Cucumber leaf spot virus

USDA-ARS?s Scientific Manuscript database

Cucumber leaf spot virus (CLSV) was originally identified from cucumber (Cucumis sativus) in Germany, but has since been found in various parts of Europe, the UK, and the Middle East, including Jordan, Saudi Arabia, Bulgaria, Poland, and Spain. CLSV is known to cause symptoms ranging from chloroti...

Bacterial Leaf Spot of Lettuce: Request for Samples

USDA-ARS?s Scientific Manuscript database

Bacterial leaf spot of lettuce caused by by Xanthomonas campestris pv. vitians has been affecting coastal California crops for many years and has become a chronic problem. Differences in pathogen genotypes have been demonstrated and correlated to disease responses on resistant and susceptible cultiv...

Investigating alternative strategies for managing bacterial angular leaf spot in strawberry nursery production

USDA-ARS?s Scientific Manuscript database

The focus of this article is to discuss some of the approaches we have tested for managing the bacterial pathogen Xanthomonas fragariae in infected strawberry nursery stock. X. fragariae causes angular leaf spot (ALS) in strawberry. The pathogen is transmitted to production fields almost exclusively...

Alternaria leaf spot in Michigan and fungicide sensitivity issues

USDA-ARS?s Scientific Manuscript database

Since 2010 there has been an increase in identification of Alternaria leaf spot on sugar beet in Michigan and other growing regions in the US and Canada. In 2016, the disease was severe enough to cause economic losses in the Michigan growing region. Michigan isolates from sugar beet were examined ...

Reaction of the BASE 120 lines to angular leaf spot in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Common bean (Phaseolus vulgaris L.) is limited by diseases such as Angular leaf spot (ALS), caused by Phaeoisariopsis griseola (Sacc.) Ferraris sin. Pseudocercospora griseola (Sacc.) Crous & U. Braun. The virulence of Phaeoisariopis griseola isolate ALS-9029-JD2 from Juana Diaz, PR was determined by...

Efficacy of management tools for control of Phytophthora plurivora leaf spot of Rhododendron, 2014

USDA-ARS?s Scientific Manuscript database

This study was conducted as part of the IR-4 Ornamental Horticulture program to evaluate fungicides and biopesticides for management of leaf spot of Rhododendron caused by Phytophthora plurivora. The experiment was conducted by treating two-year old Rhododendron plants with fungicides on September 2...

Stemphylium leaf spot of parsley in California caused by Stemphylium vesicarium

USDA-ARS?s Scientific Manuscript database

From 2009 through 2011, a previously undescribed disease occurred on commercial parsley in coastal (Ventura County) California. Symptoms of the disease consisted of circular to oval, tan to brown leaf spots and resulted in loss of crop quality and hence reduced yields. A fungus was consistently isol...

Identification and Characterization of Pseudocercospora pyricola Causing Leaf Spots on Aronia melanocarpa.

PubMed

Park, Sung-Hee; Choi, In-Young; Seo, Kyoung-Won; Kim, Jin-Ho; Galea, Victor; Shin, Hyeon-Dong

2017-03-01

Leaf spot disease on black chokeberry ( Aronia melanocarpa ) was observed at several locations in Korea during 2014-2015. Leaf spots were distinct, scattered over the leaf surface and along the leaf border, subcircular to irregular and brown surrounded by a distinct dark color, and were expanded and coalesced into irregularly shaped lesions. Severely infected leaves became dry and fell off eventually. The causative agent was identified as Pseudocercospora pyricola . Morphological observations and phylogenetic analyses of multiple genes, including internal transcribed spacer, translation elongation factor 1-alpha, actin, and the large subunit ribosomal DNA were conducted. The pathogenicity test was conducted twice yielding similar results, fulfilling Koch's postulates. To our knowledge, this is the first report on P. pyricola infection of A. melanocarpa globally.

Stability of tetraconazole-resistant isolates of Cercospora beticola after exposure to different temperature and time treatments

USDA-ARS?s Scientific Manuscript database

Cercospora leaf spot caused by Cercospora beticola is the major foliar disease effecting sugar beet (Beta vulgaris L.) production in North Dakota and Minnesota. The sterol demethylation inhibitor (DMI) fungicide tetraconazole is widely-used to manage Cercospora leaf spot. However, there has been an ...

Bacterial brown leaf spot of citrus, a new disease caused by Burkholderia andropogonis

USDA-ARS?s Scientific Manuscript database

A new bacterial disease of citrus was recently identified in Florida and named as bacterial brown leaf spot (BBLS) of citrus. BBLS-infected citrus displayed flat, circular and brownish lesions with water-soaked margins surrounded by a chlorotic halo on leaves. Based on Biolog carbon source metabolic...

Systems genetics reveals a transcriptional network associated with susceptibility in the maize-grey leaf spot pathosystem

USDA-ARS?s Scientific Manuscript database

We have applied a systems genetics approach to elucidate molecular mechanisms of maize responses to gray leaf spot (GLS) disease, caused by Cercospora zeina, a major threat to maize production globally. We conducted expression QTL (eQTL) analysis of gene expression variation measured in earleaf samp...

RNA-Sequencing of Cercospora beticola DMI-sensitive and -resistant isolates after treatment with tetraconazole identifies common and contrasting pathway induction

USDA-ARS?s Scientific Manuscript database

Cercospora beticola causes Cercospora leaf spot of sugarbeet. Cercospora leaf spot management measures often include application of the sterol demethylation inhibitor (DMI) class of fungicides. The reliance on DMIs and the consequent selection pressures imposed by their widespread use has led to th...

Cryptic diversity, pathogenicity, and evolutionary species boundaries in Cercospora populations associated with Cercospora leaf spot of Beta vulgaris

USDA-ARS?s Scientific Manuscript database

Cercospora is one of the largest genera of hyphomycetes accommodating several important phytopathogenic species associated with foliar diseases of vegetable and field crops. Cercospora leaf spot (CLS), caused by C. beticola, is a destructive disease of Beta vulgaris (sugar beet, table beet and swiss...

Identification and Characterization of Pseudocercospora pyricola Causing Leaf Spots on Aronia melanocarpa

PubMed Central

Park, Sung-Hee; Choi, In-Young; Seo, Kyoung-Won; Kim, Jin-Ho; Galea, Victor

2017-01-01

Leaf spot disease on black chokeberry (Aronia melanocarpa) was observed at several locations in Korea during 2014–2015. Leaf spots were distinct, scattered over the leaf surface and along the leaf border, subcircular to irregular and brown surrounded by a distinct dark color, and were expanded and coalesced into irregularly shaped lesions. Severely infected leaves became dry and fell off eventually. The causative agent was identified as Pseudocercospora pyricola. Morphological observations and phylogenetic analyses of multiple genes, including internal transcribed spacer, translation elongation factor 1-alpha, actin, and the large subunit ribosomal DNA were conducted. The pathogenicity test was conducted twice yielding similar results, fulfilling Koch's postulates. To our knowledge, this is the first report on P. pyricola infection of A. melanocarpa globally. PMID:28435353

Predicting favorable conditions for early leaf spot of peanut using output from the Weather Research and Forecasting (WRF) model.

PubMed

Olatinwo, Rabiu O; Prabha, Thara V; Paz, Joel O; Hoogenboom, Gerrit

2012-03-01

Early leaf spot of peanut (Arachis hypogaea L.), a disease caused by Cercospora arachidicola S. Hori, is responsible for an annual crop loss of several million dollars in the southeastern United States alone. The development of early leaf spot on peanut and subsequent spread of the spores of C. arachidicola relies on favorable weather conditions. Accurate spatio-temporal weather information is crucial for monitoring the progression of favorable conditions and determining the potential threat of the disease. Therefore, the development of a prediction model for mitigating the risk of early leaf spot in peanut production is important. The specific objective of this study was to demonstrate the application of the high-resolution Weather Research and Forecasting (WRF) model for management of early leaf spot in peanut. We coupled high-resolution weather output of the WRF, i.e. relative humidity and temperature, with the Oklahoma peanut leaf spot advisory model in predicting favorable conditions for early leaf spot infection over Georgia in 2007. Results showed a more favorable infection condition in the southeastern coastline of Georgia where the infection threshold were met sooner compared to the southwestern and central part of Georgia where the disease risk was lower. A newly introduced infection threat index indicates that the leaf spot threat threshold was met sooner at Alma, GA, compared to Tifton and Cordele, GA. The short-term prediction of weather parameters and their use in the management of peanut diseases is a viable and promising technique, which could help growers make accurate management decisions, and lower disease impact through optimum timing of fungicide applications.

Predicting favorable conditions for early leaf spot of peanut using output from the Weather Research and Forecasting (WRF) model

NASA Astrophysics Data System (ADS)

Olatinwo, Rabiu O.; Prabha, Thara V.; Paz, Joel O.; Hoogenboom, Gerrit

2012-03-01

Early leaf spot of peanut ( Arachis hypogaea L.), a disease caused by Cercospora arachidicola S. Hori, is responsible for an annual crop loss of several million dollars in the southeastern United States alone. The development of early leaf spot on peanut and subsequent spread of the spores of C. arachidicola relies on favorable weather conditions. Accurate spatio-temporal weather information is crucial for monitoring the progression of favorable conditions and determining the potential threat of the disease. Therefore, the development of a prediction model for mitigating the risk of early leaf spot in peanut production is important. The specific objective of this study was to demonstrate the application of the high-resolution Weather Research and Forecasting (WRF) model for management of early leaf spot in peanut. We coupled high-resolution weather output of the WRF, i.e. relative humidity and temperature, with the Oklahoma peanut leaf spot advisory model in predicting favorable conditions for early leaf spot infection over Georgia in 2007. Results showed a more favorable infection condition in the southeastern coastline of Georgia where the infection threshold were met sooner compared to the southwestern and central part of Georgia where the disease risk was lower. A newly introduced infection threat index indicates that the leaf spot threat threshold was met sooner at Alma, GA, compared to Tifton and Cordele, GA. The short-term prediction of weather parameters and their use in the management of peanut diseases is a viable and promising technique, which could help growers make accurate management decisions, and lower disease impact through optimum timing of fungicide applications.

Characterization of the common bean host and Pseudocercospora griseola the causative agent of angular leaf spot disease in Tanzania

USDA-ARS?s Scientific Manuscript database

Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola is one of the most important diseases of common bean in Tanzania. Breeding for resistance to this disease is complicated by the variable nature of the pathogen. In Tanzania no thorough analysis of the variability of this pathogen...

Association analysis and identification of SNP markers for Stemphylium leaf spot (Stemphylium botryosum f. sp. spinacia) resistance in spinach (Spinacia oleracea)

USDA-ARS?s Scientific Manuscript database

Stemphylium leaf spot, caused by Stemphylium botryosum f. sp. spinacia is an important disease in spinach. Use of genetic resistance is an efficient, economic and environment-friendly method to control this disease. The objective of this research was to conduct association analysis and identify SNP ...

Somaclonal variation in hybrid poplars for resistance to Septoria leaf spot

Treesearch

M.E. Ostry; D. D. Skilling

1987-01-01

Tissue culture techniques have been used to obtain hybrid poplars with putative resistance to leaf spot caused by Septoria musiva from clones previously susceptible to the disease. Stem internode explants were used to obtain proliferating callus cultures. Adventitious bud formation and shoot proliferation were then induced. Elongated shoots were excised and rooted in a...

Association analysis of bacterial leaf spot resistance and SNP markers derived from expressed sequence tags (ESTs) in lettuce (Lactuca sativa L.)

USDA-ARS?s Scientific Manuscript database

Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Since there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A total of 179 lettuce ge...

First Report of Leaf Spot Caused by Alternaria tenuissima on Black Chokeberry (Aronia melanocarpa) in Korea.

PubMed

Wee, Jung-In; Park, Jong-Han; Back, Chang-Gi; You, Young-Hyun; Chang, Taehyun

2016-09-01

In July 2015, diseased leaves of black chokeberry ( Aronia melanocarpa ) were observed in Danyang and Gochang, Korea. The symptoms appeared as circular or irregular brown leaf spots, from which Alternaria tenuissima was isolated. The isolates were cultured on potato dextrose agar, and their morphological characteristics were observed under a light microscope. The colonies were whitish to ash colored. The pathogenicity test on healthy black chokeberry leaves produced circular brown spots, in line with the original symptoms. Molecular analyses of the ITS, GPD, RPB2, and TEF genes were conducted to confirm the identity of the pathogen. The phylogeny of the multi-gene sequences indicated that the causal agent was A. tenuissima . This study is the first report of A. tenuissima leaf spot on black chokeberry ( A. melanocarpa ).

RNA-Seq analysis of resistant and susceptible sub-tropical maize lines reveals a role for kauralexins in resistance to grey leaf spot disease, caused by Cercospora zeina

USDA-ARS?s Scientific Manuscript database

Cercospora zeina is a foliar pathogen responsible for maize grey leaf spot in southern Africa that negatively impacts maize production. Plants use a variety of chemical and structural mechanisms to defend themselves against invading pathogens such as C. zeina, including the production of secondary m...

Coupling Spore Traps and Quantitative PCR Assays for Detection of Cercospora sojina, the Causal Agent of Soybean Frogeye Leaf Spot

USDA-ARS?s Scientific Manuscript database

Frogeye leaf spot (FLS), caused by Cercospora sojina Hara, is a common disease of soybean. Significant yield losses (10–60%) have been attributed to FLS. We present a novel trapping approach using Vaseline coated slides placed at a 45° angle within a passive, wind-vane spore trap used in combination...

First Report of Leaf Spot Caused by Alternaria tenuissima on Black Chokeberry (Aronia melanocarpa) in Korea

PubMed Central

Wee, Jung-In; Park, Jong-Han; Back, Chang-Gi; You, Young-Hyun

2016-01-01

In July 2015, diseased leaves of black chokeberry (Aronia melanocarpa) were observed in Danyang and Gochang, Korea. The symptoms appeared as circular or irregular brown leaf spots, from which Alternaria tenuissima was isolated. The isolates were cultured on potato dextrose agar, and their morphological characteristics were observed under a light microscope. The colonies were whitish to ash colored. The pathogenicity test on healthy black chokeberry leaves produced circular brown spots, in line with the original symptoms. Molecular analyses of the ITS, GPD, RPB2, and TEF genes were conducted to confirm the identity of the pathogen. The phylogeny of the multi-gene sequences indicated that the causal agent was A. tenuissima. This study is the first report of A. tenuissima leaf spot on black chokeberry (A. melanocarpa). PMID:27790070

Organic rice disease management using genetic resistance, cover crop and organic fertilizer

USDA-ARS?s Scientific Manuscript database

The strong market demand for organic rice has driven the continued increase of organic rice production in the US. However, growers still lack effective tools to manage narrow brown leaf spot (NBLS) caused by Cercospora janseana and brown spot caused by Cochliobolus miyabeanus, two common diseases af...

Evaluation of banana hybrids for tolerance to black leaf streak (Mycosphaerella fijiensis Morelet) in Puerto Rico

USDA-ARS?s Scientific Manuscript database

In Puerto Rico, bananas (including plantains) are important agricultural commodities; their combined production totaled 133,500 tons in 2008. Black leaf streak (BLS) and Sigatoka leaf spot diseases, caused by Mycosphaerella fijiensis and M. musicola, respectively, are responsible for significant los...

Morphological and molecular characterization of Cladosporium cladosporioides species complex causing pecan tree leaf spot.

PubMed

Walker, C; Muniz, M F B; Rolim, J M; Martins, R R O; Rosenthal, V C; Maciel, C G; Mezzomo, R; Reiniger, L R S

2016-09-16

The objective of this study was to characterize species of the Cladosporium cladosporioides complex isolated from pecan trees (Carya illinoinensis) with symptoms of leaf spot, based on morphological and molecular approaches. Morphological attributes were assessed using monosporic cultures on potato dextrose agar medium, which were examined for mycelial growth, sporulation, color, and conidia and ramoconidia size. Molecular characterization comprised isolation of DNA and subsequent amplification of the translation elongation factor 1α (TEF-1α) region. Three species of the C. cladosporioides complex were identified: C. cladosporioides, Cladosporium pseudocladosporioides, and Cladosporium subuliforme. Sporulation was the most important characteristic differentiating species of this genus. However, morphological features must be considered together with molecular analysis, as certain characters are indistinguishable between species. TEF-1αcan be effectively used to identify and group isolates belonging to the C. cladosporioides complex. The present study provides an important example of a methodology to ascertain similarity between isolates of this complex causing leaf spot in pecan trees, which should facilitate future pathogenicity studies.

Development and Utilization of InDel Markers to Identify Peanut (Arachis hypogaea L.) Disease Resistance

USDA-ARS?s Scientific Manuscript database

Peanut diseases, such as leaf spot and spotted wilt caused by Tomato Spotted Wilt Virus, can significantly reduce yield and quality. Application of marker assisted plant breeding requires the development and validation of different types of DNA molecular markers. Nearly 10,000 SSR-based molecular ...

Indirect selection for resistance to ear rot and leaf diseases in maize lines using biplots.

PubMed

Pereira, G S; Camargos, R B; Balestre, M; Von Pinho, R G; C Melo, W M

2015-09-21

Leaf disease and ear rot have caused reductions in maize yield in Brazil and other producer countries. Therefore, the aims of this study were to analyze the association between husked ear yield and the severity of maize white spot, gray leaf spot, helminthosporium, and ear rot caused by Fusarium verticillioides and Diplodia maydis using biplots in a mixed-model approach. The responses of 238 lines introduced to Brazil and four controls were evaluated using an incomplete block design with three replicates in two locations: Lavras and Uberlândia, Minas Gerais, Brazil. Two experiments were conducted in each location, one with F. verticillioides and the other with D. maydis. The mixed models elucidated the relationship between yield, leaf disease, and ear disease. Significant genotype x environment and genotype x pathogen interactions were observed. In conclusion, husked ear yield is more associated with ear rot than with the leaf diseases evaluated, justifying the indirect selection for resistance to kernel rot in maize-F. verticillioides and maize-D. maydis pathosystems by yield evaluation.

Potassium influences forage bermudagrass yield and fungal leaf disease severity in Mississippi

USDA-ARS?s Scientific Manuscript database

Leaf spot diseases are associated with K deficiency in forage bermudagrass. In 2010, a natural disease epiphytotic caused by six species of Bipolaris, Curvularia, and Exserohilum (dematiaceous hyphomycetes) was evaluated in 56 plots of ‘Tifton 44' bermudagrass in Mississippi. Pathogen occurrence, di...

Reaction of sorghum lines to zonate leaf spot and rough leaf spot

USDA-ARS?s Scientific Manuscript database

Abundant, frequent rains, along with humid and cloudy conditions during the early part of the 2015 growing season, provided conducive conditions for an unusually severe outbreak of zonate leaf spot and rough leaf spot in a block of sorghum lines at the Texas A&M AgriLife Research Farm, Burleson Coun...

Black Gum Mortality (Pest Alert)

Treesearch

USDA Forest Service

A large number of black gum trees (Nyssa Sylvatica) have been found dying in North Carolina, Tennessee, Virginia, and Georgia. The observed trees have been in the mountains of these States. The trees are often associated with dogwood trees infected with Disculd sp., which causes dogwood anthracnose. The symptoms on black gums include leaf spots, leaf blotches, leaves...

High density genetic linkage map and bin mapping for disease resistance QTLs in peanut

USDA-ARS?s Scientific Manuscript database

Mapping and identification of QTLs are important for efficient marker-assisted breeding and for analysis of the molecular mechanisms regulating traits. Diseases, such as early and late leaf spots, Tomato spotted wilt virus (TSWV), cause significant loses to peanut growers. Our goal is to develop a h...

Identification of Alfalfa Leaf Diseases Using Image Recognition Technology

PubMed Central

Qin, Feng; Liu, Dongxia; Sun, Bingda; Ruan, Liu; Ma, Zhanhong; Wang, Haiguang

2016-01-01

Common leaf spot (caused by Pseudopeziza medicaginis), rust (caused by Uromyces striatus), Leptosphaerulina leaf spot (caused by Leptosphaerulina briosiana) and Cercospora leaf spot (caused by Cercospora medicaginis) are the four common types of alfalfa leaf diseases. Timely and accurate diagnoses of these diseases are critical for disease management, alfalfa quality control and the healthy development of the alfalfa industry. In this study, the identification and diagnosis of the four types of alfalfa leaf diseases were investigated using pattern recognition algorithms based on image-processing technology. A sub-image with one or multiple typical lesions was obtained by artificial cutting from each acquired digital disease image. Then the sub-images were segmented using twelve lesion segmentation methods integrated with clustering algorithms (including K_means clustering, fuzzy C-means clustering and K_median clustering) and supervised classification algorithms (including logistic regression analysis, Naive Bayes algorithm, classification and regression tree, and linear discriminant analysis). After a comprehensive comparison, the segmentation method integrating the K_median clustering algorithm and linear discriminant analysis was chosen to obtain lesion images. After the lesion segmentation using this method, a total of 129 texture, color and shape features were extracted from the lesion images. Based on the features selected using three methods (ReliefF, 1R and correlation-based feature selection), disease recognition models were built using three supervised learning methods, including the random forest, support vector machine (SVM) and K-nearest neighbor methods. A comparison of the recognition results of the models was conducted. The results showed that when the ReliefF method was used for feature selection, the SVM model built with the most important 45 features (selected from a total of 129 features) was the optimal model. For this SVM model, the recognition accuracies of the training set and the testing set were 97.64% and 94.74%, respectively. Semi-supervised models for disease recognition were built based on the 45 effective features that were used for building the optimal SVM model. For the optimal semi-supervised models built with three ratios of labeled to unlabeled samples in the training set, the recognition accuracies of the training set and the testing set were both approximately 80%. The results indicated that image recognition of the four alfalfa leaf diseases can be implemented with high accuracy. This study provides a feasible solution for lesion image segmentation and image recognition of alfalfa leaf disease. PMID:27977767

Identification of Alfalfa Leaf Diseases Using Image Recognition Technology.

PubMed

Qin, Feng; Liu, Dongxia; Sun, Bingda; Ruan, Liu; Ma, Zhanhong; Wang, Haiguang

2016-01-01

Common leaf spot (caused by Pseudopeziza medicaginis), rust (caused by Uromyces striatus), Leptosphaerulina leaf spot (caused by Leptosphaerulina briosiana) and Cercospora leaf spot (caused by Cercospora medicaginis) are the four common types of alfalfa leaf diseases. Timely and accurate diagnoses of these diseases are critical for disease management, alfalfa quality control and the healthy development of the alfalfa industry. In this study, the identification and diagnosis of the four types of alfalfa leaf diseases were investigated using pattern recognition algorithms based on image-processing technology. A sub-image with one or multiple typical lesions was obtained by artificial cutting from each acquired digital disease image. Then the sub-images were segmented using twelve lesion segmentation methods integrated with clustering algorithms (including K_means clustering, fuzzy C-means clustering and K_median clustering) and supervised classification algorithms (including logistic regression analysis, Naive Bayes algorithm, classification and regression tree, and linear discriminant analysis). After a comprehensive comparison, the segmentation method integrating the K_median clustering algorithm and linear discriminant analysis was chosen to obtain lesion images. After the lesion segmentation using this method, a total of 129 texture, color and shape features were extracted from the lesion images. Based on the features selected using three methods (ReliefF, 1R and correlation-based feature selection), disease recognition models were built using three supervised learning methods, including the random forest, support vector machine (SVM) and K-nearest neighbor methods. A comparison of the recognition results of the models was conducted. The results showed that when the ReliefF method was used for feature selection, the SVM model built with the most important 45 features (selected from a total of 129 features) was the optimal model. For this SVM model, the recognition accuracies of the training set and the testing set were 97.64% and 94.74%, respectively. Semi-supervised models for disease recognition were built based on the 45 effective features that were used for building the optimal SVM model. For the optimal semi-supervised models built with three ratios of labeled to unlabeled samples in the training set, the recognition accuracies of the training set and the testing set were both approximately 80%. The results indicated that image recognition of the four alfalfa leaf diseases can be implemented with high accuracy. This study provides a feasible solution for lesion image segmentation and image recognition of alfalfa leaf disease.

A gene encoding maize caffeoyl-CoA O-methyltransferase confers quantitative resistance to multiple pathogens.

PubMed

Yang, Qin; He, Yijian; Kabahuma, Mercy; Chaya, Timothy; Kelly, Amy; Borrego, Eli; Bian, Yang; El Kasmi, Farid; Yang, Li; Teixeira, Paulo; Kolkman, Judith; Nelson, Rebecca; Kolomiets, Michael; L Dangl, Jeffery; Wisser, Randall; Caplan, Jeffrey; Li, Xu; Lauter, Nick; Balint-Kurti, Peter

2017-09-01

Alleles that confer multiple disease resistance (MDR) are valuable in crop improvement, although the molecular mechanisms underlying their functions remain largely unknown. A quantitative trait locus, qMdr 9.02 , associated with resistance to three important foliar maize diseases-southern leaf blight, gray leaf spot and northern leaf blight-has been identified on maize chromosome 9. Through fine-mapping, association analysis, expression analysis, insertional mutagenesis and transgenic validation, we demonstrate that ZmCCoAOMT2, which encodes a caffeoyl-CoA O-methyltransferase associated with the phenylpropanoid pathway and lignin production, is the gene within qMdr 9.02 conferring quantitative resistance to both southern leaf blight and gray leaf spot. We suggest that resistance might be caused by allelic variation at the level of both gene expression and amino acid sequence, thus resulting in differences in levels of lignin and other metabolites of the phenylpropanoid pathway and regulation of programmed cell death.

Antifungal, Mosquito Deterrent, and Larvicidal Activity of N-(benzylidene)-3-cyclohexylpropionic Acid Hydrazide Derivatives

DTIC Science & Technology

2013-01-01

chum sp.), Phomopsis and Botrytis diseases are serious problems of strawberry fruit in especially southeastern US N. Tabanca (&) A. Ali I. A...obscurans is a common fungus that causes leaf blight in strawberry and other plants, while P. viticola causes Phomopsis cane and leaf spot of grapes...The three Collet- otrichum species and P. obscurans were isolated from strawberry (Fragaria ananassa Duchesne), while P. viti- cola and B. cinerea were

Potential of Trichoderma species on Helminthosporium causing leaf spot on cane palm, Chrysalidocarpus lutescens.

PubMed

Jegathambigai, V; Karunaratne, M D S D; Svinningen, A; Mikunthan, G

2008-01-01

The cane palm, Chrysalidocarpus lutescens is one among the plant material of the export industries in Sri Lanka. The export quality of C. lutescens was declined due to the repeated occurrence of a leaf spot caused by Helminthosporium. Widespread occurrence of the leaf spot affected the cane palm production and succumb it to a huge setback in the floriculture industry in Sri Lanka. Being an export industry eco-friendly means of disease control was the prime focus for a better management of such vulnerable disease. Trichoderma is a potential bio agent, which has definite role in suppressing the inoculum of Helminthosporium sp. This study aims to evaluate the efficacy of Trichoderma species to control naturally established leaf spot in cane palm under field conditions. Three isolates of T. viride and two isolates of T. harzianum were evaluated. All the Trichoderma species performed significantly in reducing the disease incidence. T. viride + T. harzianum combination (1 x 10(10) cfu/ml) was the best compared to chemical in decreasing the mean disease severity index and improving the frequency of healthy plants. The colour of the leaves regained due to the application of Trichoderma sp. The results revealed that leaf spot incidence was lowered significantly in cane palms treated with Trichoderma species followed by treatment with combination of Trichoderma sp. and fungicides. The fungicide mixture (hexaconozole 50 g/l + Isoprothiolane 400 g/l) failed to lower the disease incidence and had no effect in suppressing the inocula of Helminthosporium, although recommended. Mixing of Trichoderma species with fungicide did not exhibit any additive effect. The combination of different species of Trichoderma would target species of Helminthosporium that exist as a complex group under field conditions. The results also proved that the existence of heterogeneity in Helminthosporium that could be tackled and effectively controlled by a combination of different species of the bio-agent, if available, to broaden the selectivity of the pathogens. The use of Trichoderma species had claimed not only to reduce the incidence of Helminthosporium but also to sustain the growth and vigor of the C. lutescens to most fit for exporting.

Field evaluation of soybean lines from a new source of resistance to Cercospora kikuchii, 2013

USDA-ARS?s Scientific Manuscript database

Purple seed stain, which is caused by the fungus Cercospora kikuchii, is an important seed disease which causes soybean seed quality losses when environmental conditions favor its growth, and harvest is delayed due to wet field conditions. Frogeye leaf spot caused by the fungus Cercospora sojina is...

Field evaluations of leaf spot resistance and yield in peanut genotypes in the United States and Bolivia

USDA-ARS?s Scientific Manuscript database

Field experiments were conducted in 2002-2006 to characterize yield potential and disease resistance to Cercospora arachidicola (early leaf spot) and Cercosporidium personatum (late leaf spot) in the Bolivian peanut (Arachis hypogaea) cultivar, Bayo Grande, and breeding lines developed from crosses ...

RosBREED: From genomics to DNA-informed breeding in strawberry

USDA-ARS?s Scientific Manuscript database

Angular leaf spot caused by Xanthomonas fragariae is the only major bacterial disease of cultivated strawberry (Fragaria ×ananassa). While this disease may cause reductions of up to 8 % of marketable yield in Florida winter annual production, no resistant cultivars have been commercialized. Wild acc...

A journey from a SSR-based low density map to a SNP-based high density map for identification of disease resistance quantitative trait loci in peanut

USDA-ARS?s Scientific Manuscript database

Mapping and identification of quantitative trait loci (QTLs) are important for efficient marker-assisted breeding. Diseases such as leaf spots and Tomato spotted wilt virus (TSWV) cause significant loses to peanut growers. The U.S. Peanut Genome Initiative (PGI) was launched in 2004, and expanded to...

Application of forwardchaining method to diagnosis of onion plant diseases

NASA Astrophysics Data System (ADS)

Sitanggang, Delima; Siregar, Saut D.; Situmeang, Suryani M. F.; Indra, Evta; Sagala, Ayu R.; Sihombing, Oloan; Nababan, Marlince; Pasaribu, Hendra; Damanik, Rudolf R.; Turnip, Mardi; Saragih, Rijois I. E.

2018-04-01

Red Onion is a tuber plant that is widely used by the people of Indonesia, both as herbs and herbal medicines. Onion farmers have limitations in identifying diseases that attack their crops.This disease can cause crop failure against the onion.This design begins with the creation of a knowledge base up to input-output design with forward chaining method. The results of this design can assist farmers in identifying their plant diseases. Based on diagnostic results of several methods that have been done testing can diagnose diseases contained in onion plants. With symptoms data that has been determined by the expert with the value of each symptom is different. As for the symptoms that have been determined that the leaves contain patches with a value of 0.3, White leaf spots value 0.4, Leaf spots form a purple zone if it is severe 0.5, Leaf tip of 0.2, Tubers rot 0.4. Based on the above diagnostic results then get the value of diagnosis 67% forward chaining with trotol disease type, Purple spotting.

Evaluation of Musa spp. hybrids for resistance to black Sigatoka, caused by Mycosphaerella fijiensis Morelet

USDA-ARS?s Scientific Manuscript database

In Puerto Rico, bananas and plantains are important agricultural commodities; their combined production totaled 133,500 tons in 2008. Black and yellow Sigatoka leaf spot diseases, caused by Mycosphaerella fijiensis and M. musicola respectively, are responsible for significant losses of these crops ...

Investigation of Peniophora nuda for biological control of Cercospora beticola and Pyrenophora teres

USDA-ARS?s Scientific Manuscript database

Peniophora nuda (Fr.) Bres. belongs to the class Agaricomycetes under the phylum Basidiomycota and has been isolated in Europe, Great Britain, North America, Hawaii (US in Oceania) and New Zealand. Net blotch caused by Pyrenophora teres and Cercospora leaf spot (CLS) caused by Cercospora beticola ar...

7 CFR 51.1212 - U.S. No. 1.

Code of Federal Regulations, 2013 CFR

2013-01-01

... which are free from decay, growth cracks, cuts which are not healed, worms, worm holes, and free from damage caused by bruises, dirt, or other foreign material, bacterial spot, scab, scale, hail injury, leaf...

7 CFR 51.1212 - U.S. No. 1.

Code of Federal Regulations, 2014 CFR

2014-01-01

... which are free from decay, growth cracks, cuts which are not healed, worms, worm holes, and free from damage caused by bruises, dirt, or other foreign material, bacterial spot, scab, scale, hail injury, leaf...

75 FR 57019 - Pesticide Product Registrations; Conditional Approval

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-17

... foliar use on soybeans to control brown spot, cercospora blight, frogeye leaf spot, leaf spot, powdery..., 2010. G. Jeffrey Herndon, Acting Director, Registration Division, Office of Pesticide Programs. [FR Doc...

Chilling Stress—The Key Predisposing Factor for Causing Alternaria alternata Infection and Leading to Cotton (Gossypium hirsutum L.) Leaf Senescence

PubMed Central

Zhao, Jingqing; Li, Sha; Jiang, Tengfei; Liu, Zhi; Zhang, Wenwei; Jian, Guiliang; Qi, Fangjun

2012-01-01

Leaf senescence plays a vital role in nutrient recycling and overall capacity to assimilate carbon dioxide. Cotton premature leaf senescence, often accompanied with unexpected short-term low temperature, has been occurring with an increasing frequency in many cotton-growing areas and causes serious reduction in yield and quality of cotton. The key factors for causing and promoting cotton premature leaf senescence are still unclear. In this case, the relationship between the pre-chilling stress and Alternaria alternata infection for causing cotton leaf senescence was investigated under precisely controlled laboratory conditions with four to five leaves stage cotton plants. The results showed short-term chilling stress could cause a certain degree of physiological impairment to cotton leaves, which could be recovered to normal levels in 2–4 days when the chilling stresses were removed. When these chilling stress injured leaves were further inoculated with A. alternata, the pronounced appearance and development of leaf spot disease, and eventually the pronounced symptoms of leaf senescence, occurred on these cotton leaves. The onset of cotton leaf senescence at this condition was also reflected in various physiological indexes such as irreversible increase in malondialdehyde (MDA) content and electrolyte leakage, irreversible decrease in soluble protein content and chlorophyll content, and irreversible damage in leaves' photosynthesis ability. The presented results demonstrated that chilling stress acted as the key predisposing factor for causing A. alternata infection and leading to cotton leaf senescence. It could be expected that the understanding of the key factors causing and promoting cotton leaf senescence would be helpful for taking appropriate management steps to prevent cotton premature leaf senescence. PMID:22558354

Lettuce breeding

USDA-ARS?s Scientific Manuscript database

In the 2016-2017 period, major efforts targeted resistance to lettuce drop caused by Sclerotinia species, Verticillium wilt, Fusarium wilt, bacterial leaf spot, corky root, downy mildew, drought tolerance, lettuce aphid, tipburn, shelf-life of salad-cut lettuce, and multiple disease resistance. Resi...

Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae) , New Record From Tartous, Syria

PubMed Central

Yaseen Ali, Ali

2014-01-01

Abstract The weeping fig thrips Gynaikothrips uzeli Zimmermann (Thysanoptera: Phlaeothripidae) is newly recorded for the first time in the leaf galls of the weeping fig tree Ficus benjamina L. (Rosales: Moraceae) in the coastal area of Tartous, Syria. The thrips caused purplish red spots on the leaf surface of the host plant and the leaves curl. G. uzeili appears to be successfully adapted to this area. PMID:25527584

Differentiation of Corynespora cassiicola and Cercospora sp. in leaf-spot diseases of Hydrangea macrophylla using a PCR-mediated method

Treesearch

M. T. Mmbaga; L. Mackasmiel; Ned Klopfenstein

2015-01-01

Corynespora cassiicola and Cercospora sp. have been identified as the most prevalent and destructive leaf-spot pathogens of garden hydrangea [Hydrangea macrophylla (Thunberg) Seringe] in the southeastern USA, but they are often difficult to accurately detect and distinguish because they often occur together in a disease complex with other pathogenic leaf-spot...

Population structure of Cercospora sojina collected from different soybean culitvars in Milan and Jackson Tennessee

USDA-ARS?s Scientific Manuscript database

Frogeye Leaf Spot (FLS) of soybean is caused by the fungal pathogen, Cercospora sojina Hara. FLS causes significant damage resulting in a yield loss of 4 to 6 Bu/Acre, mostly in the Southern U.S. Since its first report in South Carolina in 1924 it has caused significant damage resulting in a yield ...

Leaf spot disease adversely affects human health-promoting constituents and withanolide biosynthesis in Withania somnifera (L.) Dunal.

PubMed

Singh, V; Singh, B; Sharma, A; Kaur, K; Gupta, A P; Salar, R K; Hallan, V; Pati, P K

2017-01-01

The present work investigates the implication of leaf spot disease on the antioxidant potential and commercial value of pharmaceutically important constituents of Withania somnifera, a high-valued medicinal plant. Leaf spot disease was induced in W. somnifera by inoculating Alternaria alternata (Fr.) Keiss. pathogen. Total polyphenolic content and antioxidant potential showed a significant decrease during leaf spot disease. Evaluation of pharmaceutically active constituents withaferin A, withanone and withanolide A utilizing high-performance liquid chromatography showed a significant decrease in diseased samples as compared to healthy ones. Quantitative expression of major genes involved in withanolide biosynthesis also showed down-regulation in diseased samples. Alterations in the ultra-structure of chloroplasts were also analysed under transmission electron microscopy to get a better insight into the changes of withanolide biosynthesis in leaf during disease infestation. The present work suggests that when the pathogenic fungus invades the host plants, it evokes multiple responses, which could be studied at various levels. The knowledge gained from this work will provide appropriate rationale for controlling the bio-deterioration of the pharmaceutically active metabolites in W. somnifera and development of suitable strategies against leaf spot disease. This is the first study to investigate the effect of leaf spot disease on the human health-promoting constituents and withanolide biosynthesis in this high-valued medicinal plant. © 2016 The Society for Applied Microbiology.

Rapid and sensitive detection of Curvularia lunata associated with maize leaf spot based on its Clg2p gene using semi-nested PCR.

PubMed

Hou, J M; Ma, B C; Zuo, Y H; Guo, L L; Gao, S G; Wang, Y Y; Liu, T

2013-04-01

Curvularia lunata (Wakker) Boed, the causative agent of Curvularia leaf spot in maize, was determined according to conidiophore and conidium morphology in a previous study. In the current study, a sensitive polymerase chain reaction assay was developed for the detection of C. lunata. Two specific forward (ClgD1/ClgD2) and one reverse primers (ClgD3) were designed based on a Ras-related (Clg2p) gene. Eight C. lunata isolates that represent different virulent strains in maize, six other Curvularia spp., and 22 fungal plant pathogens were used to test the specificity of the primers. PCR amplification using ClgD1/ClgD3 as the first-round primers resulted in an 870-bp band from the C. lunata isolates. The detection sensitivity using ClgD1/ClgD3 was 100 pg of genomic DNA. In the second round of PCR, a 1 : 50 dilution of the first-round PCR products was used as a template with the ClgD2/ClgD3 primer pair, which increased the detection sensitivity to 1 fg. This semi-nested PCR procedure could also be used to detect C. lunata from infected maize leaves. The proposed PCR-based assay may be used for diagnosing and monitoring maize Curvularia leaf spot. The semi-nested PCR assay may provide researchers and laboratory technologists a tool to rapidly detect C. lunata, which causes maize Curvularia leaf spot, compared with histological examination. © 2012 The Society for Applied Microbiology.

Diversity of Diaporthe species associated with wood cankers of fruit and nut crops in northern California

USDA-ARS?s Scientific Manuscript database

Diaporthe ampelina, causal agent of Phomopsis cane and leaf spot of grapevine (Vitis vinifera L.), is also frequently isolated from grapevine wood, causing Phomopsis dieback. In California, Diaporthe species cause a wide range of symptoms not only on grape, but also other fruit and nut crops. To bet...

Data Mining Feature Subset Weighting and Selection Using Genetic Algorithms

DTIC Science & Technology

2002-03-01

seed-stain, anthracnose, phyllosticta-leaf-spot, alternarialeaf-spot, frog-eye-leaf- spot, diaporthe-pod-&-stem-blight, cyst - nematode , 2-4-d-injury...seed-discolor: absent,present,?. 33. seed-size: norm,lt-norm,?. 34. shriveling: absent,present,?. 35. roots: norm,rotted,galls- cysts

Thermal Infrared Hot Spot and Dependence on Canopy Geometry

NASA Technical Reports Server (NTRS)

Smith, James A.; Ballard, Jerrell R., Jr.; Smith, David E. (Technical Monitor)

2001-01-01

We perform theoretical calculations of the canopy thermal infrared (TIR) hot spot using a first principles 3-D model described earlier. Various theoretical canopies of varying leaf size and for differing canopy height are used to illustrate the magnitude of the TIR effect. Our results are similar to predicted behavior in the reflective hot spot as a function of canopy geometry and comparable to TIR measurements from the literature and our own simple ground experiments. We apply the MODTRAN atmospheric code to estimate the at-sensor variation in brightness temperature with view direction in the solar principal plane. For simple homogeneous canopies, we predict canopy thermal infrared hot spot variations of 2 degrees C at the surface with respect to nadir viewing. Dependence on leaf size is weak as long as the ratio of leaf size to canopy height is maintained. However, the angular width of the hot spot increases as the ratio of leaf diameter to canopy height increases. Atmospheric effects minimize but do not eliminate the TIR hot spot at satellite altitudes.

Survival of Xanthomonas fragariae on common materials found in strawberry nurseries

USDA-ARS?s Scientific Manuscript database

Xanthomonas fragariae causes strawberry angular leaf spot, an important disease in strawberry nursery production. To identify potential inoculum sources, the ability of X. fragariae to survive was examined on 10 common materials typically associated with strawberry nurseries (cardboard, glass, latex...

Genetic dissection of novel QTLs for resistance to leaf spots and Tomato spotted wilt virus in peanut (Arachis hypogaea L.)

USDA-ARS?s Scientific Manuscript database

Peanut is an import crop, economically and nutritiously, but high production cost is a serious challenge to peanut farmers as exemplified by chemical spray to control foliar diseases such as leaf spots and thrips, the vectors of tomato spotted wilt virus (TSWV). The objective of this research was to...

Growth sensitivity of Corynespora cassiicola to Thiophanate-methyl, Iprodione, and Fludioxonil

USDA-ARS?s Scientific Manuscript database

Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei, causal agent of Corynespora leaf spot, can cause devastating epidemics in African violet (Saintpaulia ionantha H. Wendl.) production facilities. Because of phytotoxicity and visible residue issues with some fungicides such as chlorothalonil, pro...

Downy mildews

USDA-ARS?s Scientific Manuscript database

Downy mildew of chickpea and lentil is caused by species of Peronospora. The disease occurs in many parts of the world. All aerial parts of plants are susceptible. Main symptoms include white mycelial patches on the lower leaf surface, and chlorotic to yellow spots develop on the upper surface. Per...

Biocontrol Potential of Streptomyces hydrogenans Strain DH16 toward Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus

PubMed Central

Manhas, Rajesh K.; Kaur, Talwinder

2016-01-01

Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v) of S. hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10%) and streptomycete cells significantly improved seed germination (75–80%) and vigor index (1167–1538). Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers. PMID:28018402

Transcriptomic and Proteomic Analyses of Resistant Host Responses in Arachis diogoi Challenged with Late Leaf Spot Pathogen, Phaeoisariopsis personata

PubMed Central

Kumar, Dilip; Kirti, Pulugurtha Bharadwaja

2015-01-01

Late leaf spot is a serious disease of peanut caused by the imperfect fungus, Phaeoisariopsis personata. Wild diploid species, Arachis diogoi. is reported to be highly resistant to this disease and asymptomatic. The objective of this study is to investigate the molecular responses of the wild peanut challenged with the late leaf spot pathogen using cDNA-AFLP and 2D proteomic study. A total of 233 reliable, differentially expressed genes were identified in Arachis diogoi. About one third of the TDFs exhibit no significant similarity with the known sequences in the data bases. Expressed sequence tag data showed that the characterized genes are involved in conferring resistance in the wild peanut to the pathogen challenge. Several genes for proteins involved in cell wall strengthening, hypersensitive cell death and resistance related proteins have been identified. Genes identified for other proteins appear to function in metabolism, signal transduction and defence. Nineteen TDFs based on the homology analysis of genes associated with defence, signal transduction and metabolism were further validated by quantitative real time PCR (qRT-PCR) analyses in resistant wild species in comparison with a susceptible peanut genotype in time course experiments. The proteins corresponding to six TDFs were differentially expressed at protein level also. Differentially expressed TDFs and proteins in wild peanut indicate its defence mechanism upon pathogen challenge and provide initial breakthrough of genes possibly involved in recognition events and early signalling responses to combat the pathogen through subsequent development of resistivity. This is the first attempt to elucidate the molecular basis of the response of the resistant genotype to the late leaf spot pathogen, and its defence mechanism. PMID:25646800

Fusarium agapanthi sp. nov., a novel bikaverin and fusarubin-producing leaf and stem spot pathogen of Agapanthus praecox (African lily) from Australia and Italy.

PubMed

Edwards, Jacqueline; Auer, Desmond; de Alwis, Sri-Kanthi; Summerell, Brett; Aoki, Takayuki; Proctor, Robert H; Busman, Mark; O'Donnell, Kerry

2016-09-01

This study was conducted to characterize a novel Fusarium species that caused leaf and stem spot on Agapanthus praecox (Agapanthus, African lily) in northern Italy and leaf rot and spot on the same host in Melbourne, Australia. Formally described as Fusarium agapanthi, this pathogen was analyzed using phenotypic, phytopathogenic, secondary metabolite, molecular phylogenetic and genomic data. Five strains were characterized, including one isolated in 1999 from symptomatic A. praecox in Saluzzo, Italy, and four in 2010 from diseased leaf tissue from the same host exhibiting leaf rot and spot symptoms in the Melbourne Gardens, Royal Botanic Gardens Victoria, Australia. Maximum parsimony and maximum likelihood molecular phylogenetic analyses of portions of six individual genes and the combined dataset all strongly supported F. agapanthi either as the earliest diverging genealogically exclusive lineage in the American Clade of the F. fujikuroi species complex, or alternatively a novel monotypic lineage sister to the American Clade. Koch's postulates were completed on dwarf blue- and large white-flowering varieties of A. praecox, where two isolates of F. agapanthi produced slowly spreading necrotic lesions when inoculated onto leaves and flower stems. Fusarium agapanthi is distinguished from other fusaria by the production of densely branched aerial conidiophores with polyphialides throughout the aerial mycelium on synthetic nutrient-poor agar. BLASTn searches of the F. agapanthi NRRL 31653 and NRRL 54464 (= VPRI 41787) genome sequences were conducted to predict sexual reproductive mode and mycotoxin potential. Results indicated that they possessed MAT1-2 and MAT1-1 idiomorphs, respectively, indicating that this species might be heterothallic. Furthermore, based on the presence of homologs of the bikaverin and fusarubin biosynthetic gene clusters in the F. agapanthi genomes, liquid chromatography-mass spectrometry analysis was conducted and confirmed production of these secondary metabolites in rice and corn kernel cultures of the fungus. © 2016 by The Mycological Society of America.

Oxidative stress: A link between drought and aflatoxin contamination in maize

USDA-ARS?s Scientific Manuscript database

Host resistance to diseases, such as early leaf spot (ELS), late leaf spot (LLS) and Tomato spotted wilt virus (TSWV), is critical for increasing the yield and reducing the cost for peanut farmers. With the completion of the genome sequences of two diploid ancestors of cultivated peanut, we could ge...

Show us your spots! Researchers need samples of bacterial leaf spots on celery, cilantro, parsley, and other crops.

USDA-ARS?s Scientific Manuscript database

Since 2002, a severe leaf spot disease on parsley has occurred throughout central coastal California and particularly in Monterey County. Three different bacterial pathogens (Pseudomonas syringae pv. apii, P. syringae pv. coriandricola and an organism very closely related to P. viridiflava) have bee...

Response of different common bean lines to Phaeoisariopsis griseola in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Angular leaf spot (ALS), caused by Phaeoisariopsis griseola (Sacc.) Ferraris sin. Pseudocercospora griseola (Sacc.) Crous & U. Braun., is an important disease in common bean Phaseolus vulgaris L. in the Caribbean and Central America. The wide pathogen variability makes it necessary to continuously m...

Phenotypic characterization of Cercospora sojina isolates collected from wide geographical areas

USDA-ARS?s Scientific Manuscript database

Frogeye Leaf Spot (FLS), caused by Cercospora sojina, is common in the southern and southeastern soybean production region of the USA. Recently, FLS has spread further northward into Midwestern soybean growing states, including Ohio, Indiana, Wisconsin, Michigan, Illinois, Iowa, and Missouri and sou...

Transcriptome Profiling of Buffalograss Challenged with the Leaf Spot Pathogen Curvularia inaequalis.

PubMed

Amaradasa, Bimal S; Amundsen, Keenan

2016-01-01

Buffalograss (Bouteloua dactyloides) is a low maintenance U. S. native turfgrass species with exceptional drought, heat, and cold tolerance. Leaf spot caused by Curvularia inaequalis negatively impacts buffalograss visual quality. Two leaf spot susceptible and two resistant buffalograss lines were challenged with C. inaequalis. Samples were collected from treated and untreated leaves when susceptible lines showed symptoms. Transcriptome sequencing was done and differentially expressed genes were identified. Approximately 27 million raw sequencing reads were produced per sample. More than 86% of the sequencing reads mapped to an existing buffalograss reference transcriptome. De novo assembly of unmapped reads was merged with the existing reference to produce a more complete transcriptome. There were 461 differentially expressed transcripts between the resistant and susceptible lines when challenged with the pathogen and 1552 in its absence. Previously characterized defense-related genes were identified among the differentially expressed transcripts. Twenty one resistant line transcripts were similar to genes regulating pattern triggered immunity and 20 transcripts were similar to genes regulating effector triggered immunity. There were also nine up-regulated transcripts in resistance lines which showed potential to initiate systemic acquired resistance (SAR) and three transcripts encoding pathogenesis-related proteins which are downstream products of SAR. This is the first study characterizing changes in the buffalograss transcriptome when challenged with C. inaequalis.

An arbuscular mycorrhizal fungus and Epichloë festucae var. lolii reduce Bipolaris sorokiniana disease incidence and improve perennial ryegrass growth.

PubMed

Li, Fang; Guo, Yan'e; Christensen, Michael J; Gao, Ping; Li, Yanzhong; Duan, Tingyu

2018-02-01

Leaf spot of perennial ryegrass (Lolium perenne) caused by Bipolaris sorokiniana is an important disease in temperate regions of the world. We designed this experiment to test for the combined effects of the arbuscular mycorrhizal (AM) fungus Claroideoglomus etunicatum and the grass endophyte fungus Epichloë festucae var. lolii on growth and disease occurrence in perennial ryegrass. The results show that C. etunicatum increased plant P uptake and total dry weight and that this beneficial effect was slightly enhanced when in association with the grass endophyte. The presence in plants of both the endophyte and B. sorokiniana decreased AM fungal colonization. Plants inoculated with B. sorokiniana showed the typical leaf spot symptoms 2 weeks after inoculation and the lowest disease incidence was with plants that were host to both C. etunicatum and E. festucae var. lolii. Plants with these two fungi had much higher activity of peroxidases (POD), superoxide dismutase (SOD) and catalase (CAT) and lower values of malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2 ). The AM fungus C. etunicatum and the grass endophyte fungus E. festucae var. lolii have the potential to promote perennial ryegrass growth and resistance to B. sorokiniana leaf spot.

Mapping quantitative trait loci of resistance to Tomato spotted wilt virus and leaf spots in a recombinant inbred line population of peanut (Arachis hypogae L.) from SunOleic 97R and NC94022

USDA-ARS?s Scientific Manuscript database

Peanut is vulnerable to a range of diseases, such as Tomato spotted wilt virus (TSWV) and leaf spots. The most sustainable and economical solution for managing peanut diseases is development of resistance cultivars. The new breeding line NC94022, high resistance to TSWV and moderate resistance to le...

Flowering Dogwood: (Cornus Florida). Section 7.5.9 U. S. Army Corps of Engineers Wildlife Resources Management Manual

DTIC Science & Technology

1988-07-01

damage and plant disease symptoms. Dogwood is susceptible to several fungal diseases, chiefly spot anthracnose , leaf spots, basal trunk canker, and...nectria canker. Anthracnose attacks the flowers, leaves, fruits, and young shoots, producing spot-like lesions that destroy these tissues. The fungus...fungicides prior to blooming. The fungicides used for anthracnose will usually control other leaf spot fungi (Blasingame and Cochran 1979). It should be

Description and identification of two new diseases of guariroba palm (Syagrus oleraceae) in Brazil

USDA-ARS?s Scientific Manuscript database

Guariroba is a palm species native to central Brazil. Seedlings of guariroba with leaf spots of unknown etiology were found in Patos de Minas, Minas Gerais, Brazil. The leaf spots were manifest as two different symptom types: the first lesion type consisted of necrotic spots with a rounded to elonga...

Screening ornamental cherry (Prunus) taxa for resistance to infection by Blumeriella jaapii

USDA-ARS?s Scientific Manuscript database

Ornamental flowering cherry trees are important landscape plants in the U.S., but are susceptible to a number of serious pests and disease problems. Cherry leaf spot, caused by the fungus Blumeriella jaapii, is characterized by defoliating susceptible trees in late summer, leading to weakening or ev...

