparative and functional genomics have suggested specific adaptation of Vv in the colonization of rice flowers. Anatomical studies have disclosed that Vv specifically infects rice stamen filaments before heading and intercepts seed formation. In addition, Vv can occupy the whole inner space of a spikelet embracing all floral organs and activate the rice grain-filling network, presumably for nutrient acquisition to support the development of the false smut ball. This profile provides a general overview of the rice false smut pathogen, and summarizes advances in the Vv life cycle, genomics and genetics, and the molecular Vv-rice interaction. Current understandings of the Vv-rice pathosystem indicate that it is a unique and interesting system which can enrich the study of plant-pathogen interactions. Taxonomy: Ustilaginoidea virens is the anamorph form of the pathogen (Kingdom Fungi; Phylum Ascomycota; Class Ascomycetes; Subclass Incertae sedis; Order Incertae sedis; Family Incertae sedis; Genus Ustilaginoidea). The teleomorph form is Villosiclava virens (Kingdom Fungi; Phylum Ascomycota; Class Ascomycetes; Subclass Sordariomycetes; Order Hypocreales; Family Clavicipitaceae; Genus Villosiclava). Disease symptoms: The only visible symptom is the replacement of rice grains by ball-shaped fungal mycelia, namely false smut balls. When maturing, the false smut ball is covered with powdery chlamydospores, and the colour changes to yellowish, yellowish orange, green, olive green and, finally, to greenish black. Sclerotia are often formed on the false smut balls in autumn. Identification and detection: Vv conidia are round to elliptical, measuring 3-5 μm in diameter. Chlamydospores are ornamented with prominent irregularly curved spines, which are 200-500 nm in length. The sclerotia are black, horseshoe-shaped and irregular oblong or flat, ranging from 2 to 20 mm. Nested polymerase chain reaction (PCR) and quantitative PCR have been developed to specifically detect Vv presence in rice tissues and other biotic and abiotic samples in fields. Host range: Rice is the primary host for Vv. Natural infection by Vv has been found on several paddy field weeds, including Digitaria marginata, Panicum trypheron, Echinochloa crusgalli and Imperata cylindrica. However, the occurrence of infection in these potential alternative hosts is very rare. Life cycle: Vv infects rice spikelets at the late rice booting stage, and produces false smut balls covered with dark-green chlamydospores. Occasionally, sclerotia form on the surface of false smut balls in late autumn when the temperature fluctuates greatly between day and night. Both chlamydospores and sclerotia may serve as primary infection sources. Rainfall at the rice booting stage is a major environmental factor resulting in epidemics of rice false smut disease. Disease control: The use of fungicides is the major approach for the control of Vv. Several fungicides, such as cuproxat SC, copper oxychloride, tebuconazole, propiconazole, difenoconazole and validamycin, are often applied. However, the employment of resistant rice cultivars and genes has been limited, because of the poor understanding of rice resistance to Vv. Useful websites: Villosiclava virens genome sequence: http://www.ncbi.nlm.nih.gov/Traces/wgs/?val=JHTR01#contigs. © 2015 BSPP and John Wiley & Sons Ltd.