Resistance of common bean breeding lines to Phaeoisariopsis griseola isolates from Honduras

USDA-ARS?s Scientific Manuscript database

Angular leaf spot (ALS) disease caused by Phaeoisariopsis griseola Sacc. Ferraris, is currently one of the most important factors limiting bean productivity in Central America. The development of breeding lines which combine resistance to ALS and Bean Golden Yellow Mosaic Virus (BGYMV) and tolerance...

Testing the efficacy of bicarbonates as fungicides against Cercospora beticola

USDA-ARS?s Scientific Manuscript database

Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is an economically important pathogen of sugar beets in many production areas throughout the world. The application of fungicides has been one of the most effective management tools for CLS, but their effectiveness has di...

Early detection of airborne inoculum of Magnaporthe oryzae in turfgrass fields using a quantitative LAMP assay

USDA-ARS?s Scientific Manuscript database

Gray leaf spot (GLS) is a destructive disease of perennial ryegrass caused by a host specific pathotype of the ascomycete Magnaporthe oryzae. Early diagnosis is crucial for effective disease management and the implementation of Integrated Pest Management practices. However, a rapid diagnostic protoc...

First report of DMI insensitive Cercospora beticola on sugar beet in Ontario, Canada

USDA-ARS?s Scientific Manuscript database

Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is an economically important foliar disease of sugar beet in Ontario, Canada and worldwide. Fungicides are an important tool in the control of CLS. The first demethylation inhibitor (DMI) fungicide for sugar beet was regi...

De novo genome assembly of Cercospora beticola for microsatellite marker development and validation

USDA-ARS?s Scientific Manuscript database

Cercospora leaf spot caused by Cercospora beticola is a significant threat to the production of sugar and table beet worldwide. A de novo genome assembly of C. beticola was used to develop eight polymorphic and reproducible microsatellite markers for population genetic analyses. These markers were u...

Ditylenchus drepanocercus Rediscovered in the Neotropics Causing Angular Leaf Spots on Miconia calvescens

PubMed Central

Seixas, C. D. S.; Barreto, R. W.; Freitas, L. G.; Monteiro, F. T.; Oliveira, R. D. L.

2004-01-01

During searches for pathogens to be used as classical biocontrol agents for Miconia calvescens (velvet tree), a devastating plant invader of Hawaii and French Polynesia, damaging angular leaf spots were found repeatedly. The etiological agent of this disease was identified as the nematode Ditylenchus drepanocercus. This nematode has a distinctive falciform appendage at the apex of the tail on both sexes, which allows easy identification. The nematodes were found in the lacunar parenchyma. Infected tissues have abnormally large cells (7 to 13 times the normal size). The lamina at infected areas is chlorotic, slightly thicker, and becomes necrotic with time. The best method of inoculation for this nematode was spraying plants with a suspension containing individuals of various stages on previously wounded leaves. Incubation period was determined to be 20 days. PMID:19262828

Gnomonia canker, shoot blight, and leaf spot of yellow birch.

Treesearch

Kenneth J. Jr. Kessler

1978-01-01

Describes a canker, shoot blight, and leaf spot disease of yellow birch seedlings in the northern Great Lakes region and tells how and when trees become infected by the fungal causal agent, Gnomonia setacea.

High-density genetic map using whole-genome re-sequencing for fine mapping and candidate gene discovery for disease resistance in peanut

USDA-ARS?s Scientific Manuscript database

High-density genetic linkage maps are essential for fine mapping QTLs controlling disease resistance traits, such as early leaf spot (ELS), late leaf spot (LLS), and Tomato spotted wilt virus (TSWV). With completion of the genome sequences of two diploid ancestors of cultivated peanut, we could use ...

First report of leaf spot of Convolvulus arvensis caused by Phoma macrostoma var. macrostoma in Turkey

USDA-ARS?s Scientific Manuscript database

Field bindweed (Convolvulus arvensis L.) is an exotic perennial vine that is invasive in the USA and problematic in Turkey. In May 2012, diseased Convolvulus arvensis plants were found near Ondokuz Mayis University, Samsun, Turkey. Symptoms were irregular tan-colored necrotic lesions on leaves. Leav...

First report of alternaria leaf spot of banana caused by Alternaria alternata in the United States

USDA-ARS?s Scientific Manuscript database

Research efforts were initiated in 2003 to identify and introduce banana (Musa spp.) cultivars suitable for production in Georgia. In spring and summer 2012, seven of the cultivars (Veinte Cohol, Novaria, Cacambou, Chinese Cavendish, Raja Puri, Blue Torres Island, and African Red) grown in the field...

First report of Alternaria alternata causing leaf spot on Ruth's golden aster (Pityopsis ruthii) in Tennessee

USDA-ARS?s Scientific Manuscript database

Ruth’s golden aster, Pityopsis ruthii (Small), is an endangered, herbaceous perennial plant that is only endemic to small sections of the Hiwassee and Ocoee Rivers, in Polk County, Tennessee. In July 2015, a greenhouse grown plant exhibited symptoms of disease that included elongated brown lesions o...

A loop-mediated isothermal amplification assay and sample preparation procedure for sensitive detection of Xanthomonas fragariae in strawberry

USDA-ARS?s Scientific Manuscript database

Xanthomonas fragariae is a bacterium that causes angular leaf spot of strawberry. Asymptomatic infections are common and contribute to the difficulties in disease management. The aim of this study was to develop a loop-mediated isothermal amplification (LAMP) assay with a bacterial enrichment proced...

First report of Alternaria alternata causing leaf spot on the whorled sunflower (Heilianthus verticillatus) in the southeast United States

USDA-ARS?s Scientific Manuscript database

The whorled sunflower, Helianthus verticillatus (Small), is an endangered, herbaceous perennial plant endemic to limited small tracts of land in west Tennessee, east Alabama, and west Georgia. In October 2015, plants from wild populations in Georgia and Alabama exhibited small, circular brown, necro...

Two dominant loci determine resistance to Phomopsis cane lesions in F1 families of hybrid grapevines

USDA-ARS?s Scientific Manuscript database

Phomopsis cane and leaf spot, caused by the hemibiotrophic fungus Diaporthe ampelina (syn = Phomopsis viticola), produces lesions on grapevine stems and berries, reducing productivity. Host resistance was studied on three F1 families derived from crosses involving ‘Horizon’, Illinois 547-1, Vitis ci...

A new disease of parsley (Petroselinum crispum) in California caused by a fluorescent pseudomonad related to Pseudomonas viridiflava.

USDA-ARS?s Scientific Manuscript database

In 2008 fluorescent bacteria were isolated from bacterial leaf spot symptoms on Italian parsley (Petroselinum crispum) in Ceres, California. These isolates were different from the known bacterial pathogens of parsley in California. To determine the etiology of this disease pathogenicity was evaluate...

Working Towards Disease Resistance in Peanuts Through Biotechnology

USDA-ARS?s Scientific Manuscript database

Resistant cultivars are the most desirable approach to disease control in agriculture. Early and late leaf spot are the most important foliar diseases of peanut worldwide. Significant progress for leaf spot resistance in peanut can be achieved through biotechnology. The National Peanut Research ...

Stable integration and expression of wasabi defensin gene in "Egusi" melon (Colocynthis citrullus L.) confers resistance to Fusarium wilt and Alternaria leaf spot.

PubMed

Ntui, Valentine Otang; Thirukkumaran, Gunaratnam; Azadi, Pejman; Khan, Raham Sher; Nakamura, Ikuo; Mii, Masahiro

2010-09-01

Production of "Egusi" melon (Colocynthis citrullus L.) in West Africa is limited by fungal diseases, such as Alternaria leaf spot and Fusarium wilt. In order to engineer "Egusi" resistant to these diseases, cotyledonary explants of two "Egusi" genotypes, 'Ejagham' and NHC1-130, were transformed with Agrobacterium tumefaciens strain EHA101 harbouring wasabi defensin gene (isolated from Wasabia japonica L.) in a binary vector pEKH1. After co-cultivation for 3 days, infected explants were transferred to MS medium containing 100 mg l(-l) kanamycin to select transformed tissues. After 3 weeks of culture, adventitious shoots appeared directly along the edges of the explants. As much as 19 out of 52 (36.5%) and 25 out of 71 (35.2%) of the explants in genotype NHC1-130 and 'Ejagham', respectively, formed shoots after 6 weeks of culture. As much as 74% (14 out of 19) of the shoots regenerated in genotype NHC1-130 and 72% (18 out of 25) of those produced in genotype 'Ejagham' were transgenic. A DNA fragment corresponding to the wasabi defensin gene or the selection marker nptII was amplified by PCR from the genomic DNA of all regenerated plant clones rooted on hormone-free MS medium under the same selection pressure, suggesting their transgenic nature. Southern blot analysis confirmed successful integration of 1-5 copies of the transgene. RT-PCR, northern and western blot analyses revealed that wasabi defensin gene was expressed in transgenic lines. Transgenic lines showed increased levels of resistance to Alternaria solani, which causes Alternaria leaf spot and Fusarium oxysporum, which causes Fusarium wilt, as compared to that of untransformed plants.

Multilocus sequence typing of Pseudomonas syringae sensu lato confirms previously described genomospecies and permits rapid identification of P. syringae pv. coriandricola and P. syringae pv. apii causing bacterial leaf spot on parsley.

PubMed

Bull, Carolee T; Clarke, Christopher R; Cai, Rongman; Vinatzer, Boris A; Jardini, Teresa M; Koike, Steven T

2011-07-01

Since 2002, severe leaf spotting on parsley (Petroselinum crispum) has occurred in Monterey County, CA. Either of two different pathovars of Pseudomonas syringae sensu lato were isolated from diseased leaves from eight distinct outbreaks and once from the same outbreak. Fragment analysis of DNA amplified between repetitive sequence polymerase chain reaction; 16S rDNA sequence analysis; and biochemical, physiological, and host range tests identified the pathogens as Pseudomonas syringae pv. apii and P. syringae pv. coriandricola. Koch's postulates were completed for the isolates from parsley, and host range tests with parsley isolates and pathotype strains demonstrated that P. syringae pv. apii and P. syringae pv. coriandricola cause leaf spot diseases on parsley, celery, and coriander or cilantro. In a multilocus sequence typing (MLST) approach, four housekeeping gene fragments were sequenced from 10 strains isolated from parsley and 56 pathotype strains of P. syringae. Allele sequences were uploaded to the Plant-Associated Microbes Database and a phylogenetic tree was built based on concatenated sequences. Tree topology directly corresponded to P. syringae genomospecies and P. syringae pv. apii was allocated appropriately to genomospecies 3. This is the first demonstration that MLST can accurately allocate new pathogens directly to P. syringae sensu lato genomospecies. According to MLST, P. syringae pv. coriandricola is a member of genomospecies 9, P. cannabina. In a blind test, both P. syringae pv. coriandricola and P. syringae pv. apii isolates from parsley were correctly identified to pathovar. In both cases, MLST described diversity within each pathovar that was previously unknown.

Acidovorax anthurii sp. nov., a new phytopathogenic bacterium which causes bacterial leaf-spot of anthurium.

PubMed

Gardan, L; Dauga, C; Prior, P; Gillis, M; Saddler, G S

2000-01-01

The bacterial leaf-spot of anthurium emerged during the 1980s, in the French West Indies and Trinidad. This new bacterial disease is presently wide spread and constitutes a serious limiting factor for commercial anthurium production. Twenty-nine strains isolated from leaf-spots of naturally infected anthurium were characterized and compared with reference strains belonging to the Comamonadaceae family, the genera Ralstonia and Burkholderia, and representative fluorescent pseudomonads. From artificial inoculations 25 out of 29 strains were pathogenic on anthurium. Biochemical and physiological tests, fatty acid analysis, DNA-DNA hybridization, 16S rRNA gene sequence analysis, DNA-16S RNA hybridization were performed. The 25 pathogenic strains on anthurium were clustered in one phenon closely related to phytopathogenic strains of the genus Acidovorax. Anthurium strains were 79-99% (deltaTm range 0.2-1.6) related to the strain CFBP 3232 and constituted a discrete DNA homology group indicating that they belong to the same species. DNA-rRNA hybridization, 16S rRNA sequence and fatty acid analysis confirmed that this new species belongs to the beta-subclass of Proteobacteria and to rRNA superfamily III, to the family of Comamonadaceae and to the genus Acidovorax. The name Acidovorax anthurii is proposed for this new phytopathogenic bacterium. The type strain has been deposited in the Collection Française des Bactéries Phytopathogènes as CFBP 3232T.

Production of Gentisyl Alcohol from Phoma herbarum Endophytic in Curcuma longa L. and Its Antagonistic Activity Towards Leaf Spot Pathogen Colletotrichum gloeosporioides.

PubMed

Gupta, Suruchi; Kaul, Sanjana; Singh, Baljinder; Vishwakarma, Ram A; Dhar, Manoj K

2016-11-01

Endophytes from medicinal plants represent a potential source of bioactive compounds. During the present investigation, fungal endophytes were isolated from turmeric (Curcuma longa), an important medicinal plant. A total of 207 endophytic fungal isolates were obtained from the rhizome of C. longa L. They were grouped into seven genera based on morphological and molecular data. The fungal endophytes of C. longa were evaluated for antifungal activity against Colletotrichum gloeosporioides, the causal organism of leaf spot of turmeric. The disease is a major cause for economic loss in turmeric cultivation. Endophytic Phoma herbarum showed significant activity against C. gloeosporioides and was therefore selected for further studies. A compound gentisyl alcohol was isolated from P. herbarum which showed effective antagonism against C. gloeosporioides. The organism could therefore be used as a biocontrol agent against C. gloeosporioides.

FaRXf1: a locus conferring resistance to angular leaf spot caused by Xanthomonas fragariae in octoploid strawberry.

PubMed

Roach, Jack A; Verma, Sujeet; Peres, Natalia A; Jamieson, Andrew R; van de Weg, W Eric; Bink, Marco C A M; Bassil, Nahla V; Lee, Seonghee; Whitaker, Vance M

2016-06-01

Angular leaf spot is a devastating bacterial disease of strawberry. Resistance from two wild accessions is highly heritable and controlled by a major locus on linkage group 6D. Angular leaf spot caused by Xanthomonas fragariae is the only major bacterial disease of cultivated strawberry (Fragaria ×ananassa). While this disease may cause reductions of up to 8 % of marketable yield in Florida winter annual production, no resistant cultivars have been commercialized. Wild accessions US4808 and US4809 were previously identified as resistant to the four genetic clades of X. fragariae, and introgression of the trait into commercial quality perennial-type germplasm was initiated. Previous reports indicated high heritability for the trait but proposed both single-locus and multi-locus inheritance models. The objective of this study was to determine the mode of inheritance of resistance, to identify causal loci, and to begin introgression of resistance into Florida-adapted germplasm. Resistance was observed in two years of field trials with inoculated plants that assayed four full-sib families descended from US4808 to US4809. Resistance segregated 1:1 in all families indicating control by a dominant allele at a single locus. Using a selective genotyping approach with the IStraw90 Axiom(®) SNP array and pedigree-based QTL detection, a single major-effect QTL was identified in two full-sib families, one descended from each resistant accession. High-resolution melt curve analysis validated the presence of the QTL in separate populations. The QTL was delimited to the 33.1-33.6 Mbp (F. vesca vesca v1.1 reference) and 34.8-35.3 Mbp (F. vesca bracteata v2.0 reference) regions of linkage group 6D for both resistance sources and was designated FaRXf1. Characterization of this locus will facilitate marker-assisted selection toward the development of resistant cultivars.

Bacterial Leaf Spot of Parsley: Characterization of a New Disease

USDA-ARS?s Scientific Manuscript database

Since 2002, a severe leaf spot disease on parsley has occurred throughout central coastal California and particularly in Monterey County. Two different bacterial pathogens (Pseudomonas syringae pv. apii, and P. syringae pv. coriandricola) have been associated these outbreaks on parsley. Our research...

Response of crapemyrtle varieties to Cercospora leaf spot, 2015

USDA-ARS?s Scientific Manuscript database

Crapemyrtle varieties, Lagerstroemia spp., were evaluated for Cercospora leaf spot in two field test evaluations, planted in either 2004 or 2011 at the Otis L. Floyd Nursery Research Center in McMinnville, TN. The experimental designs for both test evaluations were a randomized complete block design...

Genome assembly of the fungus Cochliobolus miyabeanus, and transcriptome analysis during early stages of infection on American wild rice (Zizania palustris L.)

USDA-ARS?s Scientific Manuscript database

Cochliobolus miyabeanus causes a severe, yield-reducing leaf spot disease on rice (Oryza sativa) and two North American specialty crops, American wildrice (Zizania palustris) and switchgrass (Panicum virgatum). Despite the importance of the pathogen in wildrice, little is known about mechanisms of p...

Mating type idiomorphs distribution and their correlation to benzimidazole-resistance in Cercospora beticola from the Central High Plains Region, USA

USDA-ARS?s Scientific Manuscript database

Cercospora leaf spot (CLS) of sugarbeet is caused by Cercospora beticola Sacc., and is one of the most destructive foliar diseases worldwide. Fungicides used for disease suppression include benzimidazoles. Resistance to benzimidazoles can develop quickly, and was first reported in C. beticola in 197...

Corynespora cassiicola f. sp. schinii, a potential biocontrol agent for the weed Schinus terebinthifolius in the United States

USDA-ARS?s Scientific Manuscript database

An isolate of Corynespora cassiicola was found in Brazil (state of Espírito Santo) causing a severe leaf spot and foliage blight on Schinus terebinthifolius (Anacardiaceae, Brazilian peppertree or ‘aroeira’) which is a major environmental weed in many tropical and sub-tropical areas of the globe, in...

First Report of a Leaf Spot caused by Sphaerulina tirolensis on Rubus phoenicolasius

USDA-ARS?s Scientific Manuscript database

Diseased leaves of Rubus phoenicolasius (wineberry) were discovered on October 11, 2013 in a small, 3x3 m, infestation at a sunny location along Indian Springs Rd., Frederick, MD (N 39.467634, W 77.461362). Although the proportion of diseased plants was estimated to be less than10 per cent of the po...

Active optical sensor assessment of spider mite damage on greenhouse beans and cotton

USDA-ARS?s Scientific Manuscript database

The two-spotted spider mite, Tetranychus urticae Koch is an important pest of cotton in mid-southern United States and causes yield reduction, and deprivation in fiber fitness. A greenhouse colony of the spider mite was used to infest cotton and pinto beans at the three-leaf and trifoliate stages, r...

Controlling Infectious Diseases in Nurseries

Treesearch

T. H. Filer

1968-01-01

At least 300 publications have been written about non-infectious and infectious diseases of tree seedlings. I will outline some of the progress that is being made in finding ways to control infectious diseases, those caused by pathogens. I will touch upon pre- and post-emergence damping-off, root rots, leaf spots, and fusiform rust, which are the most serious diseases...

Use of PCR-RFLP analysis to monitor fungicide resistance in Cercospora beticola populations from sugarbeet (Beta vulgaris) in Michigan, United States

USDA-ARS?s Scientific Manuscript database

Genetic resistance to Quinone outside inhibitor (QoI) and benzimidazole fungicides may be responsible for a recent decline in efficacy of chemical control management strategies for Cercospora leaf spot (CLS) caused by Cercospora beticola (Sacc.) in Michigan sugarbeet (Beta vulgaris L.) fields. The t...

First report of QoI resistance in Alternaria spp. infecting sugar beet (Beta vulgaris) in Michigan, USA

USDA-ARS?s Scientific Manuscript database

Alternaria leaf spot (ALS) of sugar beet is caused by Alternaria spp. in the A. alternata species complex. ALS is common wherever sugar beet is grown, but historically has been a minor issue for sugar beet production in the USA with damage usually not affecting crop yield significantly. Occurrence o...

Cercospora leaf spot: monitoring and managing fungicide resistance in populations of Cercospora beticola in Michigan

USDA-ARS?s Scientific Manuscript database

Cercospora leaf spot (CLS, Cercospora beticola) is the most serious foliar disease of sugarbeet in Michigan and Ontario.Management of CLS depends on timely fungicide applications, disease forecasting prediction models and the use of CLS resistant sugar beet varieties. Fungicides have a dominant role...

A single gene controls leaf background color in caladium (Araceae) and is tightly linked to genes for leaf main vein color, spotting and rugosity.

PubMed

Cao, Zhe; Sui, Shunzhao; Yang, Qian; Deng, Zhanao

2017-01-01

Modern cultivated caladiums ( Caladium × hortulanum ) are grown for their long-lasting and colorful leaves. Understanding the mode of inheritance for caladium leaf characteristics is critical for plant breeders to select appropriate parents, predict progeny performance, estimate breeding population sizes needed, and increase breeding efficiencies. This study was conducted to determine the mode of inheritance of two leaf background colors (lemon and green) in caladium and to understand their relationships with four other important leaf characteristics including leaf shape, main vein color, spotting, and rugosity. Seven caladium cultivars and three breeding lines were used as parents in 19 crosses, and their progeny were phenotyped for segregation of leaf traits. Results showed that the two leaf background colors are controlled by a single nuclear locus, with two alleles, LEM and lem , which control the dominant lemon and the recessive green leaf background color, respectively. The lemon-colored cultivar 'Miss Muffet' and breeding lines UF-52 and UF-53 have a heterozygous genotype LEMlem . Chi-square tests showed that the leaf background color locus LEM is independent from the leaf shape locus F , but is tightly linked to three loci ( S , V and RLF ) controlling leaf spotting, main vein color, and rugosity in caladium. A linkage map that consists of four loci controlling major caladium leaf characteristics and extends ~15 cM was developed based on the observed recombination frequencies. This is the first report on the mode of inheritance of leaf background colors in caladium and in the Araceae family. The information gained in this study will be very useful for caladium breeding and study of the inheritance of leaf colors in other ornamental aroids, an important group of ornamental plants in the world.

A single gene controls leaf background color in caladium (Araceae) and is tightly linked to genes for leaf main vein color, spotting and rugosity

PubMed Central

Cao, Zhe; Sui, Shunzhao; Yang, Qian; Deng, Zhanao

2017-01-01

Modern cultivated caladiums (Caladium×hortulanum) are grown for their long-lasting and colorful leaves. Understanding the mode of inheritance for caladium leaf characteristics is critical for plant breeders to select appropriate parents, predict progeny performance, estimate breeding population sizes needed, and increase breeding efficiencies. This study was conducted to determine the mode of inheritance of two leaf background colors (lemon and green) in caladium and to understand their relationships with four other important leaf characteristics including leaf shape, main vein color, spotting, and rugosity. Seven caladium cultivars and three breeding lines were used as parents in 19 crosses, and their progeny were phenotyped for segregation of leaf traits. Results showed that the two leaf background colors are controlled by a single nuclear locus, with two alleles, LEM and lem, which control the dominant lemon and the recessive green leaf background color, respectively. The lemon-colored cultivar ‘Miss Muffet’ and breeding lines UF-52 and UF-53 have a heterozygous genotype LEMlem. Chi-square tests showed that the leaf background color locus LEM is independent from the leaf shape locus F, but is tightly linked to three loci (S, V and RLF) controlling leaf spotting, main vein color, and rugosity in caladium. A linkage map that consists of four loci controlling major caladium leaf characteristics and extends ~15 cM was developed based on the observed recombination frequencies. This is the first report on the mode of inheritance of leaf background colors in caladium and in the Araceae family. The information gained in this study will be very useful for caladium breeding and study of the inheritance of leaf colors in other ornamental aroids, an important group of ornamental plants in the world. PMID:28101369

Differential Expression of R-genes to Associate Leaf Spot Resistance in Cultivated Peanut

USDA-ARS?s Scientific Manuscript database

Breeding for acceptable levels of Early (ELS) or Late Leaf Spot (LLS) resistance in cultivated peanut has been elusive due to extreme variability of plant response in the field and the proper combinations of resistance (R)-genes in any particular peanut line. R-genes have been shown to be involved ...

Glyphosate and fungicide effects on Cercospora leaf spot in four glyphosate-resistant sugar beet (Beta vulgaris) varieties

USDA-ARS?s Scientific Manuscript database

Glyphosate has been shown to reduce foliar diseases in soybean and wheat. In fact, currently there is a patent application for a synergistic combination of glyphosate and a fungicide for disease management. Cercospora leaf spot (Cercospora beticola) is one of the most significant foliar disease prob...

Cristulariella moricola associated with foliar blight of Camden white gum ( Eucalyptus benthamii ), a bioenergy crop

Treesearch

Doug P. Aubrey; Stephen W. Fraedrich; Thomas C. Harrington; Rabiu Olatinwo

2017-01-01

We report the association of Cristulariella moricola (Hino) Redhead with a zonate leaf spot on Eucalyptus benthamii (Myrtaceae). We observed the disease outbreak across a series of experimental E. benthamii plantings in Barnwell County, South Carolina, USA in October 2015. The disease caused nearly complete foliar necrosis of most trees in one experimental planting,...

First report of Lasmenia sp. causing rachis necrosis, flower abortion, fruit rot and leaf spots on rambutan in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Rambutan is an exotic tropical fruit that has increased in commercial importance for growers in Puerto Rico. In 2008 and 2009, fruit rot and lesions on both leaves and inflorescences were observed. A total of 276 diseased samples from these plant parts were collected at commercial orchards, Agricult...

Recent advances in research of some pest problems of hybrid populus in Michigan and Wisconsin

Treesearch

Lincoln M. Moore; Louis F. Wilson

1983-01-01

Hybrid Populus clones were examined for impact from and resistance to attack from several insects and diseases. Cottonwood leaf beetle, poplar-and-willow borer, and Septoria canker were most injurious. The spotted poplar aphid and poplar-gall saperda, even when abundant, caused only minor impact. The tarnished plant bug, a newly identified pest of...

Development of a quantitative loop-mediated isothermal amplification (qLAMP) assay for the detection of Magnaporthe oryzae airborne inoculum in turf ecosystems

USDA-ARS?s Scientific Manuscript database

Grey Leaf Spot (GLS) is a detrimental disease of perennial ryegrass caused by a host-specialized form of Magnaporthe oryzae (Mot). In order to improve turf management, a quantitative loop-mediated isothermal amplification (LAMP) assay coupled with a simple spore trap is being developed to monitor GL...

Phaeophleospora vochysiae Savi & Glienke sp. nov. Isolated from Vochysia divergens Found in the Pantanal, Brazil, Produces Bioactive Secondary Metabolites.

PubMed

Savi, Daiani C; Shaaban, Khaled A; Gos, Francielly Maria Wilke Ramos; Ponomareva, Larissa V; Thorson, Jon S; Glienke, Chirlei; Rohr, Jürgen

2018-02-15

Microorganisms associated with plants are highly diverse and can produce a large number of secondary metabolites, with antimicrobial, anti-parasitic and cytotoxic activities. We are particularly interested in exploring endophytes from medicinal plants found in the Pantanal, a unique and widely unexplored wetland in Brazil. In a bio-prospecting study, strains LGMF1213 and LGMF1215 were isolated as endophytes from Vochysia divergens, and by morphological and molecular phylogenetic analyses were characterized as Phaeophleospora vochysiae sp. nov. The chemical assessment of this species reveals three major compounds with high biological activity, cercoscosporin (1), isocercosporin (2) and the new compound 3-(sec-butyl)-6-ethyl-4,5-dihydroxy-2-methoxy-6-methylcyclohex-2-enone (3). Besides the isolation of P. vochysiae as endophyte, the production of cercosporin compounds suggest that under specific conditions this species causes leaf spots, and may turn into a pathogen, since leaf spots are commonly caused by species of Cercospora that produce related compounds. In addition, the new compound 3-(sec-butyl)-6-ethyl-4,5-dihydroxy-2-methoxy-6-methylcyclohex-2-enone showed considerable antimicrobial activity and low cytotoxicity, which needs further exploration.

Optical Inspection and Morphological Analysis of Diospyros kaki Plant Leaves for the Detection of Circular Leaf Spot Disease.

PubMed

Wijesinghe, Ruchire Eranga; Lee, Seung-Yeol; Kim, Pilun; Jung, Hee-Young; Jeon, Mansik; Kim, Jeehyun

2016-08-12

The feasibility of using the bio-photonic imaging technique to assess symptoms of circular leaf spot (CLS) disease in Diospyros kaki (persimmon) leaf samples was investigated. Leaf samples were selected from persimmon plantations and were categorized into three groups: healthy leaf samples, infected leaf samples, and healthy-looking leaf samples from infected trees. Visually non-identifiable reduction of the palisade parenchyma cell layer thickness is the main initial symptom, which occurs at the initial stage of the disease. Therefore, we established a non-destructive bio-photonic inspection method using a 1310 nm swept source optical coherence tomography (SS-OCT) system. These results confirm that this method is able to identify morphological differences between healthy leaves from infected trees and leaves from healthy and infected trees. In addition, this method has the potential to generate significant cost savings and good control of CLS disease in persimmon fields.

Optical Inspection and Morphological Analysis of Diospyros kaki Plant Leaves for the Detection of Circular Leaf Spot Disease

PubMed Central

Wijesinghe, Ruchire Eranga; Lee, Seung-Yeol; Kim, Pilun; Jung, Hee-Young; Jeon, Mansik; Kim, Jeehyun

2016-01-01

The feasibility of using the bio-photonic imaging technique to assess symptoms of circular leaf spot (CLS) disease in Diospyros kaki (persimmon) leaf samples was investigated. Leaf samples were selected from persimmon plantations and were categorized into three groups: healthy leaf samples, infected leaf samples, and healthy-looking leaf samples from infected trees. Visually non-identifiable reduction of the palisade parenchyma cell layer thickness is the main initial symptom, which occurs at the initial stage of the disease. Therefore, we established a non-destructive bio-photonic inspection method using a 1310 nm swept source optical coherence tomography (SS-OCT) system. These results confirm that this method is able to identify morphological differences between healthy leaves from infected trees and leaves from healthy and infected trees. In addition, this method has the potential to generate significant cost savings and good control of CLS disease in persimmon fields. PMID:27529250

Characterization of expressed resistance gene analogs (RGAs) from peanut expressed sequence tags (ESTs)

USDA-ARS?s Scientific Manuscript database

Cultivated peanut (Arachis hypogaea L.) is one of the most important food legume crops grown worldwide, and is a major source for edible oil and protein. However, due to low genetic variation, peanut is very vulnerable to a variety of pathogens, such as early leaf spot, late leaf spot, rust and Toma...

Biological Control of Septoria Leaf Spot Disease of Hybrid Poplar in the Field

Treesearch

Laszlo Gyenis; Neil A. Anderson; Michael E. Ostry

2003-01-01

Biological control of Septoria leaf spot of hrhrid poplars was investigated using disease-suppressive Streptomyces strains. Field experiments were conducted in 1998 and 1999 on potted trees placed in a hybrid poplar plantation near Rosemount, MN, and on field-planted trees in 1998 at St. Paul. At both locations, one resistant and three susceptible...

Identification of alleles conferring resistance to gray leaf spot in maize derived from its wild progenitor species teosinte (Zea mays ssp. parviglumis)

USDA-ARS?s Scientific Manuscript database

Gray Leaf Spot [(GLS), causal agent Cercospora zeae-maydis and Cercospora zeina] is an important maize disease in the United States. Current control methods for GLS include using resistant cultivars, crop rotation, chemical applications, and conventional tillage to reduce inoculum levels. Teosinte ...

One-step reverse transcription loop mediated isothermal amplification assay for detection of Apple chlorotic leaf spot virus

USDA-ARS?s Scientific Manuscript database

A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the detection of Apple chlorotic leaf spot virus (ACLSV) was developed. In this method, a set of four primers was designed based on the conserved regions in the coat protein gene of ACLSV, and was synthesized for the ...

Leaf and canopy reflectance spectrometry applied to the estimation of angular leaf spot disease severity of common bean crops

PubMed Central

Martínez-Martínez, Víctor; Machado, Marley L.; Pinto, Francisco A. C.

2018-01-01

This study is aimed at (i) estimating the angular leaf spot (ALS) disease severity in common beans crops in Brazil, caused by the fungus Pseudocercospora griseola, employing leaf and canopy spectral reflectance data, (ii) evaluating the informative spectral regions in the detection, and (iii) comparing the estimation accuracy when the reflectance or the first derivative reflectance (FDR) is employed. Three data sets of useful spectral reflectance measurements in the 440 to 850 nm range were employed; measurements were taken over the leaves and canopy of bean crops with different levels of disease. A system based in Principal Component Analysis (PCA) and Artificial Neural Networks (ANN) was developed to estimate the disease severity from leaf and canopy hyperspectral reflectance spectra. Levels of disease to be taken as true reference were determined from the proportion of the total leaf surface covered by necrotic lesions on RGB images. When estimating ALS disease severity in bean crops by using hyperspectral reflectance spectrometry, this study suggests that (i) successful estimations with coefficients of determination up to 0.87 can be achieved if the spectra is acquired by the spectroradiometer in contact with the leaves, (ii) unsuccessful estimations are obtained when the spectra are acquired by the spectroradiometer from one or more meters above the crop, (iii) the red to near-infrared spectral region (630–850 nm) offers the same precision in the estimation as the blue to near-infrared spectral region (440–850), and (iv) neither significant improvements nor significant detriments are achieved when the input data to the estimation processing system are the FDR spectra, instead of the reflectance spectra. PMID:29698420

Influence of regeneration method and tissue source on the frequency of somatic variation in Populus to infection by Septoria musiva

Treesearch

Michael E. Ostry; Ronald L. Hackett; Charles H. Michler; R. Serres; B. McCown

1994-01-01

Septoria leaf spot and canker are serious diseases of many hybrid poplar clones in plantations established for biomass production. Developing resistant clones through breeding is the best long-term strategy to minimize tree damage caused by this disease. Tissue culture and somaclonal selection techniques may reduce the time needed to develop disease resistance in...

HOW TO Identify and Control Leaf Spot Diseases of Black Walnut

Treesearch

W.M. Black; Dan Neely; James A. Matteoni

1977-01-01

Growing black walnut in pure stands is becoming more and more common. Although this practice has definite economic advantages, it can aggravate disease problems. This is especially true of leaf spot diseases, which multiply rapidly where large numbers of susceptible leaves are concentrated in a small area. Three such diseases are especially common on lack alnut: walnut...

Sugar beet activities of the USDA-ARS East Lansing conducted in cooperation with Saginaw Research & Extension Center during 2013 (including Project 905)

USDA-ARS?s Scientific Manuscript database

Evaluation and rating plots were planted at the Saginaw Valley Research & Extension Center (SVREC) in Frankenmuth, MI in 2013 that focused on Cercospora leaf spot and Rhizoctonia seedling disease performance of a wide range of Beta vulgaris materials. Leaf spot trials were conducted in conjunction w...

Development of a Model to Predict the Primary Infection Date of Bacterial Spot (Xanthomonas campestris pv. vesicatoria) on Hot Pepper.

PubMed

Kim, Ji-Hoon; Kang, Wee-Soo; Yun, Sung-Chul

2014-06-01

A population model of bacterial spot caused by Xanthomonas campestris pv. vesicatoria on hot pepper was developed to predict the primary disease infection date. The model estimated the pathogen population on the surface and within the leaf of the host based on the wetness period and temperature. For successful infection, at least 5,000 cells/ml of the bacterial population were required. Also, wind and rain were necessary according to regression analyses of the monitored data. Bacterial spot on the model is initiated when the pathogen population exceeds 10(15) cells/g within the leaf. The developed model was validated using 94 assessed samples from 2000 to 2007 obtained from monitored fields. Based on the validation study, the predicted initial infection dates varied based on the year rather than the location. Differences in initial infection dates between the model predictions and the monitored data in the field were minimal. For example, predicted infection dates for 7 locations were within the same month as the actual infection dates, 11 locations were within 1 month of the actual infection, and only 3 locations were more than 2 months apart from the actual infection. The predicted infection dates were mapped from 2009 to 2012; 2011 was the most severe year. Although the model was not sensitive enough to predict disease severity of less than 0.1% in the field, our model predicted bacterial spot severity of 1% or more. Therefore, this model can be applied in the field to determine when bacterial spot control is required.

Development of a Model to Predict the Primary Infection Date of Bacterial Spot (Xanthomonas campestris pv. vesicatoria) on Hot Pepper

PubMed Central

Kim, Ji-Hoon; Kang, Wee-Soo; Yun, Sung-Chul

2014-01-01

A population model of bacterial spot caused by Xanthomonas campestris pv. vesicatoria on hot pepper was developed to predict the primary disease infection date. The model estimated the pathogen population on the surface and within the leaf of the host based on the wetness period and temperature. For successful infection, at least 5,000 cells/ml of the bacterial population were required. Also, wind and rain were necessary according to regression analyses of the monitored data. Bacterial spot on the model is initiated when the pathogen population exceeds 1015 cells/g within the leaf. The developed model was validated using 94 assessed samples from 2000 to 2007 obtained from monitored fields. Based on the validation study, the predicted initial infection dates varied based on the year rather than the location. Differences in initial infection dates between the model predictions and the monitored data in the field were minimal. For example, predicted infection dates for 7 locations were within the same month as the actual infection dates, 11 locations were within 1 month of the actual infection, and only 3 locations were more than 2 months apart from the actual infection. The predicted infection dates were mapped from 2009 to 2012; 2011 was the most severe year. Although the model was not sensitive enough to predict disease severity of less than 0.1% in the field, our model predicted bacterial spot severity of 1% or more. Therefore, this model can be applied in the field to determine when bacterial spot control is required. PMID:25288995

Losses of leaf area owing to herbivory and early senescence in three tree species along a winter temperature gradient

NASA Astrophysics Data System (ADS)

González-Zurdo, P.; Escudero, A.; Nuñez, R.; Mediavilla, S.

2016-11-01

In temperate climates, evergreen leaves have to survive throughout low temperature winter periods. Freezing and chilling injuries can lead to accelerated senescence of part of the leaf surface, which contributes to a reduction of the lifespan of the photosynthetic machinery and of leaf lifetime carbon gain. Low temperatures are also associated with changes in foliar chemistry and morphology that affect consumption by herbivores. Therefore, the severity of foliar area losses caused by accelerated senescence and herbivory can change along winter temperature gradients. The aim of this study is to analyse such responses in the leaves of three evergreen species ( Quercus ilex, Q. suber and Pinus pinaster) along a climatic gradient. The leaves of all three species presented increased leaf mass per area (LMA) and higher concentrations of structural carbohydrates in cooler areas. Only the two oak species showed visible symptoms of damage caused by herbivory, this being less intense at the coldest sites. The leaves of all three species presented chlorotic and necrotic spots that increased in size with leaf age. The foliar surface affected by chlorosis and necrosis was larger at the sites with the coldest winters. Therefore, the effects of the winter cold on the lifespan of the photosynthetic machinery were contradictory: losses of leaf area due to accelerated senescence increased, but there was a decrease in losses caused by herbivory. The final consequences for carbon assimilation strongly depend on the exact timing of the appearance of the damage resulting from low temperature and grazing by herbivores.

High-resolution mapping reveals linkage between genes in common bean cultivar Ouro Negro conferring resistance to the rust, anthracnose, and angular leaf spot diseases

USDA-ARS?s Scientific Manuscript database

Rust, Anthracnose, and angular leaf spot are major diseases of common bean in the world and most particularly in the Americas and Africa, which are the largest common bean production regions of the world. The Mesoamerican black-seeded cultivar Ouro Negro is unusual in that it has resistance to all t...

Fine mapping of a quantitative resistance gene for gray leaf spot of maize (Zea mays L.) derived from teosinte (Z. mays ssp. parviglumis)

USDA-ARS?s Scientific Manuscript database

In previous work, using near isogenic line (NIL) populations in which segments of the tesosinte (Zea mays ssp. parviglumis) genome had been introgressed into the background of the maize line B73, we had identified a QTL on chromosome 8, here called Qgls8, for gray leaf spot resistance. We identified...

QTL-seq approach identified genomic regions and diagnostic markers for rust and late leaf spot resistance in groundnut (Arachis hypogaea L.)

USDA-ARS?s Scientific Manuscript database

Rust and late leaf spot (LLS) are the two major foliar fungal diseases in groundnut, and their co-occurrence leads to yield loss up to 50–70% in addition to the deterioration of fodder quality. To identify candidate genomic regions controlling rust and LLS resistance, we deployed whole genome re-seq...

Erwinia mallotivora sp., a New Pathogen of Papaya (Carica papaya) in Peninsular Malaysia

PubMed Central

Amin, Noriha Mat; Bunawan, Hamidun; Redzuan, Rohaiza Ahmad; Jaganath, Indu Bala S.

2011-01-01

Erwinia mallotivora was isolated from papaya infected with dieback disease showing the typical symptoms of greasy, water-soaked lesions and spots on leaves. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belonged to the genus Erwinia and was united in a monophyletic group with E. mallotivora DSM 4565 (AJ233414). Earlier studies had indicated that the causal agent for this disease was E. papayae. However, our current studies, through Koch’s postulate, have confirmed that papaya dieback disease is caused by E. mallotivora. To our knowledge, this is the first new discovery of E. mallotivora as a causal agent of papaya dieback disease in Peninsular Malaysia. Previous reports have suggested that E. mallotivora causes leaf spot in Mallotus japonicus. However, this research confirms it also to be pathogenic to Carica papaya. PMID:21339975

Erwinia mallotivora sp., a new pathogen of papaya (Carica papaya) in Peninsular Malaysia.

PubMed

Amin, Noriha Mat; Bunawan, Hamidun; Redzuan, Rohaiza Ahmad; Jaganath, Indu Bala S

2010-12-24

Erwinia mallotivora was isolated from papaya infected with dieback disease showing the typical symptoms of greasy, water-soaked lesions and spots on leaves. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belonged to the genus Erwinia and was united in a monophyletic group with E. mallotivora DSM 4565 (AJ233414). Earlier studies had indicated that the causal agent for this disease was E. papayae. However, our current studies, through Koch's postulate, have confirmed that papaya dieback disease is caused by E. mallotivora. To our knowledge, this is the first new discovery of E. mallotivora as a causal agent of papaya dieback disease in Peninsular Malaysia. Previous reports have suggested that E. mallotivora causes leaf spot in Mallotus japonicus. However, this research confirms it also to be pathogenic to Carica papaya.

Characterization of Mycosphaerellaceae species associated with citrus greasy spot in Panama and Spain.

PubMed

Aguilera-Cogley, Vidal Antonio; Berbegal, Mónica; Català, Santiago; Brentu, Francis Collison; Armengol, Josep; Vicent, Antonio

2017-01-01

Greasy spot of citrus, caused by Zasmidium citri-griseum (= Mycosphaerella citri), is widely distributed in the Caribbean Basin, inducing leaf spots, premature defoliation, and yield loss. Greasy spot-like symptoms were frequently observed in humid citrus-growing regions in Panama as well as in semi-arid areas in Spain, but disease aetiology was unknown. Citrus-growing areas in Panama and Spain were surveyed and isolates of Mycosphaerellaceae were obtained from citrus greasy spot lesions. A selection of isolates from Panama (n = 22) and Spain (n = 16) was assembled based on their geographical origin, citrus species, and affected tissue. The isolates were characterized based on multi-locus DNA (ITS and EF-1α) sequence analyses, morphology, growth at different temperatures, and independent pathogenicity tests on the citrus species most affected in each country. Reference isolates and sequences were also included in the analysis. Isolates from Panama were identified as Z. citri-griseum complex, and others from Spain attributed to Amycosphaerella africana. Isolates of the Z. citri-griseum complex had a significantly higher optimal growth temperature (26.8°C) than those of A. africana (19.3°C), which corresponded well with their actual biogeographical range. The isolates of the Z. citri-griseum complex from Panama induced typical greasy spot symptoms in 'Valencia' sweet orange plants and the inoculated fungi were reisolated. No symptoms were observed in plants of the 'Ortanique' tangor inoculated with A. africana. These results demonstrate the presence of citrus greasy spot, caused by Z. citri-griseum complex, in Panama whereas A. africana was associated with greasy spot-like symptoms in Spain.

High-density genetic map using whole-genome resequencing for fine mapping and candidate gene discovery for disease resistance in peanut.

PubMed

Agarwal, Gaurav; Clevenger, Josh; Pandey, Manish K; Wang, Hui; Shasidhar, Yaduru; Chu, Ye; Fountain, Jake C; Choudhary, Divya; Culbreath, Albert K; Liu, Xin; Huang, Guodong; Wang, Xingjun; Deshmukh, Rupesh; Holbrook, C Corley; Bertioli, David J; Ozias-Akins, Peggy; Jackson, Scott A; Varshney, Rajeev K; Guo, Baozhu

2018-04-10

Whole-genome resequencing (WGRS) of mapping populations has facilitated development of high-density genetic maps essential for fine mapping and candidate gene discovery for traits of interest in crop species. Leaf spots, including early leaf spot (ELS) and late leaf spot (LLS), and Tomato spotted wilt virus (TSWV) are devastating diseases in peanut causing significant yield loss. We generated WGRS data on a recombinant inbred line population, developed a SNP-based high-density genetic map, and conducted fine mapping, candidate gene discovery and marker validation for ELS, LLS and TSWV. The first sequence-based high-density map was constructed with 8869 SNPs assigned to 20 linkage groups, representing 20 chromosomes, for the 'T' population (Tifrunner × GT-C20) with a map length of 3120 cM and an average distance of 1.45 cM. The quantitative trait locus (QTL) analysis using high-density genetic map and multiple season phenotyping data identified 35 main-effect QTLs with phenotypic variation explained (PVE) from 6.32% to 47.63%. Among major-effect QTLs mapped, there were two QTLs for ELS on B05 with 47.42% PVE and B03 with 47.38% PVE, two QTLs for LLS on A05 with 47.63% and B03 with 34.03% PVE and one QTL for TSWV on B09 with 40.71% PVE. The epistasis and environment interaction analyses identified significant environmental effects on these traits. The identified QTL regions had disease resistance genes including R-genes and transcription factors. KASP markers were developed for major QTLs and validated in the population and are ready for further deployment in genomics-assisted breeding in peanut. © 2018 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Induction of necrosis via mitochondrial targeting of Melon necrotic spot virus replication protein p29 by its second transmembrane domain.

PubMed

Mochizuki, Tomofumi; Hirai, Katsuyuki; Kanda, Ayami; Ohnishi, Jun; Ohki, Takehiro; Tsuda, Shinya

2009-08-01

The virulence factor of Melon necrotic spot virus (MNSV), a virus that induces systemic necrotic spot disease on melon plants, was investigated. When the replication protein p29 was expressed in N. benthamiana using a Cucumber mosaic virus vector, necrotic spots appeared on the leaf tissue. Transmission electron microscopy revealed abnormal mitochondrial aggregation in these tissues. Fractionation of tissues expressing p29 and confocal imaging using GFP-tagged p29 revealed that p29 associated with the mitochondrial membrane as an integral membrane protein. Expression analysis of p29 deletion fragments and prediction of hydrophobic transmembrane domains (TMDs) in p29 showed that deletion of the second putative TMD from p29 led to deficiencies in both the mitochondrial localization and virulence of p29. Taken together, these results indicated that MNSV p29 interacts with the mitochondrial membrane and that p29 may be a virulence factor causing the observed necrosis.

Induction of necrosis via mitochondrial targeting of Melon necrotic spot virus replication protein p29 by its second transmembrane domain

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

Mochizuki, Tomofumi; Hirai, Katsuyuki; Kanda, Ayami

2009-08-01

The virulence factor of Melon necrotic spot virus (MNSV), a virus that induces systemic necrotic spot disease on melon plants, was investigated. When the replication protein p29 was expressed in N. benthamiana using a Cucumber mosaic virus vector, necrotic spots appeared on the leaf tissue. Transmission electron microscopy revealed abnormal mitochondrial aggregation in these tissues. Fractionation of tissues expressing p29 and confocal imaging using GFP-tagged p29 revealed that p29 associated with the mitochondrial membrane as an integral membrane protein. Expression analysis of p29 deletion fragments and prediction of hydrophobic transmembrane domains (TMDs) in p29 showed that deletion of the secondmore » putative TMD from p29 led to deficiencies in both the mitochondrial localization and virulence of p29. Taken together, these results indicated that MNSV p29 interacts with the mitochondrial membrane and that p29 may be a virulence factor causing the observed necrosis.« less

New insights into the characterization of Colletotrichum species associated with apple diseases in southern Brazil and Uruguay.

PubMed

Velho, Aline Cristina; Alaniz, Sandra; Casanova, Leticia; Mondino, Pedro; Stadnik, Marciel J

2015-04-01

Colletotrichum species are associated with Apple bitter rot (ABR) and Glomerella leaf spot (GLS). Whereas both apple diseases occur frequently in Brazil, only the former has been reported in Uruguay. This work was aimed at identifying and comparing morpho-cultural characteristics and pathogenic variability of thirty-nine Colletotrichum isolates from both countries. Sequencing of the internal transcribed spacer (ITS) rDNA, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and β-tubulin (TUB2) allowed the identification of three species causing ABR and GLS in Brazil, i.e., Colletotrichum fructicola, Colletotrichum karstii, and Colletotrichum nymphaeae; and three species causing ABR in Uruguay, i.e., C. fructicola, Colletotrichum theobromicola, and Colletotrichum melonis. Six groups of colony colours were recorded with group 1 (mycelium white to pink and in reverse pinkish) and group 2 (mycelium white to grey and in reverse pinkish) the most frequent. Isolates of C. fructicola and C. theobromicola were sensitive to benomyl, while C. karstii, C. nymphaeae, and C. melonis were resistant. Conidia were predominantly cylindrical for C. fructicola and C. karstii, fusiform for C. nymphaeae and C. melonis, and obclavate for C. theobromicola. Brazilian isolates caused ABR in wounded fruits, but only five in non-wounded ones. Uruguayan isolates produced symptoms in fruits with or without previous wounding. All Brazilian isolates from GLS and twelve from ABR were able to cause GLS symptoms, while a sole Uruguayan ABR-isolate caused leaf spot symptoms. This study gives a better insight on the new species causing apple disease in both countries and discusses their pathogenic potential. Copyright © 2014 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

New hosts of Myrothecium SPP. In brazil and a preliminary In Vitro assay of fungicides

PubMed Central

Quezado Duval, A.M.; Henz, G.P.; Paz-Lima, M.L.; Medeiros, A.R.; Miranda, B.E.C.; Pfenning, L.H.; Reis, A.

2010-01-01

Myrothecium roridum and M. verrucaria are two plant pathogenic species causing foliar spots in a large number of cultivated plants. This paper aims to study the causal agents of foliar spots in vegetable crops (sweet pepper, tomato, cucumber), ornamental plants (Spathiphyllum, Solidago canadensis, Anthurium, Dieffenbachia) and a solanaceous weed plant (Nicandra physalodes). Most of the isolates were identified as M. roridum; only the isolate ‘Myr-02’ from S. canadensis was identified as M. verrucaria. All the isolates were pathogenic to their original plant hosts and also to some other plants. Some fungicides were tested in vitro against an isolate of M. roridum and the mycelial growth recorded after seven days. Fungicides with quartenary ammonium, Tebuconzole and copper were highly effective in inhibiting the mycelial growth of M. roridum. This paper confirms the first record of M. roridum causing leaf spots in sweet pepper, tomato, Spathiphyllum, Anthurium, Dieffenbachia and N. physalodes. We also report M. roridum as causal agent of cucumber fruit rot and also M. verrucaria in tango plants. PMID:24031487

Diverse mechanisms of plant resistance to cauliflower mosaic virus revealed by leaf skeleton hybridization.

PubMed

Melcher, U; Brannan, C M; Gardner, C O; Essenberg, R C

1992-01-01

Plants not hosts for cauliflower mosaic virus (CaMV) may prevent systemic CaMV infection by interfering with dissemination of infection through the plant or by preventing viral replication and maturation. Leaf skeleton hybridization allows distinction between these two barriers. The technique assesses the spatial distribution of CaMV in an inoculated leaf by hybridization of a skeleton of the leaf with a CaMV DNA probe. Leaves or leaflets of soybean, cucumber, peanut, tomato, lettuce, spinach, pepper, onion, wheat, maize and barley, inoculated with CaMV DNA or CaMV virions were processed for leaf skeleton hybridization either immediately after inoculation or two weeks thereafter. Autoradiographic images of soybean and cucumber skeletons had many dark spots suggesting that CaMV DNA replication and local spread had occurred. Images of onion leaf skeletons prepared two weeks after inoculation with CaMV DNA had fewer spots. To test whether these spots resulted from CaMV replication, DNA was extracted from inoculated onion leaves and analyzed by electrophoresis, blotting and hybridization. Molecules recovered two weeks after inoculation resembled those inoculated, indicating absence of replication. For the other species, we found no evidence of local spread of CaMV infections. Thus, many plant species resist systemic CaMV infection by preventing replication or local spread of CaMV, while others solely prevent systemic movement of infection.

Eucalyptus microfungi known from culture. 1. Cladoriella and Fulvoflamma genera nova, with notes on some other poorly known taxa

PubMed Central

Crous, Pedro W.; Verkley, Gerard J.M.; Groenewald, Johannes Z.

2006-01-01

A study of microfungi associated with living Eucalyptus leaves and leaf litter revealed several novel and interesting taxa. Cladoriella eucalypti gen. et sp. nov. is described as a Cladosporium-like genus associated with litter collected in South Africa, while Fulvoflamma eucalypti gen. et. sp. nov. is newly described from leaf litter collected in Spain. Beta-conidia are newly reported for species of Pestalotiopsis, namely Pestalotiopsis disseminata in New Zealand, and a Pestalotiopsis sp. from Colombia. Satchmopsis brasiliensis is reported from litter in Colombia and Indonesia, while Torrendiella eucalypti is reported from leaf litter in Indonesia, and shown to have a Sporothrix-like anamorph. Leptospora rubella is reported from living Eucalyptus leaves in Colombia, where it is associated with leaf spots of Mycosphaerella longibasalis, while Macrohilum eucalypti is reported from leaf spots of Eucalyptus in New Zealand. PMID:18490971

Separation and identification of Musa acuminate Colla (banana) leaf proteins by two-dimensional gel electrophoresis and mass spectrometry.

PubMed

Lu, Y; Qi, Y X; Zhang, H; Zhang, H Q; Pu, J J; Xie, Y X

2013-12-19

To establish a proteomic reference map of Musa acuminate Colla (banana) leaf, we separated and identified leaf proteins using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and mass spectrometry (MS). Tryptic digests of 44 spots were subjected to peptide mass fingerprinting (PMF) by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS. Three spots that were not identified by MALDI-TOF MS analysis were identified by searching against the NCBInr, SwissProt, and expressed sequence tag (EST) databases. We identified 41 unique proteins. The majority of the identified leaf proteins were found to be involved in energy metabolism. The results indicate that 2D-PAGE is a sensitive and powerful technique for the separation and identification of Musa leaf proteins. A summary of the identified proteins and their putative functions is discussed.

Using SNP genetic markers to elucidate the linkage of the Co-34/Phg-3 anthracnose and angular leaf spot resistance gene cluster with the Ur-14 resistance gene

USDA-ARS?s Scientific Manuscript database

The Ouro Negro common bean cultivar contains the Co-34/Phg-3 gene cluster that confers resistance to the anthracnose (ANT) and angular leaf spot (ALS) pathogens. These genes are tightly linked on chromosome 4. Ouro Negro also has the Ur-14 rust resistance gene, reportedly in the vicinity of Co- 34; ...

Fine mapping of a quantitative resistance gene for gray leaf spot of maize (Zea mays L.) derived from teosinte (Z. mays ssp. parviglumis).

PubMed

Zhang, Xinye; Yang, Qin; Rucker, Elizabeth; Thomason, Wade; Balint-Kurti, Peter

2017-06-01

In this study we mapped the QTL Qgls8 for gray leaf spot (GLS) resistance in maize to a ~130 kb region on chromosome 8 including five predicted genes. In previous work, using near isogenic line (NIL) populations in which segments of the teosinte (Zea mays ssp. parviglumis) genome had been introgressed into the background of the maize line B73, we had identified a QTL on chromosome 8, here called Qgls8, for gray leaf spot (GLS) resistance. We identified alternate teosinte alleles at this QTL, one conferring increased GLS resistance and one increased susceptibility relative to the B73 allele. Using segregating populations derived from NIL parents carrying these contrasting alleles, we were able to delimit the QTL region to a ~130 kb (based on the B73 genome) which encompassed five predicted genes.

Protein profile of Beta vulgaris leaf apoplastic fluid and changes induced by Fe deficiency and Fe resupply

PubMed Central

Ceballos-Laita, Laura; Gutierrez-Carbonell, Elain; Lattanzio, Giuseppe; Vázquez, Saul; Contreras-Moreira, Bruno; Abadía, Anunciación; Abadía, Javier; López-Millán, Ana-Flor

2015-01-01

The fluid collected by direct leaf centrifugation has been used to study the proteome of the sugar beet apoplastic fluid as well as the changes induced by Fe deficiency and Fe resupply to Fe-deficient plants in the protein profile. Plants were grown in Fe-sufficient and Fe-deficient conditions, and Fe resupply was carried out with 45 μM Fe(III)-EDTA for 24 h. Protein extracts of leaf apoplastic fluid were analyzed by two-dimensional isoelectric focusing-SDS-PAGE electrophoresis. Gel image analysis revealed 203 consistent spots, and proteins in 81% of them (164) were identified by nLC-MS/MS using a custom made reference repository of beet protein sequences. When redundant UniProt entries were deleted, a non-redundant leaf apoplastic proteome consisting of 109 proteins was obtained. TargetP and SecretomeP algorithms predicted that 63% of them were secretory proteins. Functional classification of the non-redundant proteins indicated that stress and defense, protein metabolism, cell wall and C metabolism accounted for approximately 75% of the identified proteome. The effects of Fe-deficiency on the leaf apoplast proteome were limited, with only five spots (2.5%) changing in relative abundance, thus suggesting that protein homeostasis in the leaf apoplast fluid is well-maintained upon Fe shortage. The identification of three chitinase isoforms among proteins increasing in relative abundance with Fe-deficiency suggests that one of the few effects of Fe deficiency in the leaf apoplast proteome includes cell wall modifications. Iron resupply to Fe deficient plants changed the relative abundance of 16 spots when compared to either Fe-sufficient or Fe-deficient samples. Proteins identified in these spots can be broadly classified as those responding to Fe-resupply, which included defense and cell wall related proteins, and non-responsive, which are mainly protein metabolism related proteins and whose changes in relative abundance followed the same trend as with Fe-deficiency. PMID:25852707

Proteomic characterization of the Rph15 barley resistance gene-mediated defence responses to leaf rust

PubMed Central

2012-01-01

Background Leaf rust, caused by the biotrophic fungal pathogen Puccinia hordei, is one of the most important foliar disease of barley (Hordeum vulgare) and represents a serious threat in many production regions of the world. The leaf rust resistance gene Rph15 is of outstanding interest for resistance breeding because it confers resistance to over 350 Puccinia hordei isolates collected from around the world. Molecular and biochemical mechanisms responsible for the Rph15 effectiveness are currently not investigated. The aim of the present work was to study the Rph15-based defence responses using a proteomic approach. Results Protein pattern changes in response to the leaf rust pathogen infection were investigated in two barley near isogenic lines (NILs), Bowman (leaf rust susceptible) and Bowman-Rph15 (leaf rust resistant), differing for the introgression of the leaf rust resistance gene Rph15. Two infection time points, 24 hours and four days post inoculation (dpi), were analysed. No statistically significant differences were identified at the early time point, while at 4 dpi eighteen protein spots were significantly up or down regulated with a fold-change equal or higher than two in response to pathogen infection. Almost all the pathogen-responsive proteins were identified in the Bowman-Rph15 resistant NIL. Protein spots were characterized by LC-MS/MS analysis and found to be involved in photosynthesis and energy metabolism, carbohydrate metabolism, protein degradation and defence. Proteomic data were complemented by transcriptional analysis of the respective genes. The identified proteins can be related to modulation of the photosynthetic apparatus components, re-direction of the metabolism to sustain defence responses and deployment of defence proteins. Conclusions The identification of leaf rust infection-modulated defence responses restricted to the resistant NIL support the hypothesis that basal defence responses of Bowman, but not the Rph15 resistance gene-based ones, are suppressed or delayed by pathogen effectors to levels below the detection power of the adopted proteomic approach. Additionally, Rph15-mediated resistance processes identified mainly resides on a modulation of primary metabolism, affecting photosyntesis and carbohydrate pool. PMID:23167439

Maculosin, a host-specific phytotoxin for spotted knapweed from Alternaria alternata

PubMed Central

Stierle, Andrea C.; Cardellina, John H.; Strobel, Gary A.

1988-01-01

Several diketopiperazines have been isolated from liquid cultures of Alternaria alternata, the causal agent of black leaf blight of spotted knapweed, Centaurea maculosa Lam. One of these compounds, maculosin [the diketopiperazine cyclo(-L-Pro-L-Tyr-)], was active in the nicked-leaf bioassay at 10-5 M; synthetic maculosin possessed chemical and biological activities identical to those of the natural product. Other diketopiperazines isolated from the fungus possessed either less activity or none at all. In tests against 19 plant species, maculosin was phytotoxic only to spotted knapweed. Thus maculosin is a host-specific phytotoxin from a weed pathogen. PMID:16593989

Characterization of Mycosphaerellaceae species associated with citrus greasy spot in Panama and Spain

PubMed Central

Aguilera-Cogley, Vidal Antonio; Berbegal, Mónica; Català, Santiago; Brentu, Francis Collison; Armengol, Josep

2017-01-01

Greasy spot of citrus, caused by Zasmidium citri-griseum (= Mycosphaerella citri), is widely distributed in the Caribbean Basin, inducing leaf spots, premature defoliation, and yield loss. Greasy spot-like symptoms were frequently observed in humid citrus-growing regions in Panama as well as in semi-arid areas in Spain, but disease aetiology was unknown. Citrus-growing areas in Panama and Spain were surveyed and isolates of Mycosphaerellaceae were obtained from citrus greasy spot lesions. A selection of isolates from Panama (n = 22) and Spain (n = 16) was assembled based on their geographical origin, citrus species, and affected tissue. The isolates were characterized based on multi-locus DNA (ITS and EF-1α) sequence analyses, morphology, growth at different temperatures, and independent pathogenicity tests on the citrus species most affected in each country. Reference isolates and sequences were also included in the analysis. Isolates from Panama were identified as Z. citri-griseum complex, and others from Spain attributed to Amycosphaerella africana. Isolates of the Z. citri-griseum complex had a significantly higher optimal growth temperature (26.8°C) than those of A. africana (19.3°C), which corresponded well with their actual biogeographical range. The isolates of the Z. citri-griseum complex from Panama induced typical greasy spot symptoms in ‘Valencia’ sweet orange plants and the inoculated fungi were reisolated. No symptoms were observed in plants of the ‘Ortanique’ tangor inoculated with A. africana. These results demonstrate the presence of citrus greasy spot, caused by Z. citri-griseum complex, in Panama whereas A. africana was associated with greasy spot-like symptoms in Spain. PMID:29236789

Generation of an infectious clone of a new Korean isolate of apple chlorotic leaf spot virus (ACLSV) driven by dual 35S and T7 promoters in a versatile binary vector

USDA-ARS?s Scientific Manuscript database

The full-length sequence of a new isolate of Apple chlorotic leaf spot virus (ACLSV) from Korea was divergent, but most closely related to the Japanese isolate A4, at 84% nucleotide identity. The full-length cDNA of the Korean isolate of ACLSV was cloned into a binary vector downstream of the bacter...

Fusarium species as pathogen on orchids.

PubMed

Srivastava, Shikha; Kadooka, Chris; Uchida, Janice Y

2018-03-01

The recent surge in demand for exotic ornamental crops such as orchids has led to a rise in international production, and a sharp increase in the number of plant and plant products moving between countries. Along with the plants, diseases are also being transported and introduced into new areas. Fusarium is one of the major diseases causing pathogens infecting orchids that is spreading through international trade. Studies have identified several species of Fusarium associated with orchids, some are pathogenic and cause symptoms such as leaf and flower spots, leaf or sheath blights, pseudostem or root rots, and wilts. Infection and damage caused by Fusarium reduces the quality of plants and flowers, and can cause severe economic losses. This review documents the current status of the Fusarium-orchid interaction, and illustrates challenges and future perspectives based on the available literature. This review is the first of Fusarium and orchid interactions, and integrates diverse results that both furthers the understanding and knowledge of this disease complex, and will enable the development of effective disease management practices. Copyright © 2017 Elsevier GmbH. All rights reserved.

Bioherbicidal potential of a strain of Xanthomonas spp. for control of common cockelbur, (Santium strumarium)

USDA-ARS?s Scientific Manuscript database

Several isolates of a previously unreported disease were discovered on common cocklebur seedlings in Chicot County, Arkansas and Washington County, Mississippi. Diseased plants in nature exhibited angular-shaped leaf spotting symptoms on leaf margins and central leaf areas. The isolates were cultu...

Evaluation of indigenous bacterial strains for biocontrol of the frogeye leaf spot of soya bean caused by Cercospora sojina.

PubMed

Simonetti, E; Carmona, M A; Scandiani, M M; García, A F; Luque, A G; Correa, O S; Balestrasse, K B

2012-08-01

Assessment of biological control of Cercospora sojina, causal agent of frogeye leaf spot (FLS) of soya bean, using three indigenous bacterial strains, BNM297 (Pseudomonas fluorescens), BNM340 and BNM122 (Bacillus amyloliquefaciens). From cultures of each bacterial strain, cell suspensions and cell-free supernatants were obtained and assayed to determine their antifungal activity against C. sojina. Both mycelial growth and spore germination in vitro were more strongly inhibited by bacterial cell suspensions than by cell-free supernatants. The Bacillus strains BNM122 and BNM340 inhibited the fungal growth to a similar degree (I ≈ 52-53%), while cells from P. fluorescens BNM297 caused a lesser reduction (I ≈ 32-34%) in the fungus colony diameter. The foliar application of the two Bacillus strains on soya bean seedlings, under greenhouse conditions, significantly reduced the disease severity with respect to control soya bean seedlings and those sprayed with BNM297. This last bacterial strain was not effective in controlling FLS in vivo. Our data demonstrate that the application of antagonistic bacteria may be a promising and environmentally friendly alternative to control the FLS of soya bean.   To our knowledge, this is the first report of biological control of C. sojina by using native Bacillus strains. © 2012 The Authors. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.

Non-destructive plant health sensing using absorption spectroscopy

NASA Technical Reports Server (NTRS)

Bledsoe, Jim; Manukian, Ara; Pearce, Michael; Weiss, Lee

1988-01-01

The sensor group of the 1988 EGM 4001 class, working on NASA's Controlled Ecological Life Support Systems (CELSS) project, investigated many different plant health indicators and the technologies used to test them. The project selected by the group was to measure chlorophyll levels using absorption spectroscopy. The spectrometer measures the amount of chlorophyll in a leaf by measuring the intensity of light of a specific wavelength that is passed through a leaf. The three wavelengths of light being used corresponded to the near-IR absorption peaks of chlorophyll a, chlorophyll b, and chlorophyll-free structures. Experimentation showed that the sensor is indeed measuring levels of chlorophyll a and b and their changes before the human eye can see any changes. The detector clamp causes little damage to the leaf and will give fairly accurate readings on similar locations on a leaf, freeing the clamp from having to remain on the same spot of a leaf for all measurements. External light affects the readings only slightly so that measurements may be taken in light or dark environments. Future designs and experimentation will concentrate on reducing the size of the sensor and adapting it to a wider range of plants.

Identification of two new races of Diplocarpon rosae Wolf, the causal agent of rose black spot disease

USDA-ARS?s Scientific Manuscript database

The fungal pathogen, Diplocarpon rosae Wolf, infects only roses (Rosa spp.) and leads to rose black spot disease. Rose black spot is the most problematic disease of outdoor grown roses worldwide, due to the potential for rapid leaf yellowing and defoliation. Plants repeatedly defoliated from black ...

[Fatty acid variation in yellowfin tuna, spotted weakfish and Florida pompano when submitted to six cooking techniques].

PubMed

Castro-González, María Isabel; Maafs-Rodríguez, Ana Gabriela; Romo Pérez-Gil, Fernando

2013-03-01

The aim of the present study was to analyze the effect of six cooking techniques (steamed, foiled, foiled with banana leaf, baked, microwave-cooked and light frying) in the fatty acid content of Thunnus albacore (yellowfin tuna), Cynoscionnebulosus (spotted weakfish) and Trachinotuscarolinus (Florida pompano). After cooking the fish fillets, fatty acid analyses were performed using gas chromatography. Total lipids increased in all cooking techniques in tunaand spotted weakfish. Saturated fatty acids of tuna and spotted weakfish increased in three cooking techniques, while in Florida pompano only gas oven raised their content. Lightly frying generated the highest content of n-3 in tuna and spotted weakfish, and the lowest in Florida pompano, specie that presented less variation. In tuna fish, the most recommended cooking techniques are foiled with aluminum and microwave oven; for spotted weakfish, foiled with banana leaf; while Florida pompano can be prepared using all cooking methods except gas oven. This information is useful to enrich data from chemical composition tables, in which concentrations are usually presented in raw food.

Improvement of the Raman detection system for pesticide residues on/in fruits and vegetables

NASA Astrophysics Data System (ADS)

Li, Yan; Peng, Yankun; Zhai, Chen; Chao, Kuanglin; Qin, Jianwei

2017-05-01

Pesticide residue is one of the major challenges to fruits safety, while the traditional detection methods of pesticide residue on fruits and vegetables can't afford the demand of rapid detection in actual production because of timeconsuming. Thus rapid identification and detection methods for pesticide residue are urgently needed at present. While most Raman detection systems in the market are spot detection systems, which limits the range of application. In the study, our lab develops a Raman detection system to achieve area-scan thorough the self-developed spot detection Raman system with a control software and two devices. In the system, the scanning area is composed of many scanning spots, which means every spot needs to be detected and more time will be taken than area-scan Raman system. But lower detection limit will be achieved in this method. And some detection device is needed towards fruits and vegetables in different shape. Two detection devices are developed to detect spherical fruits and leaf vegetables. During the detection, the device will make spherical fruit rotate along its axis of symmetry, and leaf vegetables will be pressed in the test surface smoothly. The detection probe will be set to keep a proper distance to the surface of fruits and vegetables. It should make sure the laser shins on the surface of spherical fruit vertically. And two software are used to detect spherical fruits and leaf vegetables will be integrated to one, which make the operator easier to switch. Accordingly two detection devices for spherical fruits and leaf vegetables will also be portable devices to make it easier to change. In the study, a new way is developed to achieve area-scan result by spot-scan Raman detection system.

Organization and evolution of mating-type genes in three Stagonosporopsis species causing gummy stem blight of cucurbits and leaf spot and dry rot of papaya.

PubMed

Li, Hao-Xi; Gottilla, Thomas M; Brewer, Marin Talbot

2017-10-01

Population divergence and speciation of closely related lineages can result from reproductive differences leading to genetic isolation. An increasing number of fungal diseases of plants and animals have been determined to be caused by morphologically indistinguishable species that are genetically distinct, thereby representing cryptic species. We were interested in identifying if mating systems among three Stagonosporopsis species (S. citrulli, S. cucurbitacearum, and S. caricae) causing gummy stem blight (GSB) of cucurbits or leaf spot and dry rot of papaya differed, possibly underlying species divergence. Additionally, we were interested in identifying evolutionary pressures acting on the genes controlling mating in these fungi. The mating-type loci (MAT1) of three isolates from each of the three species were identified in draft genome sequences. For the three species, MAT1 was structurally identical and contained both mating-type genes necessary for sexual reproduction, which suggests that all three species are homothallic. However, both MAT1-1-1 and MAT1-2-1 were divergent among species showing rapid evolution with a much greater number of amino acid-changing substitutions detected for the reproductive genes compared with genes flanking MAT1. Positive selection was detected in MAT1-2-1, especially in the highly conserved high mobility group (MATA_HMG-box) domain. Thus, the mating-type genes are rapidly evolving in GSB fungi, but a difference in mating systems among the three species does not underlie their divergence. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Linkage and mapping of quantitative trait loci associated with angular leaf spot and powdery mildew resistance in common beans.

PubMed

Bassi, Denis; Briñez, Boris; Rosa, Juliana Santa; Oblessuc, Paula Rodrigues; Almeida, Caléo Panhoca de; Nucci, Stella Maris; Silva, Larissa Chariel Domingos da; Chiorato, Alisson Fernando; Vianello, Rosana Pereira; Camargo, Luis Eduardo Aranha; Blair, Matthew Wohlgemuth; Benchimol-Reis, Luciana Lasry

2017-01-01

Angular leaf spot (ALS) and powdery mildew (PWM) are two important fungi diseases causing significant yield losses in common beans. In this study, a new genetic linkage map was constructed using single sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs), in a segregating population derived from the AND 277 x SEA 5 cross, with 105 recombinant inbred lines. Phenotypic evaluations were performed in the greenhouse to identify quantitative trait loci (QTLs) associated with resistance by means of the composite interval mapping analysis. Four QTLs were identified for ALS resistance. The QTL ALS11AS, linked on the SNP BAR 5054, mapped on chromosome Pv11, showed the greatest effect (R2 = 26.5%) on ALS phenotypic variance. For PWM resistance, two QTLs were detected, PWM2AS and PWM11AS, on Pv2 and Pv11, explaining 7% and 66% of the phenotypic variation, respectively. Both QTLs on Pv11 were mapped on the same genomic region, suggesting that it is a pleiotropic region. The present study resulted in the identification of new markers closely linked to ALS and PWM QTLs, which can be used for marker-assisted selection, fine mapping and positional cloning.

Field performance of Populus expressing somaclonal variation in resistance to Septoria musiva

Treesearch

M. E. Ostry; K. T. Ward

2003-01-01

Over 1500 trees from two hybrid poplar clones regenerated from tissue culture and expressing somatic variation in leaf disease resistance in a laboratory leaf disk bioassay were field-tested for 5-11 years to examine their resistance to Septoria leaf spot and canker and to assess their growth characteristics compared with the source clones....

Leaf proteome alterations in the context of physiological and morphological responses to drought and heat stress in barley (Hordeum vulgare L.)

PubMed Central

von Korff, M.

2013-01-01

The objective of this study was to identify barley leaf proteins differentially regulated in response to drought and heat and the combined stresses in context of the morphological and physiological changes that also occur. The Syrian landrace Arta and the Australian cultivar Keel were subjected to drought, high temperature, or a combination of both treatments starting at heading. Changes in the leaf proteome were identified using differential gel electrophoresis and mass spectrometry. The drought treatment caused strong reductions of biomass and yield, while photosynthetic performance and the proteome were not significantly changed. In contrast, the heat treatment and the combination of heat and drought reduced photosynthetic performance and caused changes of the leaf proteome. The proteomic analysis identified 99 protein spots differentially regulated in response to heat treatment, 14 of which were regulated in a genotype-specific manner. Differentially regulated proteins predominantly had functions in photosynthesis, but also in detoxification, energy metabolism, and protein biosynthesis. The analysis indicated that de novo protein biosynthesis, protein quality control mediated by chaperones and proteases, and the use of alternative energy resources, i.e. glycolysis, play important roles in adaptation to heat stress. In addition, genetic variation identified in the proteome, in plant growth and photosynthetic performance in response to drought and heat represent stress adaption mechanisms to be exploited in future crop breeding efforts. PMID:23918963

Temperature and leaf wetness duration affect phenotypic expression of Rlm6-mediated resistance to Leptosphaeria maculans in Brassica napus.

PubMed

Huang, Yong-Ju; Evans, Neal; Li, Zi-Qin; Eckert, Maria; Chèvre, Anne-Marie; Renard, Michel; Fitt, Bruce D L

2006-01-01

Near-isogenic Brassica napus lines carrying/lacking resistance gene Rlm6 were used to investigate the effects of temperature and leaf wetness duration on phenotypic expression of Rlm6-mediated resistance. Leaves were inoculated with ascospores or conidia of Leptosphaeria maculans carrying the effector gene AvrLm6. Incubation period to the onset of lesion development, number of lesions and lesion diameter were assessed. Symptomless growth of L. maculans from leaf lesions to stems was investigated using a green fluorescent protein (GFP) expressing isolate carrying AvrLm6. L. maculans produced large grey lesions on Darmor (lacking Rlm6) at 5-25 degrees C and DarmorMX (carrying Rlm6) at 25 degrees C, but small dark spots and 'green islands' on DarmorMX at 5-20 degrees C. With increasing temperature/wetness duration, numbers of lesions/spots generally increased. GFP-expressing L. maculans grew from leaf lesions down leaf petioles to stems on DarmorMX at 25 degrees C but not at 15 degrees C. We conclude that temperature and leaf wetness duration affect the phenotypic expression of Rlm6-mediated resistance in leaves and subsequent L. maculans spread down petioles to produce stem cankers.

The development of a dense SNP-based consensus map and QTL detection for black spot resistance in five diploid rose populations [abstract

USDA-ARS?s Scientific Manuscript database

Black spot (BS) disease (Diplocarpon rosae (Lib.) Wolf) of rose is the most important leaf disease of garden roses in warm humid areas. Although the partial (horizontal) resistance to black spot has been shown to be moderately heritable, the responsible quantitative trait loci (QTL) remain unidentif...

Genetic diversity, QoI fungicide resistance, and mating type distribution of Cercospora sojina—Implications for the disease dynamics of frogeye leaf spot on soybean

PubMed Central

Shrestha, Sandesh Kumar; Cochran, Alicia; Mengistu, Alemu; Castro-Rocha, Arturo; Young-Kelly, Heather

2017-01-01

Frogeye leaf spot (FLS), caused by Cercospora sojina, causes significant damage to soybean in the U.S. One control strategy is the use of quinone outside inhibitor (QoI) fungicides. QoI resistant isolates were first reported in Tennessee (TN) in 2010. To investigate the disease dynamics of C. sojina, we collected 437 C. sojina isolates in 2015 from Jackson and Milan, TN and used 40 historical isolates collected from 2006–2009 from TN and ten additional states for comparison. A subset of 186 isolates, including historical isolates, were genotyped for 49 single nucleotide polymorphism (SNP) markers and the QoI resistance locus, revealing 35 unique genotypes. The genotypes clustered into three groups with two groups containing only sensitive isolates and the remaining group containing all resistant isolates and a dominant clonal lineage of 130 isolates. All 477 C. sojina isolates were genotyped for the QoI locus revealing 344 resistant and 133 sensitive isolates. All isolates collected prior to 2015 were QoI sensitive. Both mating type alleles (MAT1-1-1 and MAT1-2) were found in Jackson and Milan, TN and recovered from single lesions suggesting sexual recombination may play a role in the epidemiology of field populations. Analysis of C. sojina isolates using SNP markers proved useful to investigate population diversity and to elaborate on diversity as it relates to QoI resistance and mating type. PMID:28486517

The inheritance of resistance to bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians in three lettuce cultivars

PubMed Central

Hayes, Ryan J; Trent, Mark A; Truco, Maria Jose; Antonise, Rudie; Michelmore, Richard W; Bull, Carolee T

2014-01-01

Lettuce yields can be reduced by the disease bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) and host resistance is the most feasible method to reduce disease losses. The cultivars La Brillante, Pavane and Little Gem express an incompatible host–pathogen interaction as a hypersensitive response (HR) to California strains of Xcv resulting in resistance. Little was known about the inheritance of resistance; however, resistance to other lettuce pathogens is often determined by resistance gene candidates (RGCs) encoding nucleotide-binding leucine-rich repeat (NB-LRR) proteins. Therefore, we determined the inheritance of BLS resistance in the cultivars La Brillante, Little Gem and Pavane and mapped it relative to RGCs. The reaction to Xcv was analyzed in nine F1, F2 and recombinant inbred line populations of lettuce from HR×compatible or HR×HR crosses. The HR in La Brillante, Pavane and Little Gem is conditioned by single dominant genes, which are either allelic or closely linked genes. The resistance gene in La Brillante was designated Xanthomonas resistance 1 (Xar1) and mapped to lettuce linkage group 2. Xar1 is present in a genomic region that contains numerous NB-LRR encoding RGCs and functional pathogen resistance loci in the RGC2 family. The Xar1 gene confers a high level of BLS resistance in the greenhouse and field that can be introgressed into commercial lettuce cultivars to reduce BLS losses using molecular markers. PMID:26504558

Greenhouse evaluation of Bacillus subtilis AP-01 and Trichoderma harzianum AP-001 in controlling tobacco diseases.

PubMed

Maketon, Monchan; Apisitsantikul, Jirasak; Siriraweekul, Chatchai

2008-04-01

Two biological control agents, Bacillus subtilis AP-01 (Larminar(™)) and Trichoderma harzianum AP-001 (Trisan(™)) alone or/in combination were investigated in controlling three tobacco diseases, including bacterial wilt (Ralstonia solanacearum), damping-off (Pythium aphanidermatum), and frogeye leaf spot (Cercospora nicotiana). Tests were performed in greenhouse by soil sterilization prior to inoculation of the pathogens. Bacterial-wilt and damping off pathogens were drenched first and followed with the biological control agents and for comparison purposes, two chemical fungicides. But for frogeye leaf spot, which is an airborne fungus, a spraying procedure for every treatment including a chemical fungicide was applied instead of drenching. Results showed that neither B. subtilis AP-01 nor T harzianum AP-001 alone could control the bacterial wilt, but when combined, their controlling capabilities were as effective as a chemical treatment. These results were also similar for damping-off disease when used in combination. In addition, the combined B. subtilis AP-01 and T. harzianum AP-001 resulted in a good frogeye leaf spot control, which was not significantly different from the chemical treatment.

Genome-Wide Association Studies of Anthracnose and Angular Leaf Spot Resistance in Common Bean (Phaseolus vulgaris L.)

PubMed Central

Perseguini, Juliana Morini Küpper Cardoso; Oblessuc, Paula Rodrigues; Rosa, João Ricardo Bachega Feijó; Gomes, Kleber Alves; Chiorato, Alisson Fernando; Carbonell, Sérgio Augusto Morais; Garcia, Antonio Augusto Franco; Vianello, Rosana Pereira; Benchimol-Reis, Luciana Lasry

2016-01-01

The common bean (Phaseolus vulgaris L.) is the world’s most important legume for human consumption. Anthracnose (ANT; Colletotrichum lindemuthianum) and angular leaf spot (ALS; Pseudocercospora griseola) are complex diseases that cause major yield losses in common bean. Depending on the cultivar and environmental conditions, anthracnose and angular leaf spot infections can reduce crop yield drastically. This study aimed to estimate linkage disequilibrium levels and identify quantitative resistance loci (QRL) controlling resistance to both ANT and ALS diseases of 180 accessions of common bean using genome-wide association analysis. A randomized complete block design with four replicates was performed for the ANT and ALS experiments, with four plants per genotype in each replicate. Association mapping analyses were performed for ANT and ALS using a mixed linear model approach implemented in TASSEL. A total of 17 and 11 significant statistically associations involving SSRs were detected for ANT and ALS resistance loci, respectively. Using SNPs, 21 and 17 significant statistically associations were obtained for ANT and angular ALS, respectively, providing more associations with this marker. The SSR-IAC167 and PvM95 markers, both located on chromosome Pv03, and the SNP scaffold00021_89379, were associated with both diseases. The other markers were distributed across the entire common bean genome, with chromosomes Pv03 and Pv08 showing the greatest number of loci associated with ANT resistance. The chromosome Pv04 was the most saturated one, with six markers associated with ALS resistance. The telomeric region of this chromosome showed four markers located between approximately 2.5 Mb and 4.4 Mb. Our results demonstrate the great potential of genome-wide association studies to identify QRLs related to ANT and ALS in common bean. The results indicate a quantitative and complex inheritance pattern for both diseases in common bean. Our findings will contribute to more effective screening of elite germplasm to find resistance alleles for marker-assisted selection in breeding programs. PMID:26930078

Genome-Wide Association Studies of Anthracnose and Angular Leaf Spot Resistance in Common Bean (Phaseolus vulgaris L.).

PubMed

Perseguini, Juliana Morini Küpper Cardoso; Oblessuc, Paula Rodrigues; Rosa, João Ricardo Bachega Feijó; Gomes, Kleber Alves; Chiorato, Alisson Fernando; Carbonell, Sérgio Augusto Morais; Garcia, Antonio Augusto Franco; Vianello, Rosana Pereira; Benchimol-Reis, Luciana Lasry

2016-01-01

The common bean (Phaseolus vulgaris L.) is the world's most important legume for human consumption. Anthracnose (ANT; Colletotrichum lindemuthianum) and angular leaf spot (ALS; Pseudocercospora griseola) are complex diseases that cause major yield losses in common bean. Depending on the cultivar and environmental conditions, anthracnose and angular leaf spot infections can reduce crop yield drastically. This study aimed to estimate linkage disequilibrium levels and identify quantitative resistance loci (QRL) controlling resistance to both ANT and ALS diseases of 180 accessions of common bean using genome-wide association analysis. A randomized complete block design with four replicates was performed for the ANT and ALS experiments, with four plants per genotype in each replicate. Association mapping analyses were performed for ANT and ALS using a mixed linear model approach implemented in TASSEL. A total of 17 and 11 significant statistically associations involving SSRs were detected for ANT and ALS resistance loci, respectively. Using SNPs, 21 and 17 significant statistically associations were obtained for ANT and angular ALS, respectively, providing more associations with this marker. The SSR-IAC167 and PvM95 markers, both located on chromosome Pv03, and the SNP scaffold00021_89379, were associated with both diseases. The other markers were distributed across the entire common bean genome, with chromosomes Pv03 and Pv08 showing the greatest number of loci associated with ANT resistance. The chromosome Pv04 was the most saturated one, with six markers associated with ALS resistance. The telomeric region of this chromosome showed four markers located between approximately 2.5 Mb and 4.4 Mb. Our results demonstrate the great potential of genome-wide association studies to identify QRLs related to ANT and ALS in common bean. The results indicate a quantitative and complex inheritance pattern for both diseases in common bean. Our findings will contribute to more effective screening of elite germplasm to find resistance alleles for marker-assisted selection in breeding programs.

Origin of the Outbreak in France of Pseudomonas syringae pv. actinidiae Biovar 3, the Causal Agent of Bacterial Canker of Kiwifruit, Revealed by a Multilocus Variable-Number Tandem-Repeat Analysis

PubMed Central

Cunty, A.; Cesbron, S.; Poliakoff, F.; Jacques, M.-A.

2015-01-01

The first outbreaks of bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae biovar 3 were detected in France in 2010. P. syringae pv. actinidiae causes leaf spots, dieback, and canker that sometimes lead to the death of the vine. P. syringae pv. actinidifoliorum, which is pathogenic on kiwi as well, causes only leaf spots. In order to conduct an epidemiological study to track the spread of the epidemics of these two pathogens in France, we developed a multilocus variable-number tandem-repeat (VNTR) analysis (MLVA). MLVA was conducted on 340 strains of P. syringae pv. actinidiae biovar 3 isolated in Chile, China, France, Italy, and New Zealand and on 39 strains of P. syringae pv. actinidifoliorum isolated in Australia, France, and New Zealand. Eleven polymorphic VNTR loci were identified in the genomes of P. syringae pv. actinidiae biovar 3 ICMP 18744 and of P. syringae pv. actinidifoliorum ICMP 18807. MLVA enabled the structuring of P. syringae pv. actinidiae biovar 3 and P. syringae pv. actinidifoliorum strains in 55 and 16 haplotypes, respectively. MLVA and discriminant analysis of principal components revealed that strains isolated in Chile, China, and New Zealand are genetically distinct from P. syringae pv. actinidiae strains isolated in France and in Italy, which appear to be closely related at the genetic level. In contrast, no structuring was observed for P. syringae pv. actinidifoliorum. We developed an MLVA scheme to explore the diversity within P. syringae pv. actinidiae biovar 3 and to trace the dispersal routes of epidemic P. syringae pv. actinidiae biovar 3 in Europe. We suggest using this MLVA scheme to trace the dispersal routes of P. syringae pv. actinidiae at a global level. PMID:26209667

A Novel Alternaria Species Isolated from Peucedanum japonicum in Korea

PubMed Central

Deng, Jian Xin; Cho, Hye Sun; Paul, Narayan Chandra; Lee, Hyang Burm

2014-01-01

We isolated and examined a new Alternaria sp., which causes leaf spots on Peucedanum japonicum in Korea, by using molecular and morphological methods. Phylogenetic analysis based on a combined internal transcribed spacer region analysis and two protein-coding genes (gpd and Alt a1) demonstrated that the causal fungus was most closely related to A. cinerariae and A. sonchi, and relevant to A. brassicae. However, conidial morphology indicated that it is a novel species within the genus Alternaria, and therefore we have assigned the fungus a new name in this study. PMID:24808728

Evaluation of Three Protein-Extraction Methods for Proteome Analysis of Maize Leaf Midrib, a Compound Tissue Rich in Sclerenchyma Cells.

PubMed

Wang, Ning; Wu, Xiaolin; Ku, Lixia; Chen, Yanhui; Wang, Wei

2016-01-01

Leaf morphology is closely related to the growth and development of maize (Zea mays L.) plants and final kernel production. As an important part of the maize leaf, the midrib holds leaf blades in the aerial position for maximum sunlight capture. Leaf midribs of adult plants contain substantial sclerenchyma cells with heavily thickened and lignified secondary walls and have a high amount of phenolics, making protein extraction and proteome analysis difficult in leaf midrib tissue. In the present study, three protein-extraction methods that are commonly used in plant proteomics, i.e., phenol extraction, TCA/acetone extraction, and TCA/acetone/phenol extraction, were qualitatively and quantitatively evaluated based on 2DE maps and MS/MS analysis using the midribs of the 10th newly expanded leaves of maize plants. Microscopy revealed the existence of substantial amounts of sclerenchyma underneath maize midrib epidermises (particularly abaxial epidermises). The spot-number order obtained via 2DE mapping was as follows: phenol extraction (655) > TCA/acetone extraction (589) > TCA/acetone/phenol extraction (545). MS/MS analysis identified a total of 17 spots that exhibited 2-fold changes in abundance among the three methods (using phenol extraction as a control). Sixteen of the proteins identified were hydrophilic, with GRAVY values ranging from -0.026 to -0.487. For all three methods, we were able to obtain high-quality protein samples and good 2DE maps for the maize leaf midrib. However, phenol extraction produced a better 2DE map with greater resolution between spots, and TCA/acetone extraction produced higher protein yields. Thus, this paper includes a discussion regarding the possible reasons for differential protein extraction among the three methods. This study provides useful information that can be used to select suitable protein extraction methods for the proteome analysis of recalcitrant plant tissues that are rich in sclerenchyma cells.

Leaf proteomic analysis in cassava (Manihot esculenta, Crantz) during plant development, from planting of stem cutting to storage root formation.

PubMed

Mitprasat, Mashamon; Roytrakul, Sittiruk; Jiemsup, Surasak; Boonseng, Opas; Yokthongwattana, Kittisak

2011-06-01

Tuberization in cassava (Manihot esculenta Crantz) occurs simultaneously with plant development, suggesting competition of photoassimilate partitioning between the shoot and the root organs. In potato, which is the most widely studied tuber crop, there is ample evidence suggesting that metabolism and regulatory processes in leaf may have an impact on tuber formation. To search for leaf proteins putatively involved in regulating tuber generation and/or development in cassava, comparative proteomic approaches have been applied to monitor differentially expressed leaf proteins during root transition from fibrous to tuberous. Stringent cross comparison and statistical analysis between two groups with different plant ages using Student's t test with 95% significance level revealed a number of protein spots whose abundance were significantly altered (P < 0.05) during week 4 to week 8 of growth. Of these, 39 spots were successfully identified by ion trap LC-MS/MS. The proteins span various functional categories from antioxidant and defense, carbohydrate metabolism, cyanogenesis, energy metabolism, miscellaneous and unknown proteins. Results suggested possible metabolic switches in the leaf that may trigger/regulate storage root initiation and growth. This study provides a basis for further functional characterization of differentially expressed leaf proteins, which can help understand how biochemical processes in cassava leaves may be involved in storage root development.

A trade off between mlo resistance to powdery mildew and increased susceptibility of barley to a newly important disease, Ramularia leaf spot

PubMed Central

McGrann, Graham R. D.; Brown, James K. M.

2014-01-01

Ramularia leaf spot (RLS), caused by the fungus Ramularia collo-cygni, is a serious, recently emerged disease of barley in Europe and other temperate regions. This study investigated the trade off between strong resistance to powdery mildew conferred by mlo mutant alleles and increased susceptibility to RLS. In field trials and seedling tests, the presence of mlo alleles increased severity of RLS. Genetic analysis of a doubled-haploid population identified one quantitative trait locus for susceptibility to RLS, colocalizing with the mlo-11 allele for mildew resistance. The effect of mlo-11 on RLS severity was environmentally sensitive. Analysis of near-isogenic lines of different mlo mutations in various genetic backgrounds confirmed that mlo alleles increased RLS severity in seedlings and adult plants. For mlo resistance to mildew to be fully effective, the genes ROR1 and ROR2 are required. RLS symptoms were significantly reduced on mlo-5 ror double mutants but fungal DNA levels remained as high as in mlo-5 single mutants, implying that ror alleles modify the transition of the fungus from endophytism to necrotrophy. These results indicate that the widespread use of mlo resistance to control mildew may have inadvertently stimulated the emergence of RLS as a major disease of barley. PMID:24399175

Linkage and mapping of quantitative trait loci associated with angular leaf spot and powdery mildew resistance in common beans

PubMed Central

Bassi, Denis; Briñez, Boris; Rosa, Juliana Santa; Oblessuc, Paula Rodrigues; de Almeida, Caléo Panhoca; Nucci, Stella Maris; da Silva, Larissa Chariel Domingos; Chiorato, Alisson Fernando; Vianello, Rosana Pereira; Camargo, Luis Eduardo Aranha; Blair, Matthew Wohlgemuth; Benchimol-Reis, Luciana Lasry

2017-01-01

Abstract Angular leaf spot (ALS) and powdery mildew (PWM) are two important fungi diseases causing significant yield losses in common beans. In this study, a new genetic linkage map was constructed using single sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs), in a segregating population derived from the AND 277 x SEA 5 cross, with 105 recombinant inbred lines. Phenotypic evaluations were performed in the greenhouse to identify quantitative trait loci (QTLs) associated with resistance by means of the composite interval mapping analysis. Four QTLs were identified for ALS resistance. The QTL ALS11AS, linked on the SNP BAR 5054, mapped on chromosome Pv11, showed the greatest effect (R2 = 26.5%) on ALS phenotypic variance. For PWM resistance, two QTLs were detected, PWM2AS and PWM11AS, on Pv2 and Pv11, explaining 7% and 66% of the phenotypic variation, respectively. Both QTLs on Pv11 were mapped on the same genomic region, suggesting that it is a pleiotropic region. The present study resulted in the identification of new markers closely linked to ALS and PWM QTLs, which can be used for marker-assisted selection, fine mapping and positional cloning. PMID:28222201

Comparative proteomic analysis of oil palm leaves infected with Ganoderma boninense revealed changes in proteins involved in photosynthesis, carbohydrate metabolism, and immunity and defense.

PubMed

Jeffery Daim, Leona Daniela; Ooi, Tony Eng Keong; Ithnin, Nalisha; Mohd Yusof, Hirzun; Kulaveerasingam, Harikrishna; Abdul Majid, Nazia; Karsani, Saiful Anuar

2015-08-01

The basidiomycete fungal pathogen Ganoderma boninense is the causative agent for the incurable basal stem rot (BSR) disease in oil palm. This disease causes significant annual crop losses in the oil palm industry. Currently, there is no effective method for disease control and elimination, nor is any molecular marker for early detection of the disease available. An understanding of how BSR affects protein expression in plants may help identify and/or assist in the development of an early detection protocol. Although the mode of infection of BSR disease is primarily via the root system, defense-related genes have been shown to be expressed in both the root and leafs. Thus, to provide an insight into the changes in the global protein expression profile in infected plants, comparative 2DE was performed on leaf tissues sampled from palms with and without artificial inoculation of the Ganoderma fungus. Comparative 2DE revealed that 54 protein spots changed in abundance. A total of 51 protein spots were successfully identified by LC-QTOF MS/MS. The majority of these proteins were those involved in photosynthesis, carbohydrate metabolism as well as immunity and defense. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Induction of salicylic acid-mediated defense response in perennial ryegrass against infection by Magnaporthe oryzae.

PubMed

Rahman, Alamgir; Kuldau, Gretchen A; Uddin, Wakar

2014-06-01

Incorporation of plant defense activators is an innovative approach to development of an integrated strategy for the management of turfgrass diseases. The effects of salicylic acid (SA), benzothiadiazole (BTH, chemical analog of SA), jasmonic acid (JA), and ethephon (ET, an ethylene-releasing compound) on development of gray leaf spot in perennial ryegrass (Lolium perenne L.) caused by Magnaporthe oryzae were evaluated. Gray leaf spot disease incidence and severity were significantly decreased when plants were treated prior to inoculation with SA, BTH, and partially by ET but not by JA. Accumulation of endogenous SA and elevated expression of pathogenesis-related (PR)-1, PR-3.1, and PR-5 genes were associated with inoculation of plants by M. oryzae. Treatment of plants with SA enhanced expression levels of PR-3.1 and PR-5 but did not affect the PR-1 level, whereas BTH treatment enhanced relative expression levels of all three PR genes. Microscopic observations of leaves inoculated with M. oryzae revealed higher frequencies of callose deposition at the penetration sites in SA- and BTH-treated plants compared with the control plants (treated with water). These results suggest that early and higher induction of these genes by systemic resistance inducers may provide perennial ryegrass with a substantial advantage to defend against infection by M. oryzae.

Distribution of Tomato spotted wilt virus in dahlia plants.

PubMed

Asano, S; Hirayama, Y; Matsushita, Y

2017-04-01

Tomato spotted wilt virus (TSWV) causes significant losses in the production of the ornamental plant Dahlia variabilis in Japan. The purpose of this study was to examine the distribution of TSWV in dahlia plants and identify plant parts that can be used in the selection of TSWV-free plants. The distribution of TSWV was investigated using reverse transcriptional polymerase chain reaction (RT-PCR) and tissue blot immunoassay. The detection rate of TSWV in latent infected compound leaves was the highest in the petiole, and it decreased from the veins and rachis to the lamina. The tissue blot immunoassays of the leaflets showed an uneven distribution of TSWV, especially along the edge of the leaf blade. In stems, the detection rate of TSWV was high partway up the stem compared to that in the upper and the lower parts of the stem during the vegetative growth stage. A highly uneven distribution was observed in the bulb. Our results indicated that middle parts of the stem as well as the petioles, rachis, and veins of compound leaves are suitable for detection of TSWV in dahlias. This study is the first to report uneven distribution of TSWV in dahlia plants. In this study, the distribution of Tomato spotted wilt virus (TSWV) in various parts of dahlia plants was investigated for the first time. The distribution of TSWV was uneven in compound leaves, leaflets, stems, and bulbs. The middle parts of the stem or the petiole and leaf veins should be sampled to detect TSWV when selecting healthy plants. © 2017 The Society for Applied Microbiology.

Salicylic acid confers enhanced resistance to Glomerella leaf spot in apple.

PubMed

Zhang, Ying; Shi, Xiangpeng; Li, Baohua; Zhang, Qingming; Liang, Wenxing; Wang, Caixia

2016-09-01

Glomerella leaf spot (GLS) caused by Glomerella cingulata is a newly emergent disease that results in severe defoliation and fruit spots in apple. Currently, there are no effective means to control this disease except for the traditional fungicide sprays. Induced resistance by elicitors against pathogens infection is a widely accepted eco-friendly strategy. In the present study, we investigated whether exogenous application of salicylic acid (SA) could improve resistance to GLS in a highly susceptible apple cultivar (Malus domestica Borkh. cv. 'Gala') and the underlying mechanisms. The results showed that pretreatment with SA, at 0.1-1.0 mM, induced strong resistance against GLS in 'Gala' apple leaves, with SA treated leaves showing significant reduction in lesion numbers and disease index. Concurrent with the enhanced disease resistance, SA treatment markedly increased the total antioxidant capacity (T-AOC) and defence-related enzyme activities, including catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO). As expected, SA treatment also induced the expression levels of five pathogenesis-related (PR) genes including PR1, PR5, PR8, Chitinase and β-1,3-glucanase. Furthermore, the most pronounced and/or rapid increase was observed in leaves treated with SA and subsequently inoculated with G. cingulata compared to the treatment with SA or inoculation with the pathogen. Together, these results suggest that exogenous SA triggered increase in reactive oxygen species levels and the antioxidant system might be responsible for enhanced resistance against G. cingulata in 'Gala' apple leaves. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

A maize caffeoyl-CoA O-methyltransferase gene confers quantitative resistance to multiple pathogens

USDA-ARS?s Scientific Manuscript database

Alleles that confer multiple disease resistance (MDR) are valuable in crop improvement though molecular mechanisms underlying their functions remain largely unknown. A QTL, qMdr9.02, associated with resistance to three important foliar maize diseases, southern leaf blight (SLB), gray leaf spot (GLS)...

Molecular characterization of Xanthomonas strains responsible for bacterial leaf spot of tomato in Ethiopia

USDA-ARS?s Scientific Manuscript database

Bacterial spot of tomato (BST) is a major constraint to tomato production in Ethiopia and many other countries leading to significant crop losses. In the present study, using pathogenicity tests, sensitivity to copper and streptomycin, and multilocus sequence analysis, a diverse group of Xanthomonas...

Characterization of partial resistance to black spot disease of Rosa spp.

USDA-ARS?s Scientific Manuscript database

Black spot disease (BSD) is one of the most serious diseases of garden roses. Both complete (vertical) resistance and partial (horizontal) resistance have been identified in 16 rose genotypes using two laboratory assays, the detached leaf assay (DLA) and the whole plant inoculation (WPI) approaches...

Stomatal characteristics and infection biology of Pyrenopeziza betulicola in Betula pendula trees grown under elevated CO2 and O3.

PubMed

Riikonen, Johanna; Syrjälä, Leena; Tulva, Ingmar; Mänd, Pille; Oksanen, Elina; Poteri, Marja; Vapaavuori, Elina

2008-11-01

Two silver birch clones were exposed to ambient and elevated concentrations of CO(2) and O(3), and their combination for 3 years, using open-top chambers. We evaluated the effects of elevated CO(2) and O(3) on stomatal conductance (g(s)), density (SD) and index (SI), length of the guard cells, and epidermal cell size and number, with respect to crown position and leaf type. The relationship between the infection biology of the fungus (Pyrenopeziza betulicola) causing leaf spot disease and stomatal characteristics was also studied. Leaf type was an important determinant of O(3) response in silver birch, while crown position and clone played only a minor role. Elevated CO(2) reduced the g(s), but had otherwise no significant effect on the parameters studied. No significant interactions between elevated CO(2) and O(3) were found. The infection biology of P. betulicola was not correlated with SD or g(s), but it did occasionally correlate positively with the length of the guard cells.

Atmospheric cold plasma jet for plant disease treatment

NASA Astrophysics Data System (ADS)

Zhang, Xianhui; Liu, Dongping; Zhou, Renwu; Song, Ying; Sun, Yue; Zhang, Qi; Niu, Jinhai; Fan, Hongyu; Yang, Si-ze

2014-01-01

This study shows that the atmospheric cold plasma jet is capable of curing the fungus-infected plant leaves and controlling the spread of infection as an attractive tool for plant disease management. The healing effect was significantly dependent on the size of the black spots infected with fungal cells and the leaf age. The leaves with the diameter of black spots of <2 mm can completely recover from the fungus-infected state. The plasma-generated species passing through the microns-sized stomas in a leaf can weaken the function of the oil vacuoles and cell membrane of fungal cells, resulting in plasma-induced inactivation.

Mapping Late Leaf Spot Resistance in Peanut (Arachis hypogaea) Using QTL-seq Reveals Markers for Marker-Assisted Selection.

PubMed

Clevenger, Josh; Chu, Ye; Chavarro, Carolina; Botton, Stephanie; Culbreath, Albert; Isleib, Thomas G; Holbrook, C C; Ozias-Akins, Peggy

2018-01-01

Late leaf spot (LLS; Cercosporidium personatum ) is a major fungal disease of cultivated peanut ( Arachis hypogaea ). A recombinant inbred line population segregating for quantitative field resistance was used to identify quantitative trait loci (QTL) using QTL-seq. High rates of false positive SNP calls using established methods in this allotetraploid crop obscured significant QTLs. To resolve this problem, robust parental SNPs were first identified using polyploid-specific SNP identification pipelines, leading to discovery of significant QTLs for LLS resistance. These QTLs were confirmed over 4 years of field data. Selection with markers linked to these QTLs resulted in a significant increase in resistance, showing that these markers can be immediately applied in breeding programs. This study demonstrates that QTL-seq can be used to rapidly identify QTLs controlling highly quantitative traits in polyploid crops with complex genomes. Markers identified can then be deployed in breeding programs, increasing the efficiency of selection using molecular tools. Key Message: Field resistance to late leaf spot is a quantitative trait controlled by many QTLs. Using polyploid-specific methods, QTL-seq is faster and more cost effective than QTL mapping.

Mapping Late Leaf Spot Resistance in Peanut (Arachis hypogaea) Using QTL-seq Reveals Markers for Marker-Assisted Selection

PubMed Central

Clevenger, Josh; Chu, Ye; Chavarro, Carolina; Botton, Stephanie; Culbreath, Albert; Isleib, Thomas G.; Holbrook, C. C.; Ozias-Akins, Peggy

2018-01-01

Late leaf spot (LLS; Cercosporidium personatum) is a major fungal disease of cultivated peanut (Arachis hypogaea). A recombinant inbred line population segregating for quantitative field resistance was used to identify quantitative trait loci (QTL) using QTL-seq. High rates of false positive SNP calls using established methods in this allotetraploid crop obscured significant QTLs. To resolve this problem, robust parental SNPs were first identified using polyploid-specific SNP identification pipelines, leading to discovery of significant QTLs for LLS resistance. These QTLs were confirmed over 4 years of field data. Selection with markers linked to these QTLs resulted in a significant increase in resistance, showing that these markers can be immediately applied in breeding programs. This study demonstrates that QTL-seq can be used to rapidly identify QTLs controlling highly quantitative traits in polyploid crops with complex genomes. Markers identified can then be deployed in breeding programs, increasing the efficiency of selection using molecular tools. Key Message: Field resistance to late leaf spot is a quantitative trait controlled by many QTLs. Using polyploid-specific methods, QTL-seq is faster and more cost effective than QTL mapping. PMID:29459876

Colonization and Movement of Xanthomonas fragariae in Strawberry Tissues.

PubMed

Wang, Hehe; McTavish, Christine; Turechek, William W

2018-06-01

Xanthomonas fragariae causes angular leaf spot of strawberry, an important disease in strawberry growing regions worldwide. To better understand how X. fragariae multiplies and moves in strawberry plants, a green fluorescent protein (GFP)-labeled strain was constructed and used to monitor the pathogen's presence in leaf, petiole, and crown tissue with fluorescence microscopy following natural and wound inoculation in three strawberry cultivars. Taqman PCR was used to quantify bacterial densities in these same tissues regardless of the presence of GFP signal. Results showed X. fragariae colonized leaf mesophyll, the top 1 cm portion of the petiole adjacent to the leaf blade, and was occasionally found colonizing xylem vessels down to the middle of the petioles. The colonization of vascular bundles and the limited systemic movement that was observed appeared to be a passive process, of which the frequency increased with wounding and direct infiltration of bacteria into leaf veins. X. fragariae was able to directly enter petioles and colonize the space under the epidermis. Systemic movement of the bacteria into crown and other uninoculated tissues was not detected visually by GFP. However, X. fragariae was occasionally detected in these tissues by qPCR, but at quantities very near the qPCR detection limit. Petiole tissue harboring bacteria introduced either by direct entry through natural openings or wounds, or by systemic movement from infected foliar tissue, likely serves as a main source of initial inoculum in field plantings.

[Progress in researches on pathogens, epidemiology and integrated control of diseases on Salvia miltiorrhiza in China].

PubMed

Wang, Tie-Lin; Guan, Wei; Sun, Kai; Wang, Sheng; Chi, Xiu-Lian; Guo, Lan-Ping

2018-06-01

Danshen (Salvia miltiorrhiza) is a perennial herbal plant as a bulk commodity of traditional Chinese medicinal material. With the growing market demand, the planting scale of Danshen has been fast enlarged. The occurance of diseases on Danshen has become as a major threaten of its production. Root diseases are most devastated on Danshen. Rootrot is the most important disease, and Fusarium wilt comes second. Leaf spot occurs most on aerial part of Danshen. In the Danshen industry, the chemical control is most commonly used, with biological agents as supplements. This review summarized the symptom, pathogen, epidemiology, and control method of 7 diseases on Danshen (rootrot, Fusarium wilt, southern blight, root knot nematode, leaf spot, leaf red and virus diseases), providing guidelines for disease diagnostics, pathogen isolation and identification, proper pesticide application and integrated control. Copyright© by the Chinese Pharmaceutical Association.

Assessment of spore presence for Cercospora beticola as demonstrated by sentinel beets

USDA-ARS?s Scientific Manuscript database

Cercospora beticola, the causal agent of Cercospora leaf spot (CLS) in Beta vulgaris (sugar, table, and leaf beet), is an important pathogen globally. Disease forecasting models are widely used to aid in CLS management for sugar beet. Most models rely on weather data to predict infection periods but...

The genetics of leaf flecking in maize and its relationship to plant defense and disease resistance

USDA-ARS?s Scientific Manuscript database

Physiological/genetic leaf spotting, or flecking, is a mild lesion phenotype observed on the leaves of several commonly used maize inbred lines and has been anecdotally linked to enhanced broad-spectrum disease resistance. Flecking was assessed in the maize nested association mapping (NAM) populati...

Leaf-morphology-assisted selection for resistance to two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) in carnations (Dianthus caryophyllus L).

PubMed

Seki, Kousuke

2016-10-01

The development of a cultivar resistant to the two-spotted spider mite has provided both ecological and economic benefits to the production of cut flowers. This study aimed to clarify the mechanism of resistance to mites using an inbred population of carnations. In the resistant and susceptible plants selected from an inbred population, a difference was recognised in the thickness of the abaxial palisade tissue by microscopic examination of the damaged leaf. Therefore, it was assumed that mites displayed feeding preferences within the internal leaf structure of the carnation leaf. The suitability of the host plant for mites was investigated using several cultivars selected using an index of the thickness from the abaxial leaf surface to the spongy tissue. The results suggested that the cultivar associated with a thicker abaxial tissue lowered the intrinsic rate of natural increase of the mites. The cultivars with a thicker abaxial tissue of over 120 µm showed slight damage in the field test. The ability of mites to feed on the spongy tissue during an early life stage from hatching to adult emergence was critical. It was possible to select a cultivar that is resistant to mites under a real cultivation environment by observing the internal structure of the leaf. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

HyperART: non-invasive quantification of leaf traits using hyperspectral absorption-reflectance-transmittance imaging.

PubMed

Bergsträsser, Sergej; Fanourakis, Dimitrios; Schmittgen, Simone; Cendrero-Mateo, Maria Pilar; Jansen, Marcus; Scharr, Hanno; Rascher, Uwe

2015-01-01

Combined assessment of leaf reflectance and transmittance is currently limited to spot (point) measurements. This study introduces a tailor-made hyperspectral absorption-reflectance-transmittance imaging (HyperART) system, yielding a non-invasive determination of both reflectance and transmittance of the whole leaf. We addressed its applicability for analysing plant traits, i.e. assessing Cercospora beticola disease severity or leaf chlorophyll content. To test the accuracy of the obtained data, these were compared with reflectance and transmittance measurements of selected leaves acquired by the point spectroradiometer ASD FieldSpec, equipped with the FluoWat device. The working principle of the HyperART system relies on the upward redirection of transmitted and reflected light (range of 400 to 2500 nm) of a plant sample towards two line scanners. By using both the reflectance and transmittance image, an image of leaf absorption can be calculated. The comparison with the dynamically high-resolution ASD FieldSpec data showed good correlation, underlying the accuracy of the HyperART system. Our experiments showed that variation in both leaf chlorophyll content of four different crop species, due to different fertilization regimes during growth, and fungal symptoms on sugar beet leaves could be accurately estimated and monitored. The use of leaf reflectance and transmittance, as well as their sum (by which the non-absorbed radiation is calculated) obtained by the HyperART system gave considerably improved results in classification of Cercospora leaf spot disease and determination of chlorophyll content. The HyperART system offers the possibility for non-invasive and accurate mapping of leaf transmittance and absorption, significantly expanding the applicability of reflectance, based on mapping spectroscopy, in plant sciences. Therefore, the HyperART system may be readily employed for non-invasive determination of the spatio-temporal dynamics of various plant properties.

New Rust Disease of Korean Willow (Salix koreensis) Caused by Melampsora yezoensis, Unrecorded Pathogen in Korea.

PubMed

Yun, Yeo Hong; Ahn, Geum Ran; Yoon, Seong Kwon; Kim, Hoo Hyun; Son, Seung Yeol; Kim, Seong Hwan

2016-12-01

During the growing season of 2015, leaf specimens with yellow rust spots were collected from Salix koreensis Andersson, known as Korean willow, in riverine areas in Cheonan, Korea. The fungus on S. koreensis was identified as the rust species, Melampsora yezoensis , based on the morphology of urediniospores observed by light and scanning electron microscopy, and the molecular properties of the internal transcribed spacer rDNA region. Pathogenicity tests confirmed that the urediniospores are the causal agent of the rust symptoms on the leaves and young stems of S. koreensis . Here, we report a new rust disease of S. koreensis caused by the rust fungus, M. yezoensis , a previously unrecorded rust pathogen in Korea.

Secretome weaponries of Cochliobolus lunatus interacting with potato leaf at different temperature regimes reveal a CL[xxxx]LHM - motif

PubMed Central

2014-01-01

Background Plant and animal pathogenic fungus Cochliobolus lunatus cause great economic damages worldwide every year. C. lunatus displays an increased temperature dependent-virulence to a wide range of hosts. Nonetheless, this phenomenon is poorly understood due to lack of insights on the coordinated secretome weaponries produced by C. lunatus under heat-stress conditions on putative hosts. To understand the mechanism better, we dissected the secretome of C. lunatus interacting with potato (Solanum tuberosum L.) leaf at different temperature regimes. Results C. lunatus produced melanized colonizing hyphae in and on potato leaf, finely modulated the ambient pH as a function of temperature and secreted diverse set of proteins. Using two dimensional gel electrophoresis (2-D) and mass spectrometry (MS) technology, we observed discrete secretomes at 20°C, 28°C and 38°C. A total of 21 differentially expressed peptide spots and 10 unique peptide spots (that did not align on the gels) matched with 28 unique protein models predicted from C. lunatus m118 v.2 genome peptides. Furthermore, C. lunatus secreted peptides via classical and non-classical pathways related to virulence, proteolysis, nucleic acid metabolism, carbohydrate metabolism, heat stress, signal trafficking and some with unidentified catalytic domains. Conclusions We have identified a set of 5 soluble candidate effectors of unknown function from C. lunatus secretome weaponries against potato crop at different temperature regimes. Our findings demonstrate that C. lunatus has a repertoire of signature secretome which mediates thermo-pathogenicity and share a leucine rich “CL[xxxx]LHM”-motif. Considering the rapidly evolving temperature dependent-virulence and host diversity of C. lunatus, this data will be useful for designing new protection strategies. PMID:24650331

Secretome weaponries of Cochliobolus lunatus interacting with potato leaf at different temperature regimes reveal a CL[xxxx]LHM - motif.

PubMed

Louis, Bengyella; Waikhom, Sayanika Devi; Roy, Pranab; Bhardwaj, Pardeep Kumar; Singh, Mohendro Wakambam; Goyari, Sailendra; Sharma, Chandradev K; Talukdar, Narayan Chandra

2014-03-20

Plant and animal pathogenic fungus Cochliobolus lunatus cause great economic damages worldwide every year. C. lunatus displays an increased temperature dependent-virulence to a wide range of hosts. Nonetheless, this phenomenon is poorly understood due to lack of insights on the coordinated secretome weaponries produced by C. lunatus under heat-stress conditions on putative hosts. To understand the mechanism better, we dissected the secretome of C. lunatus interacting with potato (Solanum tuberosum L.) leaf at different temperature regimes. C. lunatus produced melanized colonizing hyphae in and on potato leaf, finely modulated the ambient pH as a function of temperature and secreted diverse set of proteins. Using two dimensional gel electrophoresis (2-D) and mass spectrometry (MS) technology, we observed discrete secretomes at 20°C, 28°C and 38°C. A total of 21 differentially expressed peptide spots and 10 unique peptide spots (that did not align on the gels) matched with 28 unique protein models predicted from C. lunatus m118 v.2 genome peptides. Furthermore, C. lunatus secreted peptides via classical and non-classical pathways related to virulence, proteolysis, nucleic acid metabolism, carbohydrate metabolism, heat stress, signal trafficking and some with unidentified catalytic domains. We have identified a set of 5 soluble candidate effectors of unknown function from C. lunatus secretome weaponries against potato crop at different temperature regimes. Our findings demonstrate that C. lunatus has a repertoire of signature secretome which mediates thermo-pathogenicity and share a leucine rich "CL[xxxx]LHM"-motif. Considering the rapidly evolving temperature dependent-virulence and host diversity of C. lunatus, this data will be useful for designing new protection strategies.

Stomatal conductance, canopy temperature, and leaf area index estimation using remote sensing and OBIA techniques

Treesearch

S. Panda; D.M. Amatya; G. Hoogenboom

2014-01-01

Remotely sensed images including LANDSAT, SPOT, NAIP orthoimagery, and LiDAR and relevant processing tools can be used to predict plant stomatal conductance (gs), leaf area index (LAI), and canopy temperature, vegetation density, albedo, and soil moisture using vegetation indices like normalized difference vegetation index (NDVI) or soil adjusted...

Progress on genetic linkage maps, traits/QTLs, and utilization in two recombinant inbred line populations of peanuts (Arachis hypogaea L.)

USDA-ARS?s Scientific Manuscript database

Peanut, a highly nutritional crop, is used in edible products or crushed for cooking oil, and is susceptible to a range of diseases, including Tomato spotted wilt virus (TSWV), early and late leaf spot (ELS and LLS). Losses in productivity and quality are also attributable to environmental stresses ...

Origin of the Outbreak in France of Pseudomonas syringae pv. actinidiae Biovar 3, the Causal Agent of Bacterial Canker of Kiwifruit, Revealed by a Multilocus Variable-Number Tandem-Repeat Analysis.

PubMed

Cunty, A; Cesbron, S; Poliakoff, F; Jacques, M-A; Manceau, C

2015-10-01

The first outbreaks of bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae biovar 3 were detected in France in 2010. P. syringae pv. actinidiae causes leaf spots, dieback, and canker that sometimes lead to the death of the vine. P. syringae pv. actinidifoliorum, which is pathogenic on kiwi as well, causes only leaf spots. In order to conduct an epidemiological study to track the spread of the epidemics of these two pathogens in France, we developed a multilocus variable-number tandem-repeat (VNTR) analysis (MLVA). MLVA was conducted on 340 strains of P. syringae pv. actinidiae biovar 3 isolated in Chile, China, France, Italy, and New Zealand and on 39 strains of P. syringae pv. actinidifoliorum isolated in Australia, France, and New Zealand. Eleven polymorphic VNTR loci were identified in the genomes of P. syringae pv. actinidiae biovar 3 ICMP 18744 and of P. syringae pv. actinidifoliorum ICMP 18807. MLVA enabled the structuring of P. syringae pv. actinidiae biovar 3 and P. syringae pv. actinidifoliorum strains in 55 and 16 haplotypes, respectively. MLVA and discriminant analysis of principal components revealed that strains isolated in Chile, China, and New Zealand are genetically distinct from P. syringae pv. actinidiae strains isolated in France and in Italy, which appear to be closely related at the genetic level. In contrast, no structuring was observed for P. syringae pv. actinidifoliorum. We developed an MLVA scheme to explore the diversity within P. syringae pv. actinidiae biovar 3 and to trace the dispersal routes of epidemic P. syringae pv. actinidiae biovar 3 in Europe. We suggest using this MLVA scheme to trace the dispersal routes of P. syringae pv. actinidiae at a global level. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The Efficiency of Noni (Morinda citrifolia L.) Essential Oil on the Control of Leaf Spot Caused by Exserohilum turcicum in Maize Culture.

PubMed

Silva, Janaina Costa E; Mourão, Dalmarcia de Sousa Carlos; Lima, Fabia Silva de Oliveira; Sarmento, Renato de Almeida; Dalcin, Mateus Sunti; Aguiar, Raimundo Wagner de Souza; Santos, Gil Rodrigues Dos

2017-08-14

The objective of this work was to evaluate the efficiency of noni essential oil on the control of Exserohilum turcicum , a causative agent of Exserohilum spot in maize culture. In the sanitary test 400 seeds were incubated using the blotter test method. For the transmissibility test, the fragments of damaged leaves of seedlings were removed and put into a potato, dextrose and agar (PDA) culture environment. To verify the pathogenicity, Koch´s postulates were performed. In the phytotoxicity test different concentrations of noni oil were applied in maize seedlings. E. turcicum conidia were submitted to different concentrations of noni oil. In the preventive and curative tests noni essential oils were applied before and after the conidia inoculation, respectively. The results revealed the presence of fungi of the genres Aspergillus , Penicillium , Rhizopus , Fusarium , and Exserohilum in the maize seeds. The pathogenicity of E. turcicum and also the transmission of this fungus from the seeds to the maize seedlings was confirmed. The inhibition of conidia germination was proportional to the concentration increase. The preventive application of noni essential oil was the most efficient on the control of Exserohilum spot.

The Efficiency of Noni (Morinda citrifolia L.) Essential Oil on the Control of Leaf Spot Caused by Exserohilum turcicum in Maize Culture

PubMed Central

Silva, Janaina Costa E; Mourão, Dalmarcia de Sousa Carlos; Lima, Fabia Silva de Oliveira; Sarmento, Renato de Almeida; Dalcin, Mateus Sunti; Aguiar, Raimundo Wagner de Souza

2017-01-01

The objective of this work was to evaluate the efficiency of noni essential oil on the control of Exserohilum turcicum, a causative agent of Exserohilum spot in maize culture. In the sanitary test 400 seeds were incubated using the blotter test method. For the transmissibility test, the fragments of damaged leaves of seedlings were removed and put into a potato, dextrose and agar (PDA) culture environment. To verify the pathogenicity, Koch´s postulates were performed. In the phytotoxicity test different concentrations of noni oil were applied in maize seedlings. E. turcicum conidia were submitted to different concentrations of noni oil. In the preventive and curative tests noni essential oils were applied before and after the conidia inoculation, respectively. The results revealed the presence of fungi of the genres Aspergillus, Penicillium, Rhizopus, Fusarium, and Exserohilum in the maize seeds. The pathogenicity of E. turcicum and also the transmission of this fungus from the seeds to the maize seedlings was confirmed. The inhibition of conidia germination was proportional to the concentration increase. The preventive application of noni essential oil was the most efficient on the control of Exserohilum spot. PMID:28930274

Quantification of rice brown leaf spot through Taqman real-time PCR specific to the unigene encoding Cochliobolus miyabeanus SCYTALONE DEHYDRATASE1 involved in fungal melanin biosynthesis.

PubMed

Su'udi, Mukhamad; Park, Jong-Mi; Kang, Woo-Ri; Park, Sang-Ryeol; Hwang, Duk-Ju; Ahn, Il-Pyung

2012-12-01

Rice brown leaf spot is a major disease in the rice paddy field. The causal agent Cochliobolus miyabeanus is an ascomycete fungus and a representative necrotrophic pathogen in the investigation of rice-microbe interactions. The aims of this research were to identify a quantitative evaluation method to determine the amount of C. miyabeanus proliferation in planta and determine the method's sensitivity. Real-time polymerase chain reaction (PCR) was employed in combination with the primer pair and Taqman probe specific to CmSCD1, a C. miyabeanus unigene encoding SCYTALONE DEHYDRATASE, which is involved in fungal melanin biosynthesis. Comparative analysis of the nucleotide sequences of CmSCD1 from Korean strains with those from the Japanese and Taiwanese strains revealed some sequence differences. Based on the crossing point (CP) values from Taqman real-time PCR containing a series of increasing concentrations of cloned amplicon or fungal genomic DNA, linear regressions with a high level of reliability (R(2)>0.997) were constructed. This system was able to estimate fungal genomic DNA at the picogram level. The reliability of this equation was further confirmed using DNA samples from both resistant and susceptible cultivars infected with C. miyabeanus. In summary, our quantitative system is a powerful alternative in brown leaf spot forecasting and in the consistent evaluation of disease progression.

Essential Oil of Cymbopogon citratus on the Control of the Curvularia Leaf Spot Disease on Maize.

PubMed

Mourão, Dalmarcia de Sousa Carlos; Ferreira de Souza Pereira, Talita; Souza, Danival José de; Chagas Júnior, Aloísio Freitas; Dalcin, Mateus Sunti; Veloso, Ronice Alves; Leão, Evelynne Urzêdo; Santos, Gil Rodrigues Dos

2017-08-20

The Curvularia Leaf Spot is becoming more common due to the culture expansion and the low resistance of the cultivated genotypes in tropical regions. Thus, the objective was to evaluate the fungitoxicity of the essential oil of Cymbopogon citratus upon the phytopathogen Curvularia lunata , causative agent of the Curvularia Leaf Spot. There was realized pathogenicity tests of C. lunata in maize plants, phytotoxicity of the essential oil of C. citratus and gas chromatography attached, germination tests of the conidia, and of in vitro inhibition of C. lunata . Also, there were realized tests aiming at verifying the phytopathogen control in vivo. In the pathogenicity tests, there were verified symptoms of the disease in all of the suspensions tested on plants. It was observed that the essential oil concentrations of 7.5 µL mL -1 to 50 µL mL -1 were phytotoxic. The majoritarian chemical components of the essential oil of C. citratus were Geranial (41.46%) and Neral (32.43%). The concentrations of 5 and 7.5 µL mL -1 inhibited 100% of conidia germination. None of the concentrations evaluated effectively inhibited C. lunata mycelial growth in in vitro tests. In the preventive control, the concentration of 7.5 µL mL -1 was sufficient for the reduction of the progress of the disease, however the curative control was not efficient on the tested dosages.

Characterization of Apricot pseudo-chlorotic leaf spot virus, A Novel Trichovirus Isolated from Stone Fruit Trees.

PubMed

Liberti, D; Marais, A; Svanella-Dumas, L; Dulucq, M J; Alioto, D; Ragozzino, A; Rodoni, B; Candresse, T

2005-04-01

ABSTRACT A trichovirus closely related to Apple chlorotic leaf spot virus (ACLSV) was detected in symptomatic apricot and Japanese plum from Italy. The Sus2 isolate of this agent cross-reacted with anti-ACLSV polyclonal reagents but was not detected by broad-specificity anti- ACLSV monoclonal antibodies. It had particles with typical trichovirus morphology but, contrary to ACLSV, was unable to infect Chenopodium quinoa and C. amaranticolor. The sequence of its genome (7,494 nucleotides [nt], missing only approximately 30 to 40 nt of the 5' terminal sequence) and the partial sequence of another isolate were determined. The new virus has a genomic organization similar to that of ACLSV, with three open reading frames coding for a replication-associated protein (RNA-dependent RNA polymerase), a movement protein, and a capsid protein, respectively. However, it had only approximately 65 to 67% nucleotide identity with sequenced isolates of ACLSV. The differences in serology, host range, genome sequence, and phylogenetic reconstructions for all viral proteins support the idea that this agent should be considered a new virus, for which the name Apricot pseudo-chlorotic leaf spot virus (APCLSV) is proposed. APCLSV shows substantial sequence variability and has been recovered from various Prunus sources coming from seven countries, an indication that it is likely to have a wide geographical distribution.

Yeast two-hybrid and pull-down assays propose an interaction between P50 of apple chlorotic leaf spot virus and PR-10 of Malus sylvestris cv. R12740-7A.

PubMed

Wang, Y; Li, N; Zhao, X; Hu, J; He, Y; Hu, T; Wang, S; Wang, Y; Cao, K

Apple chlorotic leaf spot virus (ACLSV) movement protein (P50) is involved in cell-to-cell transport and influences the long-distance spread of silencing activity. Previously, we obtained 69 P50-interacting proteins from Malus sylvestris cv. R12740-7A and using bioinformatics analyzed their biological functions. In this study, we used the GAL4-based two-hybrid yeast system and His pull-down assays to confirm an interaction between PR-10 of M. sylvestris cv. R12740-7A and ACLSV P50. Our results provide a theoretical basis for further research on the biological function of PR-10 in ACLSV infection and the interacting mechanism between host and virus.

Loci on chromosomes 1A and 2A affect resistance to tan (yellow) spot in wheat populations not segregating for tsn1.

PubMed

Shankar, Manisha; Jorgensen, Dorthe; Taylor, Julian; Chalmers, Ken J; Fox, Rebecca; Hollaway, Grant J; Neate, Stephen M; McLean, Mark S; Vassos, Elysia; Golzar, Hossein; Loughman, Robert; Mather, Diane E

2017-12-01

QTL for tan spot resistance were mapped on wheat chromosomes 1A and 2A. Lines were developed with resistance alleles at these loci and at the tsn1 locus on chromosome 5B. These lines expressed significantly higher resistance than the parent with tsn1 only. Tan spot (syn. yellow spot and yellow leaf spot) caused by Pyrenophora tritici-repentis is an important foliar disease of wheat in Australia. Few resistance genes have been mapped in Australian germplasm and only one, known as tsn1 located on chromosome 5B, is known in Australian breeding programs. This gene confers insensitivity to the fungal effector ToxA. The main aim of this study was to map novel resistance loci in two populations: Calingiri/Wyalkatchem, which is fixed for the ToxA-insensitivity allele tsn1, and IGW2574/Annuello, which is fixed for the ToxA-sensitivity allele Tsn1. A second aim was to combine new loci with tsn1 to develop lines with improved resistance. Tan spot severity was evaluated at various growth stages and in multiple environments. Symptom severity traits exhibited quantitative variation. The most significant quantitative trait loci (QTL) were detected on chromosomes 2A and 1A. The QTL on 2A explained up to 29.2% of the genotypic variation in the Calingiri/Wyalkatchem population with the resistance allele contributed by Wyalkatchem. The QTL on 1A explained up to 28.1% of the genotypic variation in the IGW2574/Annuello population with the resistance allele contributed by Annuello. The resistance alleles at both QTL were successfully combined with tsn1 to develop lines that express significantly better resistance at both seedling and adult plant stages than Calingiri which has tsn1 only.

Clustering and cellular distribution characteristics of virus particles of Tomato spotted wilt virus and Tomato zonate spot virus in different plant hosts.

PubMed

Zhang, Zhongkai; Zheng, Kuanyu; Dong, Jiahong; Fang, Qi; Hong, Jian; Wang, Xifeng

2016-01-19

Tomato spotted wilt virus (TSWV) and Tomato zonate spot virus (TZSV) are the two dominant species of thrip-transmitted tospoviruses, cause significant losses in crop yield in Yunnan and its neighboring provinces in China. TSWV and TZSV belong to different serogroup of tospoviruses but induce similar symptoms in the same host plant species, which makes diagnostic difficult. We used different electron microscopy preparing methods to investigate clustering and cellular distribution of TSWV and TZSV in the host plant species. Negative staining of samples infected with TSWV and TZSV revealed that particles usually clustered in the vesicles, including single particle (SP), double particles clustering (DPC), triple particles clustering (TPC). In the immunogold labeling negative staining against proteins of TZSV, the antibodies against Gn protein were stained more strongly than the N protein. Ultrathin section and high pressure freeze (HPF)-electron microscopy preparations revealed that TSWV particles were distributed in the cisternae of endoplasmic reticulum (ER), filamentous inclusions (FI) and Golgi bodies in the mesophyll cells. The TSWV particles clustered as multiple particles clustering (MPC) and distributed in globular viroplasm or cisternae of ER in the top leaf cell. TZSV particles were distributed more abundantly in the swollen membrane of ER in the mesophyll cell than those in the phloem parenchyma cells and were not observed in the top leaf cell. However, TZSV virions were mainly present as single particle in the cytoplasm, with few clustering as MPC. In this study, we identified TSWV and TZSV particles had the distinct cellular distribution patterns in the cytoplasm from different tissues and host plants. This is the first report of specific clustering characteristics of tospoviruses particles as well as the cellular distribution of TSWV particles in the FI and globular viroplasm where as TZSV particles inside the membrane of ER. These results indicated that tospoviruses particles possessed specific and similar clustering in the saps of diseased plants. Furthermore, the results of this study will also provide a basis for further study on the tospoviruses assembling, maturation and movement.

Allelopathic Monoterpenes Interfere with Arabidopsis thaliana Cuticular Waxes and Enhance Transpiration

PubMed Central

Kussmann, Petra; Knop, Mona; Kriegs, Bettina; Gresens, Frank; Eichert, Thomas; Ulbrich, Andreas; Marx, Friedhelm; Fabricius, Heinz; Goldbach, Heiner; Noga, Georg

2007-01-01

Exposure to the allelopathic monoterpenes camphor (100 mg/10 L) and menthol (50 mg/10 L) for 24 h enhanced transpiration of Arabidopsis thaliana fully developed rosette leaves similar to de-waxing. As ascertained by ESEM analyses the leaf surfaces were spotted with platelet like structures which seem to be partly mixed with the lipophilic epicuticular layers. The structures are supposed to contain the condensed monoterpenes, which could be identified by GC. Long term exposure (more than 48 h) to 100 mg/50 mg killed the plants by desiccation, a 24 h exposure caused necrotic spots that became visible one to two days after the treatment. Examinations of the stomatal apertures indicated that monoterpenes induced stomatal opening followed by extreme swelling and a final break down of the protoplasts. Exposure of Arabidopsis thaliana to volatiles of Mentha piperita, Lavandula latifolia and Artemisia camphorata resulted in a dramatic increase of the stomata aperture but swelling of the protoplasts was less exhibited. In contrast to de-waxing, expression of the fatty acid condensing enzyme encoding CER6 gene and de novo synthesis of CER6 protein was not induced after 24 h of exposure to the monoterpenes. The aim of the study was to demonstrate that the lipophilic layers of the leaf surface and the stomata are primary targets of monoterpene allelopathic attack. Enhanced transpiration results from a combination of affected lipophilic wax layers and a disturbed stomata function. PMID:19516993

Comparison of Models and Whole-Genome Profiling Approaches for Genomic-Enabled Prediction of Septoria Tritici Blotch, Stagonospora Nodorum Blotch, and Tan Spot Resistance in Wheat.

PubMed

Juliana, Philomin; Singh, Ravi P; Singh, Pawan K; Crossa, Jose; Rutkoski, Jessica E; Poland, Jesse A; Bergstrom, Gary C; Sorrells, Mark E

2017-07-01

The leaf spotting diseases in wheat that include Septoria tritici blotch (STB) caused by , Stagonospora nodorum blotch (SNB) caused by , and tan spot (TS) caused by pose challenges to breeding programs in selecting for resistance. A promising approach that could enable selection prior to phenotyping is genomic selection that uses genome-wide markers to estimate breeding values (BVs) for quantitative traits. To evaluate this approach for seedling and/or adult plant resistance (APR) to STB, SNB, and TS, we compared the predictive ability of least-squares (LS) approach with genomic-enabled prediction models including genomic best linear unbiased predictor (GBLUP), Bayesian ridge regression (BRR), Bayes A (BA), Bayes B (BB), Bayes Cπ (BC), Bayesian least absolute shrinkage and selection operator (BL), and reproducing kernel Hilbert spaces markers (RKHS-M), a pedigree-based model (RKHS-P) and RKHS markers and pedigree (RKHS-MP). We observed that LS gave the lowest prediction accuracies and RKHS-MP, the highest. The genomic-enabled prediction models and RKHS-P gave similar accuracies. The increase in accuracy using genomic prediction models over LS was 48%. The mean genomic prediction accuracies were 0.45 for STB (APR), 0.55 for SNB (seedling), 0.66 for TS (seedling) and 0.48 for TS (APR). We also compared markers from two whole-genome profiling approaches: genotyping by sequencing (GBS) and diversity arrays technology sequencing (DArTseq) for prediction. While, GBS markers performed slightly better than DArTseq, combining markers from the two approaches did not improve accuracies. We conclude that implementing GS in breeding for these diseases would help to achieve higher accuracies and rapid gains from selection. Copyright © 2017 Crop Science Society of America.

High-resolution mapping reveals linkage between genes in common bean cultivar Ouro Negro conferring resistance to the rust, anthracnose, and angular leaf spot diseases.

PubMed

Valentini, Giseli; Gonçalves-Vidigal, Maria Celeste; Hurtado-Gonzales, Oscar P; de Lima Castro, Sandra Aparecida; Cregan, Perry B; Song, Qijian; Pastor-Corrales, Marcial A

2017-08-01

Co-segregation analysis and high-throughput genotyping using SNP, SSR, and KASP markers demonstrated genetic linkage between Ur-14 and Co-3 4 /Phg-3 loci conferring resistance to the rust, anthracnose and angular leaf spot diseases of common bean. Rust, anthracnose, and angular leaf spot are major diseases of common bean in the Americas and Africa. The cultivar Ouro Negro has the Ur-14 gene that confers broad spectrum resistance to rust and the gene cluster Co-3 4 /Phg-3 containing two tightly linked genes conferring resistance to anthracnose and angular leaf spot, respectively. We used co-segregation analysis and high-throughput genotyping of 179 F 2:3 families from the Rudá (susceptible) × Ouro Negro (resistant) cross-phenotyped separately with races of the rust and anthracnose pathogens. The results confirmed that Ur-14 and Co-3 4 /Phg-3 cluster in Ouro Negro conferred resistance to rust and anthracnose, respectively, and that Ur-14 and the Co-3 4 /Phg-3 cluster were closely linked. Genotyping the F 2:3 families, first with 5398 SNPs on the Illumina BeadChip BARCBEAN6K_3 and with 15 SSR, and eight KASP markers, specifically designed for the candidate region containing Ur-14 and Co-3 4 /Phg-3, permitted the creation of a high-resolution genetic linkage map which revealed that Ur-14 was positioned at 2.2 cM from Co-3 4 /Phg-3 on the short arm of chromosome Pv04 of the common bean genome. Five flanking SSR markers were tightly linked at 0.1 and 0.2 cM from Ur-14, and two flanking KASP markers were tightly linked at 0.1 and 0.3 cM from Co-3 4 /Phg-3. Many other SSR, SNP, and KASP markers were also linked to these genes. These markers will be useful for the development of common bean cultivars combining the important Ur-14 and Co-3 4 /Phg-3 genes conferring resistance to three of the most destructive diseases of common bean.

Presence of Extracellular DNA during Biofilm Formation by Xanthomonas citri subsp. citri Strains with Different Host Range.

PubMed

Sena-Vélez, Marta; Redondo, Cristina; Graham, James H; Cubero, Jaime

2016-01-01

Xanthomonas citri subsp. citri (Xcc) A strain causes citrus bacterial canker, a serious leaf, fruit and stem spotting disease of several Citrus species. X. alfalfae subsp. citrumelonis (Xac) is the cause of citrus bacterial spot, a minor disease of citrus nursery plants and X. campestris pv. campestris (Xc) is a systemic pathogen that causes black rot of cabbage. Xanthomonas spp. form biofilms in planta that facilitate the host infection process. Herein, the role of extracellular DNA (eDNA) was evaluated in the formation and stabilization of the biofilm matrix at different stages of biofilm development. Fluorescence and light microscopy, as well as DNAse treatments, were used to determine the presence of eDNA in biofilms and bacterial cultures. DNAse treatments of Xcc strains and Xac reduced biofilm formation at the initial stage of development, as well as disrupted preformed biofilm. By comparison, no significant effect of the DNAse was detected for biofilm formation by Xc. DNAse effects on biofilm formation or disruption varied among Xcc strains and Xanthomonas species which suggest different roles for eDNA. Variation in the structure of fibers containing eDNA in biofilms, bacterial cultures, and in twitching motility was also visualized by microscopy. The proposed roles for eDNA are as an adhesin in the early stages of biofilm formation, as an structural component of mature bacterial aggregates, and twitching motility structures.

Physiological and Proteomics Analyses Reveal Low-Phosphorus Stress Affected the Regulation of Photosynthesis in Soybean.

PubMed

Chu, Shanshan; Li, Hongyan; Zhang, Xiangqian; Yu, Kaiye; Chao, Maoni; Han, Suoyi; Zhang, Dan

2018-06-06

Previous studies have revealed a significant genetic relationship between phosphorus (P)-efficiency and photosynthesis-related traits in soybean. In this study, we used proteome profiling in combination with expression analysis, biochemical investigations, and leaf ultrastructural analysis to identify the underlying physiological and molecular responses. The expression analysis and ultrastructural analysis showed that the photosynthesis key genes were decreased at transcript levels and the leaf mesophyll and chloroplast were severely damaged after low-P stress. Approximately 55 protein spots showed changes under low-P condition by mass spectrometry, of which 17 were involved in various photosynthetic processes. Further analysis revealed the depression of photosynthesis caused by low-P stress mainly involves the regulation of leaf structure, adenosine triphosphate (ATP) synthesis, absorption and transportation of CO₂, photosynthetic electron transport, production of assimilatory power, and levels of enzymes related to the Calvin cycle. In summary, our findings indicated that the existence of a stringent relationship between P supply and the genomic control of photosynthesis in soybean. As an important strategy to protect soybean photosynthesis, P could maintain the stability of cell structure, up-regulate the enzymes’ activities, recover the process of photosystem II (PSII), and induce the expression of low-P responsive genes and proteins.

``Sleeping with the enemy''—predator-induced diapause in a mite

NASA Astrophysics Data System (ADS)

Kroon, Annemarie; Veenendaal, René L.; Bruin, Jan; Egas, Martijn; Sabelis, Maurice W.

2008-12-01

Diapause in arthropods is a physiological state of dormancy that is generally thought to promote survival during harsh seasons and dispersal, but it may also serve to avoid predation in space and time. Here, we show that predation-related odours induce diapause in female adult spider mites. We argue that this response allows them to move into an area where they are free of enemies, yet forced to survive without food. Spider mites are specialised leaf feeders, but—in late summer—they experience severe predation on leaves. Hence, they face a dilemma: to stay on the leaf and risk being eaten or to move away from the leaf and risk death from starvation and thirst. Female two-spotted spider mites solve this dilemma by dramatically changing their physiology when exposed to predation-associated cues. This allows them to disperse away from leaves and to survive in winter refuges in the bark of trees or in the soil. We conclude that the mere presence of predation-associated cues causes some herbivorous mites to seek refuge, thereby retarding the growth rate of the population as a whole: a trait-mediated indirect effect that may have consequences for the stability of predator prey systems and for ecosystem structure.

Cloning and function analysis of a drought-inducible gene associated with resistance to Curvularia leaf spot in maize.

PubMed

Zhu, Jiewei; Huang, Xiuli; Liu, Tong; Gao, Shigang; Chen, Jie

2012-08-01

ZmDIP was cloned and its function against Curvularia lunata was analyzed, according to a previous finding on a drought-inducible protein in resistant maize identified through MALDI-TOF-MS/MS. The ZmDIP expression varied in roots, leaf sheaths, and young, as well as old, leaves of different maize inbred lines. The ZmDIP transcript level changed in leaves over the course of time after inoculation with C. lunata. A prokaryotic expression analysis demonstrated that the gene can regulate the salt stress tolerance of Escherichia coli. The ZmDIP transient expression in the maize leaf showed that the gene was also linked to leaf resistance against the C. lunata infection. ZmDIP-mediated ROS and ABA signaling pathways were inferred to be closely associated with maize leaf resistance to the pathogen infection.

Essential Oil of Cymbopogon citratus on the Control of the Curvularia Leaf Spot Disease on Maize

PubMed Central

Mourão, Dalmarcia de Sousa Carlos; Ferreira de Souza Pereira, Talita; de Souza, Danival José; Chagas Júnior, Aloísio Freitas; Veloso, Ronice Alves; Leão, Evelynne Urzêdo

2017-01-01

The Curvularia Leaf Spot is becoming more common due to the culture expansion and the low resistance of the cultivated genotypes in tropical regions. Thus, the objective was to evaluate the fungitoxicity of the essential oil of Cymbopogon citratus upon the phytopathogen Curvularia lunata, causative agent of the Curvularia Leaf Spot. There was realized pathogenicity tests of C. lunata in maize plants, phytotoxicity of the essential oil of C. citratus and gas chromatography attached, germination tests of the conidia, and of in vitro inhibition of C. lunata. Also, there were realized tests aiming at verifying the phytopathogen control in vivo. In the pathogenicity tests, there were verified symptoms of the disease in all of the suspensions tested on plants. It was observed that the essential oil concentrations of 7.5 µL mL−1 to 50 µL mL−1 were phytotoxic. The majoritarian chemical components of the essential oil of C. citratus were Geranial (41.46%) and Neral (32.43%). The concentrations of 5 and 7.5 µL mL−1 inhibited 100% of conidia germination. None of the concentrations evaluated effectively inhibited C. lunata mycelial growth in in vitro tests. In the preventive control, the concentration of 7.5 µL mL−1 was sufficient for the reduction of the progress of the disease, however the curative control was not efficient on the tested dosages. PMID:28930276

Molecular Mapping of High Resistance to Bacterial Leaf Spot in Lettuce PI 358001-1.

PubMed

Wang, Yunwen; Lu, Huangjun; Hu, Jinguo

2016-11-01

Lettuce (Lactuca sativa L.) is a diploid (2n = 18) with a genome size of 2,600 Mbp, and belongs to the family Compositae. Bacterial leaf spot (BLS), caused by Xanthomonas campestris pv. vitians, is a major disease of lettuce worldwide. Leaf lettuce PI 358001-1 has been characterized as an accession highly resistant to BLS and has white seed. In order to understand inheritance of the high resistance in this germplasm line, an F 3 population consisting of 163 families was developed from the cross PI 358001-1 × 'Tall Guzmaine' (a susceptible Romaine lettuce variety with black seed). The segregation ratio of reaction to disease by seedling inoculation with X. campestris pv. vitians L7 strain in the F 3 families was shown to be 32:82:48 homozygous resistant/heterozygous/homozygous susceptible, fitting to 1:2:1 (n = 162, χ 2 = 3.19, P = 0.20). The segregation ratio of seed color by checking F 2 plants was 122:41 black/white, fitting to 3:1 (n = 163, χ 2 = 0.002, P = 0.96). The results indicated that both BLS resistance and seed color were inherited as a dominant gene mode. A genetic linkage map based on 124 randomly selected F 2 plants was developed to enable molecular mapping of the BLS resistance and the seed color trait. In total, 199 markers, comprising 176 amplified fragment length polymorphisms, 16 simple-sequence repeats, 5 resistant gene candidate markers, and 2 cleaved amplified polymorphic sequences (CAPS) markers were assigned to six linkage groups. The dominant resistance gene to BLS (Xcvr) was mapped on linkage group 2 and the gene locus y for seed color was identified on linkage group 5. Due to the nature of a single gene inheritance, the high-resistance gene should be readily transferred to adapted lettuce cultivars to battle against the devastating disease of lettuce.

7 CFR 51.1212 - U.S. No. 1.

Code of Federal Regulations, 2012 CFR

2012-01-01

... which are mature but not soft or overripe, well formed, and which are free from decay, growth cracks... foreign material, bacterial spot, scab, scale, hail injury, leaf or limb rubs, split pits, other disease...

7 CFR 51.1212 - U.S. No. 1.

Code of Federal Regulations, 2010 CFR

2010-01-01

... which are mature but not soft or overripe, well formed, and which are free from decay, growth cracks... foreign material, bacterial spot, scab, scale, hail injury, leaf or limb rubs, split pits, other disease...

7 CFR 51.1210 - U.S. Fancy.

Code of Federal Regulations, 2012 CFR

2012-01-01

... which are mature but not soft or overripe, well formed and which are free from decay, bacterial spot, cuts which are not healed, growth cracks, hail injury, scab, scale, split pits, worms, worm holes, leaf...

7 CFR 51.1212 - U.S. No. 1.

Code of Federal Regulations, 2011 CFR

2011-01-01

... which are mature but not soft or overripe, well formed, and which are free from decay, growth cracks... foreign material, bacterial spot, scab, scale, hail injury, leaf or limb rubs, split pits, other disease...

7 CFR 51.1210 - U.S. Fancy.

Code of Federal Regulations, 2010 CFR

2010-01-01

... which are mature but not soft or overripe, well formed and which are free from decay, bacterial spot, cuts which are not healed, growth cracks, hail injury, scab, scale, split pits, worms, worm holes, leaf...

7 CFR 51.1210 - U.S. Fancy.

Code of Federal Regulations, 2011 CFR

2011-01-01

... which are mature but not soft or overripe, well formed and which are free from decay, bacterial spot, cuts which are not healed, growth cracks, hail injury, scab, scale, split pits, worms, worm holes, leaf...

Mycosphaerella fijiensis, the black leaf streak pathogen of banana: progress towards understanding pathogen biology and detection, disease development, and the challenges of control.

PubMed

Churchill, Alice C L

2011-05-01

Banana (Musa spp.) is grown throughout the tropical and subtropical regions of the world. The fruits are a key staple food in many developing countries and a source of income for subsistence farmers. Bananas are also a major, multibillion-dollar export commodity for consumption primarily in developed countries, where few banana cultivars are grown. The fungal pathogen Mycosphaerella fijiensis causes black leaf streak disease (BLSD; aka black Sigatoka leaf spot) on the majority of edible banana cultivars grown worldwide. The fact that most of these cultivars are sterile and unsuitable for the breeding of resistant lines necessitates the extensive use of fungicides as the primary means of disease control. BLSD is a significant threat to the food security of resource-poor populations who cannot afford fungicides, and increases the environmental and health hazards where large-acreage monocultures of banana (Cavendish subgroup, AAA genome) are grown for export. Mycosphaerella fijiensis M. Morelet is a sexual, heterothallic fungus having Pseudocercospora fijiensis (M. Morelet) Deighton as the anamorph stage. It is a haploid, hemibiotrophic ascomycete within the class Dothideomycetes, order Capnodiales and family Mycosphaerellaceae. Its taxonomic placement is based on DNA phylogeny, morphological analyses and cultural characteristics. Mycosphaerella fijiensis is a leaf pathogen that causes reddish-brown streaks running parallel to the leaf veins, which aggregate to form larger, dark-brown to black compound streaks. These streaks eventually form fusiform or elliptical lesions that coalesce, form a water-soaked border with a yellow halo and, eventually, merge to cause extensive leaf necrosis. The disease does not kill the plants immediately, but weakens them by decreasing the photosynthetic capacity of leaves, causing a reduction in the quantity and quality of fruit, and inducing the premature ripening of fruit harvested from infected plants. Although Musa spp. are the primary hosts of M. fijiensis, the ornamental plant Heliconia psittacorum has been reported as an alternative host. Several valuable tools and resources have been developed to overcome some of the challenges of studying this host-pathogen system. These include a DNA-mediated fungal transformation system and the ability to conduct targeted gene disruptions, reliable quantitative plant bioassays, diagnostic probes to detect and differentiate M. fijiensis from related pathogens and to distinguish strains of different mating types, and a genome sequence that has revealed a wealth of gene sequences and molecular markers to be utilized in functional and population biology studies. http://bananas.bioversityinternational.org/, http://genome.jgi-psf.org/Mycfi2/Mycfi2.home.html, http://www.isppweb.org/names_banana_pathogen.asp#fun, http://www.promusa.org/. © 2010 THE AUTHOR. MOLECULAR PLANT PATHOLOGY © 2010 BSPP AND BLACKWELL PUBLISHING LTD.

Morphological and Genetic Analysis of Four Color Morphs of Bean Leaf Beetle.

PubMed

Tiroesele, Bamphitlhi; Skoda, Steven R; Hunt, Thomas E; Lee, Donald J; Ullah, Muhammad Irfan; Molina-Ochoa, Jaime; Foster, John E

2018-03-01

Bean leaf beetle (BLB), Cerotoma trifurcata (Forster; Coleoptera: Chrysomelidae), exhibits considerable color variation but little is known about the underlying genetic structure and gene flow among color phenotypes. Genetic and morphological variation among four color phenotypes-green with spots (G+S), green without spots (G-S), red with spots (R+S) and red without spots (R-S)-were analyzed using amplified fragment length polymorphisms (AFLP) and morphometrics, respectively. AFLP generated 175 markers that showed ≥80% polymorphism. Analysis of molecular variance (AMOVA) indicated that genetic variation was greatest within phenotypes (82.6-84.0%); gene flow among the four phenotypes was relatively high (Nm = 3.82). The dendrogram and STRUCTURE analysis indicated some population divergence of G-S from the other phenotypes. Morphological parameters were similar among phenotypes except that R+S showed significant differences in weight and body-length. Canonical variables 1 and 2, based on average morphometric characters, accounted for 98% of the total variation; some divergence was indicated between G+S and R+S from each other and from the G-S/R-S BLB color morphs. The pattern of genetic variation indicated potential divergence of G-S and G+S from each other and from R-S and R+S. Although these results indicate that the four different color morphs are not genetically or reproductively isolated, there is some genetic differentiation/structure and morphological dissimilarity suggesting weak/incomplete isolation.

Manipulation of Frankliniella occidentalis (Thysanoptera: Thripidae) by Tomato Spotted Wilt Virus (Tospovirus) Via the Host Plant Nutrients to Enhance Its Transmission and Spread

PubMed Central

Shalileh, Sheida; Moualeu, Dany Pascal; Poehling, Hans-Michael

2016-01-01

Earlier studies have shown that Tomato spotted wilt virus (TSWV) influences the biology, performance, and behavioral patterns of its vector Frankliniella occidentalis Pergande. In this study, using Capsicum annuum L. as the host plant, we aimed to determine the manipulation of F. occidentalis by TSWV through switching of the diet (+ or −TSWV) during vector’s development. Behavioral patterns, fitness, as well as vector performance were evaluated. The specific parameters investigated included longevity/survival, fecundity, development time, feeding, and preferential behavior. F. occidentalis were reared on either TSWV-infected (exposed) or healthy leaves (non-exposed) throughout their larval stages. The emerging adults were then individually transferred to either healthy or TSWV-infected leaf disks. This resulted into four treatments, consisting of exposed or non-exposed thrips reared on either infected or healthy leaf disks as adults. All F. occidentalis exposed to TSWV in their larval stages had shorter development time regardless of the adults’ diet. Whereas, the ones that were later reared on healthy leaf disks as adults recorded the highest longevity and reproduction rate. Furthermore, adults of F. occidentalis that were exposed to TSWV in their larval stages showed preference toward healthy leaf disks (−TSWV), whereas the non-exposed significantly preferred the infected leaf disks (+TSWV). These are further indications that TSWV modifies the nutritional content of its host plants, which influences vector’s biology and preferential behavior, in favor of its multiplication and dispersal. The findings offer additional explanation to the often aggressive spread of the virus in crop stands. PMID:27566527

Classification of fecal contamination on leafy greens by hyperspectral imaging

NASA Astrophysics Data System (ADS)

Yang, Chun-Chieh; Jun, Won; Kim, Moon S.; Chao, Kaunglin; Kang, Sukwon; Chan, Diane E.; Lefcourt, Alan

2010-04-01

This paper reported the development of hyperspectral fluorescence imaging system using ultraviolet-A excitation (320-400 nm) for detection of bovine fecal contaminants on the abaxial and adaxial surfaces of romaine lettuce and baby spinach leaves. Six spots of fecal contamination were applied to each of 40 lettuce and 40 spinach leaves. In this study, the wavebands at 666 nm and 680 nm were selected by the correlation analysis. The two-band ratio, 666 nm / 680 nm, of fluorescence intensity was used to differentiate the contaminated spots from uncontaminated leaf area. The proposed method could accurately detect all of the contaminated spots.

Elevated Genetic Diversity in the Emerging Blueberry Pathogen Exobasidium maculosum.

PubMed

Stewart, Jane E; Brooks, Kyle; Brannen, Phillip M; Cline, William O; Brewer, Marin T

2015-01-01

Emerging diseases caused by fungi are increasing at an alarming rate. Exobasidium leaf and fruit spot of blueberry, caused by the fungus Exobasidium maculosum, is an emerging disease that has rapidly increased in prevalence throughout the southeastern USA, severely reducing fruit quality in some plantings. The objectives of this study were to determine the genetic diversity of E. maculosum in the southeastern USA to elucidate the basis of disease emergence and to investigate if populations of E. maculosum are structured by geography, host species, or tissue type. We sequenced three conserved loci from 82 isolates collected from leaves and fruit of rabbiteye blueberry (Vaccinium virgatum), highbush blueberry (V. corymbosum), and southern highbush blueberry (V. corymbosum hybrids) from commercial fields in Georgia and North Carolina, USA, and 6 isolates from lowbush blueberry (V. angustifolium) from Maine, USA, and Nova Scotia, Canada. Populations of E. maculosum from the southeastern USA and from lowbush blueberry in Maine and Nova Scotia are distinct, but do not represent unique species. No difference in genetic structure was detected between different host tissues or among different host species within the southeastern USA; however, differentiation was detected between populations in Georgia and North Carolina. Overall, E. maculosum showed extreme genetic diversity within the conserved loci with 286 segregating sites among the 1,775 sequenced nucleotides and each isolate representing a unique multilocus haplotype. However, 94% of the nucleotide substitutions were silent, so despite the high number of mutations, selective constraints have limited changes to the amino acid sequences of the housekeeping genes. Overall, these results suggest that the emergence of Exobasidium leaf and fruit spot is not due to a recent introduction or host shift, or the recent evolution of aggressive genotypes of E. maculosum, but more likely as a result of an increasing host population or an environmental change.

Elevated Genetic Diversity in the Emerging Blueberry Pathogen Exobasidium maculosum

PubMed Central

Stewart, Jane E.; Brooks, Kyle; Brannen, Phillip M.; Cline, William O.; Brewer, Marin T.

2015-01-01

Emerging diseases caused by fungi are increasing at an alarming rate. Exobasidium leaf and fruit spot of blueberry, caused by the fungus Exobasidium maculosum, is an emerging disease that has rapidly increased in prevalence throughout the southeastern USA, severely reducing fruit quality in some plantings. The objectives of this study were to determine the genetic diversity of E. maculosum in the southeastern USA to elucidate the basis of disease emergence and to investigate if populations of E. maculosum are structured by geography, host species, or tissue type. We sequenced three conserved loci from 82 isolates collected from leaves and fruit of rabbiteye blueberry (Vaccinium virgatum), highbush blueberry (V. corymbosum), and southern highbush blueberry (V. corymbosum hybrids) from commercial fields in Georgia and North Carolina, USA, and 6 isolates from lowbush blueberry (V. angustifolium) from Maine, USA, and Nova Scotia, Canada. Populations of E. maculosum from the southeastern USA and from lowbush blueberry in Maine and Nova Scotia are distinct, but do not represent unique species. No difference in genetic structure was detected between different host tissues or among different host species within the southeastern USA; however, differentiation was detected between populations in Georgia and North Carolina. Overall, E. maculosum showed extreme genetic diversity within the conserved loci with 286 segregating sites among the 1,775 sequenced nucleotides and each isolate representing a unique multilocus haplotype. However, 94% of the nucleotide substitutions were silent, so despite the high number of mutations, selective constraints have limited changes to the amino acid sequences of the housekeeping genes. Overall, these results suggest that the emergence of Exobasidium leaf and fruit spot is not due to a recent introduction or host shift, or the recent evolution of aggressive genotypes of E. maculosum, but more likely as a result of an increasing host population or an environmental change. PMID:26207812

Species of Cercospora associated with grey leaf spot of maize

PubMed Central

Crous, Pedro W.; Groenewald, Johannes Z.; Groenewald, Marizeth; Caldwell, Pat; Braun, Uwe; Harrington, Thomas C.

2006-01-01

Grey leaf spot is a serious yield-reducing disease of maize (Zea mays) in many parts of the world where this crop is cultivated. The causal organism associated with the disease is Cercospora zeae-maydis. Two potential sibling species have been recognized as Groups I and II. The DNA sequences for the internal transcribed spacers (ITS1 & ITS2), the 5.8S rRNA gene, elongation factor 1-α, histone H3, actin and calmodulin gene regions suggest that Groups I and II are two distinct species. Furthermore, Cercospora zeae-maydis (Group I) can be distinguished from C. zeina sp. nov. (Group II) by its faster growth rate on artificial media, the ability to produce cercosporin, longer conidiophores, and broadly fusiform conidia. A PCR-based test that distinguishes the two species was developed using species-specific primers designed from the histone H3 gene. PMID:18490979

Screening of Potential Inhibitor against Coat Protein of Apple Chlorotic Leaf Spot Virus.

PubMed

Purohit, Rituraj; Kumar, Sachin; Hallan, Vipin

2018-06-01

In this study, we analyzed Coat protein (CP) of Apple chlorotic leaf spot virus (ACLSV), an important latent virus on Apple. Incidence of the virus is upto 60% in various apple cultivars, affecting yield losses of the order of 10-40% (depending upon the cultivar). CP plays an important role as the sole building block of the viral capsid. Homology approach was used to model 193 amino acid sequence of the coat protein. We used various servers such as ConSurf, TargetS, OSML, COACH, COFACTOR for the prediction of active site residues in coat protein. Virtual screening strategy was employed to search potential inhibitors for CP. Top twenty screened molecules considered for drugability, and toxicity analysis and one potential molecule was further analyzed by docking analysis. Here, we reported a potent molecule which could inhibit the formation of viron assembly by targeting the CP protein of virus.

Characterization of apple stem grooving virus and apple chlorotic leaf spot virus identified in a crab apple tree.

PubMed

Li, Yongqiang; Deng, Congliang; Bian, Yong; Zhao, Xiaoli; Zhou, Qi

2017-04-01

Apple stem grooving virus (ASGV), apple chlorotic leaf spot virus (ACLSV), and prunus necrotic ringspot virus (PNRSV) were identified in a crab apple tree by small RNA deep sequencing. The complete genome sequence of ACLSV isolate BJ (ACLSV-BJ) was 7554 nucleotides and shared 67.0%-83.0% nucleotide sequence identity with other ACLSV isolates. A phylogenetic tree based on the complete genome sequence of all available ACLSV isolates showed that ACLSV-BJ clustered with the isolates SY01 from hawthorn, MO5 from apple, and JB, KMS and YH from pear. The complete nucleotide sequence of ASGV-BJ was 6509 nucleotides (nt) long and shared 78.2%-80.7% nucleotide sequence identity with other isolates. ASGV-BJ and the isolate ASGV_kfp clustered together in the phylogenetic tree as an independent clade. Recombination analysis showed that isolate ASGV-BJ was a naturally occurring recombinant.

Antagonism of rice phylloplane fungi against Cercospora oryzae

NASA Astrophysics Data System (ADS)

Mardani, A.; Hadiwiyono

2018-03-01

Narrow brown leaf spot (NBLS) caused by Cercospora oryzae Miyake is one of the important obstacle in rice cultivation that can decrease the productivity up to 40%. It has been known well that some phylloplane fungi are antagonistic to some leaf diseases. Phylloplane fungi of rice however haven’t been studied much and poorly understood as biological control agent of rice pathogen such C. oryzae. The research aimed to study the antagonism of some phylloplane fungi of rice against C. oryzae. At least 14 isolates of phylloplane fungi were collected which consisted of six pathogenic and eight nonpathogenic variants. All of nonpathogenic isolates were antagonistic against C. oryzae both in vitro and only one isolate could not inhibit the infection of the pathogen in vivo. Some isolates were identified as Aspergillus, Mucor, Penicillium, Fusarium, and Trichoderma. The isolate of Mucor and Fusarium could inhibit the highest growth of pathogen on potato dextrose medium that were at 36.0% and 35.5% respectively. Whereas on artificial inoculation on rice, some isolates such Penicillium and Fusarium could inhibit most effectively and were significantly different to Mencozeb application with dosage 5g L-1.

Development of a GFP expression vector for Cucurbit chlorotic yellows virus.

PubMed

Wei, Ying; Han, Xiaoyu; Wang, Zhenyue; Gu, Qinsheng; Li, Honglian; Chen, Linlin; Sun, Bingjian; Shi, Yan

2018-05-24

Cucurbit chlorotic yellows virus (CCYV), a bipartite crinivirus, causes chlorotic leaf spots and yellowing symptoms on cucurbit leaves. We previously developed an infectious clone of CCYV. Limited work has been conducted on the construction of a crinivirus green fluorescence protein (GFP) expression vector to date. We constructed a CCYV GFP expression vector using the "add a gene" strategy based on CCYV RNA2 cDNA constrcut. Three resultant clones, pCCYVGFP SGC , pCCYVGFP CGC , and pCCYVGFP CGS, were constructed with different promoters used to initiate GFP and CP expression. At 25 dpi GFP fluorescence was detectable not only in leaf veins but also in the surrounding cells. pCCYVGFP CGC -infected cucumber leaves exhibited cell spread at 25 dpi, whereas pCCYVGFP SGC and pCCYVGFP CGS were mainly found in single cells. Further observation of pCCYVGFP CGC GFP expression at 30 dpi, 40 dpi, and 50 dpi showed phloem-limited localization in the systemic leaves. We developed of a CCYV GFP expression vector that will be useful for further study of CCYV movement in cucurbits.

Emergence of wheat blast in Bangladesh was caused by a South American lineage of Magnaporthe oryzae.

PubMed

Islam, M Tofazzal; Croll, Daniel; Gladieux, Pierre; Soanes, Darren M; Persoons, Antoine; Bhattacharjee, Pallab; Hossain, Md Shaid; Gupta, Dipali Rani; Rahman, Md Mahbubur; Mahboob, M Golam; Cook, Nicola; Salam, Moin U; Surovy, Musrat Zahan; Sancho, Vanessa Bueno; Maciel, João Leodato Nunes; NhaniJúnior, Antonio; Castroagudín, Vanina Lilián; Reges, Juliana T de Assis; Ceresini, Paulo Cezar; Ravel, Sebastien; Kellner, Ronny; Fournier, Elisabeth; Tharreau, Didier; Lebrun, Marc-Henri; McDonald, Bruce A; Stitt, Timothy; Swan, Daniel; Talbot, Nicholas J; Saunders, Diane G O; Win, Joe; Kamoun, Sophien

2016-10-03

In February 2016, a new fungal disease was spotted in wheat fields across eight districts in Bangladesh. The epidemic spread to an estimated 15,000 hectares, about 16 % of the cultivated wheat area in Bangladesh, with yield losses reaching up to 100 %. Within weeks of the onset of the epidemic, we performed transcriptome sequencing of symptomatic leaf samples collected directly from Bangladeshi fields. Reinoculation of seedlings with strains isolated from infected wheat grains showed wheat blast symptoms on leaves of wheat but not rice. Our phylogenomic and population genomic analyses revealed that the wheat blast outbreak in Bangladesh was most likely caused by a wheat-infecting South American lineage of the blast fungus Magnaporthe oryzae. Our findings suggest that genomic surveillance can be rapidly applied to monitor plant disease outbreaks and provide valuable information regarding the identity and origin of the infectious agent.

Proteomic Analysis of Albumins and Globulins from Wheat Variety Chinese Spring and Its Fine Deletion Line 3BS-8

PubMed Central

Ma, Chao-Ying; Gao, Li-Yan; Li, Ning; Li, Xiao-Hui; Ma, Wu-Jun; Appels, Rudi; Yan, Yue-Ming

2012-01-01

The relationship between chromosome deletion in wheat and protein expression were investigated using Chinese Spring and fine deletion line 3BS-8. Through 2-DE (2-D electrophoresis) analysis, no differentially expressed proteins (DEPs) were found in leaf samples; however, 47 DEPs showed at least two-fold abundance variation (p < 0.05) in matured wheat grains and 21 spots were identified by tandem MALDI-TOF/TOF-MS. Among the identified spots, four were cultivar-specific, including three (spots B15, B16, and B21) in Chinese Spring and one in 3BS-8 (spot B10). Among variety-different DEPs between Chinese Spring and 3BS-8, most spots showed a higher express profile in CS; only four spots showed up-regulated expression tendency in 3BS-8. An interesting observation was that more than half of the identified protein spots were involved in storage proteins, of which 11 spots were identified as globulins. According to these results, we can presume that the encoded genes of protein spots B15, B16, and B21 were located on the chromosome segment deleted in 3BS-8. PMID:23202959

Leaf microbiota in an agroecosystem: spatiotemporal variation in bacterial community composition on field-grown lettuce

PubMed Central

Rastogi, Gurdeep; Sbodio, Adrian; Tech, Jan J; Suslow, Trevor V; Coaker, Gitta L; Leveau, Johan H J

2012-01-01

The presence, size and importance of bacterial communities on plant leaf surfaces are widely appreciated. However, information is scarce regarding their composition and how it changes along geographical and seasonal scales. We collected 106 samples of field-grown Romaine lettuce from commercial production regions in California and Arizona during the 2009–2010 crop cycle. Total bacterial populations averaged between 105 and 106 per gram of tissue, whereas counts of culturable bacteria were on average one (summer season) or two (winter season) orders of magnitude lower. Pyrosequencing of 16S rRNA gene amplicons from 88 samples revealed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the most abundantly represented phyla. At the genus level, Pseudomonas, Bacillus, Massilia, Arthrobacter and Pantoea were the most consistently found across samples, suggesting that they form the bacterial ‘core' phyllosphere microbiota on lettuce. The foliar presence of Xanthomonas campestris pv. vitians, which is the causal agent of bacterial leaf spot of lettuce, correlated positively with the relative representation of bacteria from the genus Alkanindiges, but negatively with Bacillus, Erwinia and Pantoea. Summer samples showed an overrepresentation of Enterobacteriaceae sequences and culturable coliforms compared with winter samples. The distance between fields or the timing of a dust storm, but not Romaine cultivar, explained differences in bacterial community composition between several of the fields sampled. As one of the largest surveys of leaf surface microbiology, this study offers new insights into the extent and underlying causes of variability in bacterial community composition on plant leaves as a function of time, space and environment. PMID:22534606

A comparison between the first four thematic mapper reflective bands and other satellite sensor systems for vegetational monitoring

NASA Technical Reports Server (NTRS)

Tucker, C. J.

1978-01-01

The first four Landsat-D thematic mapper sensors were evaluated and compared to the RBV and MSS sensors from Landsats-1, 2, and 3, Colvocoresses' proposed 'operational Landsat' three band system, and the French SPOT three band system using simulation/integration techniques and in situ collected spectral reflectance data. Sensors were evaluated by their ability to discriminate vegetation biomass, chlorophyll concentration, and leaf water content. The thematic mapper and SPOT bands were superior in a spectral resolution context to the other three sensor systems for vegetational applications. Significant improvements are expected for vegetational analyses from Landsat-D thematic mapper and SPOT imagery over MSS and RBV imagery.

Evaluation of SPOT imagery for the estimation of grassland biomass

NASA Astrophysics Data System (ADS)

Dusseux, P.; Hubert-Moy, L.; Corpetti, T.; Vertès, F.

2015-06-01

In many regions, a decrease in grasslands and change in their management, which are associated with agricultural intensification, have been observed in the last half-century. Such changes in agricultural practices have caused negative environmental effects that include water pollution, soil degradation and biodiversity loss. Moreover, climate-driven changes in grassland productivity could have serious consequences for the profitability of agriculture. The aim of this study was to assess the ability of remotely sensed data with high spatial resolution to estimate grassland biomass in agricultural areas. A vegetation index, namely the Normalized Difference Vegetation Index (NDVI), and two biophysical variables, the Leaf Area Index (LAI) and the fraction of Vegetation Cover (fCOVER) were computed using five SPOT images acquired during the growing season. In parallel, ground-based information on grassland growth was collected to calculate biomass values. The analysis of the relationship between the variables derived from the remotely sensed data and the biomass observed in the field shows that LAI outperforms NDVI and fCOVER to estimate biomass (R2 values of 0.68 against 0.30 and 0.50, respectively). The squared Pearson correlation coefficient between observed and estimated biomass using LAI derived from SPOT images reached 0.73. Biomass maps generated from remotely sensed data were then used to estimate grass reserves at the farm scale in the perspective of operational monitoring and forecasting.

Manipulation of Frankliniella occidentalis (Thysanoptera: Thripidae) by Tomato Spotted Wilt Virus (Tospovirus) Via the Host Plant Nutrients to Enhance Its Transmission and Spread.

PubMed

Shalileh, Sheida; Ogada, Pamella Akoth; Moualeu, Dany Pascal; Poehling, Hans-Michael

2016-10-01

Earlier studies have shown that Tomato spotted wilt virus (TSWV) influences the biology, performance, and behavioral patterns of its vector Frankliniella occidentalis Pergande. In this study, using Capsicum annuum L. as the host plant, we aimed to determine the manipulation of F. occidentalis by TSWV through switching of the diet (+ or -TSWV) during vector's development. Behavioral patterns, fitness, as well as vector performance were evaluated. The specific parameters investigated included longevity/survival, fecundity, development time, feeding, and preferential behavior. F. occidentalis were reared on either TSWV-infected (exposed) or healthy leaves (non-exposed) throughout their larval stages. The emerging adults were then individually transferred to either healthy or TSWV-infected leaf disks. This resulted into four treatments, consisting of exposed or non-exposed thrips reared on either infected or healthy leaf disks as adults. All F. occidentalis exposed to TSWV in their larval stages had shorter development time regardless of the adults' diet. Whereas, the ones that were later reared on healthy leaf disks as adults recorded the highest longevity and reproduction rate. Furthermore, adults of F. occidentalis that were exposed to TSWV in their larval stages showed preference toward healthy leaf disks (-TSWV), whereas the non-exposed significantly preferred the infected leaf disks (+TSWV). These are further indications that TSWV modifies the nutritional content of its host plants, which influences vector's biology and preferential behavior, in favor of its multiplication and dispersal. The findings offer additional explanation to the often aggressive spread of the virus in crop stands. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America.

2D-DIGE-based proteome expression changes in leaves of rice seedlings exposed to low-level gamma radiation at Iitate village, Fukushima

PubMed Central

Hayashi, Gohei; Moro, Carlo F; Rohila, Jai Singh; Shibato, Junko; Kubo, Akihiro; Imanaka, Tetsuji; Kimura, Shinzo; Ozawa, Shoji; Fukutani, Satoshi; Endo, Satoru; Ichikawa, Katsuki; Agrawal, Ganesh Kumar; Shioda, Seiji; Hori, Motohide; Fukumoto, Manabu; Rakwal, Randeep

2015-01-01

The present study continues our previous research on investigating the biological effects of low-level gamma radiation in rice at the heavily contaminated Iitate village in Fukushima, by extending the experiments to unraveling the leaf proteome. 14-days-old plants of Japonica rice (Oryza sativa L. cv. Nipponbare) were subjected to gamma radiation level of upto 4 µSv/h, for 72 h. Following exposure, leaf samples were taken from the around 190 µSv/3 d exposed seedling and total proteins were extracted. The gamma irradiated leaf and control leaf (harvested at the start of the experiment) protein lysates were used in a 2-D differential gel electrophoresis (2D-DIGE) experiment using CyDye labeling in order to asses which spots were differentially represented, a novelty of the study. 2D-DIGE analysis revealed 91 spots with significantly different expression between samples (60 positive, 31 negative). MALDI-TOF and TOF/TOF mass spectrometry analyses revealed those as comprising of 59 different proteins (50 up-accumulated, 9 down-accumulated). The identified proteins were subdivided into 10 categories, according to their biological function, which indicated that the majority of the differentially expressed proteins consisted of the general (non-energy) metabolism and stress response categories. Proteome-wide data point to some effects of low-level gamma radiation exposure on the metabolism of rice leaves. PMID:26451896

Modulation of oxidative responses by a virulent isolate of Colletotrichum fructicola in apple leaves.

PubMed

Velho, Aline Cristina; Rockenbach, Mathias F; Mondino, Pedro; Stadnik, Marciel J

2016-10-01

Apple bitter rot (ABR) and Glomerella leaf spot (GLS) can be caused by Colletotrichum fructicola. Although both diseases can occur simultaneously in orchards, some isolates show clear organ specialization. Thus, this work was aimed to compare microscopically the development of preinfective structures of ABR- and GLS isolates and their impact on the enzymatic oxidant defense system during the leaf infection process. On leaves, conidial germlings of GLS-isolate formed appressoria mostly sessile. In contrast, those of ABR-isolate were pedicellate and formed multiple melanized appressoria probably as a sign of unsuccessful infection attempts. Neither ABR- nor GLS isolate triggered hypersensitive response in apple leaves. In overall, the activity of scavenging enzymes was higher and long-lasting in leaves inoculated by GLS- than by ABR isolate and control. Guaiacol peroxidase, catalase, and glutathione reductase had activity peaks within 24 h after inoculation (HAI). Ascorbate peroxidase activity was higher only in GLS-infected leaves at 6 HAI, while superoxide dismutase remained unaltered. A lower level of hydrogen peroxide (H2O2) was determined in GLS-infected plants at 48 HAI, but the electrolyte leakage markedly increased. Disease symptoms in leaves were only caused by GLS-isolate. Results suggest that the virulent isolate coordinately downregulates the oxidative plant defense responses enabling its successful establishment in apple leaves. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Emerging viruses in Florida and the Caribbean

USDA-ARS?s Scientific Manuscript database

Multiple thrips-, whitefly- and aphid-transmitted viruses have recently emerged or re-emerged in vegetable and ornamental crops in Florida and the Caribbean. Tomato spotted wilt virus (a thrips-transmitted tospovirus) and Tomato yellow leaf curl virus (a whitefly-transmitted begomovirus) have histor...

Preliminary application of tapered glass capillary microbeam in MeV-PIXE mapping of longan leaf for elemental concentration distribution analysis

NASA Astrophysics Data System (ADS)

Natyanun, S.; Unai, S.; Yu, L. D.; Tippawan, U.; Pussadee, N.

2017-09-01

This study was aimed at understanding elemental concentration distribution in local longan leaf for how the plant was affected by the environment or agricultural operation. The analysis applied the MeV-microbeam particle induced X-ray emission (PIXE) mapping technique using a home-developed tapered glass capillary microbeam system at Chiang Mai University. The microbeam was 2-MeV proton beam in 130 µm in diameter. The studying interest was in the difference in the elemental concentrations distributed between the leaf midrib and lamina areas. The micro proton beam analyzed the leaf sample across the leaf midrib edge to the leaf lamina area for total 9 data requisition spots. The resulting data were colored to form a 1D-map of the elemental concentration distribution. Seven dominant elements, Al, S, Cl, K, Ca, Sc and Fe, were identified, the first six of which were found having higher concentrations in the midrib area than in the lamina area, while the Fe concentration was in an opposite trend to that of the others.

Two alternative recessive quantitative trait loci influence resistance to spring black stem and leaf spot in Medicago truncatula.

PubMed

Kamphuis, Lars G; Lichtenzveig, Judith; Oliver, Richard P; Ellwood, Simon R

2008-03-26

Knowledge of the genetic basis of plant resistance to necrotrophic pathogens is incomplete and has been characterised in relatively few pathosystems. In this study, the cytology and genetics of resistance to spring black stem and leaf spot caused by Phoma medicaginis, an economically important necrotrophic pathogen of Medicago spp., was examined in the model legume M. truncatula. Macroscopically, the resistant response of accession SA27063 was characterised by small, hypersensitive-like spots following inoculation while the susceptible interaction with accessions A17 and SA3054 showed necrotic lesions and spreading chlorosis. No unique cytological differences were observed during early infection (<48 h) between the resistant and susceptible genotypes, except pathogen growth was restricted to one or a few host cells in SA27063. In both interactions reactive oxygen intermediates and phenolic compounds were produced, and cell death occurred. Two F2 populations segregating for resistance to spring black stem and leaf spot were established between SA27063 and the two susceptible accessions, A17 and SA3054. The cross between SA27063 and A17 represented a wider cross than between SA27063 and SA3054, as evidenced by higher genetic polymorphism, reduced fertility and aberrant phenotypes of F2 progeny. In the SA27063 x A17 F2 population a highly significant quantitative trait locus (QTL, LOD = 7.37; P < 0.00001) named resistance to the necrotroph Phoma medicaginis one (rnpm1) genetically mapped to the top arm of linkage group 4 (LG4). rnpm1 explained 33.6% of the phenotypic variance in the population's response to infection depicted on a 1-5 scale and was tightly linked to marker AW256637. A second highly significant QTL (LOD = 6.77; P < 0.00001), rnpm2, was located on the lower arm of LG8 in the SA27063 x SA3054 map. rnpm2 explained 29.6% of the phenotypic variance and was fine mapped to a 0.8 cM interval between markers h2_16a6a and h2_21h11d. rnpm1 is tightly linked to a cluster of Toll/Interleukin1 receptor-nucleotide binding site-leucine-rich repeat (TIR-NBS-LRR) genes and disease resistance protein-like genes, while no resistance gene analogues (RGAs) are apparent in the genomic sequence of the reference accession A17 at the rnpm2 locus. The induction of defence responses and cell death in the susceptible interaction following infection by P. medicaginis suggested this pathogen is not negatively affected by these responses and may promote them. A QTL for resistance was revealed in each of two populations derived from crosses between a resistant accession and two different susceptible accessions. Both loci are recessive in nature, and the simplest explanation for the existence of two separate QTLs is the occurrence of host genotype-specific susceptibility loci that may interact with undetermined P. medicaginis virulence factors.

Effective protein extraction protocol for proteomics studies of Jerusalem artichoke leaves.

PubMed

Zhang, Meide; Shen, Shihua

2013-07-01

Protein extraction is a crucial step for proteomics studies. To establish an effective protein extraction protocol suitable for two-dimensional electrophoresis (2DE) analysis in Jerusalem artichoke (Helianthus tuberosus L.), three different protein extraction methods-trichloroacetic acid/acetone, Mg/NP-40, and phenol/ammonium acetate-were evaluated using Jerusalem artichoke leaves as source materials. Of the three methods, trichloroacetic acid/acetone yielded the best protein separation pattern and highest number of protein spots in 2DE analysis. Proteins highly abundant in leaves, such as Rubisco, are typically problematic during leaf 2DE analysis, however, and this disadvantage was evident using trichloroacetic acid/acetone. To reduce the influence of abundant proteins on the detection of low-abundance proteins, we optimized the trichloroacetic acid/acetone method by incorporating a PEG fractionation approach. After optimization, 363 additional (36.2%) protein spots were detected on the 2DE gel. Our results suggest that trichloroacetic acid/acetone method is a better protein extraction technique than Mg/NP-40 and phenol/ammonium acetate in Jerusalem artichoke leaf 2DE analysis, and that trichloroacetic acid/acetone method combined with PEG fractionation procedure is the most effective approach for leaf 2DE analysis of Jerusalem artichoke. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Topography and crop management are key factors for the development of american leaf spot epidemics on coffee in costa rica.

PubMed

Avelino, Jacques; Cabut, Sandrine; Barboza, Bernardo; Barquero, Miguel; Alfaro, Ronny; Esquivel, César; Durand, Jean-François; Cilas, Christian

2007-12-01

ABSTRACT We monitored the development of American leaf spot of coffee, a disease caused by the gemmiferous fungus Mycena citricolor, in 57 plots in Costa Rica for 1 or 2 years in order to gain a clearer understanding of conditions conducive to the disease and improve its control. During the investigation, characteristics of the coffee trees, crop management, and the environment were recorded. For the analyses, we used partial least-squares regression via the spline functions (PLSS), which is a nonlinear extension to partial least-squares regression (PLS). The fungus developed well in areas located between approximately 1,100 and 1,550 m above sea level. Slopes were conducive to its development, but eastern-facing slopes were less affected than the others, probably because they were more exposed to sunlight, especially in the rainy season. The distance between planting rows, the shade percentage, coffee tree height, the type of shade, and the pruning system explained disease intensity due to their effects on coffee tree shading and, possibly, on the humidity conditions in the plot. Forest trees and fruit trees intercropped with coffee provided particularly propitious conditions. Apparently, fertilization was unfavorable for the disease, probably due to dilution phenomena associated with faster coffee tree growth. Finally, series of wet spells interspersed with dry spells, which were frequent in the middle of the rainy season, were critical for the disease, probably because they affected the production and release of gemmae and their viability. These results could be used to draw up a map of epidemic risks taking topographical factors into account. To reduce those risks and improve chemical control, our results suggested that farmers should space planting rows further apart, maintain light shading in the plantation, and prune their coffee trees.

Variation in the outcomes of an ant-plant system: Fire and leaf fungus infection reduce benefits to plants with extrafloral nectaries

PubMed Central

Pires, L. P.; Del-Claro, K.

2014-01-01

Abstract Interactions between species are evolutionary malleable and may suffer changes in small timescales. Environmental disturbances, such as fire, can deeply affect species interactions, but how they influence the outcome of a mutualistic interaction has yet to be studied. In order to test the hypothesis that an environmental disturbance, in this case fire, may produce differences in the outcome of the association of ants with the extrafloral-nectaries-bearing plant Qualea multiflora Mart. (Myrtales: Vochysiaceae), a previous study was replicated, but this time after fire incidence, at the same study site and with the same plant species. Eight ant species visited Q. multiflora , and the most abundant genera were Crematogaster , Cephalotes , and Camponotus . Herbivores were found in branches with and without ants with no statistical difference, but foliar herbivory was always higher in branchs where ants were absent. Leaves were infested by fungi, and fungi spots were higher in branches where ants were present. Compared to the previous study, it was clearly observed that ant benefits to Q. multiflora varied over time. The most common ant species still protected leaves against chewing herbivores, but a new kind of leaf damage appeared, namely fungi spots. Data also support that ants may be acting as vectors of fungi spores on plants, as ant visited branches had higher fungus incidence than non-visited branches. Fire is a major source of disturbance in tropical savannas, and we suggest that it can cause strong variation in the outcomes of interactions between ants and plants with extrafloral nectaries in the Brazilian tropical savanna. PMID:25368040

Foliar Diseases of Apiaceae Crops in Coastal California

USDA-ARS?s Scientific Manuscript database

The number of outbreaks of leaf spot, blight and streak diseases on celery, cilantro, fennel and parsley has been increasing throughout central coastal California and particularly in Monterey County since 2002. Two different bacterial pathogens (Pseudomonas syringae pv. apii, and P. syringae pv. cor...

New Generation of Resistant Sugar Beet Varieties for Advanced Integrated Management of Cercospora Leaf Spot in Central Europe

PubMed Central

Vogel, Johannes; Kenter, Christine; Holst, Carsten; Märländer, Bernward

2018-01-01

Cercospora leaf spot (CLS) epidemics in sugar beet have been increasing in recent years causing higher use of fungicides. Concomitantly, the availability of effective fungicides is at risk because of resistance development in the fungus, the lack of new active ingredients as well as restrictive approval practices. A key option for an integrated management of CLS is cultivation of resistant varieties. Because of the yield penalty in resistant varieties, acceptance in commercial practice so far has been low. The aim of our study was to characterize recent sugar beet varieties registered in Germany in terms of resistance and tolerance to CLS and their value for integrated pest management. The genetic basis of CLS resistance in varieties is protected by intellectual property rights even after variety registration and not open to the public due to economic competition. To gain reliable data for cultivation, varieties have to be tested for their resistance traits under field conditions at varying levels of infection with Cercospora beticola. In collaboration with variety related stakeholders, 15 sugar beet varieties were tested in 49 field trials in Germany from 2014 to 2016 for their yield response to CLS. The trials were set up in a split-plot design with and without infection (i.e., with and without fungicide). The classification of varietal reaction to CLS is based on symptomatic leaf area (susceptibility) and the resulting relative yield loss (tolerance). Since the relation between both parameters varied among varieties, it was used as an additional parameter to describe tolerance. On this basis, three groups of varieties were identified. They can be characterized as a susceptible, a resistant and a presumably tolerant cluster. A comparison of the data with an older dataset originating from 2009 to 2011 revealed that yield performance of recent varieties with resistance to C. beticola caught up with susceptible varieties due to breeding progress. They showed no yield penalty in the absence of the disease and better economic performance than susceptible varieties. It is assumed that these varieties will allow a substantial reduction of fungicide use for an advanced integrated pest management under central European conditions. PMID:29535743

New Generation of Resistant Sugar Beet Varieties for Advanced Integrated Management of Cercospora Leaf Spot in Central Europe.

PubMed

Vogel, Johannes; Kenter, Christine; Holst, Carsten; Märländer, Bernward

2018-01-01

Cercospora leaf spot (CLS) epidemics in sugar beet have been increasing in recent years causing higher use of fungicides. Concomitantly, the availability of effective fungicides is at risk because of resistance development in the fungus, the lack of new active ingredients as well as restrictive approval practices. A key option for an integrated management of CLS is cultivation of resistant varieties. Because of the yield penalty in resistant varieties, acceptance in commercial practice so far has been low. The aim of our study was to characterize recent sugar beet varieties registered in Germany in terms of resistance and tolerance to CLS and their value for integrated pest management. The genetic basis of CLS resistance in varieties is protected by intellectual property rights even after variety registration and not open to the public due to economic competition. To gain reliable data for cultivation, varieties have to be tested for their resistance traits under field conditions at varying levels of infection with Cercospora beticola . In collaboration with variety related stakeholders, 15 sugar beet varieties were tested in 49 field trials in Germany from 2014 to 2016 for their yield response to CLS. The trials were set up in a split-plot design with and without infection (i.e., with and without fungicide). The classification of varietal reaction to CLS is based on symptomatic leaf area (susceptibility) and the resulting relative yield loss (tolerance). Since the relation between both parameters varied among varieties, it was used as an additional parameter to describe tolerance. On this basis, three groups of varieties were identified. They can be characterized as a susceptible, a resistant and a presumably tolerant cluster. A comparison of the data with an older dataset originating from 2009 to 2011 revealed that yield performance of recent varieties with resistance to C. beticola caught up with susceptible varieties due to breeding progress. They showed no yield penalty in the absence of the disease and better economic performance than susceptible varieties. It is assumed that these varieties will allow a substantial reduction of fungicide use for an advanced integrated pest management under central European conditions.

Effects of foliar applied nickel on tomato plants. [Lycopersicon esculentum

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

Cash, R.C.; Leone, I.A.

Shoot-applied nickel (Ni) treatments produced symptomatology, foliar Ni accumulation, and cytological changes in tomato (Lycopersicon esculentum Mill.) similar to those caused by treatments with root-applied nickel (Ni). Leaf damage resulting from 100 ..mu..g/ml foliar Ni-treatments consisted of interveinal chlorosis and spotting necrosis which appeared histologically as tissue collapse, cell clumping, and chloroplast disintegration. Shoot-treated plants accumulated more Ni in leaves than in roots; whereas the reverse was true in root-treated plants. Interference with root-to-shoot manganese translocation was attributed to attenuated vascular tissue and phloem blockage. Evidence of reduced nutrient transport and inhibited meristem activity due to Ni toxicity presents amore » potential for crop damage from excessive Ni in the atmosphere as well as in the soil environment.« less

Silicon induced systemic defense responses in perennial ryegrass against Magnaporthe oryzae infection

USDA-ARS?s Scientific Manuscript database

Sustainable integrated disease management for gray leaf spot of perennial ryegrass may involve use of plant defense elicitors with compatible traditional fungicides to reduce disease incidence and severity. Silicon (Si) is a potential inducer or modulator of plant defenses against different pathogen...

Leaf waxes and thrips resistance in onion

USDA-ARS?s Scientific Manuscript database

Onion thrips is an important insect pest of onion that damages leaves and bulbs, reduces yields, and transmits important diseases such as iris yellow spot virus and bacterial rots. Growers would benefit from onions resistant to thrips in order to reduce insecticide applications and provide more sust...

A new optical leaf-clip meter for simultaneous non-destructive assessment of leaf chlorophyll and epidermal flavonoids

PubMed Central

Cerovic, Zoran G; Masdoumier, Guillaume; Ghozlen, NaÏma Ben; Latouche, Gwendal

2012-01-01

We have characterized a new commercial chlorophyll (Chl) and flavonoid (Flav) meter called Dualex 4 Scientific (Dx4). We compared this device to two other Chl meters, the SPAD-502 and the CCM-200. In addition, Dx4 was compared to the leaf-clip Dualex 3 that measures only epidermal Flav. Dx4 is factory-calibrated to provide a linear response to increasing leaf Chl content in units of µg cm–2, as opposed to both SPAD-502 and CCM-200 that have a non-linear response to leaf Chl content. Our comparative calibration by Chl extraction confirmed these responses. It seems that the linear response of Dx4 derives from the use of 710 nm as the sampling wavelength for transmittance. The major advantage of Dx4 is its simultaneous assessment of Chl and Flav on the same leaf spot. This allows the generation of the nitrogen balance index (NBI) used for crop surveys and nitrogen nutrition management. The Dx4 leaf clip, that incorporates a GPS receiver, can be useful for non-destructive estimation of leaf Chl and Flav contents for ecophysiological research and ground truthing of remote sensing of vegetation. In this work, we also propose a consensus equation for the transformation of SPAD units into leaf Chl content, for general use. PMID:22568678

A new optical leaf-clip meter for simultaneous non-destructive assessment of leaf chlorophyll and epidermal flavonoids.

PubMed

Cerovic, Zoran G; Masdoumier, Guillaume; Ghozlen, Naïma Ben; Latouche, Gwendal

2012-11-01

We have characterized a new commercial chlorophyll (Chl) and flavonoid (Flav) meter called Dualex 4 Scientific (Dx4). We compared this device to two other Chl meters, the SPAD-502 and the CCM-200. In addition, Dx4 was compared to the leaf-clip Dualex 3 that measures only epidermal Flav. Dx4 is factory-calibrated to provide a linear response to increasing leaf Chl content in units of µg cm(-2), as opposed to both SPAD-502 and CCM-200 that have a non-linear response to leaf Chl content. Our comparative calibration by Chl extraction confirmed these responses. It seems that the linear response of Dx4 derives from the use of 710 nm as the sampling wavelength for transmittance. The major advantage of Dx4 is its simultaneous assessment of Chl and Flav on the same leaf spot. This allows the generation of the nitrogen balance index (NBI) used for crop surveys and nitrogen nutrition management. The Dx4 leaf clip, that incorporates a GPS receiver, can be useful for non-destructive estimation of leaf Chl and Flav contents for ecophysiological research and ground truthing of remote sensing of vegetation. In this work, we also propose a consensus equation for the transformation of SPAD units into leaf Chl content, for general use. Copyright © Physiologia Plantarum 2012.

First report of Colletotrichum lupini on Lupinus hartwegii and L. mutabilis

USDA-ARS?s Scientific Manuscript database

During the 2013 winter cut flower production season, a severe anthracnose epidemic was observed on Lupinus mutabilis (syn L. cruckshanksii) on a commercial flower farm in Martin County, FL. Approximately 50% of the crop was lost to the disease. Symptoms included mild leaf spots, but more typically...

Diseases of Landscape Ornamentals. Slide Script.

ERIC Educational Resources Information Center

Powell, Charles C.; Sydnor, T. Davis

This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with recognizing and controlling diseases found on ornamental landscape plants. Included in the script are narrations for use with a total of 80 slides illustrating various foliar diseases (anthracnose, black spot, hawthorn leaf blight,…

Genomics of peanut leaf-spot pathogens; and RNA-interference-mediated control of aflatoxins

USDA-ARS?s Scientific Manuscript database

An overview update of the research done at USDA-ARS National Peanut Research Laboratory will be presented: including: the release of the Cercospora arachidicola genome, sequencing of Cercosporidium personatum, a workflow to study genetic diversity of aflatoxigenic Aspergillus, and progress on the us...

Global genotype flow in Cercospora beticola populations confirmed through genotyping-by-sequencing

USDA-ARS?s Scientific Manuscript database

Genotyping-by-sequencing (GBS) was conducted on 333 Cercospora isolates collected from Beta vulgaris (sugar beet, table beet and Swiss chard) in the USA and Europe. Cercospora beticola was confirmed as the species predominantly isolated from leaves with Cercospora leaf spot (CLS) symptoms. However, ...

An evaluation of the first four LANDSAT-D thematic mapper reflective sensors for monitoring vegetation: A comparison with other satellite sensor systems

NASA Technical Reports Server (NTRS)

Tucker, C. J.

1978-01-01

The first four LANDSAT-D thematic mapper sensors were evaluated and compared to: the return beam vidicon (RBV) and multispectral scanners (MSS) sensors from LANDSATS 1, 2, and 3; Colvocoresses' proposed 'operational LANDSAT' three band system; and the French SPOT three band system using simulation/intergration techniques and in situ collected spectral reflectance data. Sensors were evaluated by their ability to discriminate vegetation biomass, chlorophyll concentration, and leaf water content. The thematic mapper and SPOT bands were found to be superior in a spectral resolution context to the other three sensor systems for vegetational applications. Significant improvements are expected for most vegetational analyses from LANDSAT-D thematic mapper and SPOT imagery over MSS and RBV imagery.

Epidemiological Features and Trends of Brown Spot of Pear Disease Based on the Diversity of Pathogen Populations and Climate Change Effects.

PubMed

Moragrega, Concepció; Puig, Mireia; Ruz, Lídia; Montesinos, Emilio; Llorente, Isidre

2018-02-01

Brown spot of pear, caused by the fungus Stemphylium vesicarium, is an emerging disease of economic importance in several pear-growing areas in Europe. In recent years, new control strategies combining sanitation practices and fungicide applications according to developed forecasting models have been introduced to manage the disease. However, the pathogenic and saprophytic behavior of this pathogen makes it difficult to manage the disease. In addition, climate change can also result in variations in the severity and geographical distribution of the disease. In this study, ecological and epidemiological aspects of brown spot of pear disease related to inoculum characterization and climate change impact were elucidated. The pathogenic variation in S. vesicarium populations from pear orchards and its relationship to inoculum sources (air samples, leaf debris, and infected host and nonhost tissues) was determined using multivariate analysis. In total, six variables related to infection and disease development on cultivar Conference pear detached leaves of 110 S. vesicarium isolates were analyzed. A high proportion of isolates (42%) were nonpathogenic to pear; 85% of these nonpathogenic isolates were recovered from air samples. Most isolates recovered from lesions (93%) and pseudothecia (83%) were pathogenic to pear. A group of pathogenic isolates rapidly infected cultivar Conference pear leaves resulted in disease increase that followed a monomolecular model, whereas some S. vesicarium isolates required a period of time after inoculation to initiate infection and resulted in disease increase that followed a logistic model. The latter group was mainly composed of isolates recovered from pseudothecia on leaf debris, whereas the former group was mainly composed of isolates recovered from lesions on pear fruit and leaves. The relationship between the source of inoculum and pathogenic/aggressiveness profile was confirmed by principal component analysis. The effect of climate change on disease risk was analyzed in two pear-growing areas of Spain under two scenarios (A2 and B1) and for three periods (2005 to 2009, 2041 to 2060, and 2081 to 2100). Simulations showed that the level of risk predicted by BSPcast model increased to high or very high under the two scenarios and was differentially distributed in the two regions. This study is an example of how epidemiological models can be used to predict not only the onset of infections but also how climate change could affect brown spot of pear. [Formula: see text] Copyright © 2018 The Author(s). This is an open-access article distributed under the CC BY-NC-ND 4.0 International license .

Proteomic profiling of mature leaves from oil palm (Elaeis guineensis Jacq.).

PubMed

Tan, Hooi Sin; Jacoby, Richard P; Ong-Abdullah, Meilina; Taylor, Nicolas L; Liddell, Susan; Chee, Wong Wei; Chin, Chiew Foan

2017-04-01

Oil palm is one of the most productive oil bearing crops grown in Southeast Asia. Due to the dwindling availability of agricultural land and increasing demand for high yielding oil palm seedlings, clonal propagation is vital to the oil palm industry. Most commonly, leaf explants are used for in vitro micropropagation of oil palm and to optimize this process it is important to unravel the physiological and molecular mechanisms underlying somatic embryo production from leaves. In this study, a proteomic approach was used to determine protein abundance of mature oil palm leaves. To do this, leaf proteins were extracted using TCA/acetone precipitation protocol and separated by 2DE. A total of 191 protein spots were observed on the 2D gels and 67 of the most abundant protein spots that were consistently observed were selected for further analysis with 35 successfully identified using MALDI TOF/TOF MS. The majority of proteins were classified as being involved in photosynthesis, metabolism, cellular biogenesis, stress response, and transport. This study provides the first proteomic assessment of oil palm leaves in this important oil crop and demonstrates the successful identification of selected proteins spots using the Malaysian Palm Oil Board (MPOB) Elaeis guineensis EST and NCBI-protein databases. The MS data have been deposited in the ProteomeXchange Consortium database with the data set identifier PXD001307. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Occurrence of gum spots in black cherry after partial harvest cutting

Treesearch

Charles O. Rexrode; H. Clay Smith; H. Clay Smith

1990-01-01

Bark beetles, primarily the bark beetle Phlosotribus liminori (Harris), are the major cause of gum spots in sawtimber-size black cherry Prunus serotina Ehrh. Approximately 90 percent of all gum spots in the bole sections are caused by bark beetles. Gum spots were studied in 95 black cherry trees near Parsons, West Virginia. Over 50 percent of the bark beetle-caused gum...

Active optical sensor assessment of spider mite damage on greenhouse beans and cotton.

PubMed

Martin, Daniel E; Latheef, Mohamed A

2018-02-01

The two-spotted spider mite, Tetranychus urticae Koch, is an important pest of cotton in mid-southern USA and causes yield reduction and deprivation in fiber fitness. Cotton and pinto beans grown in the greenhouse were infested with spider mites at the three-leaf and trifoliate stages, respectively. Spider mite damage on cotton and bean canopies expressed as normalized difference vegetation index indicative of changes in plant health was measured for 27 consecutive days. Plant health decreased incrementally for cotton until day 21 when complete destruction occurred. Thereafter, regrowth reversed decline in plant health. On spider mite treated beans, plant vigor plateaued until day 11 when plant health declined incrementally. Results indicate that pinto beans were better suited as a host plant than cotton for rearing T. urticae in the laboratory.

Identification and characterization of expressed resistance gene analogs (RGSs) from peanut (Arachis hypogaea L.) expressed sequence tags (ESTs)

USDA-ARS?s Scientific Manuscript database

Cultivated peanut (Arachis hypogaea L.) is an important food legume grown worldwide for providing edible oil and protein. However, due to scarcity of genetic diversity, peanut is very vulnerable to a variety of pathogens, such as rust (Puccinia arachidis Speg.), early leaf spot (Cercospora arachidic...

Molecular cloning and characterization of a ToxA-like gene from the maize pathogen Cochliobolus heterostrophus

USDA-ARS?s Scientific Manuscript database

ToxA, the first discovered fungal proteinaceous host-selective toxin, was originally identified from the tan spot fungus Pyrenophora tritici-repentis (Ptr). Homologues of the PtrToxA gene have not been identified from any other ascomycetes except the leaf/glume blotch fungus Stagonospora nodorum, w...

Multilocus sequence typing of Pseudomonas syringae sensu lato confirms previously described genomospecies and permits rapid identification.

USDA-ARS?s Scientific Manuscript database

Since 2002, severe leaf spotting on parsley (Petroselinum crispum L.) has occurred in Monterey County, California. One of two different pathovars of Pseudomonas syringae sensu lato were isolated from diseased leaves from seven distinct outbreaks and twice from the same outbreak (2002 and 2009). Frag...

Biochemical analysis of leaf waxes and thrips resistance in onion selections

USDA-ARS?s Scientific Manuscript database

Thrips (Thrips tabaci) is a serious insect pest of onion and is a vector for Iris yellow spot virus (IYSV). Lower amounts of epicuticular waxes on onion leaves have been associated with fewer thrips, less feeding damage, and lower incidence of IYSV. In this study, 10 onion selections that showed les...

Identification and frequency of Phytophthora species associated with foliar diseases in California ornamental nurseries

Treesearch

L. E. Yakabe; C. L. Blomquist; S. L. Thomas; J. D. MacDonald

2009-01-01

Numerous ornamental nurseries in 32 California counties were surveyed for leaf spots as part of the California Department of Food and Agriculture mandated surveys targeting Phytophthora ramorum. Tissue collected during the 2005 and 2006 surveys was initially screened by a Phytophthora-specific enzyme-linked immunosorbent assay...

Cryotherapy by encapsulation-dehydration is effective for in vitro eradication of latent viruses from ‘Marubakaido’ apple rootstock

USDA-ARS?s Scientific Manuscript database

Apple stem pitting virus (ASPV), Apple chlorotic leaf spot virus (ACLSV) and Apple stem grooving virus (ASGV) are several major viral pathogens of apple trees, responsible for substantial damage to the world's apple industry. This study aimed to evaluate the effectiveness of encapsulation-dehydratio...

Soil moisture mediated interaction between Polygonatum biflorum and leaf spot disease

Treesearch

Robert J. II Warren; Erin Mordecai

2010-01-01

Fungal pathogens can regulate the abundance and distribution of natural plant populations by inhibiting the growth, survival, and reproduction of their hosts. The abiotic environment is a crucial component in host–pathogen interactions in natural plant populations as favorable conditions drive pathogen development, reproduction, and persistence. Foliar plant pathogens...

Evaluation of effects of fertilizers on narrow brown leaf spot in organic rice, 2010

USDA-ARS?s Scientific Manuscript database

The experiment was established in a field of League soil (3% sand, 32% silt, and 64% clay) under organic management for many years at the Texas A&M University System's Agrilife Research and Extension Center, Beaumont. The experiment was conducted as a two factorial experimental design with five orga...

'Lufkin Red' and 'Lufkin White' winter-hardy hibiscus (Hibiscus x laevis All.)

USDA-ARS?s Scientific Manuscript database

USDA ARS announces the release of ‘Lufkin Red’ and ‘Lufkin White’ winter-hardy native hibiscuses.Both clones have desirable horticultural traits in combination with demonstrated high levels of field resistance to the leaf spot complex that is problematic on winter-hardy hibiscus clones in areas wit...

Foliicolous fungi from Arctostaphylos pungens in Mexico.

PubMed

Moreno-Rico, Onésimo; Groenewald, Johannes Z; Crous, Pedro W

2014-06-01

Arctostaphylos pungens "Manzanita" is an important shrub in the southwestern USA, and northern and central Mexico. Manzanita bears apple-like fruit that is utilised for a range of edible products. Over the past two years, several foliar disease problems were noted on this host in the San José de Gracia region of Mexico. The aim of the present study was to elucidate their identity through the analysis of morphological characters and DNA phylogeny (based on the large subunit nuclear ribosomal RNA gene and the ITS spacers and the intervening 5.8S rRNA gene of the nrDNA operon) of the fungi associated with these disease symptoms. Three species are newly described: Phaeococcomyces mexicanus sp. nov., a presumed epiphyte, and two species associated with leaf spots and defoliation, namely Coccomyces arctostaphyloides sp. nov. and Passalora arctostaphyli sp. nov. A fourth species is also associated with leaf spots and tip dieback is Harknessia arctostaphyli, for which an epitype is designated. All species can co-occur on the same shrub, which adds to the stress experienced by the plant, leading to further defoliation and dieback.

BOREAS Level-3s SPOT Imagery: Scaled At-sensor Radiance in LGSOWG Format

NASA Technical Reports Server (NTRS)

Strub, Richard; Nickeson, Jaime; Newcomer, Jeffrey A.; Hall, Forrest G. (Editor); Cihlar, Josef

2000-01-01

For BOReal Ecosystem-Atmosphere Study (BOREAS), the level-3s Satellite Pour l'Observation de la Terre (SPOT) data, along with the other remotely sensed images, were collected in order to provide spatially extensive information over the primary study areas. This information includes radiant energy, detailed land cover, and biophysical parameter maps such as Fraction of Photosynthetically Active Radiation (FPAR) and Leaf Area Index (LAI). The SPOT images acquired for the BOREAS project were selected primarily to fill temporal gaps in the Landsat Thematic Mapper (TM) image data collection. CCRS collected and supplied the level-3s images to BOREAS Information System (BORIS) for use in the remote sensing research activities. Spatially, the level-3s images cover 60- by 60-km portions of the BOREAS Northern Study Area (NSA) and Southern Study Area (SSA). Temporally, the images cover the period of 17-Apr-1994 to 30-Aug-1996. The images are available in binary image format files. Due to copyright issues, the SPOT images may not be publicly available.

Pathogenic and Nonpathogenic Lifestyles in Colletotrichum acutatum from Strawberry and Other Plants.

PubMed

Freeman, S; Horowitz, S; Sharon, A

2001-10-01

ABSTRACT Anthracnose is one of the major fungal diseases of strawberry occurring worldwide. In Israel, the disease is caused primarily by the species Colletotrichum acutatum. The pathogen causes black spot on fruit, root necrosis, and crown rot resulting in mortality of transplants in the field. The host range and specificity of C. acutatum from strawberry was examined on pepper, eggplant, tomato, bean, and strawberry under greenhouse conditions. The fungus was recovered from all plant species over a 3-month period but caused disease symptoms only on strawberry. Epiphytic and endophytic (colonization) fungal growth in the different plant species was confirmed by reisolation from leaf tissues and by polymerase chain reaction (PCR)-specific primer amplification. C. acutatum was also isolated from healthy looking, asymptomatic plants of the weed genera Vicia and Conyza. Isolates that were recovered from the weeds caused disease symptoms on strawberry and were positively identified as C. acutatum by PCR. The habitation of a large number of plant species, including weeds, by C. acutatum suggests that, although it causes disease only on strawberry and anemone in Israel, this fungus can persist on many other plant species. Therefore, plants that are not considered hosts of C. acutatum may serve as a potential inoculum source for strawberry infection and permit survival of the pathogen between seasons.

Evaluation of one dimensional analytical models for vegetation canopies

NASA Technical Reports Server (NTRS)

Goel, Narendra S.; Kuusk, Andres

1992-01-01

The SAIL model for one-dimensional homogeneous vegetation canopies has been modified to include the specular reflectance and hot spot effects. This modified model and the Nilson-Kuusk model are evaluated by comparing the reflectances given by them against those given by a radiosity-based computer model, Diana, for a set of canopies, characterized by different leaf area index (LAI) and leaf angle distribution (LAD). It is shown that for homogeneous canopies, the analytical models are generally quite accurate in the visible region, but not in the infrared region. For architecturally realistic heterogeneous canopies of the type found in nature, these models fall short. These shortcomings are quantified.

Curvularia microspora sp. nov. associated with leaf diseases of Hippeastrum striatum in China.

PubMed

Liang, Yin; Ran, Shuang-Fei; Bhat, Jayarama; Hyde, Kevin D; Wang, Yong; Zhao, De-Gang

2018-01-01

An undescribed Curvularia sp. was isolated from the leaf spot disease of Barbados Lily ( Hippeastrum striatum (Lam.) Moore). Phylogenetic analyses of combined ITS, 28S, GPD1 and TEF1 sequence data place nine strains of this species in the trifolii -clade, but they clustered together as an independent lineage with strong support. This species was morphologically compared with related species in the trifolii -clade. Based on differences in morphology and phylogeny, it is concluded that this species is a new taxon, introduced as Curvularia microspora sp. nov. Pathogenicity testing determined the new species to be pathogenic on H. striatum .

Guava diseases in Hawaii and the characterization of Pestalotiopsis spp. affecting guava

USDA-ARS?s Scientific Manuscript database

Guava (Psidium guajava L.), one of the most widely grown plants in the tropics, is very susceptible to disease which can decrease its marketability. Leaf and fruit spot diseases commonly occur on guava grown in Hawaii. A disease survey was conducted on more than 50 accessions grown at the USDA/ARS T...

Apply Pesticides Correctly, A Guide for Commercial Applicators: Ornamental and Turfgrass Pest Control.

ERIC Educational Resources Information Center

Wamsley, Mary Ann, Ed.; Vermeire, Donna M., Ed.

This guide contains basic information to meet specific standards for pesticide applicators. The text is concerned with recognition and control of ornamental and turfgrass pests such as leaf spot, scab, powdery mildew, galls, grubs and weeds. A section of the text is also devoted to environmental concerns to be considered when undertaking pest…

Host resistance to Botrytis bunch rot in Vitis spp. and its correlation with Botrytis leaf spot

USDA-ARS?s Scientific Manuscript database

Botrytis cinerea, the causal agent of Botrytis bunch rot, is the number one postharvest disease of fresh grapes in the U.S. Fungicide applications are used to manage the disease, but resistant isolates are common and postharvest losses occur annually. Host resistance is needed for long-term manageme...

Evaluation of host resistance to Botrytis bunch rot in Vitis spp. and its correlation with Botrytis leaf spot

USDA-ARS?s Scientific Manuscript database

Botrytis cinerea, the causal agent of Botrytis bunch rot and gray mold, is the number one postharvest disease of fresh grapes in the United States. Fungicide applications are used to manage the disease, but fungicide-resistant isolates are common and postharvest losses occur annually. Host resistanc...

Management of sheath blight and narrow brown leaf spot with biocontrol agents in organic rice, 2010

USDA-ARS?s Scientific Manuscript database

The experiment was established in a field of League-type soil (3% sand, 32% silt, and 64% clay) under organic management for many years at the Texas A&M University System's Agrilife Research and Extension Center, Beaumont. Plots consisted of seven 18-ft rows, and spaced 7 inches between rows. There ...

Lipid Profiles in Wheat Cultivars Resistant and Susceptible to Tan Spot and the Effect of Disease on the Profiles

PubMed Central

Kim, Dongwon; Jeannotte, Richard; Welti, Ruth; Bockus, William W.

2013-01-01

Lipid profiles in wheat leaves and the effects of tan spot on the profiles were quantified by mass spectrometry. Inoculation with Pyrenophora tritici-repentis significantly reduced the amount of leaf lipids, including the major plastidic lipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), which together accounted for 89% of the mass spectral signal of detected lipids in wheat leaves. Levels of these lipids in susceptible cultivars dropped much more quickly during infection than those in resistant cultivars. Furthermore, cultivars resistant or susceptible to tan spot displayed different lipid profiles; leaves of resistant cultivars had more MGDG and DGDG than susceptible ones, even in non-inoculated plants. Lipid compositional data from leaves of 20 non-inoculated winter wheat cultivars were regressed against an index of disease susceptibility and fitted with a linear model. This analysis demonstrated a significant relationship between resistance and levels of plastidic galactolipids and indicated that cultivars with high resistance to tan spot uniformly had more MGDG and DGDG than cultivars with high susceptibility. These findings suggest that lipid composition of wheat leaves may be a determining factor in the resistance response of cultivars to tan spot. PMID:23035632

Gum spots caused by cambium miners in black cherry in West Virginia

Treesearch

Charles O. Rexrode; John E. Baumgras

1980-01-01

Six types of gum spots in black cherry, Prunus serotina Ehrh. were associated with parenchyma flecks caused by the cambium miner Phytobia pruni (Gross). The number of parenchyma flecks and associated gum spots increased with the height of the tree. Four percent of the flecks produced gum spots in the first 18 to 20 feet of the...

Gum spots in black cherry caused by natural attacks of peach bark beetle

Treesearch

Charles O. Rexrode

1981-01-01

Peach bark beetles, Phloeotribus liminaris (Harris), made abortive attacks on healthy black cherry, Prunus serotina Ehrh., trees. The beetle attacks caused five types of gum spots in the wood and a gummy exudate on the bark. The most extensive and common types of gum spot were single and multiple rows of interray gum spots that...

More Cercospora Species Infect Soybeans across the Americas than Meets the Eye

PubMed Central

Soares, Ana Paula Gomes; Guillin, Eduardo A.; Borges, Leandro Luiz; da Silva, Amanda C. T.; de Almeida, Álvaro M. R.; Grijalba, Pablo E.; Gottlieb, Alexandra M.; Bluhm, Burton H.; de Oliveira, Luiz Orlando

2015-01-01

Diseases of soybean caused by Cercospora spp. are endemic throughout the world’s soybean production regions. Species diversity in the genus Cercospora has been underestimated due to overdependence on morphological characteristics, symptoms, and host associations. Currently, only two species (Cercospora kikuchii and C. sojina) are recognized to infect soybean; C. kikuchii causes Cercospora leaf blight (CLB) and purple seed stain (PSS), whereas C. sojina causes frogeye leaf spot. To assess cryptic speciation among pathogens causing CLB and PSS, phylogenetic and phylogeographic analyses were performed with isolates from the top three soybean producing countries (USA, Brazil, and Argentina; collectively accounting for ~80% of global production). Eight nuclear genes and one mitochondrial gene were partially sequenced and analyzed. Additionally, amino acid substitutions conferring fungicide resistance were surveyed, and the production of cercosporin (a polyketide toxin produced by many Cercospora spp.) was assessed. From these analyses, the long-held assumption of C. kikuchii as the single causal agent of CLB and PSS was rejected experimentally. Four cercosporin-producing lineages were uncovered with origins (about 1 Mya) predicted to predate agriculture. Some of the Cercospora spp. newly associated with CLB and PSS appear to represent undescribed species; others were not previously reported to infect soybeans. Lineage 1, which contained the ex-type strain of C. kikuchii, was monophyletic and occurred in Argentina and Brazil. In contrast, lineages 2 and 3 were polyphyletic and contained wide-host range species complexes. Lineage 4 was monophyletic, thrived in Argentina and the USA, and included the generalist Cercospora cf. flagellaris. Interlineage recombination was detected, along with a high frequency of mutations linked to fungicide resistance in lineages 2 and 3. These findings point to cryptic Cercospora species as underappreciated global considerations for soybean production and phytosanitary vigilance, and urge a reassessment of host-specificity as a diagnostic tool for Cercospora. PMID:26252018

More Cercospora Species Infect Soybeans across the Americas than Meets the Eye.

PubMed

Soares, Ana Paula Gomes; Guillin, Eduardo A; Borges, Leandro Luiz; Silva, Amanda C T da; Almeida, Álvaro M R de; Grijalba, Pablo E; Gottlieb, Alexandra M; Bluhm, Burton H; Oliveira, Luiz Orlando de

2015-01-01

Diseases of soybean caused by Cercospora spp. are endemic throughout the world's soybean production regions. Species diversity in the genus Cercospora has been underestimated due to overdependence on morphological characteristics, symptoms, and host associations. Currently, only two species (Cercospora kikuchii and C. sojina) are recognized to infect soybean; C. kikuchii causes Cercospora leaf blight (CLB) and purple seed stain (PSS), whereas C. sojina causes frogeye leaf spot. To assess cryptic speciation among pathogens causing CLB and PSS, phylogenetic and phylogeographic analyses were performed with isolates from the top three soybean producing countries (USA, Brazil, and Argentina; collectively accounting for ~80% of global production). Eight nuclear genes and one mitochondrial gene were partially sequenced and analyzed. Additionally, amino acid substitutions conferring fungicide resistance were surveyed, and the production of cercosporin (a polyketide toxin produced by many Cercospora spp.) was assessed. From these analyses, the long-held assumption of C. kikuchii as the single causal agent of CLB and PSS was rejected experimentally. Four cercosporin-producing lineages were uncovered with origins (about 1 Mya) predicted to predate agriculture. Some of the Cercospora spp. newly associated with CLB and PSS appear to represent undescribed species; others were not previously reported to infect soybeans. Lineage 1, which contained the ex-type strain of C. kikuchii, was monophyletic and occurred in Argentina and Brazil. In contrast, lineages 2 and 3 were polyphyletic and contained wide-host range species complexes. Lineage 4 was monophyletic, thrived in Argentina and the USA, and included the generalist Cercospora cf. flagellaris. Interlineage recombination was detected, along with a high frequency of mutations linked to fungicide resistance in lineages 2 and 3. These findings point to cryptic Cercospora species as underappreciated global considerations for soybean production and phytosanitary vigilance, and urge a reassessment of host-specificity as a diagnostic tool for Cercospora.

Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice

PubMed Central

Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

2016-01-01

Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen. PMID:27436950

Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice.

PubMed

Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

2016-06-01

Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen.

Plant Pathogen-Induced Water-Soaking Promotes Salmonella enterica Growth on Tomato Leaves

PubMed Central

Potnis, Neha; Colee, James; Jones, Jeffrey B.

2015-01-01

Plant pathogen infection is a critical factor for the persistence of Salmonella enterica on plants. We investigated the mechanisms responsible for the persistence of S. enterica on diseased tomato plants by using four diverse bacterial spot Xanthomonas species that differ in disease severities. Xanthomonas euvesicatoria and X. gardneri infection fostered S. enterica growth, while X. perforans infection did not induce growth but supported the persistence of S. enterica. X. vesicatoria-infected leaves harbored S. enterica populations similar to those on healthy leaves. Growth of S. enterica was associated with extensive water-soaking and necrosis in X. euvesicatoria- and X. gardneri-infected plants. The contribution of water-soaking to the growth of S. enterica was corroborated by an increased growth of populations on water-saturated leaves in the absence of a plant pathogen. S. enterica aggregates were observed with bacterial spot lesions caused by either X. euvesicatoria or X. vesicatoria; however, more S. enterica aggregates formed on X. euvesicatoria-infected leaves as a result of larger lesion sizes per leaf area and extensive water-soaking. Sparsely distributed lesions caused by X. vesicatoria infection do not support the overall growth of S. enterica or aggregates in areas without lesions or water-soaking; S. enterica was observed as single cells and not aggregates. Thus, pathogen-induced water-soaking and necrosis allow S. enterica to replicate and proliferate on tomato leaves. The finding that the pathogen-induced virulence phenotype affects the fate of S. enterica populations in diseased plants suggests that targeting of plant pathogen disease is important in controlling S. enterica populations on plants. PMID:26386057

Effects of leaf wetness duration and temperature on infection of Prunus by Xanthomonas arboricola pv. pruni.

PubMed

Morales, Gerard; Moragrega, Concepció; Montesinos, Emilio; Llorente, Isidre

2018-01-01

Xanthomonas arboricola pv. pruni is the causal agent of bacterial spot disease of stone fruits and almond. The bacterium is distributed throughout the major stone-fruit-producing areas of the World and is considered a quarantine organism in the European Union according to the Council Directive 2000/29/EC, and by the European and Mediterranean Plant Protection Organization. The effect of leaf wetness duration and temperature on infection of Prunus by X. arboricola pv. pruni was determined in controlled environment experiments. Potted plants of the peach-almond hybrid GF-677 were inoculated with bacterial suspensions and exposed to combinations of six leaf wetness durations (from 0 to 24 h) and seven fixed temperatures (from 5 to 35°C) during the infection period. Then, plants were transferred to a biosafety greenhouse, removed from bags, and incubated at optimal conditions for disease development. Although leaf wetness was required for infection of Prunus by X. arboricola pv. pruni, temperature had a greater effect than leaf wetness duration on disease severity. The combined effect of wetness duration and temperature on disease severity was quantified using a modification of the Weibull equation proposed by Duthie. The reduced-form of Duthie's model obtained by nonlinear regression analysis fitted well to data (R = 0.87 and R2adj = 0.85), and all parameters were significantly different from 0. The estimated optimal temperature for infection by X. arboricola pv. pruni was 28.9°C. Wetness periods longer than 10 h at temperatures close to 20°C, or 5 h at temperatures between 25 and 35°C were necessary to cause high disease severity. The predictive capacity of the model was evaluated using an additional set of data obtained from new wetness duration-temperature combinations. In 92% of the events the observed severity agreed with the predicted level of infection risk. The risk chart derived from the reduced form of Duthie's model can be used to estimate the potential risk for infection of Prunus by X. arboricola pv. pruni based on observed or forecasted temperature and wetness duration.

Exploiting Natural Variation to Uncover an Alkene Biosynthetic Enzyme in Poplar

DOE PAGES

Gonzales-Vigil, Eliana; Hefer, Charles A.; von Loessl, Michelle E.; ...

2017-07-20

Alkenes are linear hydrocarbons with one or more double bonds. Despite their potential as biofuels and precursors for specialty chemicals, the underlying biochemistry and genetics of alkene biosynthesis in plants remain elusive. Here, we report on a screen of natural accessions of poplar (Populus trichocarpa), revealing that the leaf cuticular waxes are predominantly composed of alkanes and alkenes. Interestingly, the accumulation of alkenes increases with leaf development, is limited to the abaxial side of the leaf, and is impaired in a few accessions. Among other genes, a b-ketoacyl CoA synthase gene (PotriKCS1) was downregulated in leaves from non-alkene-producing accessions. Wemore » demonstrated biochemically that PotriKCS1 elongates monounsaturated fatty acids and is responsible for the recruitment of unsaturated substrates to the cuticular wax. Moreover, we found significant associations between the presence of alkenes and tree growth and resistance to leaf spot. These findings highlight the crucial role of cuticular waxes as the first point of contact with the environment, and they provide a foundation for engineering long-chain monounsaturated oils in other species.« less

Exploiting Natural Variation to Uncover an Alkene Biosynthetic Enzyme in Poplar

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

Gonzales-Vigil, Eliana; Hefer, Charles A.; von Loessl, Michelle E.

Alkenes are linear hydrocarbons with one or more double bonds. Despite their potential as biofuels and precursors for specialty chemicals, the underlying biochemistry and genetics of alkene biosynthesis in plants remain elusive. Here, we report on a screen of natural accessions of poplar (Populus trichocarpa), revealing that the leaf cuticular waxes are predominantly composed of alkanes and alkenes. Interestingly, the accumulation of alkenes increases with leaf development, is limited to the abaxial side of the leaf, and is impaired in a few accessions. Among other genes, a b-ketoacyl CoA synthase gene (PotriKCS1) was downregulated in leaves from non-alkene-producing accessions. Wemore » demonstrated biochemically that PotriKCS1 elongates monounsaturated fatty acids and is responsible for the recruitment of unsaturated substrates to the cuticular wax. Moreover, we found significant associations between the presence of alkenes and tree growth and resistance to leaf spot. These findings highlight the crucial role of cuticular waxes as the first point of contact with the environment, and they provide a foundation for engineering long-chain monounsaturated oils in other species.« less

Sugar beet activities of the USDA-ARS East Lansing conducted in cooperation with Saginaw Research & Extension Center during 2016

USDA-ARS?s Scientific Manuscript database

Evaluation and rating plots were planted at the Saginaw Valley Research & Extension Center (SVREC) in Frankenmuth, MI in 2016 that focused on Cercospora leaf spot (CLS) and Rhizoctonia crown and root rot (CRR) disease performance of a wide range of Beta vulgaris materials. CLS and CRR trials were co...

Acaricidal and oviposition deterring effects of santalol identified in sandalwood oil against two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae).

PubMed

Roh, Hyun Sik; Lim, Eu Gene; Kim, Jinwoo; Park, Chung Gyoo

2011-12-01

Thirty-four plant essential oils were screened for their acaricidal and oviposition deterrent activities against two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), in the laboratory using a leaf-dip bioassay. From initial trials, sandalwood and common thyme oils were observed to be the most effective against TSSM adult females. Subsequent trials confirmed that only sandalwood oil was significantly active (87.2 ± 2.9% mortality) against TSSM adult females. Sandalwood oil also demonstrated oviposition deterring effects based on a 89.3% reduction of the total number of eggs on leaf disks treated with the oil. GC-MS analysis revealed that the main components of the sandalwood oil were α-santalol (45.8%), β-santalol (20.6%), β-sinensal (9.4%), and epi-β-santalol (3.3%). A mixture of α- and β-santalol (51.0:22.9, respectively) produced significantly higher mortality (85.5 ± 2.9%) and oviposition deterrent effects (94.7% reduction in the number of eggs) than the control. Phytotoxicity was not shown on rose shoots to which a 0.1% solution of sandalwood oil was applied.

Look-up-table approach for leaf area index retrieval from remotely sensed data based on scale information

NASA Astrophysics Data System (ADS)

Zhu, Xiaohua; Li, Chuanrong; Tang, Lingli

2018-03-01

Leaf area index (LAI) is a key structural characteristic of vegetation and plays a significant role in global change research. Several methods and remotely sensed data have been evaluated for LAI estimation. This study aimed to evaluate the suitability of the look-up-table (LUT) approach for crop LAI retrieval from Satellite Pour l'Observation de la Terre (SPOT)-5 data and establish an LUT approach for LAI inversion based on scale information. The LAI inversion result was validated by in situ LAI measurements, indicating that the LUT generated based on the PROSAIL (PROSPECT+SAIL: properties spectra + scattering by arbitrarily inclined leaves) model was suitable for crop LAI estimation, with a root mean square error (RMSE) of ˜0.31m2 / m2 and determination coefficient (R2) of 0.65. The scale effect of crop LAI was analyzed based on Taylor expansion theory, indicating that when the SPOT data aggregated by 200 × 200 pixel, the relative error is significant with 13.7%. Finally, an LUT method integrated with scale information was proposed in this article, improving the inversion accuracy with RMSE of 0.20 m2 / m2 and R2 of 0.83.

Metabolic Response of Strawberry (Fragaria x ananassa) Leaves Exposed to the Angular Leaf Spot Bacterium (Xanthomonas fragariae).

PubMed

Kim, Min-Sun; Jin, Jong Sung; Kwak, Youn-Sig; Hwang, Geum-Sook

2016-03-09

Plants have evolved various defense mechanisms against biotic stress. The most common mechanism involves the production of metabolites that act as defense compounds. Bacterial angular leaf spot disease (Xanthomonas fragariae) of the strawberry (Fragaria x ananassa) has become increasingly destructive to strawberry leaves and plant production. In this study, we examined metabolic changes associated with the establishment of long-term bacterial disease stress using UPLC-QTOF mass spectrometry. Infected leaves showed decreased levels of gallic acid derivatives and ellagitannins, which are related to the plant defense system. The levels of phenylalanine, tryptophan, and salicylic acid as precursors of aromatic secondary metabolites were increased in inoculated leaves, whereas levels of coumaric acid, quinic acid, and flavonoids were decreased in infected plants, which are involved in the phenylpropanoid pathway. In addition, phenylalanine ammonia-lyase (PAL) activity, a key enzyme in the phenylpropanoid pathway, was decreased following infection. These results suggest that long-term bacterial disease stress may lead to down-regulation of select molecules of the phenylpropanoid metabolic pathway in strawberry leaves. This approach could be applied to explore the metabolic pathway associated with plant protection/breeding in strawberry leaves.

Depletion of abundant plant RuBisCO protein using the protamine sulfate precipitation method.

PubMed

Kim, Yu Ji; Lee, Hye Min; Wang, Yiming; Wu, Jingni; Kim, Sang Gon; Kang, Kyu Young; Park, Ki Hun; Kim, Yong Chul; Choi, In Soo; Agrawal, Ganesh Kumar; Rakwal, Randeep; Kim, Sun Tae

2013-07-01

Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the most abundant plant leaf protein, hampering deep analysis of the leaf proteome. Here, we describe a novel protamine sulfate precipitation (PSP) method for the depletion of RuBisCO. For this purpose, soybean leaf total proteins were extracted using Tris-Mg/NP-40 extraction buffer. Obtained clear supernatant was subjected to the PSP method, followed by 13% SDS-PAGE analysis of total, PS-supernatant and -precipitation derived protein samples. In a dose-dependent experiment, 0.1% w/v PS was found to be sufficient for precipitating RuBisCO large and small subunits (LSU and SSU). Western blot analysis confirmed no detection of RuBisCO LSU in the PS-supernatant proteins. Application of this method to Arabidopsis, rice, and maize leaf proteins revealed results similar to soybean. Furthermore, 2DE analyses of PS-treated soybean leaf displayed enriched protein profile for the protein sample derived from the PS-supernatant than total proteins. Some enriched 2D spots were subjected to MALDI-TOF-TOF analysis and were successfully assigned for their protein identity. Hence, the PSP method is: (i) simple, fast, economical, and reproducible for RuBisCO precipitation from the plant leaf sample; (ii) applicable to both dicot and monocot plants; and (iii) suitable for downstream proteomics analysis. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Risk Assessment Model for Bacterial Leaf Spot of Pepper (Capsicum annuum), Caused by Xanthomonas euvesicatoria, Based on Concentrations of Macronutrients, Micronutrients, and Micronutrient Ratios.

PubMed

Dutta, B; Langston, D B; Luo, X; Carlson, S; Kichler, J; Gitaitis, R

2017-11-01

The phytopathogenic bacterium Xanthomonas euvesicatoria causes bacterial leaf spot (BLS) of pepper and has a worldwide distribution. BLS is difficult to control and an integrated management strategy that incorporates crop rotation, use of clean seed and clean plants, weed control, resistant varieties, applications of bactericides, biocontrol agents, and systemic acquired resistance (SAR) inducers is generally recommended. However, even with that arsenal of weapons, BLS can still be responsible for severe losses under favorable environmental conditions. Thus, additional tools need to be added to an overall integrated management strategy to combat BLS. In this article, we developed several models from 2012 to 2014 that were based on how macronutrients, micronutrients, and micronutrient ratios affect BLS severity. Factors used to select a model for validation included highly significant P values, high adjusted R 2 values, low variance inflation factor values (<5), root mean square error, Mallow's Cp, and high Akaike's information criterion correction values. In addition, salicylic acid (SA) concentrations and relative expression of nonexpresser pathogenesis-related gene1 (NPR1) and pathogenesis-related protein 1 (PR1) in pepper tissues were also considered in model selection. A model (ECGA1) consisting of concentrations of copper, manganese, potassium, and the iron/zinc ratio as independent variables was used for validation in three different commercial pepper fields in Georgia: Colquitt County and Worth County in 2015 and Tift County in 2016. When area under the disease progress curve (AUDPC) values for two field sites (Colquitt and Worth Counties) in 2015 were pulled together and plotted against ECGA1-predicted values for both sites, the resulting relationship was highly significant (P = 0.0001) with an R 2 value of 0.92. A significant relationship between observed AUDPC versus predicted values was also observed in Tift County in 2016 (P < 0.001; adjusted R 2 = 0.98). Relative gene expression of both NPR1 and PR1 genes was significantly (P < 0.01) higher in pepper grown in predicted low-risk sites compared with pepper from high-risk sites in Colquitt, Worth, and Tift Counties. Although BLS severity will fluctuate depending on environmental conditions, the data indicate that the level of risk at a particular location may be influenced by how macronutrient and micronutrient concentrations affect plant disease resistance genes in the SAR pathway.

A new virus in Luteoviridae is associated with raspberry leaf curl disease

USDA-ARS?s Scientific Manuscript database

To determine the etiology of Raspberry Leaf Curl Disease (RLCD), which causes leaf curling, leaf distortion, leaf chlorosis, shoot dwarfing, shoot proliferation in raspberries and can kill plants within three years, a next generation sequences approach was applied. Two red raspberry plants collected...

The 50-kDa protein of Apple chlorotic leaf spot virus interferes with intracellular and intercellular targeting and tubule-inducing activity of the 39-kDa protein of Grapevine berry inner necrosis virus.

PubMed

Isogai, M; Saitou, Y; Takahashi, N; Itabashi, T; Terada, M; Satoh, H; Yoshikawa, N

2003-03-01

To understand why transgenic Nicotiana occidentalis plants expressing a functional movement protein (MP) of Apple chlorotic leaf spot virus (ACLSV) show specific resistance to Grapevine berry inner necrosis virus (GINV), the MPs of ACLSV (50KP) and GINV (39KP) were fused to green, yellow, or cyan fluorescent proteins (GFP, YFP, or CFP). These fusion proteins were transiently expressed in leaf cells of both transgenic (50KP) and nontransgenic (NT) plants, and the intracellular and intercellular trafficking and tubule-inducing activity of these proteins were compared. The results indicate that in epidermal cells and protoplasts from 50KP plant leaves, the trafficking and tubule-inducing activities of GINV-39KP were specifically blocked while those of ACLSV-50KP and Apple stem grooving virus MP (36KP) were not affected. Additionally, when 39KP-YFP and 50KP-CFP were coexpressed in the leaf epidermis of NT plants, the fluorescence of both proteins was confined to single cells, indicating that 50KP-CFP interferes with the cell-to-cell trafficking of 39KP-YFP and vice versa. Mutational analyses of 50KP showed that the deletion mutants that retained the activities described above still blocked cell-to-cell trafficking of 39KP, but the dysfunctional 50KP mutants could no longer impede cell-to-cell movement of 39KP. Transgenic plants expressing the functional 50KP deletion mutants showed specific resistance against GINV. In contrast, transgenic plants expressing the dysfunctional 50KP mutants did not show any resistance to the virus. From these results, we conclude that the specific resistance of 50KP plants to GINV is due to the ability of the 50KP to block intracellular and intercellular trafficking of GINV 39KP.

Boron accumulation and toxicity in hybrid poplar (Populus nigra × euramericana).

PubMed

Rees, Rainer; Robinson, Brett H; Menon, Manoj; Lehmann, Eberhard; Günthardt-Goerg, Madeleine S; Schulin, Rainer

2011-12-15

Poplars accumulate high B concentrations and are thus used for the phytomanagement of B contaminated soils. Here, we performed pot experiments in which Populus nigra × euramericana were grown on a substrate with B concentrations ranging from 13 to 280 mg kg(-1) as H(3)BO(3). Salix viminalis, Brassica juncea, and Lupinus albus were grown under some growing conditions for comparison. Poplar growth was unaffected at soil B treatment levels up to 93 mg kg(-1). Growth was progressively reduced at levels of 168 and 280 mg kg(-1). None of the other species survived at these substrate B levels. At leaf B concentrations <900 mg kg(-1) only <10% of the poplar leaf area showed signs of toxicity. Neutron radiography revealed that chlorotic leaf tissues had B concentrations of 1000-2000 mg kg(-1), while necrotic tissues had >2000 mg kg(-1). Average B concentrations of up to 3500 mg kg(-1) were found in leaves, while spots within leaves had concentrations >7000 mg kg(-1), showing that B accumulation in leaf tissue continued even after the onset of necrosis. The B accumulation ability of P. nigra × euramericana is associated with B hypertolerance in the living tissue and storage of B in dead leaf tissue.

Characterization and fine mapping of a light-dependent leaf lesion mimic mutant 1 in rice.

PubMed

Wang, Jing; Ye, Bangquan; Yin, Junjie; Yuan, Can; Zhou, Xiaogang; Li, Weitao; He, Min; Wang, Jichun; Chen, Weilan; Qin, Peng; Ma, Bintian; Wang, Yuping; Li, Shigui; Chen, Xuewei

2015-12-01

Plants that spontaneously produce lesion mimics or spots, without any signs of obvious adversity, such as pesticide and mechanical damage, or pathogen infection, are so-called lesion mimic mutants (lmms). In rice, many lmms exhibit enhanced resistance to pathogens, which provides a unique opportunity to uncover the molecular mechanism underlying lmms. We isolated a rice light-dependent leaf lesion mimic mutant 1 (llm1). Lesion spots appeared in the leaves of the llm1 mutant at the tillering stage. Furthermore, the mutant llm1 had similar agronomic traits to wild type rice. Trypan blue and diamiobenzidine staining analyses revealed that the lesion spot formation on the llm1 mutant was due to programmed cell death and reactive oxygen species. The chloroplasts were severely damaged in the llm1 mutant, suggesting that chloroplast damage was associated with the formation of lesion spots in llm1. More importantly, llm1 exhibited enhanced resistance to bacterial blight pathogens within increased expression of pathogenesis related genes (PRs). Using a map-based cloning approach, we delimited the LLM1 locus to a 121-kb interval between two simple sequence repeat markers, RM17470 and RM17473, on chromosome 4. We sequenced the candidate genes on the interval and found that a base mutation had substituted adenine phosphate for thymine in the last exon of LOC_Os04g52130, which led to an amino acid change (Asp(388) to Val) in the llm1 mutant. Our investigation showed that the putative coproporphyrinogen III oxidase (CPOX) encoded by LOC_Os04g52130 was produced by LLM1 and that amino acid Asp(388) was essential for CPOX function. Our study provides the basis for further investigations into the mechanism underlying lesion mimic initiation associated with LLM1. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Proteomic analysis shows that stress response proteins are significantly up-regulated in resistant diploid wheat (Triticum monococcum) in response to attack by the grain aphid (Sitobion avenae).

PubMed

Guan, Wenzhu; Ferry, Natalie; Edwards, Martin G; Bell, Howard A; Othman, Hamizah; Gatehouse, John A; Gatehouse, Angharad M R

2015-01-01

The grain aphid Sitobion avenae (F.) is a major pest of wheat, acting as a virus vector as well as causing direct plant damage. Commonly grown wheat varieties in the UK have only limited resistance to this pest. The present study was carried out to investigate the potential of a diploid wheat line (ACC20 PGR1755), reported as exhibiting resistance to S. avenae, to serve as a source of resistance genes. The diploid wheat line was confirmed as partially resistant, substantially reducing the fecundity, longevity and growth rate of the aphid. Proteomic analysis showed that approximately 200 protein spots were reproducibly detected in leaf extracts from both the resistant line and a comparable susceptible line (ACC5 PGR1735) using two-dimensional gel electrophoresis and image comparison software. Twenty-four spots were significantly up-regulated (>2-fold) in the resistant line after 24 h of aphid feeding (13 and 11 involved in local and systemic responses, respectively). Approximately 50 % of all differentially expressed protein spots were identified by a combination of database searching with MS and MS/MS data, revealing that the majority of proteins up-regulated by aphid infestation were involved in metabolic processes (including photosynthesis) and transcriptional regulation. However, in the resistant line only, several stress response proteins (including NBS-LRR-like proteins) and oxidative stress response proteins were identified as up-regulated in response to aphid feeding, as well as proteins involved in DNA synthesis/replication/repair. This study indicates that the resistant diploid line ACC20 PGR1755 may provide a valuable resource in breeding wheat for resistance to aphids.

Ozone injury on Bel W-3 tobacco controlled by at least two genes

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

Taylor, G.S.

1968-08-01

Tobacco varieties differ widely in susceptibility to injury by ozone in polluted air. Ordinarily, this injury appears as small flecks on the upper surface of the leaf. The highly susceptible variety Bel W-3, commonly used as an indicator plant for ozone, develops both the flecking plus larger brown or white spots which interfere with the assessment of injury. The highly resistant breeding line 6524 develops no spots but only a few flecks under like conditions. The F/sub 1/ of Bel W-3 x 6524 is intermediate, showing flecks but fewer spots than Bel W-3. The F/sub 2/, however, segregated into 40%more » highly resistant, 10% highly susceptible, and 50% intermediate individuals. When exposed to ozone, resistant plants developed only a few small flecks, and susceptible plants responded as does Bel W-3. Among the plants in the intermediate group were individuals that formed only larger brown or white spots without fleck. Plants with the severe spot reaction showed injury on the calyx remnant surrounding the seed pod. Microbial infection was not involved. This is the first evidence that the severe symptoms of ozone injury on Bel W-3 are a combination of reactions controlled by at least two separate genes.« less

Leaf morphological and genetic differentiation between Quercus rubra L. and Q. ellipsoidalis E.J. Hill populations in contrasting environments

Treesearch

Oliver Gailing; Jennifer Lind; Erik Lilleskov

2012-01-01

Hybridization is considered to play an important role in speciation and evolution. Given the predicted northward tree migration in the eastern USA due to the impact of climate change, hybridization between related species is expected to become more frequent due to overlapping distribution ranges in the future. Oak species are "hot spots" of contemporary...

Growth and physiological response of four shortleaf pine families to herbicidal control of herbaceous competition

Treesearch

Jimmie L. Yeiser; James P. Barnett

1991-01-01

Four open-pollinated families of short-leaf pine (Pinus echinata Mill.) seedlings were planted near Peryville, AR, in February 1988. Three herbaceous weed control were tested for each family along with an untreated check. A single treatment of 3 oz. ai/ac of Oust was applied in April 1988 for spot, band, and total control of herbs. Total control was...

Leaf flush in black walnut at several midwest locations

Treesearch

Calvin F. Bey

1972-01-01

Late spring frosts damage the tender new growth of black walnut trees, and the earliest trees to break dormancy are vulnerable for the longest period. Walnut trees growing in coves and low spots (frost pockets) are most vulnerable. If the terminal shoot is killed, one or more lateral buds at the base of the newly killed shoot commonly develop; generally, the result is...

Proteomics of rice and Cochliobolus miyabeanus fungal interaction: insight into proteins at intracellular and extracellular spaces.

PubMed

Kim, Jin Yeong; Wu, Jingni; Kwon, Soon Jae; Oh, Haram; Lee, So Eui; Kim, Sang Gon; Wang, Yiming; Agrawal, Ganesh Kumar; Rakwal, Randeep; Kang, Kyu Young; Ahn, Il-Pyung; Kim, Beom-Gi; Kim, Sun Tae

2014-10-01

Necrotrophic fungal pathogen Cochliobolus miyabeanus causes brown spot disease in rice leaves upon infection, resulting in critical rice yield loss. To better understand the rice-C. miyabeanus interaction, we employed proteomic approaches to establish differential proteomes of total and secreted proteins from the inoculated leaves. The 2DE approach after PEG-fractionation of total proteins coupled with MS (MALDI-TOF/TOF and nESI-LC-MS/MS) analyses led to identification of 49 unique proteins out of 63 differential spots. SDS-PAGE in combination with nESI-LC-MS/MS shotgun approach was applied to identify secreted proteins in the leaf apoplast upon infection and resulted in cataloging of 501 unique proteins, of which 470 and 31 proteins were secreted from rice and C. miyabeanus, respectively. Proteins mapped onto metabolic pathways implied their reprogramming upon infection. The enzymes involved in Calvin cycle and glycolysis decreased in their protein abundance, whereas enzymes in the TCA cycle, amino acids, and ethylene biosynthesis increased. Differential proteomes also generated distribution of identified proteins in the intracellular and extracellular spaces, providing a better insight into defense responses of proteins in rice against C. miyabeanus. Established proteome of the rice-C. miyabeanus interaction serves not only as a good resource for the scientific community but also highlights its significance from biological aspects. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inheritance and bulked segregant analysis of leaf rust and stem rust resistance genes in eight durum wheat genotypes

USDA-ARS?s Scientific Manuscript database

Leaf rust, caused by Puccinia triticina (Pt) and stem rust caused by Puccinia graminis f. sp. tritici (Pgt) are important diseases of durum wheat. This study determined the inheritance and genomic locations of leaf rust resistance (Lr) genes to Pt-race BBBQJ and stem rust resistance (Sr) genes to Pg...

Brown-Spot Needle Blight of Pines

Treesearch

W.R. Phelps; A.G. Kais; T.H. Nicholls

1978-01-01

Brown-spot needle blight, caused by Scirrhia acicola (Dearn.) Siggers, delays growth and causes mortality of longleaf pine (Pinus palustris Mill.). Brown spot reduces total annual growth of southern pines by more than 16 million cubic feet (0.453 million cubic meters) of timber. Damage is most severe on longleaf seedlings in the grass stage; i.e., those that have not...

How do leaf hydraulics limit stomatal conductance at high water vapour pressure deficits?

PubMed

Bunce, James A

2006-08-01

A reduction in leaf stomatal conductance (g) with increasing leaf-to-air difference in water vapour pressure (D) is nearly ubiquitous. Ecological comparisons of sensitivity have led to the hypothesis that the reduction in g with increasing D serves to maintain leaf water potentials above those that would cause loss of hydraulic conductance. A reduction in leaf water potential is commonly hypothesized to cause stomatal closure at high D. The importance of these particular hydraulic factors was tested by exposing Abutilon theophrasti, Glycine max, Gossypium hirsutum and Xanthium strumarium to D high enough to reduce g and then decreasing ambient carbon dioxide concentration ([CO2]), and observing the resulting changes in g, transpiration rate and leaf water potential, and their reversibility. Reducing the [CO2] at high D increased g and transpiration rate and lowered leaf water potential. The abnormally high transpiration rates did not result in reductions in hydraulic conductance. Results indicate that low water potential effects on g at high D could be overcome by low [CO2], and that even lower leaf water potentials did not cause a reduction in hydraulic conductance in these well-watered plants. Reduced g at high D in these species resulted primarily from increased stomatal sensitivity to [CO2] at high D, and this increased sensitivity may mediate stomatal responses to leaf hydraulics at high D.

Plant pathogen-induced water-soaking promotes Salmonella enterica growth on tomato leaves.

PubMed

Potnis, Neha; Colee, James; Jones, Jeffrey B; Barak, Jeri D

2015-12-01

Plant pathogen infection is a critical factor for the persistence of Salmonella enterica on plants. We investigated the mechanisms responsible for the persistence of S. enterica on diseased tomato plants by using four diverse bacterial spot Xanthomonas species that differ in disease severities. Xanthomonas euvesicatoria and X. gardneri infection fostered S. enterica growth, while X. perforans infection did not induce growth but supported the persistence of S. enterica. X. vesicatoria-infected leaves harbored S. enterica populations similar to those on healthy leaves. Growth of S. enterica was associated with extensive water-soaking and necrosis in X. euvesicatoria- and X. gardneri-infected plants. The contribution of water-soaking to the growth of S. enterica was corroborated by an increased growth of populations on water-saturated leaves in the absence of a plant pathogen. S. enterica aggregates were observed with bacterial spot lesions caused by either X. euvesicatoria or X. vesicatoria; however, more S. enterica aggregates formed on X. euvesicatoria-infected leaves as a result of larger lesion sizes per leaf area and extensive water-soaking. Sparsely distributed lesions caused by X. vesicatoria infection do not support the overall growth of S. enterica or aggregates in areas without lesions or water-soaking; S. enterica was observed as single cells and not aggregates. Thus, pathogen-induced water-soaking and necrosis allow S. enterica to replicate and proliferate on tomato leaves. The finding that the pathogen-induced virulence phenotype affects the fate of S. enterica populations in diseased plants suggests that targeting of plant pathogen disease is important in controlling S. enterica populations on plants. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

[Complications and cause of death in mexican children with rocky mountain spotted fever].

PubMed

Martínez-Medina, Miguel Ángel; Rascón-Alcantar, Adela

Rocky Mountain spotted fever is a life threatening disease caused by Rickettsia rickettsia, characterized by multisystem involvement. We studied 19 dead children with Rocky Mountain spotted fever. All children who were suspected of having rickettsial infections were defined as having Rocky Mountain spotted fever by serology test and clinical features. Through the analysis of each case, we identified the clinical profile and complications associated to the death of a patient. In nine (69.2%) of 13 cases that died in the first three days of admission, the associated condition was septic shock. Others complications included respiratory distress causes by non-cardiogenic pulmonary edema, renal impairment, and multiple organ damage. The main cause of death in this study was septic shock. The fatality rate from Rocky Mountain spotted fever can be related to the severity of the infection, delay in diagnosis, and delay in initiation of antibiotic therapy. Pulmonary edema and cerebral edema can be usually precipitated by administration of excess intravenous fluids.

Cellular protein receptors of maculosin, a host specific phytotoxin of spotted knapweed (Centaurea maculosa L.).

PubMed

Park, S H; Strobel, G A

1994-01-05

Maculosin (the diketopiperazine, cyclo (L-Pro-L-Tyr)) is a host specific phytotoxin produced by Alternaria alternata on spotted knapweed (Centaurea maculosa L.). Receptors for this phytotoxin have been isolated from spotted knapweed. Knapweed leaves possess most of the maculosin-binding activity in the cytosolic fraction. However, activity was also observed in the whole membrane fraction of the leaf. The binding component of the cytosolic fraction was identified as a protein(s) because of its heat-lability and sensitivity to proteases. A 16-fold purification of a toxin-binding protein was carried out by ammonium sulfate fractionation, and Sephadex G-200, and maculosin-affinity column chromatography. The affinity column was prepared with epoxy activated Sepharose 6B to which the phenolic group of maculosin was attached. The receptor was estimated to contain more than one binding protein by native and SDS-PAGE. At least one of the maculosin-binding proteins was identified as ribulose-1,5-biphosphate carboxylase (RuBPcase).

Bacterial Leaf Scorch of Amenity Trees a Wide-Spread Problem of Economic Significance to the Urban Forest

Treesearch

James Lashomb; Alan Iskra; Ann Brooks Gould; George Hamilton

2003-01-01

Bacterial leaf scorch (BLS) of amenity trees is caused by the bacterium Xylella fastidiosa, a xylem-limited pathogen that causes water stress resulting in leaf scorch, decline, and eventual death of affected trees. Recent surveys indicate that BLS is widespread throughout the eastern half of the United States. In New Jersey, BLS primarily affects red and pin oaks...

Expression of apoplast-targeted plant defensin MtDef4.2 confers resistance to leaf rust pathogen Puccinia triticina but does not affect mycorrhizal symbiosis in transgenic wheat

USDA-ARS?s Scientific Manuscript database

Rust diseases caused by Puccinia spp. pose a major threat to global wheat production. Puccinia triticina (Pt), an obligate basidiomycete biotroph, causes leaf rust disease which incurs yield losses of up to 50% in wheat. Historically, resistant wheat cultivars have been used to control leaf rust, bu...

New insights into the roles of host gene-necrotrophic effector interactions in governing susceptibility of durum wheat to tan spot and Septoria nodorum blotch

USDA-ARS?s Scientific Manuscript database

Tan spot and Septoria nodorum blotch (SNB) are important diseases of wheat caused by the necrotrophic fungi Pyrenophora tritici-repentis and Parastagonospora nodorum, respectively. The P. tritici-repentis necrotrophic effector (NE) Ptr ToxB causes tan spot when recognized by the Tsc2 gene. The NE To...

Preventing Spread of Vine leafroll virus and Vine Mealybug

USDA-ARS?s Scientific Manuscript database

Leafroll disease in grapevines is caused by a complex of 11 species of viruses and occurs throughout the California's grape regions but causes more damage in the cooler wine grape regions. These viruses cause leaf chlorosis and leaf margins to roll downward. Leafroll can reduce berry yields up to ...

[Research on the spectral feature and identification of the surface vegetation stressed by stored CO2 underground leakage].

PubMed

Chen, Yun-Hao; Jiang, Jin-Bao; Steven, Michael D; Gong, A-Du; Li, Yi-Fan

2012-07-01

With the global climate warming, reducing greenhouse gas emissions becomes a focused problem for the world. The carbon capture and storage (CCS) techniques could mitigate CO2 into atmosphere, but there is a risk in case that the CO2 leaks from underground. The objective of this paper is to study the chlorophyll contents (SPAD value), relative water contents (RWC) and leaf spectra changing features of beetroot under CO2 leakage stress through field experiment. The result shows that the chlorophyll contents and RWC of beetroot under CO2 leakage stress become lower than the control beetroot', and the leaf reflectance increases in the 550 nm region and decreases in the 680nm region. A new vegetation index (R550/R680) was designed for identifying beetroot under CO2 leakage stress, and the result indicates that the vegetation index R550/R680 could identify the beetroots after CO2 leakage for 7 days. The index has strong sensitivity, stability and identification for monitoring the beetroots under CO2 stress. The result of this paper has very important meaning and application values for selecting spots of CCS project, monitoring and evaluating land-surface ecology under CO2 stress and monitoring the leakage spots by using remote sensing.

A new species of spotted leaf frog, genus Phasmahyla (Amphibia, Phyllomedusidae) from Southeast Brazil.

PubMed

Pereira, Elvis Almeida; Rocha, Lucas Custódio Lomba; Folly, Henrique; da Silva, Hélio Ricardo; Santana, Diego José

2018-01-01

Based on concordant differences in male advertisement call, tadpole morphology, and absence of haplotype sharing in the barcoding 16S mitochondrial DNA, we describe here a new species of spotted leaf frog of the genus Phasmahyla from Atlantic Forest, State of Rio de Janeiro, Southeast Brazil. The new species is most similar to P. cochranae (type locality) and P. spectabilis (type locality). It differs from these species by the size of the calcar, moderate-sized body (snout-vent length 30.4-34.4 mm in adult eight males), and in the advertisement call. The tadpoles of Phasmahyla lisbella sp. nov. differ from P. exilis , P. spectabilis , P. timbo , P. guttata and P. jandaia because they do not have row of teeth in the anterior part; differ from P. cruzi by the shape of the anterior end of the oral disc. Through genetic data (phylogenetic distance and haplotype genealogy) we diagnosed the new species where the genetic divergences among its congeners is about 3-6% in a fragment of the 16S rRNA gene, which is above the threshold typically characterizing distinct species of anurans. However, the new species can be distinguished from other congeneric species based on an integrative approach (molecular, bioacoustics, larval, and adult morphology).

Subcellular-level resolution MALDI-MS imaging of maize leaf metabolites by MALDI-linear ion trap-Orbitrap mass spectrometer

DOE PAGES

Korte, Andrew R.; Yandeau-Nelson, Marna D.; Nikolau, Basil J.; ...

2015-01-25

A significant limiting factor in achieving high spatial resolution for matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) imaging is the size of the laser spot at the sample surface. We present modifications to the beam-delivery optics of a commercial MALDI-linear ion trap-Orbitrap instrument, incorporating an external Nd:YAG laser, beam-shaping optics, and an aspheric focusing lens, to reduce the minimum laser spot size from ~50 μm for the commercial configuration down to ~9 μm for the modified configuration. This improved system was applied for MALDI-MS imaging of cross sections of juvenile maize leaves at 5-μm spatial resolution using an oversampling method. Theremore » are a variety of different metabolites including amino acids, glycerolipids, and defense-related compounds were imaged at a spatial resolution well below the size of a single cell. Such images provide unprecedented insights into the metabolism associated with the different tissue types of the maize leaf, which is known to asymmetrically distribute the reactions of C4 photosynthesis among the mesophyll and bundle sheath cell types. The metabolite ion images correlate with the optical images that reveal the structures of the different tissues, and previously known and newly revealed asymmetric metabolic features are observed.« less

First report of Phyllosticta citricarpa and description of two new species, P. paracapitalensis and P. paracitricarpa, from citrus in Europe.

PubMed

Guarnaccia, V; Groenewald, J Z; Li, H; Glienke, C; Carstens, E; Hattingh, V; Fourie, P H; Crous, P W

2017-06-01

The genus Phyllosticta occurs worldwide, and contains numerous plant pathogenic, endophytic and saprobic species. Phyllosticta citricarpa is the causal agent of Citrus Black Spot disease (CBS), affecting fruits and leaves of several citrus hosts ( Rutaceae ), and can also be isolated from asymptomatic citrus tissues. Citrus Black Spot occurs in citrus-growing regions with warm summer rainfall climates, but is absent in countries of the European Union (EU). Phyllosticta capitalensis is morphologically similar to P. citricarpa , but is a non-pathogenic endophyte, commonly isolated from citrus leaves and fruits and a wide range of other hosts, and is known to occur in Europe. To determine which Phyllosticta spp. occur within citrus growing regions of EU countries, several surveys were conducted (2015-2017) in the major citrus production areas of Greece, Italy, Malta, Portugal and Spain to collect both living plant material and leaf litter in commercial nurseries, orchards, gardens, backyards and plant collections. A total of 64 Phyllosticta isolates were obtained from citrus in Europe, of which 52 were included in a multi-locus (ITS, actA , tef1 , gapdh , LSU and rpb2 genes) DNA dataset. Two isolates from Florida (USA), three isolates from China, and several reference strains from Australia, South Africa and South America were included in the overall 99 isolate dataset. Based on the data obtained, two known species were identified, namely P. capitalensis (from asymptomatic living leaves of Citrus spp.) in Greece, Italy, Malta, Portugal and Spain, and P. citricarpa (from leaf litter of C . sinensis and C . limon ) in Italy, Malta and Portugal. Moreover, two new species were described, namely P. paracapitalensis (from asymptomatic living leaves of Citrus spp.) in Italy and Spain, and P. paracitricarpa (from leaf litter of C . limon ) in Greece. On a genotypic level, isolates of P . citricarpa populations from Italy and Malta (MAT1-2-1) represented a single clone, and those from Portugal (MAT1-1-1) another. Isolates of P. citricarpa and P. paracitricarpa were able to induce atypical lesions (necrosis) in artificially inoculated mature sweet orange fruit, while P. capitalensis and P. paracapitalensis induced no lesions. The Phyllosticta species recovered were not found to be widespread, and were not associated with disease symptoms, indicating that the fungi persisted over time, but did not cause disease.

Peach leaf responses to soil and cement dust pollution.

PubMed

Maletsika, Persefoni A; Nanos, George D; Stavroulakis, George G

2015-10-01

Dust pollution can negatively affect plant productivity in hot, dry and with high irradiance areas during summer. Soil or cement dust were applied on peach trees growing in a Mediterranean area with the above climatic characteristics. Soil and cement dust accumulation onto the leaves decreased the photosynthetically active radiation (PAR) available to the leaves without causing any shade effect. Soil and mainly cement dust deposition onto the leaves decreased stomatal conductance, photosynthetic and transpiration rates, and water use efficiency due possibly to stomatal blockage and other leaf cellular effects. In early autumn, rain events removed soil dust and leaf functions partly recovered, while cement dust created a crust partially remaining onto the leaves and causing more permanent stress. Leaf characteristics were differentially affected by the two dusts studied due to their different hydraulic properties. Leaf total chlorophyll decreased and total phenol content increased with dust accumulation late in the summer compared to control leaves due to intense oxidative stress. The two dusts did not cause serious metal imbalances to the leaves, except of lower leaf K content.

Encephalitis

MedlinePlus

... and the germs that cause Lyme disease and Rocky Mountain spotted fever (transmitted through tick bites). Viruses that cause childhood ... Cold Sores (HSV-1) West Nile Virus Meningitis Rocky Mountain Spotted Fever Lyme Disease View more About Us Contact Us ...

Constitutive expression of the xylanase inhibitor TAXI-III delays Fusarium head blight symptoms in durum wheat transgenic plants.

PubMed

Moscetti, Ilaria; Tundo, Silvio; Janni, Michela; Sella, Luca; Gazzetti, Katia; Tauzin, Alexandra; Giardina, Thierry; Masci, Stefania; Favaron, Francesco; D'Ovidio, Renato

2013-12-01

Cereals contain xylanase inhibitor (XI) proteins which inhibit microbial xylanases and are considered part of the defense mechanisms to counteract microbial pathogens. Nevertheless, in planta evidence for this role has not been reported yet. Therefore, we produced a number of transgenic plants constitutively overexpressing TAXI-III, a member of the TAXI type XI that is induced by pathogen infection. Results showed that TAXI-III endows the transgenic wheat with new inhibition capacities. We also showed that TAXI-III is correctly secreted into the apoplast and possesses the expected inhibition parameters against microbial xylanases. The new inhibition properties of the transgenic plants correlate with a significant delay of Fusarium head blight disease symptoms caused by Fusarium graminearum but do not significantly influence leaf spot symptoms caused by Bipolaris sorokiniana. We showed that this contrasting result can be due to the different capacity of TAXI-III to inhibit the xylanase activity of these two fungal pathogens. These results provide, for the first time, clear evidence in planta that XI are involved in plant defense against fungal pathogens and show the potential to manipulate TAXI-III accumulation to improve wheat resistance against F. graminearum.

Extracellular synthesis of silver nanoparticles using the leaf extract of Coleus amboinicus Lour

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

Narayanan, Kannan Badri; Sakthivel, Natarajan, E-mail: puns2005@gmail.com

2011-10-15

Highlights: {yields} Synthesis of AgNPs using the leaf extract of Coleus amboinicus L. was described. {yields} UV-vis absorption spectra showed the formation of isotrophic AgNPs at 437 nm in 6 h. {yields} XRD analysis showed intense peaks corresponding to fcc structure of AgNPs. {yields} HR-TEM analysis revealed the formation of stable anisotrophic and isotrophic AgNPs. -- Abstract: In the present investigation, Coleus amboinicus Lour. leaf extract-mediated green chemistry approach for the synthesis of silver nanoparticles was described. The nanoparticles were characterized by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR) and transmissionmore » electron microscopy (TEM). The influence of leaf extract on the control of size and shape of silver nanoparticles is reported. Upon an increase in the concentration of leaf extract, there was a shift in the shape of nanoparticles from anisotrophic nanostructures like triangle, decahedral and hexagonal to isotrophic spherical nanoparticles. Crystalline nature of fcc structured nanoparticles was confirmed by XRD spectrum with peaks corresponding to (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes and bright circular spots in the selected-area electron diffraction (SAED). Such environment friendly and sustainable methods are non-toxic, cheap and alternative to hazardous chemical procedures.« less

Seasonal variability of foliar photosynthetic and morphological traits and drought impacts in a Mediterranean mixed forest.

PubMed

Sperlich, D; Chang, C T; Peñuelas, J; Gracia, C; Sabaté, S

2015-05-01

The Mediterranean region is a hot spot of climate change vulnerable to increased droughts and heat waves. Scaling carbon fluxes from leaf to landscape levels is particularly challenging under drought conditions. We aimed to improve the mechanistic understanding of the seasonal acclimation of photosynthesis and morphology in sunlit and shaded leaves of four Mediterranean trees (Quercus ilex L., Pinus halepensis Mill., Arbutus unedo L. and Quercus pubescens Willd.) under natural conditions. Vc,max and Jmax were not constant, and mesophyll conductance was not infinite, as assumed in most terrestrial biosphere models, but varied significantly between seasons, tree species and leaf position. Favourable conditions in winter led to photosynthetic recovery and growth in the evergreens. Under moderate drought, adjustments in the photo/biochemistry and stomatal/mesophyllic diffusion behaviour effectively protected the photosynthetic machineries. Severe drought, however, induced early leaf senescence mostly in A. unedo and Q. pubescens, and significantly increased leaf mass per area in Q. ilex and P. halepensis. Shaded leaves had lower photosynthetic potentials but cushioned negative effects during stress periods. Species-specificity, seasonal variations and leaf position are key factors to explain vegetation responses to abiotic stress and hold great potential to reduce uncertainties in terrestrial biosphere models especially under drought conditions. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The lead-lag relationships between spot and futures prices of natural gas

NASA Astrophysics Data System (ADS)

Zhang, Yahui; Liu, Li

2018-01-01

The lead-lag relationships between spot and futures markets are of great interest for academics. Previous studies neglect the possibility of nonlinear behaviors which may be caused by asymmetry or persistence. To fill this gap, this paper uses the MF-DCCA method and the linear and nonlinear causality tests to explore the causal relationships between natural gas spot and futures prices in the New York Mercantile Exchange. We find that spot and futures prices are positive cross-correlated, the natural gas futures can linearly Granger cause spot price, and there are bidirectional nonlinear causality relationships between natural gas spot and futures prices. Further, we explore the sources of nonlinear causality relationships, and find that the volatility spillover can partly explain the nonlinear causality and affect their cross-correlations.

Studies on Typhus and Spotted Fever.

DTIC Science & Technology

1981-02-01

Rocky Mountain spotted fever , DNA, homology, genome, lymphocytes, immunity...spotted fever group. Certain studies have suggested that R. canada may be able to cause a severe illness in man clinically similar to Rocky Mountain spotted fever (Z...the Conference and are also in press. 10. Paul Fiset, Charles L. Wisseman, Jr., A. Farhang-Azad, Harvey Fischman. Rocky Mountain Spotted Fever

Local Impacts of Mercury Emissions from the Three Pennsylvania Coal Fired Power Plants.

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

Sullivan,T.; Adams,J.; Bender, M.

2008-02-01

The Clean Air Interstate Rule (CAIR) and the Clean Air Mercury Rule (CAMR) as proposed by the U.S. Environmental Protection Agency (EPA) when fully implemented will lead to reduction in mercury emissions from coal-fired power plants by 70 percent to fifteen tons per year by 2018. The EPA estimates that mercury deposition would be reduced 8 percent on average in the Eastern United States. The CAMR permits cap-and-trade approach that requires the nationwide emissions to meet the prescribed level, but do not require controls on each individual power plant. This has led to concerns that there may be hot-spots ofmore » mercury contamination near power plants. Partially because of this concern, many states including Pennsylvania have implemented, or are considering, state regulations that are stricter on mercury emissions than those in the CAMR. This study examined the possibility that coal-fired power plants act as local sources leading to mercury 'hot spots'. Soil and oak leaf samples from around three large U.S. coal-fired power plants in Western Pennsylvania were collected and analyzed for evidence of 'hot spots'. These three plants (Conemaugh, Homer City, and Keystone) are separated by a total distance of approximately 30 miles. Each emits over 500 pounds of mercury per year which is well above average for mercury emissions from coal plants in the U.S. Soil and oak leaf sampling programs were performed around each power plant. Sampling rings one-mile apart were used with eight or nine locations on each ring. The prevailing winds in the region are from the west. For this reason, sampling was conducted out to 10 miles from the Conemaugh plant which is southeast of the others. The other plants were sampled to a distance of five miles. The objectives were to determine if local mercury hot spots exist, to determine if they could be attributed to deposition of coal-fired power plant emissions, and to determine if they correlated with wind patterns. The study found the following: (1) There was some correlation between the prevailing wind direction and measured soil and oak leaf concentrations. This correlation was not statistically significant, but higher soil concentrations were generally found in the east and southeast from the plants and lower soil concentrations were found west/southwest from the plants. The prevailing winds are to the east. The Conemaugh plant which was the most southeast of the three plants did have the highest average oak leaf and soil mercury concentrations. Based on emissions, the Keystone plant would be expected to see the highest concentrations as it emitted about 25% more mercury than the other two plants. (2) The results of this study did not turn up strong evidence for large areas (several square miles) of elevated mercury concentrations around the three coal-fired power plants that were tested. This does not mean that there is no effect, there was some evidence of increasing mercury content to the east and south of these plants, however, the trends were not statistically significant suggesting that if the effects exist, they are small.« less

Proteome Analysis of Date Palm (Phoenix dactylifera L.) under Severe Drought and Salt Stress.

PubMed

El Rabey, Haddad A; Al-Malki, Abdulrahman L; Abulnaja, Khalid O

2016-01-01

Date palm cultivars differently tolerate salinity and drought stress. This study was carried out to study the response of date palm to severe salinity and drought based on leaf proteome analysis. Eighteen-month-old date palm plants were subjected to severe salt (48 g/L NaCl) and drought (82.5 g/L PEG or no irrigation) conditions for one month. Using a protein 2D electrophoresis method, 55 protein spots were analyzed using mass spectrometry. ATP synthase CF1 alpha chains were significantly upregulated under all three stress conditions. Changes in the abundance of RubisCO activase and one of the RubisCO fragments were significant in the same spots only for salt stress and drought stress with no irrigation, and oxygen-evolving enhancer protein 2 was changed in different spots. Transketolase was significantly changed only in drought stress with PEG. The expression of salt and drought stress genes of the chosen protein spots was either overexpressed or downexpressed as revealed by the high or low protein abundance, respectively. In addition, all drought tolerance genes due to no irrigation were downregulated. In conclusion, the proteome analysis of date palm under salinity and drought conditions indicated that both salinity and drought tolerance genes were differentially expressed resulting in high or low protein abundance of the chosen protein spots as a result of exposure to drought and salinity stress condition.

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

Treesearch

Diane L. Wagner; Linda DeFoliart; Patricia Doak; Jenny Schneiderheinze

2008-01-01

The aspen leaf miner, Phyllocnistis populiella, feeds on the contents of epidermal cells on both top (adaxial) and bottom (abaxial) surfaces of quaking aspen leaves, leaving the photosynthetic tissue of the mesophyll intact. This type of feeding is taxonomically restricted to a small subset of leaf mining insects but can cause widespread plant...

Improved tolerance toward fungal diseases in transgenic Cavendish banana (Musa spp. AAA group) cv. Grand Nain.

PubMed

Vishnevetsky, Jane; White, Thomas L; Palmateer, Aaron J; Flaishman, Moshe; Cohen, Yuval; Elad, Yigal; Velcheva, Margarita; Hanania, Uri; Sahar, Nachman; Dgani, Oded; Perl, Avihai

2011-02-01

The most devastating disease currently threatening to destroy the banana industry worldwide is undoubtedly Sigatoka Leaf spot disease caused by Mycosphaerella fijiensis. In this study, we developed a transformation system for banana and expressed the endochitinase gene ThEn-42 from Trichoderma harzianum together with the grape stilbene synthase (StSy) gene in transgenic banana plants under the control of the 35S promoter and the inducible PR-10 promoter, respectively. The superoxide dismutase gene Cu,Zn-SOD from tomato, under control of the ubiquitin promoter, was added to this cassette to improve scavenging of free radicals generated during fungal attack. A 4-year field trial demonstrated several transgenic banana lines with improved tolerance to Sigatoka. As the genes conferring Sigatoka tolerance may have a wide range of anti-fungal activities we also inoculated the regenerated banana plants with Botrytis cinerea. The best transgenic lines exhibiting Sigatoka tolerance were also found to have tolerance to B. cinerea in laboratory assays.

Changes in hydraulic conductance cause the difference in growth response to short-term salt stress between salt-tolerant and -sensitive black gram (Vigna mungo) varieties.

PubMed

Win, Khin Thuzar; Oo, Aung Zaw; Ookawa, Taiichiro; Kanekatsu, Motoki; Hirasawa, Tadashii

2016-04-01

Black gram (Vigna mungo) is an important crop in Asia, However, most black gram varieties are salt-sensitive. The causes of varietal differences in salt-induced growth reduction between two black gram varieties, 'U-Taung-2' (salt-tolerant; BT) and 'Mut Pe Khaing To' (salt-sensitive; BS), were examined the potential for the first step toward the genetic improvement of salt tolerance. Seedlings grown in vermiculite irrigated with full-strength Hoagland solution were treated with 0mM NaCl (control) or 225 mM NaCl for up to 10 days. In the 225 mM NaCl treatment, plant growth rate, net assimilation rate, mean leaf area, leaf water potential, and leaf photosynthesis were reduced more in BS than in BT plants. Leaf water potential was closely related to leaf photosynthesis, net assimilation rate, and increase in leaf area. In response to salinity stress, hydraulic conductance of the root, stem, and petiole decreased more strongly in BS than in BT plants. The reduction in stem and petiole hydraulic conductance was caused by cavitation, whereas the reduction in root hydraulic conductance in BS plants was caused by a reduction in root surface area and hydraulic conductivity. We conclude that the different reduction in hydraulic conductance is a cause of the differences in the growth response between the two black gram varieties under short-term salt stress. Copyright © 2016 Elsevier GmbH. All rights reserved.

Webinar Presentation: Using Metabolomics with Neonatal Blood Spots to Discover Causes of Childhood Leukemia

EPA Pesticide Factsheets

This presentation, Using Metabolomics with Neonatal Blood Spots to Discover Causes of Childhood Leukemia, was given at the NIEHS/EPA Children's Centers 2016 Webinar Series: Exposome held on May 11, 2016.

Endophyte-Mediated Modulation of Defense-Related Genes and Systemic Resistance in Withania somnifera (L.) Dunal under Alternaria alternata Stress.

PubMed

Mishra, Aradhana; Singh, Satyendra Pratap; Mahfooz, Sahil; Singh, Surendra Pratap; Bhattacharya, Arpita; Mishra, Nishtha; Nautiyal, C S

2018-04-15

Endophytes have been explored and found to perform an important role in plant health. However, their effects on the host physiological function and disease management remain elusive. The present study aimed to assess the potential effects of endophytes, singly as well as in combination, in Withania somnifera (L.) Dunal, on various physiological parameters and systemic defense mechanisms against Alternaria alternata Seeds primed with the endophytic bacteria Bacillus amyloliquefaciens and Pseudomonas fluorescens individually and in combination demonstrated an enhanced vigor index and germination rate. Interestingly, plants treated with the two-microbe combination showed the lowest plant mortality rate (28%) under A. alternata stress. Physiological profiling of treated plants showed improved photosynthesis, respiration, transpiration, and stomatal conductance under pathogenic stress. Additionally, these endophytes not only augmented defense enzymes and antioxidant activity in treated plants but also enhanced the expression of salicylic acid- and jasmonic acid-responsive genes in the stressed plants. Reductions in reactive oxygen species (ROS) and reactive nitrogen species (RNS) along with enhanced callose deposition in host plant leaves corroborated well with the above findings. Altogether, the study provides novel insights into the underlying mechanisms behind the tripartite interaction of endophyte- A. alternata - W. somnifera and underscores their ability to boost plant health under pathogen stress. IMPORTANCE W. somnifera is well known for producing several medicinally important secondary metabolites. These secondary metabolites are required by various pharmaceutical sectors to produce life-saving drugs. However, the cultivation of W. somnifera faces severe challenge from leaf spot disease caused by A. alternata To keep pace with the rising demand for this plant and considering its capacity for cultivation under field conditions, the present study was undertaken to develop approaches to enhance production of W. somnifera through intervention using endophytes. Application of bacterial endophytes not only suppresses the pathogenicity of A. alternata but also mitigates excessive ROS/RNS generation via enhanced physiological processes and antioxidant machinery. Expression profiling of plant defense-related genes further validates the efficacy of bacterial endophytes against leaf spot disease. Copyright © 2018 American Society for Microbiology.

Neofusicoccum ribis Associated with Leaf Blight on Rubber (Hevea brasiliensis) in Peninsular Malaysia

PubMed Central

Nyaka Ngobisa, A. I. C.; Zainal Abidin, M. A.; Wong, M. Y.; Wan Noordin, M. W. D.

2013-01-01

Hevea brasiliensis is a natural source of rubber and an important plantation tree species in Malaysia. Leaf blight disease caused by Fusicoccum substantially reduces the growth and performance of H. brasiliensis. The aim of this study was to use a combination of both morphological characteristics and molecular data to clarify the taxonomic position of the fungus associated with leaf blight disease. Fusicoccum species were isolated from infected leaves collected from plantations at 3 widely separated locations – Selangor, Perak, and Johor states – in Peninsular Malaysia in 2010. All the isolates were identified according to their conidial patterns and DNA sequences generated from internal transcribed spacers (ITS1 and ITS2), the 5.8S rRNA, and an unknown locus (BotF15) containing microsatellite repeats. Based on taxonomic and sequence data, Neofusicoccum ribis was identified as the main cause of leaf blight disease in H. brasiliensis in commercial plantations in Malaysia. A pathogenicity trial on detached leaves further confirmed that N. ribis causes leaf blight disease. N. ribis is an important leaf pathogen, and its detection in Malaysia has important implications for future planting of H. brasiliensis. PMID:25288924

Neofusicoccum ribis Associated with Leaf Blight on Rubber (Hevea brasiliensis) in Peninsular Malaysia.

PubMed

Nyaka Ngobisa, A I C; Zainal Abidin, M A; Wong, M Y; Wan Noordin, M W D

2013-03-01

Hevea brasiliensis is a natural source of rubber and an important plantation tree species in Malaysia. Leaf blight disease caused by Fusicoccum substantially reduces the growth and performance of H. brasiliensis. The aim of this study was to use a combination of both morphological characteristics and molecular data to clarify the taxonomic position of the fungus associated with leaf blight disease. Fusicoccum species were isolated from infected leaves collected from plantations at 3 widely separated locations - Selangor, Perak, and Johor states - in Peninsular Malaysia in 2010. All the isolates were identified according to their conidial patterns and DNA sequences generated from internal transcribed spacers (ITS1 and ITS2), the 5.8S rRNA, and an unknown locus (BotF15) containing microsatellite repeats. Based on taxonomic and sequence data, Neofusicoccum ribis was identified as the main cause of leaf blight disease in H. brasiliensis in commercial plantations in Malaysia. A pathogenicity trial on detached leaves further confirmed that N. ribis causes leaf blight disease. N. ribis is an important leaf pathogen, and its detection in Malaysia has important implications for future planting of H. brasiliensis.

Birthmarks - pigmented

MedlinePlus

Hairy nevus; Nevi; Mole; Cafe-au-lait spots; Congenital nevus ... Different types of birthmarks have different causes. Cafe-au-lait spots are common at or after birth. Someone who has many of these spots may have a genetic disorder called neurofibromatosis . ...

The Cause of the Hot Spot in Vegetation Canopies and Soils: Shadow-Hiding Versus Coherent Backscatter

NASA Technical Reports Server (NTRS)

Hapke, Bruce; DiMucci, Dominick; Nelson, Robert; Smythe, William

1996-01-01

Two different mechanisms, shadow-hiding and coherent backscatter, can cause a hot spot, or opposition effect, in the bidirectional reflectance of vegetation and soils. Because the two mechanisms sample different properties, it is important to know which one is primarily responsible in a given medium. This question can be answered by measuring the bidirectional reflectance in circularly polarized light. If the results of the limited experiments reported here can be extrapolated to a wider range of materials, it appears that the primary cause of the hot spot in most vegetation canopies and in moist, clumpy soils is shadow-hiding. However, in vegetation with large numbers of wavelength-sized structures, such as mosses, and in dry, fine-grained soils, the hot spot is dominated by coherent backscatter.

A Constrained Maximization Model for inspecting the impact of leaf shape on optimal leaf size and stoma resistance

NASA Astrophysics Data System (ADS)

Ding, J.; Johnson, E. A.; Martin, Y. E.

2017-12-01

Leaf is the basic production unit of plants. Water is the most critical resource of plants. Its availability controls primary productivity of plants by affecting leaf carbon budget. To avoid the damage of cavitation from lowering vein water potential t caused by evapotranspiration, the leaf must increase the stomatal resistance to reduce evapotranspiration rate. This comes at the cost of reduced carbon fixing rate as increasing stoma resistance meanwhile slows carbon intake rate. Studies suggest that stoma will operate at an optimal resistance to maximize the carbon gain with respect to water. Different plant species have different leaf shapes, a genetically determined trait. Further, on the same plant leaf size can vary many times in size that is related to soil moisture, an indicator of water availability. According to metabolic scaling theory, increasing leaf size will increase total xylem resistance of vein, which may also constrain leaf carbon budget. We present a Constrained Maximization Model of leaf (leaf CMM) that incorporates metabolic theory into the coupling of evapotranspiration and carbon fixation to examine how leaf size, stoma resistance and maximum net leaf primary productivity change with petiole xylem water potential. The model connects vein network structure to leaf shape and use the difference between petiole xylem water potential and the critical minor vein cavitation forming water potential as the budget. The CMM shows that both maximum net leaf primary production and optimal leaf size increase with petiole xylem water potential while optimal stoma resistance decreases. Narrow leaf has overall lower optimal leaf size and maximum net leaf carbon gain and higher optimal stoma resistance than those of broad leaf. This is because with small width to length ratio, total xylem resistance increases faster with leaf size. Total xylem resistance of narrow leaf increases faster with leaf size causing higher average and marginal cost of xylem water potential with respect to net leaf carbon gain. With same leaf area, total xylem resistance of narrow leaf is higher than broad leaf. Given same stoma resistance and petiole water potential, narrow leaf will lose more xylem water potential than broad leaf. Consequently, narrow leaf has smaller size and higher stoma resistance at optimum.

Development of a global LAI estimation algorithm for JAXA's new earth observation satellite sensor, GCOM-C/SGLI

NASA Astrophysics Data System (ADS)

Ono, Y.; Murakami, H.; Kobayashi, H.; Nasahara, K. N.; Kajiwara, K.; Honda, Y.

2014-12-01

Leaf Area Index (LAI) is defined as the one-side green leaf area per unit ground surface area. Global LAI products, such as MOD15 (Terra&Aqua/MODIS) and CYCLOPES (SPOT/VEGETATION) are used for many global terrestrial carbon models. Japan Aerospace eXploration Agency (JAXA) is planning to launch GCOM-C (Global Change Observation Mission-Climate) which carries SGLI (Second-generation GLobal Imager) in the Japanese Fiscal Year 2017. SGLI has the features, such as 17-channel from near ultraviolet to thermal infrared, 250-m spatial resolution, polarization, and multi-angle (nadir and ±45-deg. along-track slant) observation. In the GCOM-C/SGLI land science team, LAI is scheduled to be generated from GCOM-C/SGLI observation data as a standard product (daily 250-m). In extisting algorithms, LAI is estimated by the reverse analysis of vegetation radiative transfer models (RTMs) using multi-spectral and mono-angle observation data. Here, understory layer in vegetation RTMs is assumed by plane parallel (green leaves + soil) which set up arbitrary understroy LAI. However, actual understory consists of various elements, such as green leaves, dead leaves, branches, soil, and snow. Therefore, if understory in vegetation RTMs differs from reality, it will cause an error of LAI to estimate. This report describes an algorithm which estimates LAI in consideration of the influence of understory using GCOM-C/SGLI multi-spectral and multi-angle observation data.

Global invasive Cochliobolus species: cohort of destroyers with implications in food losses and insecurity in the twenty-first century.

PubMed

Bengyella, Louis; Yekwa, Elsie Laban; Nawaz, Kiran; Iftikhar, Sehrish; Tambo, Ernest; Alisoltani, Arghavan; Feto, Naser Aliye; Roy, Pranab

2018-01-01

Matching the global food demand by 2050 and to ensure the stability of food security in over than 99 countries, it is necessary to scale up the production of food such as sorghum, wheat, rice, maize and sugarcane which are however natural hosts of Cochliobolus species. Cochliobolus species major epidemics such as the Great Bengal famine, Southern corn leaf blight, and Northern leaf spot blight were associated with substantial economic losses in the past decades. Thus, there is an urgent need to establish a specific coordinated global surveillance program for the migration of invasive Cochliobolus species, planning contextual control programs engaging all agricultural stakeholders and information sharing in real time for prevention of disastrous Cochliobolus disease outbreak effects. We discuss pertinent outcome of interactions of cash crops with Cochliobolus species having devastating impact on the livelihood of farmers and food security. While post-genomic era elucidated prominent differences among Cochliobolus heterostrophus, C. carbonum, C. victoriae, C. lunatus and C. miyabeanus, their destructive potentials and implications in food losses remained unearthed. Intriguingly, the annual colossal losses caused by Cochliobolus species in the production perspective of sorghum, wheat, rice, maize, cassava and soybean is estimated over 10 billion USD worldwide. This paper provides a comprehensive analysis of the invasive Cochliobolus species distribution and diversity, evolving pathogenicity, persistent diseases, threats and epidemics, consequences on food crops production and increasing global food insecurity issues.

Clusia hilariana and Eugenia uniflora as bioindicators of atmospheric pollutants emitted by an iron pelletizing factory in Brazil.

PubMed

da Silva, Luzimar Campos; de Araújo, Talita Oliveira; Siqueira-Silva, Advanio Inácio; Pereira, Tiago Augusto Rodrigues; Castro, Letícia Nalon; Silva, Eduardo Chagas; Oliva, Marco Antonio; Azevedo, Aristéa Alves

2017-12-01

The objectives of this work were to evaluate if the pollution emitted by the pelletizing factory causes visual symptoms and/or anatomical changes in exposed Eugenia uniflora and Clusia hilariana, in active biomonitoring, at different distances from a pelletizing factory. We characterize the symptomatology, anatomical, and histochemistry alterations induced in the two species. There was no difference in the symptomatology in relation to the different distances of the emitting source. The foliar symptoms found in C. hilariana were chlorosis, necrosis, and foliar abscission and, in E. uniflora, were observed necrosis punctuais, purple spots in the leaves, and increase in the emission of new leaves completely purplish. The two species presented formation of a cicatrization tissue. E. uniflora presented reduction in the thickness of leaf. In C. hilariana, it was visualized hyperplasia of the cells and the adaxial epidermis did not appear collapsed due to thick cuticle and cuticular flanges. Leaves of C. hilariana showed positive staining for iron, protein, starch, and phenolic compounds. E. uniflora showed positive staining for total phenolic compounds and starch. Micromorphologically, there was accumulation of particulate matter on the leaf surface, obstruction of the stomata, and scaling of the epicuticular wax in both species. It was concluded that the visual and anatomical symptoms were efficient in the diagnosis of the stress factor. C. hilariana and E. uniflora showed to be good bioindicators of the atmospheric pollutants emitted by the pelletizing factory.

Unveiling Members of Colletotrichum acutatum Species Complex Causing Colletotrichum Leaf Disease of Hevea brasiliensis in Sri Lanka.

PubMed

Hunupolagama, D M; Chandrasekharan, N V; Wijesundera, W S S; Kathriarachchi, H S; Fernando, T H P S; Wijesundera, R L C

2017-06-01

Colletotrichum is an important fungal genus with great diversity, which causes anthracnose of a variety of crop plants including rubber trees. Colletotrichum acutatum and Colletotrichum gloeosporioides have been identified as the major causative agents of Colletotrichum leaf disease of rubber trees in Sri Lanka based on morphology, pathogenicity, and the analysis of internally transcribed spacer sequences of the nuclear ribosomal DNA. This study has been conducted to investigate the members of the C. acutatum species complex causing rubber leaf disease using a morphological and multi gene approach. For the first time in Sri Lanka, Colletotrichum simmondsii, Colletotrichum laticiphilum, Colletotrichum nymphaeae, and Colletotrichum citri have been identified as causative agents of Colletotrichum leaf disease in addition to C. acutatum s. str. Among them, C. simmondsii has been recognized as the major causative agent.

Cellulase from Trichoderma harzianum interacts with roots and triggers induced systemic resistance to foliar disease in maize

PubMed Central

Saravanakumar, Kandasamy; Fan, Lili; Fu, Kehe; Yu, Chuanjin; Wang, Meng; Xia, Hai; Sun, Jianan; Li, Yaqian; Chen, Jie

2016-01-01

Trichoderma harzianum is well known to exhibit induced systemic resistance (ISR) to Curvularia leaf spot. We previously reported that a C6 zinc finger protein (Thc6) is responsible for a major contribution to the ISR to the leaf disease, but the types of effectors and the signals mediated by Thc6 from Trichoderma are unclear. In this work, we demonstrated that two hydrolases, Thph1 and Thph2, from T. harzianum were regulated by Thc6. Furthermore, an electrophoretic mobility shift assay (EMSA) study revealed that Thc6 regulated mRNA expression by binding to GGCTAA and GGCTAAA in the promoters of the Thph1 and Thph2 genes, respectively. Moreover, the Thph1 and Thph2 proteins triggered the transient production of reactive oxygen species (ROS) and elevated the free cytosolic calcium levels in maize leaf. Furthermore, the genes related to the jasmonate/ethylene signaling pathway were up-regulated in the wild-type maize strain. However, the ΔThph1- or ΔThph2-deletion mutants could not activate the immune defense-related genes in maize to protect against leaf disease. Therefore, we conclude that functional Thph1 and Thph2 may be required in T. harzianum to activate ISR in maize. PMID:27830829

Cellulase from Trichoderma harzianum interacts with roots and triggers induced systemic resistance to foliar disease in maize.

PubMed

Saravanakumar, Kandasamy; Fan, Lili; Fu, Kehe; Yu, Chuanjin; Wang, Meng; Xia, Hai; Sun, Jianan; Li, Yaqian; Chen, Jie

2016-11-10

Trichoderma harzianum is well known to exhibit induced systemic resistance (ISR) to Curvularia leaf spot. We previously reported that a C6 zinc finger protein (Thc6) is responsible for a major contribution to the ISR to the leaf disease, but the types of effectors and the signals mediated by Thc6 from Trichoderma are unclear. In this work, we demonstrated that two hydrolases, Thph1 and Thph2, from T. harzianum were regulated by Thc6. Furthermore, an electrophoretic mobility shift assay (EMSA) study revealed that Thc6 regulated mRNA expression by binding to GGCTAA and GGCTAAA in the promoters of the Thph1 and Thph2 genes, respectively. Moreover, the Thph1 and Thph2 proteins triggered the transient production of reactive oxygen species (ROS) and elevated the free cytosolic calcium levels in maize leaf. Furthermore, the genes related to the jasmonate/ethylene signaling pathway were up-regulated in the wild-type maize strain. However, the ΔThph1- or ΔThph2-deletion mutants could not activate the immune defense-related genes in maize to protect against leaf disease. Therefore, we conclude that functional Thph1 and Thph2 may be required in T. harzianum to activate ISR in maize.

Mass-transport limitations in spot-based microarrays.

PubMed

Zhao, Ming; Wang, Xuefeng; Nolte, David

2010-09-20

Mass transport of analyte to surface-immobilized affinity reagents is the fundamental bottleneck for sensitive detection in solid-support microarrays and biosensors. Analyte depletion in the volume adjacent to the sensor causes deviation from ideal association, significantly slows down reaction kinetics, and causes inhomogeneous binding across the sensor surface. In this paper we use high-resolution molecular interferometric imaging (MI2), a label-free optical interferometry technique for direct detection of molecular films, to study the inhomogeneous distribution of intra-spot binding across 100 micron-diameter protein spots. By measuring intra-spot binding inhomogeneity, reaction kinetics can be determined accurately when combined with a numerical three-dimensional finite element model. To ensure homogeneous binding across a spot, a critical flow rate is identified in terms of the association rate k(a) and the spot diameter. The binding inhomogeneity across a spot can be used to distinguish high-affinity low-concentration specific reactions from low-affinity high-concentration non-specific binding of background proteins.

Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields-An ecofriendly approach.

PubMed

Ghosh, Swapan Kumar; Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

2018-01-01

Aloe vera (L.) Burm.f. is a highly important and extensively cultivated medicinal plant and that is also extensively used in the cosmetic industry. It has been frequently reported to suffer from Alternaria leaf spot disease in various parts of the world. Various fungicides used to combat this disease, have deleterious effects on the environment and on pharmacologically important constituents of Aloe vera. To avoid the harmful effects of fungicides an ecofriendly approach has been adopted here. A weekly survey was conducted during 2013-2015 in and around North 24 Parganas (West Bengal) to obtain the percentage of disease index (PDI). For biological control of the disease, screening of the antagonistic efficacy of biocontrol agents was carried out through the in vitro dual-culture-plate method and scanning electron microscopy (SEM) was used to study the mechanism. The in vitro effects of fungicides on the radial growth of the pathogen were evaluated through the poison food method and were compared with potent antagonistic fungi. Field application of potent antagonistic fungi was conducted through the dip-and-spray method. The results showed that, the PDI peaked during the hot and humid conditions of May to September (76.57%-98.57%) but decreased during the winter, December-January (35.71-46.66%). Trichoderma asperellum exerted the greatest inhibition of the radial growth of A. brassicae acting through non volatile (70.39%) and volatile metabolites (72.17%). A SEM study confirmed the hyperparasitic nature of T. asperellum through hyphal coiling-T. asperellum was similar to 2% blitox-50 (73.92%) and better than 2% bavistin (59.77%) (in vitro). In agricultural field trials (2013-15), Trichoderma application restricted the disease to the smallest area (PDI 24.00-29.33%) in comparison to untreated plots (73.33%). In conclusion, saplings treated with the dip method (108 spores / mL) and sprayed 4 times with a spore suspension of biocontrol agents such as T. asperellum, T. viride and T. harzianum, standardized at a rate of 2.5 L / plot (36 sq ft) (108 spores/ mL) are suggested for the ecofriendly management of this epidemic leaf spot disease of Aloe vera in agricultural fields.

Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields—An ecofriendly approach

PubMed Central

Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

2018-01-01

Aloe vera (L.) Burm.f. is a highly important and extensively cultivated medicinal plant and that is also extensively used in the cosmetic industry. It has been frequently reported to suffer from Alternaria leaf spot disease in various parts of the world. Various fungicides used to combat this disease, have deleterious effects on the environment and on pharmacologically important constituents of Aloe vera. To avoid the harmful effects of fungicides an ecofriendly approach has been adopted here. A weekly survey was conducted during 2013–2015 in and around North 24 Parganas (West Bengal) to obtain the percentage of disease index (PDI). For biological control of the disease, screening of the antagonistic efficacy of biocontrol agents was carried out through the in vitro dual-culture-plate method and scanning electron microscopy (SEM) was used to study the mechanism. The in vitro effects of fungicides on the radial growth of the pathogen were evaluated through the poison food method and were compared with potent antagonistic fungi. Field application of potent antagonistic fungi was conducted through the dip-and-spray method. The results showed that, the PDI peaked during the hot and humid conditions of May to September (76.57%–98.57%) but decreased during the winter, December-January (35.71–46.66%). Trichoderma asperellum exerted the greatest inhibition of the radial growth of A. brassicae acting through non volatile (70.39%) and volatile metabolites (72.17%). A SEM study confirmed the hyperparasitic nature of T. asperellum through hyphal coiling-T. asperellum was similar to 2% blitox-50 (73.92%) and better than 2% bavistin (59.77%) (in vitro). In agricultural field trials (2013–15), Trichoderma application restricted the disease to the smallest area (PDI 24.00–29.33%) in comparison to untreated plots (73.33%). In conclusion, saplings treated with the dip method (108 spores / mL) and sprayed 4 times with a spore suspension of biocontrol agents such as T. asperellum, T. viride and T. harzianum, standardized at a rate of 2.5 L / plot (36 sq ft) (108 spores/ mL) are suggested for the ecofriendly management of this epidemic leaf spot disease of Aloe vera in agricultural fields. PMID:29579070

Biogenic nano-scale silver particles by Tephrosia purpurea leaf extract and their inborn antimicrobial activity

NASA Astrophysics Data System (ADS)

Ajitha, B.; Ashok Kumar Reddy, Y.; Reddy, P. Sreedhara

2014-03-01

In this paper we report the green synthesis of silver nanoparticles (Ag NPs) using Tephrosia purpurea leaf extract. The biomolecules present in the leaf extract are responsible for the formation of Ag NPs and they found to play dual role of both reducing as well as capping agents. The high crystallinity of Ag NPs is evident from bright circular spot array of SAED pattern and diffraction peaks in XRD profile. The synthesized Ag NPs are found to be nearly spherical ones with size approximately ∼20 nm. FTIR spectrum evidences the presence of different functional groups of biomolecules participated in encapsulating Ag NPs and the possible mechanism of Ag NPs formation was also suggested. Appearance of yellow color and surface plasmon resonance (SPR) peak at 425 nm confirms the Ag NPs formation. PL spectra showed decrement in luminescence intensity at higher excitation wavelengths. Antimicrobial activity of Ag NPs showed better inhibitory activity towards Pseudomonas spp. and Penicillium spp. compared to other test pathogens using standard Kirby-Bauer disc diffusion assay.

Salinity stress inhibits bean leaf expansion by reducing turgor, not wall extensibility

NASA Technical Reports Server (NTRS)

Neumann, P. M.; Van Volkenburgh, E.; Cleland, R. E.

1988-01-01

Treatment of bean (Phaseolus vulgaris L.) seedlings with low levels of salinity (50 or 100 millimolar NaCl) decreased the rate of light-induced leaf cell expansion in the primary leaves over a 3 day period. This decrease could be due to a reduction in one or both of the primary cellular growth parameters: wall extensibility and cell turgor. Wall extensibility was assessed by the Instron technique. Salinity did not decrease extensibility and caused small increases relative to the controls after 72 hours. On the other hand, 50 millimolar NaCl caused a significant reduction in leaf bulk turgor at 24 hours; adaptive decreases in leaf osmotic potential (osmotic adjustment) were more than compensated by parallel decreases in xylem tension potential and the leaf apoplastic solute potential, resulting in a decreased leaf water potential. It is concluded that in bean seedlings, mild salinity initially affects leaf growth rate by a decrease in turgor rather than by a reduction in wall extensibility. Moreover, long-term salinization (10 days) resulted in an apparent mechanical adjustment, i.e. an increase in wall extensibility, which may help counteract reductions in turgor and maintain leaf growth rates.

The Cucumber leaf spot virus p25 auxiliary replicase protein binds and modifies the endoplasmic reticulum via N-terminal transmembrane domains

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

Ghoshal, Kankana; Theilmann, Jane; Reade, Ron

2014-11-15

Cucumber leaf spot virus (CLSV) is a member of the Aureusvirus genus, family Tombusviridae. The auxiliary replicase of Tombusvirids has been found to localize to endoplasmic reticulum (ER), peroxisomes or mitochondria; however, localization of the auxiliary replicase of aureusviruses has not been determined. We have found that the auxiliary replicase of CLSV (p25) fused to GFP colocalizes with ER and that three predicted transmembrane domains (TMDs) at the N-terminus of p25 are sufficient for targeting, although the second and third TMDs play the most prominent roles. Confocal analysis of CLSV infected 16C plants shows that the ER becomes modified includingmore » the formation of punctae at connections between ER tubules and in association with the nucleus. Ultrastructural analysis shows that the cytoplasm contains numerous vesicles which are also found between the perinuclear ER and nuclear membrane. It is proposed that these vesicles correspond to modified ER used as sites for CLSV replication. - Highlights: • The CLSV p25 auxiliary replicase targets the endoplasmic reticulum (ER). • Targeting of CLSV p25 is associated with ER restructuring. • Restructuring of the ER occurs during CLSV infection. • CLSV p25 contains 3 predicted transmembrane domains 2 of which are required for ER targeting. • Vesicles derived from the ER may be sites of CLSV replication.« less

Identification of gibberellin acid-responsive proteins in rice leaf sheath using proteomics.

PubMed

Gu, Jia-Yu; Wang, Ye; Zhang, Xu; Zhang, Shi-Hua; Gao, Yin; An, Cheng-Cai

2010-06-01

The phytohormone gibberellin acid (GA) controls many aspects of plant development. In this study, we identified proteins that are differentially expressed between the rice (Oryza sativa L.) GA-deficient cultivar, Aijiaonante, and its parental line, Nante. Proteins were extracted from rice leaf sheath and examined by 2DGE. Among more than 1200 protein spots reproducibly detected on each gel, 29 were found to be highly up-regulated by GAs in Nante, and 6 were down-regulated by GAs in Aijiaonante. These 35 proteins were identified by MALDI-TOF MS and were classified into three groups based on their putative function in metabolism, stress/defense processes and signal transduction. These data suggest that metabolic pathways are the main target of regulation by GAs during rice development. Our results provide new information about the involvement of GAs in rice development.

Clinical and prognostic value of spot urinary creatinine in chronic heart failure-An analysis from GISSI-HF.

PubMed

Ter Maaten, Jozine M; Maggioni, Aldo Pietro; Latini, Roberto; Masson, Serge; Tognoni, Gianni; Tavazzi, Luigi; Signorini, Stefano; Voors, Adriaan A; Damman, Kevin

2017-06-01

This study aimed to identify patient characteristics associated with low urinary creatinine in morning spot urine and investigate its association with clinical outcome. Twenty-four-hour creatinine excretion is an established marker of muscle mass in heart failure and other populations. Spot urine creatinine might be an easy obtainable, cheap marker of muscle wasting and prognosis in heart failure (HF) patients. Spot urine creatinine concentration was measured in 2130 patients included in the GISSI-HF trial. We evaluated the prognostic value of urinary creatinine and its relation with clinical variables. Median spot urinary creatinine was 0.80 (IQR 0.50-1.10) g/L. Lower spot urinary creatinine was associated with older age, smaller height and weight, higher NYHA class, worse renal function and more frequent spironolactone and diuretic use (all P<.02). During a median follow-up of 2.8 years, 655 patients (31%) experienced the combined endpoint of all-cause mortality or HF hospitalization. Lower urinary creatinine was independently associated with an increased risk of all-cause mortality or HF hospitalization (HR, 1.59 [1.21-2.08] per log decrease, P=.001), and all-cause mortality (HR, 1.75 [1.25-2.45] per log decrease, P=.001). Lower urinary creatinine, measured in morning spot urine in patients with chronic HF, is associated with worse renal function, smaller body size, more severe HF and is independently associated with an increased risk of all-cause death and HF hospitalization. Copyright © 2017 Elsevier Inc. All rights reserved.

First report of Xiphinema rivesi (Nematoda, Longidoridae) in Washington State

USDA-ARS?s Scientific Manuscript database

The dagger nematode Xiphinema rivesi Dalmasso 1969 transmits several viruses in North America and Europe (2), causing severe yield reduction in crops. During a routine survey of cherry orchards suffering from cherry rasp leaf disease caused by Cherry rasp leaf virus (CRLV) (genus Cheravirus) in Che...

Recovery Plan for Red Leaf Blotch of Soybean Caused by Phoma glycinicola

USDA-ARS?s Scientific Manuscript database

Red leaf blotch (RLB) of soybean is caused by the fungal pathogen Phoma glycinicola, formerly known in the plant pathology literature as Pyrenochaeta glycines, Dactuliophora glycines, and Dactuliochaeata glycines. The disease presently occurs in only a few African countries on soybean and a wild leg...

An unusual burn caused by hot argy wormwood leaf water

PubMed Central

Liang, Xun; Chen, Xu-Lin; Wang, Fei; Guo, Feng

2011-01-01

An unusual burn case caused by hot wormwood leaf water was discussed. A 29-year-old woman sustained a 7% second-degree burn on both buttocks and left thigh. This case report highlights a rare cause of a chemical burn that may become more common with increasing use of this Chinese traditional medicine. The prevention measures of this burn injury were also presented. PMID:24765332

The sentinel tree nursery as an early warning system for pathway risk assessment: Fungal pathogens associated with Chinese woody plants commonly shipped to Europe

PubMed Central

Vettraino, Anna Maria; Li, Hong-Mei; Eschen, Rene; Morales-Rodriguez, Carmen

2017-01-01

Introduction of and invasion by alien plant pathogens represents the main cause of emerging infectious diseases affecting domesticated and wild plant species worldwide. The trade in living plants is the most common pathway of introduction. Many of the alien tree pathogens recently introduced into Europe were not previously included on any quarantine lists. To help determine the potential risk of pest introduction through trading of ornamental plants, a sentinel nursery was established in Beijing, China in 2008. The sentinel nursery planting included four of the most common ornamental woody species shipped to Europe including Ilex cornuta var. fortunae, Zelkova schneideriana, Fraxinus chinensis and Buxus microphylla. Symptoms developing on these species within the sentinel nursery were detected in 2013 and consisted of necrotic spots on leaves, canker and stem necrosis, shoot blight and shoot necrosis. Fungi associated with the trees and their symptoms included Alternaria alternata detected from all hosts; Diaporthe liquidambaris and Diaporthe capsici from bark and leaf necrosis of Zelkova schneideriana; Botryosphaeria dothidea and Nothophoma quercina from stem cankers on Fraxinus chinensis and leaf necrosis on Ilex cornuta; and Pseudonectria foliicola from leaf necrosis on Buxus microphylla. Next generation sequencing analysis from asymptomatic tissues detected eighteen OTU’s at species level among which some taxa had not been previously recorded in Europe. These results clearly demonstrate that looking at trees of internationally traded species in the region of origin can reveal the presence of potentially harmful organisms of major forestry, landscape or crop trees. Results of this study also provide an indication as to how some disease agents can be introduced using pathways other than the co-generic hosts. Hence, sentinel nurseries represent one potential mechanism to address the current lack of knowledge about pests in the countries from where live plants are shipped and the threats they represent to native flora and crops in importing countries. PMID:29186190

A ToxA-like protein from Cochliobolus heterostrophus induces light-dependent leaf necrosis and acts as a virulence factor with host selectivity on maize.

PubMed

Lu, Shunwen; Gillian Turgeon, B; Edwards, Michael C

2015-08-01

ToxA, the first discovered fungal proteinaceous host-selective toxin (HST), was originally identified in 1989 from the tan spot fungus Pyrenophora tritici-repentis (Ptr). About 25years later, a homolog was identified in the leaf/glume blotch fungus Stagonospora nodorum (Parastagonospora nodorum), also a pathogen of wheat. Here we report the identification and function of a ToxA-like protein from the maize pathogen Cochliobolus heterostrophus (Ch) that possesses necrosis-inducing activity specifically against maize. ChToxA is encoded by a 535-bp open reading frame featuring a ToxA-specific intron with unusual splicing sites (5'-ATAAGT…TAC-3') at conserved positions relative to PtrToxA. The protein shows 64% similarity to PtrToxA and is predicted to adopt a similar three-dimensional structure, although lacking the arginyl-glycyl-aspartic acid (RGD) motif reported to be required for internalization into sensitive wheat mesophyll cells. Reverse-transcriptase PCR revealed that the ChTOXA gene expression is up-regulated in planta, relative to axenic culture. Plant assays indicated that the recombinant ChToxA protein induces light-dependent leaf necrosis in a host-selective manner on maize inbred lines. Gene deletion experiments confirmed that ChtoxA mutants are reduced in virulence on specific ChToxA-sensitive maize lines, relative to virulence caused by wild-type strains. Database searches identified potential ChToxA homologues in other plant-pathogenic ascomycetes. Sequence and phylogenetic analyses revealed that the corresponding ToxA-like proteins include one member recently shown to be associated with formation of penetration hypha. These results provide the first evidence that C. heterostrophus is capable of producing proteinaceous HSTs as virulence factors in addition to well-known secondary metabolite-type toxins produced biosynthetically by polyketide synthase megaenzymes. Further studies on ChToxA may provide new insights into effector evolution in host-pathogen interactions. Published by Elsevier Inc.

The sentinel tree nursery as an early warning system for pathway risk assessment: Fungal pathogens associated with Chinese woody plants commonly shipped to Europe.

PubMed

Vettraino, Anna Maria; Li, Hong-Mei; Eschen, Rene; Morales-Rodriguez, Carmen; Vannini, Andrea

2017-01-01

Introduction of and invasion by alien plant pathogens represents the main cause of emerging infectious diseases affecting domesticated and wild plant species worldwide. The trade in living plants is the most common pathway of introduction. Many of the alien tree pathogens recently introduced into Europe were not previously included on any quarantine lists. To help determine the potential risk of pest introduction through trading of ornamental plants, a sentinel nursery was established in Beijing, China in 2008. The sentinel nursery planting included four of the most common ornamental woody species shipped to Europe including Ilex cornuta var. fortunae, Zelkova schneideriana, Fraxinus chinensis and Buxus microphylla. Symptoms developing on these species within the sentinel nursery were detected in 2013 and consisted of necrotic spots on leaves, canker and stem necrosis, shoot blight and shoot necrosis. Fungi associated with the trees and their symptoms included Alternaria alternata detected from all hosts; Diaporthe liquidambaris and Diaporthe capsici from bark and leaf necrosis of Zelkova schneideriana; Botryosphaeria dothidea and Nothophoma quercina from stem cankers on Fraxinus chinensis and leaf necrosis on Ilex cornuta; and Pseudonectria foliicola from leaf necrosis on Buxus microphylla. Next generation sequencing analysis from asymptomatic tissues detected eighteen OTU's at species level among which some taxa had not been previously recorded in Europe. These results clearly demonstrate that looking at trees of internationally traded species in the region of origin can reveal the presence of potentially harmful organisms of major forestry, landscape or crop trees. Results of this study also provide an indication as to how some disease agents can be introduced using pathways other than the co-generic hosts. Hence, sentinel nurseries represent one potential mechanism to address the current lack of knowledge about pests in the countries from where live plants are shipped and the threats they represent to native flora and crops in importing countries.

Litsea cubeba leaf essential oil from Vietnam: chemical diversity and its impacts on antibacterial activity.

PubMed

Nguyen, H V; Meile, J-C; Lebrun, M; Caruso, D; Chu-Ky, S; Sarter, S

2018-03-01

The threat of bacterial resistance to antibiotics has created an urgent need to develop new antimicrobials. The aim of this study was to characterize the chemical diversity of Litsea cubeba leaf essential oil (EO) and its impacts on the antibacterial activity against pathogenic bacteria. Essential oils collected from seven provinces in North Vietnam (n = 25) were characterized by their high content in either 1,8-cineole or linalool. Linalool-type EOs were more effective against the eight bacterial strains tested than 1,8-cineole-type. Oil samples, LC19 (50% 1,8-cineole) and BV27 (94% linalool), were selected to investigate their antibacterial mechanisms against Escherichia coli. A strong bactericidal effect was observed after 4 and 2 h of exposure respectively. Microscopic analysis of treated E. coli cultures clearly showed that EOs caused changes in cell morphology, loss of integrity and permeability of the cell membrane, as well as DNA loss. However, the effects of both EOs were distinct. LC19 mostly affected cell membrane, led to a significant cell filamentation rate and altered cell width, whereas BV27 damaged cell membrane integrity leading to cell permeabilization and altered nucleoid morphology with the appearance of spot and visibly altered compaction. This study aimed to characterize the chemical diversity of Litsea cubeba leaf essential oil (EO) and its impacts on its antibacterial activity. Two major chemotypes (1,8-cineole or linalool rich) were identified in North Vietnam and both were bactericidal against several pathogenic bacteria. A distinct inhibitory effect of EO samples on Escherichia coli was observed. 1,8-cineole-rich sample (LC19) affected cell membrane, led to cell filamentation and perturbation of cell width, while the linalool-rich one (BV27) induced damages in the cell membrane and changes in the nucleoid morphology. The study demonstrates the importance of considering chemotype variations in terms of chemical composition as well as the mode of action. © 2017 The Society for Applied Microbiology.

77 FR 75007 - Importation of Sand Pears From China

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-19

..., pear fruit moth. Alternaria gaisen Nagano, the cause of black spot of pear. Amphitetranychus viennensis... requirements, Rice, Vegetables. Accordingly, we are amending 7 CFR part 319 as follows: PART 319--FOREIGN... quarantine pests: Acrobasis pyrivorella, pear fruit moth; Alternaria gaisen Nagano, the cause of black spot...

Biofabricated Silver Nanoparticles Act as a Strong Fungicide against Bipolaris sorokiniana Causing Spot Blotch Disease in Wheat

PubMed Central

Singh, Akanksha; Keswani, Chetan; Naqvi, Alim H.; Singh, H. B.

2014-01-01

The present study is focused on the extracellular synthesis of silver nanoparticles (AgNPs) using culture supernatant of an agriculturally important bacterium, Serratia sp. BHU-S4 and demonstrates its effective application for the management of spot blotch disease in wheat. The biosynthesis of AgNPs by Serratia sp. BHU-S4 (denoted as bsAgNPs) was monitored by UV–visible spectrum that showed the surface plasmon resonance (SPR) peak at 410 nm, an important characteristic of AgNPs. Furthermore, the structural, morphological, elemental, functional and thermal characterization of bsAgNPs was carried out using the X-ray diffraction (XRD), electron and atomic microscopies, energy dispersive X-ray (EDAX) spectrometer, FTIR spectroscopy and thermogravimetric analyzer (TGA), respectively. The bsAgNPs were spherical in shape with size range of ∼10 to 20 nm. The XRD and EDAX analysis confirmed successful biosynthesis and crystalline nature of AgNPs. The bsAgNPs exhibited strong antifungal activity against Bipolaris sorokiniana, the spot blotch pathogen of wheat. Interestingly, 2, 4 and 10 µg/ml concentrations of bsAgNPs accounted for complete inhibition of conidial germination, whereas in the absence of bsAgNPs, conidial germination was 100%. A detached leaf bioassay revealed prominent conidial germination on wheat leaves infected with B. sorokiniana conidial suspension alone, while the germination of conidia was totally inhibited when the leaves were treated with bsAgNPs. The results were further authenticated under green house conditions, where application of bsAgNPs significantly reduced B. sorokiniana infection in wheat plants. Histochemical staining revealed a significant role of bsAgNPs treatment in inducing lignin deposition in vascular bundles. In summary, our findings represent the efficient application of bsAgNPs in plant disease management, indicating the exciting possibilities of nanofungicide employing agriculturally important bacteria. PMID:24840186

FluorMODgui V3.0: A graphic user interface for the spectral simulation of leaf and canopy chlorophyll fluorescence

NASA Astrophysics Data System (ADS)

Zarco-Tejada, P. J.; Miller, J. R.; Pedrós, R.; Verhoef, W.; Berger, M.

2006-06-01

The FluorMODgui Graphic User Interface (GUI) software package developed within the frame of the FluorMOD project Development of a Vegetation Fluorescence Canopy Model is presented in this manuscript. The FluorMOD project was launched in 2002 by the European Space Agency (ESA) to advance the science of vegetation fluorescence simulation through the development and integration of leaf and canopy fluorescence models based on physical methods. The design of airborne or space missions dedicated to the measurement of solar-induced chlorophyll fluorescence using remote-sensing instruments require physical methods for quantitative feasibility analysis and sensor specification studies. The FluorMODgui model developed as part of this project is designed to simulate the effects of chlorophyll fluorescence at leaf and canopy levels using atmospheric inputs, running the leaf model, FluorMODleaf, and the canopy model, FluorSAIL, independently, through a coupling scheme, and by a multiple iteration protocol to simulate changes in the viewing geometry and atmospheric characteristics. Inputs for the FluorMODleaf model are the number of leaf layers, chlorophyll a+ b content, water equivalent thickness, dry matter content, fluorescence quantum efficiency, temperature, species type, and stoichiometry. Inputs for the FluorSAIL canopy model are a MODTRAN-4 6-parameter spectra or measured direct horizontal irradiance and diffuse irradiance spectra, a soil reflectance spectrum, leaf reflectance & transmittance spectra and a excitation-fluorescence response matrix in upward and downward directions (all from FluorMODleaf), 2 PAR-dependent coefficients for the fluorescence response to light level, relative azimuth angle and viewing zenith angle, canopy leaf area index, leaf inclination distribution function, and a hot spot parameter. Outputs available in the 400-1000 nm spectral range from the graphical user interface, FluorMODgui, are the leaf spectral reflectance and transmittance, and the canopy reflectance, with and without fluorescence effects. In addition, solar and sky irradiance on the ground, radiance with and without fluorescence on the ground, and top-of-atmosphere (TOA) radiances for bare soil and surroundings same as target are also produced. The models and documentation regarding the FluorMOD project can be downloaded at http://www.ias.csic.es/fluormod.

Correlation between dislocations and leakage current of p-n diodes on a free-standing GaN substrate

NASA Astrophysics Data System (ADS)

Usami, Shigeyoshi; Ando, Yuto; Tanaka, Atsushi; Nagamatsu, Kentaro; Deki, Manato; Kushimoto, Maki; Nitta, Shugo; Honda, Yoshio; Amano, Hiroshi; Sugawara, Yoshihiro; Yao, Yong-Zhao; Ishikawa, Yukari

2018-04-01

Dislocations that cause a reverse leakage current in vertical p-n diodes on a GaN free-standing substrate were investigated. Under a high reverse bias, dot-like leakage spots were observed using an emission microscope. Subsequent cathodoluminescence (CL) observations revealed that the leakage spots coincided with part of the CL dark spots, indicating that some types of dislocation cause reverse leakage. When etch pits were formed on the dislocations by KOH etching, three sizes of etch pits were obtained (large, medium, and small). Among these etch pits, only the medium pits coincided with leakage spots. Additionally, transmission electron microscopy observations revealed that pure screw dislocations are present under the leakage spots. The results revealed that 1c pure screw dislocations are related to the reverse leakage in vertical p-n diodes.

Niclosamide inhibits leaf blight caused by Xanthomonas oryzae in rice

PubMed Central

Kim, Sung-Il; Song, Jong Tae; Jeong, Jin-Yong; Seo, Hak Soo

2016-01-01

Rice leaf blight, which is caused by the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo), results in huge losses in grain yield. Here, we show that Xoo-induced rice leaf blight is effectively controlled by niclosamide, an oral antihelminthic drug and molluscicide, which also functions as an anti-tumor agent. Niclosamide directly inhibited the growth of the three Xoo strains PXO99, 10208 and K3a. Niclosamide moved long distances from the site of local application to distant rice tissues. Niclosamide also increased the levels of salicylate and induced the expression of defense-related genes such as OsPR1 and OsWRKY45, which suppressed Xoo-induced leaf wilting. Niclosamide had no detrimental effects on vegetative/reproductive growth and yield. These combined results indicate that niclosamide can be used to block bacterial leaf blight in rice with no negative side effects. PMID:26879887

An unusual burn caused by hot argy wormwood leaf water

PubMed Central

Liang, X.; Chen, X.-L.; Wang, F.; Guo, F.

2011-01-01

Summary An unusual burn case caused by hot wormwood leaf water is discussed. A 29-yr-old woman sustained a 7% seconddegree burn on both buttocks and the left thigh. This case report highlights a rare cause of chemical burn that may become more common with increasing use of this method of traditional Chinese medicine. Measures for preventing this type of burn injury are also presented. PMID:22396673

Kilauea volcano: the degassing of a hot spot

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

Gerlach, T.M.

1986-03-01

Hot spots such as Kilauea volcano can degas by a one-stage eruptive process or a two-stage process involving eruptive and noneruptive degassing. One stage degassing occurs during sustained summit eruptions and causes a direct environmental impact. Although generally less efficient than the one-stage degassing process, two stage degassing can cause 1 to 2 orders of magnitude greater impact in just a few hours during flank eruptions. Hot spot volcanos with resupplied crustal magma chambers may be capable of maintaining an equivalent impact from CO/sub 2/ and S outgassing during both eruptive and noneruptive periods. On average, a hot spot volcanomore » such as Kilauea is a minor polluter compared to man.« less

Evaluation of 19,460 Wheat Accessions Conserved in the Indian National Genebank to Identify New Sources of Resistance to Rust and Spot Blotch Diseases.

PubMed

Kumar, Sundeep; Archak, Sunil; Tyagi, R K; Kumar, Jagdish; Vk, Vikas; Jacob, Sherry R; Srinivasan, Kalyani; Radhamani, J; Parimalan, R; Sivaswamy, M; Tyagi, Sandhya; Yadav, Mamata; Kumari, Jyotisna; Deepali; Sharma, Sandeep; Bhagat, Indoo; Meeta, Madhu; Bains, N S; Chowdhury, A K; Saha, B C; Bhattacharya, P M; Kumari, Jyoti; Singh, M C; Gangwar, O P; Prasad, P; Bharadwaj, S C; Gogoi, Robin; Sharma, J B; Gm, Sandeep Kumar; Saharan, M S; Bag, Manas; Roy, Anirban; Prasad, T V; Sharma, R K; Dutta, M; Sharma, Indu; Bansal, K C

2016-01-01

A comprehensive germplasm evaluation study of wheat accessions conserved in the Indian National Genebank was conducted to identify sources of rust and spot blotch resistance. Genebank accessions comprising three species of wheat-Triticum aestivum, T. durum and T. dicoccum were screened sequentially at multiple disease hotspots, during the 2011-14 crop seasons, carrying only resistant accessions to the next step of evaluation. Wheat accessions which were found to be resistant in the field were then assayed for seedling resistance and profiled using molecular markers. In the primary evaluation, 19,460 accessions were screened at Wellington (Tamil Nadu), a hotspot for wheat rusts. We identified 4925 accessions to be resistant and these were further evaluated at Gurdaspur (Punjab), a hotspot for stripe rust and at Cooch Behar (West Bengal), a hotspot for spot blotch. The second round evaluation identified 498 accessions potentially resistant to multiple rusts and 868 accessions potentially resistant to spot blotch. Evaluation of rust resistant accessions for seedling resistance against seven virulent pathotypes of three rusts under artificial epiphytotic conditions identified 137 accessions potentially resistant to multiple rusts. Molecular analysis to identify different combinations of genetic loci imparting resistance to leaf rust, stem rust, stripe rust and spot blotch using linked molecular markers, identified 45 wheat accessions containing known resistance genes against all three rusts as well as a QTL for spot blotch resistance. The resistant germplasm accessions, particularly against stripe rust, identified in this study can be excellent potential candidates to be employed for breeding resistance into the background of high yielding wheat cultivars through conventional or molecular breeding approaches, and are expected to contribute toward food security at national and global levels.

Evaluation of 19,460 Wheat Accessions Conserved in the Indian National Genebank to Identify New Sources of Resistance to Rust and Spot Blotch Diseases

PubMed Central

Jacob, Sherry R.; Srinivasan, Kalyani; Radhamani, J.; Parimalan, R.; Sivaswamy, M.; Tyagi, Sandhya; Yadav, Mamata; Kumari, Jyotisna; Deepali; Sharma, Sandeep; Bhagat, Indoo; Meeta, Madhu; Bains, N. S.; Chowdhury, A. K.; Saha, B. C.; Bhattacharya, P. M.; Kumari, Jyoti; Singh, M. C.; Gangwar, O. P.; Prasad, P.; Bharadwaj, S. C.; Gogoi, Robin; Sharma, J. B.; GM, Sandeep Kumar; Saharan, M. S.; Bag, Manas; Roy, Anirban; Prasad, T. V.; Sharma, R. K.; Dutta, M.; Sharma, Indu; Bansal, K. C.

2016-01-01

A comprehensive germplasm evaluation study of wheat accessions conserved in the Indian National Genebank was conducted to identify sources of rust and spot blotch resistance. Genebank accessions comprising three species of wheat–Triticum aestivum, T. durum and T. dicoccum were screened sequentially at multiple disease hotspots, during the 2011–14 crop seasons, carrying only resistant accessions to the next step of evaluation. Wheat accessions which were found to be resistant in the field were then assayed for seedling resistance and profiled using molecular markers. In the primary evaluation, 19,460 accessions were screened at Wellington (Tamil Nadu), a hotspot for wheat rusts. We identified 4925 accessions to be resistant and these were further evaluated at Gurdaspur (Punjab), a hotspot for stripe rust and at Cooch Behar (West Bengal), a hotspot for spot blotch. The second round evaluation identified 498 accessions potentially resistant to multiple rusts and 868 accessions potentially resistant to spot blotch. Evaluation of rust resistant accessions for seedling resistance against seven virulent pathotypes of three rusts under artificial epiphytotic conditions identified 137 accessions potentially resistant to multiple rusts. Molecular analysis to identify different combinations of genetic loci imparting resistance to leaf rust, stem rust, stripe rust and spot blotch using linked molecular markers, identified 45 wheat accessions containing known resistance genes against all three rusts as well as a QTL for spot blotch resistance. The resistant germplasm accessions, particularly against stripe rust, identified in this study can be excellent potential candidates to be employed for breeding resistance into the background of high yielding wheat cultivars through conventional or molecular breeding approaches, and are expected to contribute toward food security at national and global levels. PMID:27942031

7 CFR 51.1221 - Damage.

Code of Federal Regulations, 2011 CFR

2011-01-01

... defect, shall be considered as damage: (a) Bacterial spot, when cracked, or when aggregating more than 3/8 inch in diameter; (b) Scab spots, when cracked, or when aggregating more than 3/8 inch in diameter... diameter; (f) Split pit, when causing any unhealed crack, or when causing any crack which is readily...

Mapping a new black spot resistance locus in rose [abstract

USDA-ARS?s Scientific Manuscript database

Rose black spot, caused by Diplocarpon rosae, is one of the most devastating foliar diseases of cultivated roses (Rosa hybrida). The pathogen is globally distributed and has the potential to cause large economic losses in the outdoor rose industry. Genetic resistance is the most economical disease m...

Identification and Chacterization of new strains of Enterobacter spp. causing Mulberry (Morus alba) wilt disease in China

USDA-ARS?s Scientific Manuscript database

A new mulberry wilt disease (MWD) was recently identified in Hangzhou, Zhejiang province, China. Typical symptoms of the disease are dark brown discolorations in vascular tissues, leaf wilt, defoliation, and tree decline. Unlike the bacterial wilt disease caused by Ralstonia solanacearum, the leaf w...

Characterization of Xylella fastidiosa pear leaf scorch strain in Taiwan through whole genome sequence analyses

USDA-ARS?s Scientific Manuscript database

Xylella fastidiosa is a Gram-negative bacterium causing diseases in many economically important crops mostly in the Americas but also in Asia and Europe. A strain of X. fastidiosa was found to cause pear leaf scorch (PLS) disease in Taiwan in 1992. Because of nutritional fastidiousness, characteriza...

First report of leaf rust of blueberry caused by Thekopsora minima in Mexico

USDA-ARS?s Scientific Manuscript database

Blueberry (Vaccinium corymbosum L.) is becoming an important crop in the states of Jalisco and Michoacan in Mexico. As the area under blueberry cultivation increases, new diseases causing severe losses are appearing. Leaf rust is one of the most destructive diseases of blueberry in Mexico. Sori on t...

Two whole genome sequences of Xylella fastidiosa (strains M12 and M23) causing almond leaf scorch disease in California

USDA-ARS?s Scientific Manuscript database

Xylella fastidiosa is a Gram negative, nutritionally fastidious plant pathogenic bacterium that causes many economically important diseases including almond leaf scorch disease (ALSD) and Pierce’s disease of grape in California, as well as citrus variegated chlorosis in South America. Genome inform...

Status of Sugarcane yellow leaf virus and its impact in different progenies

USDA-ARS?s Scientific Manuscript database

Yellow leaf disease caused by Sugarcane yellow leaf virus (SCYLV) a Polerovirus is an important disease for sugarcane industries worldwide. High yield losses up to 50% were reported in susceptible varieties. Most of the commercial cultivars in Florida are infected with SCYLV; therefore, there is a ...

Theoretical and experimental errors for in situ measurements of plant water potential.

PubMed

Shackel, K A

1984-07-01

Errors in psychrometrically determined values of leaf water potential caused by tissue resistance to water vapor exchange and by lack of thermal equilibrium were evaluated using commercial in situ psychrometers (Wescor Inc., Logan, UT) on leaves of Tradescantia virginiana (L.). Theoretical errors in the dewpoint method of operation for these sensors were demonstrated. After correction for these errors, in situ measurements of leaf water potential indicated substantial errors caused by tissue resistance to water vapor exchange (4 to 6% reduction in apparent water potential per second of cooling time used) resulting from humidity depletions in the psychrometer chamber during the Peltier condensation process. These errors were avoided by use of a modified procedure for dewpoint measurement. Large changes in apparent water potential were caused by leaf and psychrometer exposure to moderate levels of irradiance. These changes were correlated with relatively small shifts in psychrometer zero offsets (-0.6 to -1.0 megapascals per microvolt), indicating substantial errors caused by nonisothermal conditions between the leaf and the psychrometer. Explicit correction for these errors is not possible with the current psychrometer design.

Theoretical and Experimental Errors for In Situ Measurements of Plant Water Potential 1

PubMed Central

Shackel, Kenneth A.

1984-01-01

Errors in psychrometrically determined values of leaf water potential caused by tissue resistance to water vapor exchange and by lack of thermal equilibrium were evaluated using commercial in situ psychrometers (Wescor Inc., Logan, UT) on leaves of Tradescantia virginiana (L.). Theoretical errors in the dewpoint method of operation for these sensors were demonstrated. After correction for these errors, in situ measurements of leaf water potential indicated substantial errors caused by tissue resistance to water vapor exchange (4 to 6% reduction in apparent water potential per second of cooling time used) resulting from humidity depletions in the psychrometer chamber during the Peltier condensation process. These errors were avoided by use of a modified procedure for dewpoint measurement. Large changes in apparent water potential were caused by leaf and psychrometer exposure to moderate levels of irradiance. These changes were correlated with relatively small shifts in psychrometer zero offsets (−0.6 to −1.0 megapascals per microvolt), indicating substantial errors caused by nonisothermal conditions between the leaf and the psychrometer. Explicit correction for these errors is not possible with the current psychrometer design. PMID:16663701

Cacao Phylloplane: The First Battlefield against Moniliophthora perniciosa, Which Causes Witches' Broom Disease.

PubMed

Almeida, D S M; Gramacho, K P; Cardoso, T H S; Micheli, F; Alvim, F C; Pirovani, C P

2017-07-01

The phylloplane is the first contact surface between Theobroma cacao and the fungus Moniliophthora perniciosa, which causes witches' broom disease (WBD). We evaluated the index of short glandular trichomes (SGT) in the cacao phylloplane and the effect of irrigation on the disease index of cacao genotypes with or without resistance to WBD, and identified proteins present in the phylloplane. The resistant genotype CCN51 and susceptible Catongo presented a mean index of 1,600 and 700 SGT cm -2 , respectively. The disease index in plants under drip irrigation was reduced by approximately 30% compared with plants under sprinkler irrigation prior to inoculation. Leaf water wash (LWW) of the cacao inhibited the germination of spores by up to 98%. Proteins from the LWW of CCN51 were analyzed by two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by tandem mass spectrometry. The gel showed 71 spots and identified a total of 42 proteins (28 from the plant and 14 from bacteria). Proteins related to defense and synthesis of defense metabolites and involved in nucleic acid metabolism were identified. The results support the hypothesis that the proteins and water-soluble compounds secreted to the cacao phylloplane participate in the defense against pathogens. They also suggest that SGT can contribute to the resistance of cacao.

The Arabidopsis RING-Type E3 Ligase TEAR1 Controls Leaf Development by Targeting the TIE1 Transcriptional Repressor for Degradation[OPEN

PubMed Central

Zhang, Jinzhe; Wei, Baoye; Yuan, Rongrong; Yu, Hao

2017-01-01

The developmental plasticity of leaf size and shape is important for leaf function and plant survival. However, the mechanisms by which plants form diverse leaves in response to environmental conditions are not well understood. Here, we identified TIE1-ASSOCIATED RING-TYPE E3 LIGASE1 (TEAR1) and found that it regulates leaf development by promoting the degradation of TCP INTERACTOR-CONTAINING EAR MOTIF PROTEIN1 (TIE1), an important repressor of CINCINNATA (CIN)-like TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors, which are key for leaf development. TEAR1 contains a typical C3H2C3-type RING domain and has E3 ligase activity. We show that TEAR1 interacts with the TCP repressor TIE1, which is ubiquitinated in vivo and degraded by the 26S proteasome system. We demonstrate that TEAR1 is colocalized with TIE1 in nuclei and negatively regulates TIE1 protein levels. Overexpression of TEAR1 rescued leaf defects caused by TIE1 overexpression, whereas disruption of TEAR1 resulted in leaf phenotypes resembling those caused by TIE1 overexpression or TCP dysfunction. Deficiency in TEAR partially rescued the leaf defects of TCP4 overexpression line and enhanced the wavy leaf phenotypes of jaw-5D. We propose that TEAR1 positively regulates CIN-like TCP activity to promote leaf development by mediating the degradation of the TCP repressor TIE1. PMID:28100709

Foraging on Individual Leaves by an Intracellular Feeding Insect Is Not Associated with Leaf Biomechanical Properties or Leaf Orientation

PubMed Central

Fiene, Justin; Kalns, Lauren; Nansen, Christian; Bernal, Julio; Harris, Marvin; Sword, Gregory A.

2013-01-01

Nearly all herbivorous arthropods make foraging-decisions on individual leaves, yet systematic investigations of the adaptive significance and ecological factors structuring these decisions are rare with most attention given to chewing herbivores. This study investigated why an intracellular feeding herbivore, Western flower thrips (WFT) Frankliniella occidentalis Pergande, generally avoids feeding on the adaxial leaf surface of cotton cotyledons. WFT showed a significant aversion to adaxial-feeding even when excised-cotyledons were turned up-side (abaxial-side ‘up’), suggesting that negative-phototaxis was not a primary cause of thrips foraging patterns. No-choice bioassays in which individual WFT females were confined to either the abaxial or adaxial leaf surface showed that 35% fewer offspring were produced when only adaxial feeding was allowed, which coincided with 32% less plant feeding on that surface. To test the hypothesis that leaf biomechanical properties inhibited thrips feeding on the adaxial surface, we used a penetrometer to measure two variables related to the ‘toughness’ of each leaf surface. Neither variable negatively co-varied with feeding. Thus, while avoiding the upper leaf surface was an adaptive foraging strategy, the proximate cause remains to be elucidated, but is likely due, in part, to certain leaf properties that inhibit feeding. PMID:24260510

Refining a major QTL controlling spotted wilt disease resistance in cultivated peanut (Arachis hypogaea L.)and evaluating its contribution to the resistance variations in peanut germplasm

USDA-ARS?s Scientific Manuscript database

Spotted wilt, caused by tomato spotted wilt virus (TSWV), has been one of major diseases in cultivated peanut grown in the southeastern United States (US) since 1990. Previously a major quantitative trait locus (QTL) controlling spotted wilt disease resistance was mapped to an interval of 2.55 cent...

Leaf area and photosynthesis of newly emerged trifoliolate leaves are regulated by mature leaves in soybean.

PubMed

Wu, Yushan; Gong, Wanzhuo; Wang, Yangmei; Yong, Taiwen; Yang, Feng; Liu, Weigui; Wu, Xiaoling; Du, Junbo; Shu, Kai; Liu, Jiang; Liu, Chunyan; Yang, Wenyu

2018-03-29

Leaf anatomy and the stomatal development of developing leaves of plants have been shown to be regulated by the same light environment as that of mature leaves, but no report has yet been written on whether such a long-distance signal from mature leaves regulates the total leaf area of newly emerged leaves. To explore this question, we created an investigation in which we collected data on the leaf area, leaf mass per area (LMA), leaf anatomy, cell size, cell number, gas exchange and soluble sugar content of leaves from three soybean varieties grown under full sunlight (NS), shaded mature leaves (MS) or whole plants grown in shade (WS). Our results show that MS or WS cause a marked decline both in leaf area and LMA in newly developing leaves. Leaf anatomy also showed characteristics of shade leaves with decreased leaf thickness, palisade tissue thickness, sponge tissue thickness, cell size and cell numbers. In addition, in the MS and WS treatments, newly developed leaves exhibited lower net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (E), but higher carbon dioxide (CO 2 ) concentration in the intercellular space (Ci) than plants grown in full sunlight. Moreover, soluble sugar content was significantly decreased in newly developed leaves in MS and WS treatments. These results clearly indicate that (1) leaf area, leaf anatomical structure, and photosynthetic function of newly developing leaves are regulated by a systemic irradiance signal from mature leaves; (2) decreased cell size and cell number are the major cause of smaller and thinner leaves in shade; and (3) sugars could possibly act as candidate signal substances to regulate leaf area systemically.

Dissecting black spot resistance in polyploid hybrid roses

USDA-ARS?s Scientific Manuscript database

Devastating foliar diseases, such as black spot caused by Diplocarpon rosae, pose constant threats to the ornamental quality of outdoor grown roses. Black spot is primarily managed though the use of fungicides, however, there is a high demand for resistant roses which require low chemical inputs. To...

Suppression of greasy spot disease caused by Mycosphaerella citri Whiteside on grapefruit trees in an organic orchard using an aqueous organic mixture of composted cornmeal, humic acid, molasses, and fish oil vs vegetable oil

USDA-ARS?s Scientific Manuscript database

Greasy spot disease of citrus, caused by the fungus Mycosphaerella citri Whiteside, afflicts citrus trees in all citrus-growing areas of the United States, eastern Mexico, Central America, and the Caribbean islands, causing premature defoliation, blemished fruit, and reduced tree vigor, yield, and f...

Does subepithelial hemorrhage cause persistence of laryngeal granuloma?

PubMed

Yumoto, Eiji; Sanuki, Tetsuji; Miyamaru, Satoru; Kumai, Yoshihiko

2008-05-01

To determine the incidence of black spots after resolution of laryngeal granuloma (LG), to compare the disease duration from the beginning of treatment to resolution between patients with and without black spots, and to assess the histologic findings of LG in resected or biopsied specimens. Retrospective. Forty-six patients with LG on the cartilaginous portion of the vocal fold were included. Their clinical records were reviewed. Histologic specimens were re-examined. Causes of LG were postintubation in 10 patients, unilateral vocal fold immobility in 1, Candida infection in 1, and were not specified in 34 (either hyperfunctional vocal abuse, laryngopharyngeal regurgitation, or both). Of the 10 patients with postintubation LG, 9 resolved; of the 33 patients with LG from other causes, 21 resolved. Of the 28 resolved patients, 12 developed a black spot at the previous lesion site. Of the 18 patients whose LG resolved without surgical intervention, 11 developed a black spot at the previous lesion site, and the remaining 7 patients did not develop any black spots. The treatment period until LG resolution was significantly longer among patients with a black spot than those without a spot (P = .0372). Histologic examination revealed the presence of hemosiderin accumulation accompanied by infiltration of lymphocytes and macrophages in 8 of the 16 patients who had their LGs resected or biopsied. Accumulation of hemosiderin in the subepithelial layer, together with little blood flow and dense connective tissue in the cartilaginous portion of the vocal fold, are important factors contributing to the persistence of LG.

Novel sources of leaf rust resistance in winter wheat

USDA-ARS?s Scientific Manuscript database

Leaf rust is one of the most widespread diseases of wheat, causing significant yield losses. More than 70 leaf rust resistance genes have been reported, but most of them have lost their effectiveness in the southern Great Plains of the USA. Thus continuous search for new sources of resistance is e...

Does elevated CO2 protect photosynthesis from damage by high temperature via modifying leaf water status in maize seedlings?

USDA-ARS?s Scientific Manuscript database

Because high temperatures under field conditions are associated with high water vapor pressure deficits, often causing leaf desiccation, we hypothesized that decreased stomatal conductance at elevated carbon dioxide may increase leaf water potential and protect photosynthesis in C4 species from dama...

Nitrogen Can Alleviate the Inhibition of Photosynthesis Caused by High Temperature Stress under Both Steady-State and Flecked Irradiance.

PubMed

Huang, Guanjun; Zhang, Qiangqiang; Wei, Xinghai; Peng, Shaobing; Li, Yong

2017-01-01

Nitrogen is one of the most important elements for plants and is closely related to photosynthesis. High temperature stress significantly inhibits photosynthesis under both steady-state and flecked irradiance. However, it is not known whether nitrogen can affect the decrease in photosynthesis caused by high temperature, especially under flecked irradiance. In the present study, a pot experiment was conducted under two nitrogen (N) supplies with rice plants, and the steady-state and dynamic photosynthesis rates were measured under 28 and 40°C. High temperature significantly increased leaf hydraulic conductance ( K leaf ) under high N supply (HN) but not under low N supply (LN). The increased K leaf maintained a constant leaf water potential (Ψ leaf ) and steady-state stomatal conductance ( g s,sat ) under HN, while the Ψ leaf and g s,sat significantly decreased under high temperature in LN conditions. This resulted in a more severe decrease in steady-state photosynthesis ( A sat ) under high temperature in the LN conditions. After shifting from low to high light, high temperature significantly delayed the recovery of photosynthesis, which resulted in more carbon loss under flecked irradiance. These effects were obtained under HN to a lesser extent than under LN supply. Therefore, it is concluded that nitrogen can alleviate the inhibition of photosynthesis caused by high temperature stress under both steady-state and flecked irradiance.

Rose parental characterization and population development for the identification of novel rose black spot resistance genes [abstract

USDA-ARS?s Scientific Manuscript database

Rose black spot disease, caused by the pathogen Diplocarpon rosae Wolf, is one of the most widespread and serious diseases of outdoor-grown roses worldwide. Defoliation caused by the disease compromises ornamental value, and repeated defoliation events weakens plants and can lead to plant death. Bot...

Relationship of soil properties and sugarcane yields to red stripe in Louisiana

USDA-ARS?s Scientific Manuscript database

Red stripe of sugarcane caused by Acidovorax avenae subsp. avenae consists of two forms: leaf stripe and top rot. Symptoms of red stripe in Louisiana observed by the authors between 1985 and 2010 were limited to the leaf stripe form which caused no apparent yield loss. During 2010, the more severe t...

Black-spot poison ivy.

PubMed

Schram, Sarah E; Willey, Andrea; Lee, Peter K; Bohjanen, Kimberly A; Warshaw, Erin M

2008-01-01

In black-spot poison ivy dermatitis, a black lacquerlike substance forms on the skin when poison ivy resin is exposed to air. Although the Toxicodendron group of plants is estimated to be the most common cause of allergic contact dermatitis in the United States, black-spot poison ivy dermatitis is relatively rare.

Molecular Detection of Rickettsia amblyommii in Amblyomma americanum Parasitizing Humans

DTIC Science & Technology

2010-01-01

Rocky Mountain spotted fever [RMSF...diseases in North Carolina: is "Rickettsia amblyommii" a possible cause of rickettsiosis reported as Rocky Mountain spotted fever ? Vector Borne Zoonot...HN, et al. Rickettsia parkeri rickettsiosis and its clinical distinction from Rocky Mountain spotted fever . Clin Infect Dis 2008; 47:1188-

Characterizing and identifying black spot resistance genes in polyploid roses

USDA-ARS?s Scientific Manuscript database

The ornamental quality of outdoor grown roses (Rosa hybrida) is under constant threat from foliar diseases, such as black spot caused by Diplocarpon rosae. Fungicides are primarily used to manage black spot; however, there is a high consumer demand for disease resistant roses which eliminate the nee...

Reversible and irreversible drought-induced changes in the anther proteome of rice (Oryza sativa L.) genotypes IR64 and Moroberekan.

PubMed

Liu, Jian-Xiang; Bennett, John

2011-01-01

Crop yield is most sensitive to water deficit during the reproductive stage. For rice, the most sensitive yield component is spikelet fertility and the most sensitive stage is immediately before heading. Here, we examined the effect of drought on the anther proteome of two rice genotypes: Moroberekan and IR64. Water was withheld for 3 d before heading (3DBH) in well watered controls for 5 d until the flag leaf relative water content (RWC) had declined to 45-50%. Plants were then re-watered and heading occurred 2-3 d later, representing a delay of 4-5 d relative to controls. The anther proteins were separated at 3 DBH, at the end of the stress period, and at heading in stressed/re-watered plants and controls by two-dimensional (2-D) gel electrophoresis, and 93 protein spots were affected reproducibly in abundance by drought during the experiment across two rice genotypes. After drought stress, upon re-watering, expressions of 24 protein spots were irreversible in both genotypes, 60 protein spots were irreversible in IR64 but reversible in Moroberekan, only nine protein spots were irreversible in Moroberekan while reversible in IR64. Among them, there were 14 newly drought-induced protein spots in IR64; none of them was reversible on re-watering. However, there were 13 newly drought-induced protein spots in Moroberekan, 10 of them were reversible on re-watering, including six drought-induced protein spots that were not reversed in IR64. Taken together, our proteomics data reveal that drought-tolerant genotype Moroberekan possessed better recovery capability following drought and re-watering at the anther proteome level than the drought-sensitive genotype IR64. The disruptions of drought to rice anther development and pollen cell functions are also discussed in the paper.

Impacts of including forest understory brightness and foliage clumping information from multiangular measurements on leaf area index mapping over North America

NASA Astrophysics Data System (ADS)

Pisek, Jan; Chen, Jing M.; Alikas, Krista; Deng, Feng

2010-09-01

A new leaf area index (LAI) data set in 10 day intervals with consideration of the understory reflectance and foliage clumping effects over North America for 1 year is developed. The data set brings effectively together measurements from multiple sensors with complementary capabilities (SPOT-VEGETATION, Multiangle Imaging Spectroradiometer, POLDER). First, the temporal consistency analysis indicated the new product is on par with other available LAI data sets currently used by the community. Second, with the removal of the background (understory in forests, moss, litter, and soil) effect on the forest overstory LAI retrieval, slightly different LAI reductions were found between needleleaf and broadleaf forests. This is caused by the more clumped nature of needleleaf forests, especially at higher LAI values, which allows more light to penetrate through the overstory canopy, making the understory more visible for equal LAI as compared to broadleaf forests. This is found over a representative set of 105 CEOS Benchmark Land Multisite Analysis and Intercomparison of Products sites in North America used for indirect validation. Third, the data set was directly validated and compared with Moderate Resolution Imaging Spectroradiometer Collection 5 LAI product using results from the BigFoot project for available forest test sites. This study demonstrates that the fusion of data inputs between multiple sensors can indeed lead to improved products and that multiangle remote sensing can help us to address effectively the issues (separating the signal from the understory and overstory, foliage clumping) that could not be solved via the means of the conventional mono-angle remote sensing.

Antibacterial Activity of Pharbitin, Isolated from the Seeds of Pharbitis nil, against Various Plant Pathogenic Bacteria.

PubMed

Nguyen, Hoa Thi; Yu, Nan Hee; Park, Ae Ran; Park, Hae Woong; Kim, In Seon; Kim, Jin-Cheol

2017-10-28

This study aimed to isolate and characterize antibacterial metabolites from Pharbitis nil seeds and investigate their antibacterial activity against various plant pathogenic bacteria. The methanol extract of P. nil seeds showed the strongest activity against Xanthomonas arboricola pv. pruni (Xap) with a minimum inhibition concentration (MIC) value of 250 μg/ml. Among the three solvent layers obtained from the methanol extract of P. nil seeds, only the butanol layer displayed the activity with an MIC value of 125 μg/ml against Xap. An antibacterial fraction was obtained from P. nil seeds by repeated column chromatography and identified as pharbitin, a crude resin glycoside, by instrumental analysis. The antibacterial activity of pharbitin was tested in vitro against 14 phytopathogenic bacteria, and it was found to inhibit Ralstonia solanacearum and four Xanthomonas species. The minimum inhibitory concentration values against the five bacteria were 125-500 μg/ml for the n-butanol layer and 31.25-125 μg/ml for pharbitin. In a detached peach leaf assay, it effectively suppressed the development of bacterial leaf spot, with a control value of 87.5% at 500 μg/ml. In addition, pharbitin strongly reduced the development of bacterial wilt on tomato seedlings by 97.4% at 250 μg/ml, 7 days after inoculation. These findings suggest that the crude extract of P. nil seeds can be used as an alternative biopesticide for the control of plant diseases caused by R. solanacearum and Xanthomonas spp. This is the first report on the antibacterial activity of pharbitin against phytopathogenic bacteria.

Absence of plant uptake and translocation of polybrominated biphenyls (PBBs).

PubMed

Chou, S F; Jacobs, L W; Penner, D; Tiedje, J M

1978-04-01

Studies of polybrominated biphenyl (PBB) uptake by plants have been conducted in hydroponic solutions and in greenhouse experiments with soil. Autoradiograms of corn and soybean seedlings grown in hydroponic solutions showed no translocation of 14C-PBB from 14C-PBB-treated solutions to plant tops or within the leaf from 14C-PBB-treated spots on the upper leaf surface. A significant portion of the 14C-PBB associated with the roots was removed when the roots were dipped in acetone. Three root crops (radishes, carrots, and onions) were grown in two soils, each treated with a mixture of FireMaster BP-6 (PBB) and 14C-PBB to achieve final concentrations of 100 ppm and 100 ppb. All roots showed more PBB when grown in the soil with the lower clay and organic matter content than they did when grown in the soil with more clay and organic matter. In the latter soil (clay loam) no PBB was detected in any roots from the 100 ppb treatment. More PBB was associated with roots of carrot than of radish or onion. Corn leaf whorls containing dust from a PBB contamination soil and washed radishes from a heavily contaminated garden showed no PBB.

Comparative proteomics of leaves found at different stem positions of maize seedlings.

PubMed

Chen, Yi-Bo; Wang, Dan; Ge, Xuan-Liang; Zhao, Biligen-Gaowa; Wang, Xu-Chu; Wang, Bai-Chen

2016-07-01

To better understand the roles of leaves at different stem positions during plant development, we measured the physiological properties of leaves 1-4 on maize seedling stems, and performed a proteomics study to investigate the differences in protein expression in the four leaves using two-dimensional difference gel electrophoresis and tandem mass spectrometry in conjunction with database searching. A total of 167 significantly differentially expressed protein spots were found and identified. Of these, 35% are involved in photosynthesis. By further analysis of the data, we speculated that in leaf 1 the seedling has started to transition from a heterotroph to an autotroph, development of leaf 2 is the time at which the seedling fully transitions from a heterotroph to an autotroph, and leaf maturity was reached only with fully expanded leaves 3 and 4, although there were still some protein expression differences in the two leaves. These results suggest that the different leaves make different contributions to maize seedling growth via modulation of the expression of the photosynthetic proteins. Together, these results provide insight into the roles of the different maize leaves as the plant develops from a heterotroph to an autotroph. Copyright © 2016 Elsevier GmbH. All rights reserved.

A one-step multiplex RT-PCR assay for simultaneous detection of four viruses that infect peach.

PubMed

Yu, Y; Zhao, Z; Jiang, D; Wu, Z; Li, S

2013-10-01

A multiplex reverse transcription polymerase chain reaction (mRT-PCR) assay was developed to enable the simultaneous detection and differentiation of four viruses that infect peach, namely Apple chlorotic leaf spot virus (ACLSV), Cherry green ring mottle virus (CGRMV), Prunus necrotic ringspot virus (PNRSV) and Apricot pseudo-chlorotic leaf spot virus (APCLSV). In this study, four pairs of primers, one specific for each virus, were designed; the corresponding PCR products were 632, 439, 346 and 282 bp in length for ACLSV, CGRMV, PNRSV and APCLSV, respectively, and the fragments could be distinguished clearly by agarose gel electrophoresis. The sensitivity and specificity of the method were tested using individual RT-PCR and enzyme-linked immunosorbent assay (ELISA), and the identity of the RT-PCR amplification products was also confirmed by DNA sequencing. The results of RT-PCR and ELISA, along with batch detection using samples collected from peach orchards, revealed that this rapid and simple technique is an effective way to identify the four viruses simultaneously. The mRT-PCR assay described in this study was developed for the simultaneous detection of four peach viruses from infected peach samples is reliable and sensitive. In contrast to conventional uniplex RT-PCR, mRT-PCR is more efficient, reducing costs, time and handling when testing large numbers of samples. This rapid and simple method is useful for large-scale surveys of viruses that infect peach. © 2013 The Society for Applied Microbiology.

Xylem Cavitation in the Leaf of Prunus laurocerasus and Its Impact on Leaf Hydraulics1

PubMed Central

Nardini, Andrea; Tyree, Melvin T.; Salleo, Sebastiano

2001-01-01

This paper reports how water stress correlates with changes in hydraulic conductivity of stems, leaf midrib, and whole leaves of Prunus laurocerasus. Water stress caused cavitation-induced dysfunction in vessels of P. laurocerasus. Cavitation was detected acoustically by counts of ultrasonic acoustic emissions and by the loss of hydraulic conductivity measured by a vacuum chamber method. Stems and midribs were approximately equally vulnerable to cavitations. Although midribs suffered a 70% loss of hydraulic conductance at leaf water potentials of −1.5 MPa, there was less than a 10% loss of hydraulic conductance in whole leaves. Cutting and sealing the midrib 20 mm from the leaf base caused only a 30% loss of conduction of the whole leaf. A high-pressure flow meter was used to measure conductance of whole leaves and as the leaf was progressively cut back from tip to base. These data were fitted to a model of hydraulic conductance of leaves that explained the above results, i.e. redundancy in hydraulic pathways whereby water can flow around embolized regions in the leaf, makes whole leaves relatively insensitive to significant changes in conductance of the midrib. The onset of cavitation events in P. laurocerasus leaves correlated with the onset of stomatal closure as found recently in studies of other species in our laboratory. PMID:11299351

Hydraulic properties of rice and the response of gas exchange to water stress.

PubMed

Stiller, Volker; Lafitte, H Renee; Sperry, John S

2003-07-01

We investigated the role of xylem cavitation, plant hydraulic conductance, and root pressure in the response of rice (Oryza sativa) gas exchange to water stress. In the field (Philippines), the percentage loss of xylem conductivity (PLC) from cavitation exceeded 60% in leaves even in watered controls. The PLC versus leaf water potential relationship indicated diurnal refilling of cavitated xylem. The leaf water potential causing 50 PLC (P(50)) was -1.6 MPa and did not differ between upland versus lowland rice varieties. Greenhouse-grown varieties (Utah) were more resistant to cavitation with a 50 PLC of -1.9 MPa but also showed no difference between varieties. Six-day droughts caused concomitant reductions in leaf-specific photosynthetic rate, leaf diffusive conductance, and soil-leaf hydraulic conductance that were associated with cavitation-inducing water potentials and the disappearance of nightly root pressure. The return of root pressure after drought was associated with the complete recovery of leaf diffusive conductance, leaf-specific photosynthetic rate, and soil-leaf hydraulic conductance. Root pressure after the 6-d drought (61.2 +/- 8.8 kPa) was stimulated 7-fold compared with well-watered plants before drought (8.5 +/- 3.8 kPa). The results indicate: (a) that xylem cavitation plays a major role in the reduction of plant hydraulic conductance during drought, and (b) that rice can readily reverse cavitation, possibly aided by nocturnal root pressure.

Multiple forms of ADP-glucose pyrophosphorylase from tomato fruit

NASA Technical Reports Server (NTRS)

Chen, B. Y.; Janes, H. W.

1997-01-01

ADP-glucose pyrophosphorylase (AGP) was purified from tomato (Lycopersicon esculentum Mill.) fruit to apparent homogeneity. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis the enzyme migrated as two close bands with molecular weights of 50,000 and 51,000. Two-dimensional polyacrylamide gel electrophoresis analysis of the purified enzyme, however, revealed at least five major protein spots that could be distinguished by their slight differences in net charge and molecular weight. Whereas all of the spots were recognized by the antiserum raised against tomato fruit AGP holoenzyme, only three of them reacted strongly with antiserum raised against the potato tuber AGP large subunit, and the other two spots (with lower molecular weights) reacted specifically with antisera raised against spinach leaf AGP holoenzyme and the potato tuber AGP small subunit. The results suggest the existence of at least three isoforms of the AGP large subunit and two isoforms of the small subunit in tomato fruit in vivo. The native molecular mass of the enzyme determined by gel filtration was 220 +/- 10 kD, indicating a tetrameric structure for AGP from tomato fruit. The purified enzyme is very sensitive to 3-phosphoglycerate/inorganic phosphate regulation.

Determining the spatial variability of crop yields of two different climatic regions in Southwest Germany

NASA Astrophysics Data System (ADS)

Eshonkulov, Ravshan; Poyda, Arne; Ingwersen, Joachim; Streck, Thilo

2017-04-01

Assessing the spatial variability of soil physical properties is crucial for agricultural land management. We determined the spatial variability within two agricultural fields in the regions of Kraichgau and Swabian Jura in Southwest Germany. We determined soil physical properties and recorded the temporal development of soil mineral nitrogen (N) and water content as well as that of plant variables (phenology, biomass, leaf area index (LAI), N content, green vegetation fraction (GVF). The work was conducted during the vegetation periods of 2015 and 2016 in winter wheat, and winter rapeseed in Kraichgau and winter barley and silage maize on Swabian Jura. Measurements were taken in three-weekly intervals. On each field, we identified three plots with reduced plant development using high-resolution (RapidEye) satellite images ("cold spots"). Measurements taken on these cold spots were compared to those from five established (long-term) reference plots representing the average field variability. The software EXPERT-N was used to simulate the soil crop system at both cold spots and reference plots. Sensitivity analyses were conducted to identify the most important parameters for the determination of spatial variability in crop growth dynamics.

Genome-wide association mapping reveals novel QTL for seedling leaf rust resistance in a worldwide collection of winter wheat

USDA-ARS?s Scientific Manuscript database

Leaf rust is a major disease that causes significant wheat yield losses worldwide. Growing resistant cultivars is an effective approach to reduce disease losses. The short-lived nature of leaf rust resistance (Lr) genes necessitates a continuous search for novel sources of resistance. We performe...

Transcriptomics reveals multiple resistance mechanisms against cotton leaf curl disease in a naturally immune cotton species, Gossypium arboreum

USDA-ARS?s Scientific Manuscript database

Cotton is an economically important crop affected by a number of abiotic and biotic stresses. Cotton leaf curl disease (CLCuD) is caused by virus in the genus Begomovirus (family Geminiviridae), collectively called cotton leaf curl viruses (CLCuVs). It is one of the most devastating virual diseases ...

Genetics of leaf rust resistance in the hard red winter wheat cultivars Santa Fe and Duster

USDA-ARS?s Scientific Manuscript database

Leaf rust caused by Puccinia triticina is a common and important disease of hard red winter wheat in the Great Plains of the United States. The hard red winter wheat cultivars 'Santa Fe' and 'Duster' have had effective leaf rust resistance since their release in 2003 and 2006, respectively. Both cul...

First report of pecan bacterial leaf scorch caused by Xylella fastidiosa in pecan (Carya illinoinensis) in Arizona, New Mexico, California, and Texas

USDA-ARS?s Scientific Manuscript database

Pecan bacterial leaf scorch (PBLS) is a chronic disease that can cause major yield losses in pecan orchards. In the 2015-16 growing seasons, symptoms consistent with PBLS were observed in commercial pecan cultivars in AZ, NM, CA and TX. Symptoms included tan to light brown necrotic lesions, which ...

Effect of Leaf Water Potential on Internal Humidity and CO 2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure

DOE PAGES

Vesala, Timo; Sevanto, Sanna; Grönholm, Tiia; ...

2017-02-06

The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flatmore » surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO 2, thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO 2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Here, our results indicate that the reduction in vapor pressures of water and CO 2 could enhance plant water use efficiency up to about 10% at a leaf water potential of -2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. Lastly, the omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO 2 concentration based on leaf gas exchange measurements. Manufactures of leaf gas exchange measurement systems should incorporate leaf water potentials in measurement set-ups.« less

Effect of Leaf Water Potential on Internal Humidity and CO 2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure

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

Vesala, Timo; Sevanto, Sanna; Grönholm, Tiia

The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flatmore » surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO 2, thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO 2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Here, our results indicate that the reduction in vapor pressures of water and CO 2 could enhance plant water use efficiency up to about 10% at a leaf water potential of -2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. Lastly, the omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO 2 concentration based on leaf gas exchange measurements. Manufactures of leaf gas exchange measurement systems should incorporate leaf water potentials in measurement set-ups.« less

Effect of Leaf Water Potential on Internal Humidity and CO2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure

PubMed Central

Vesala, Timo; Sevanto, Sanna; Grönholm, Tiia; Salmon, Yann; Nikinmaa, Eero; Hari, Pertti; Hölttä, Teemu

2017-01-01

The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flat surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO2, thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Our results indicate that the reduction in vapor pressures of water and CO2 could enhance plant water use efficiency up to about 10% at a leaf water potential of −2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. The omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO2 concentration based on leaf gas exchange measurements. Manufactures of leaf gas exchange measurement systems should incorporate leaf water potentials in measurement set-ups. PMID:28220128

Effect of Leaf Water Potential on Internal Humidity and CO2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure.

PubMed

Vesala, Timo; Sevanto, Sanna; Grönholm, Tiia; Salmon, Yann; Nikinmaa, Eero; Hari, Pertti; Hölttä, Teemu

2017-01-01

The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flat surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO 2 , thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO 2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Our results indicate that the reduction in vapor pressures of water and CO 2 could enhance plant water use efficiency up to about 10% at a leaf water potential of -2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. The omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO 2 concentration based on leaf gas exchange measurements. Manufactures of leaf gas exchange measurement systems should incorporate leaf water potentials in measurement set-ups.

Spotted owl roost and nest site selection in northwestern California

Treesearch

J.A. Blakesley; A.B. Franklin; R.J. Gutierrez

1992-01-01

We directly observed roost and nest site selection in a population of northern spotted owls (Strix occidentalis caurina) in northwestern California during 1985-89. Because of potential biases caused by use of radio telemetry in previous studies, we examined habitat use relative to habitat availability at a level not previously reported for spotted...

Effects of genotype and isolate on expression of dollar spot in seashore paspalum

USDA-ARS?s Scientific Manuscript database

Seashore paspalum (Paspalum vaginatum Swartz) is a warm-season turfgrass species primarily utilized on golf courses and athletic fields and is often impacted by dollar spot disease. Dollar spot, caused by Sclerotinia homoeocarpa F.T. Bennett, is a major fungal disease and the most common turfgrass p...

Outbreak of Rocky Mountain spotted fever in Córdoba, Colombia.

PubMed

Hidalgo, Marylin; Miranda, Jorge; Heredia, Damaris; Zambrano, Pilar; Vesga, Juan Fernando; Lizarazo, Diana; Mattar, Salim; Valbuena, Gustavo

2011-02-01

Rocky Mountain spotted fever (RMSF) is a tick-borne disease caused by the obligate intracellular bacterium Rickettsia rickettsii. Although RMSF was first reported in Colombia in 1937, it remains a neglected disease. Herein, we describe the investigation of a large cluster of cases of spotted fever rickettsiosis in a new area of Colombia.

The efficacy of breeding for brown spot disease resistance in longleaf pine

Treesearch

D.P. Gwaze; Larry H. Lott; C. Dana Nelson

2003-01-01

The study objective was to determine whether selection for brown spot disease (caused by Scirrhia acicola (Dearn.) Siggers) resistance in longleaf pine (Pinus palustris Mill.) is beneficial for areas where brown spot is not present. Two groups of selections, comprising those that performed (survival and growth) well in the presence...

7 CFR 30.5 - Class.

Code of Federal Regulations, 2012 CFR

2012-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.5 Class. One of the major divisions of leaf tobacco based on the distinct characteristics of the tobacco caused...

7 CFR 30.5 - Class.

Code of Federal Regulations, 2013 CFR

2013-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.5 Class. One of the major divisions of leaf tobacco based on the distinct characteristics of the tobacco caused...

7 CFR 30.5 - Class.

Code of Federal Regulations, 2010 CFR

2010-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.5 Class. One of the major divisions of leaf tobacco based on the distinct characteristics of the tobacco caused...

7 CFR 30.5 - Class.

Code of Federal Regulations, 2011 CFR

2011-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.5 Class. One of the major divisions of leaf tobacco based on the distinct characteristics of the tobacco caused...

7 CFR 30.5 - Class.

Code of Federal Regulations, 2014 CFR

2014-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.5 Class. One of the major divisions of leaf tobacco based on the distinct characteristics of the tobacco caused...

First Report of Black Spot Disease Caused by Alternaria alternata on Sweet Persimmon Fruits

PubMed Central

Lee, Jung Han; Kim, Jinwoo

2013-01-01

Black spot of sweet persimmon, caused by Alternaria alternata, occurred in an orchard in Gyeongnam province, Korea in 2012. The symptom was appearance of 0.5 to 4 cm black spots on the surface of fruit. The pathogen was isolated from flesh of disease lesions. The causal agent was identified as A. alternata by morphological characteristics and sequencers of the internal transcribed spacer (ITS) 1 and ITS4 regions of rRNA. Artificial inoculation of the pathogen resulted in development of disease symptoms and the re-isolated pathogen showed characteristics of A. alternata. PMID:24198674

In vitro lethal efficacy of leaf extract of Cannabis sativa Linn on the larvae of Chironomous samoensis Edward: an insect of public health concern.

PubMed

Roy, Bishnupada; Dutta, B K

2003-11-01

Leaf extract of C. sativa causes paralysis leading to death in larvae of C. samoensis. The extract brought a drastic change in the morphology of sensilla trichoidea and the general body cuticle. The larvae exposed to the leaf extract also showed a significant reduction in the concentration of Mg and Fe, while Mn showed only slight average increase. Since the sensilla trichoidea has nerve connection, it is expected that the toxic principle of the leaf extract has affected the central nervous system. The significant reduction of the level of Fe indicates that the extract could cause the reduction in oxygen binding capacity of the haemolymph, thereby acting as a respiratory poison in addition to its known role as a neurotoxic substance.

Genetics of Leaf Rust Resistance in the Soft Red Winter Wheat Cultivars Coker 9663 and Pioneer 26R61

USDA-ARS?s Scientific Manuscript database

Leaf rust, caused by the fungus Puccinia triticina, is an important disease of soft red winter wheat cultivars that are grown in the southern and eastern United States. The objectives of this study were to identify the leaf rust resistance genes in two soft red winter wheat cultivars, Coker 9663 and...

Engineered disease resistance in cotton using RNA-interference to knock down cotton leaf curl kokhran virus-Burewala and cotton leaf curl Multan betasatellite

USDA-ARS?s Scientific Manuscript database

Cotton Leaf Curl virus Disease (CLCuD) has caused enormous losses in cotton (Gossypium hirsutum) production in Pakistan. RNA interference (RNAi) is an emerging technique that could knock out CLCuD by targeting different regions of the pathogen genome that are important for replication, transcription...

Survey of Sycamore Plantations for Canker, Leaf Scorch, and Dieback

Treesearch

T. H. Filer; D. T. Cooper; R. J. Collins; R. Wolfe

1975-01-01

Twenty-six sycamore plantations surveyed in Louisiana, Mississippi, Arkansas, and Tennessee in 1973 had leaf scorch symptoms; cankers caused mor tality in six lower Mississippi Delta s tands. Symptoms of the disease are leaf scorch, top diebac k, and trunk canker. No trees under 4 years old had dieback, and none unde r 6 years old had lethal trunk canker.

An entomopathogenic fungus and nematode prove ineffective for biocontrol of an invasive leaf miner Profenusa thomsoni in Alaska

Treesearch

Robert Progar; J.J. Kruse; John Lundquist; K.P. Zogas; M.J. Rinella

2015-01-01

A non-native invasive sawfly, the amber-marked birch leaf miner Profenusa thomsoni (Konow), was first detected in south-central Alaska in 1996 and is now widely distributed throughout urban and wild birch trees in Alaska. Impacts have been considered primarily aesthetic because leaf miners cause leaves of birch trees (Betula...

Herbivores alter plant-wind interactions by acting as a point mass on leaves and by removing leaf tissue.

PubMed

Kothari, Adit R; Burnett, Nicholas P

2017-09-01

In nature, plants regularly interact with herbivores and with wind. Herbivores can wound and alter the structure of plants, whereas wind can exert aerodynamic forces that cause the plants to flutter or sway. While herbivory has many negative consequences for plants, fluttering in wind can be beneficial for plants by facilitating gas exchange and loss of excess heat. Little is known about how herbivores affect plant motion in wind. We tested how the mass of an herbivore resting on a broad leaf of the tulip tree Liriodendron tulipifera , and the damage caused by herbivores, affected the motion of the leaf in wind. For this, we placed mimics of herbivores on the leaves, varying each herbivore's mass or position, and used high-speed video to measure how the herbivore mimics affected leaf movement and reconfiguration at two wind speeds inside a laboratory wind tunnel. In a similar setup, we tested how naturally occurring herbivore damage on the leaves affected leaf movement and reconfiguration. We found that the mass of an herbivore resting on a leaf can change that leaf's orientation relative to the wind and interfere with the ability of the leaf to reconfigure into a smaller, more streamlined shape. A large herbivore load slowed the leaf's fluttering frequency, while naturally occurring damage from herbivores increased the leaf's fluttering frequency. We conclude that herbivores can alter the physical interactions between wind and plants by two methods: (1) acting as a point mass on the plant while it is feeding and (2) removing tissue from the plant. Altering a plant's interaction with wind can have physical and physiological consequences for the plant. Thus, future studies of plants in nature should consider the effect of herbivory on plant-wind interactions, and vice versa.

Factors controlling plasticity of leaf morphology in Robinia pseudoacacia L. II: the impact of water stress on leaf morphology of seedlings grown in a controlled environment chamber

Treesearch

M.T. Tyree

2012-01-01

Context. The cause of morphological plasticity of leaves within the crowns of tall trees still debated. Whether it is driven by irradiance or hydraulic constraints is inconclusive. In a previous study, we hypothesized that water stress caused between-site and within-tree morphological variability in mature Robinia trees.

First report of dollar spot disease, caused by Sclerotinia homoeocarpa, of Agrostis stolonifera in Sweden

USDA-ARS?s Scientific Manuscript database

Dollar spot is a destructive and widespread disease affecting most grass species grown as turf, but until recently it has been absent from the Scandinavian countries of northern Europe. In the fall of 2014, disease symptoms consistent with dollar spot were observed on a golf course fairway in Sweden...

Use of NAP gene to manipulate leaf senescence in plants

DOEpatents

Gan, Susheng; Guo, Yongfeng

2013-04-16

The present invention discloses transgenic plants having an altered level of NAP protein compared to that of a non-transgenic plant, where the transgenic plants display an altered leaf senescence phenotype relative to a non-transgenic plant, as well as mutant plants comprising an inactivated NAP gene, where mutant plants display a delayed leaf senescence phenotype compared to that of a non-mutant plant. The present invention also discloses methods for delaying leaf senescence in a plant, as well as methods of making a mutant plant having a decreased level of NAP protein compared to that of a non-mutant plant, where the mutant plant displays a delayed leaf senescence phenotype relative to a non-mutant plant. Methods for causing precocious leaf senescence or promoting leaf senescence in a plant are also disclosed. Also disclosed are methods of identifying a candidate plant suitable for breeding that displays a delayed leaf senescence and/or enhanced yield phenotype.

Effect of greenhouse conditions on the leaf apoplastic proteome of Coffea arabica plants.

PubMed

Guerra-Guimarães, Leonor; Vieira, Ana; Chaves, Inês; Pinheiro, Carla; Queiroz, Vagner; Renaut, Jenny; Ricardo, Cândido P

2014-06-02

This work describes the coffee leaf apoplastic proteome and its modulation by the greenhouse conditions. The apoplastic fluid (APF) was obtained by leaf vacuum infiltration, and the recovered proteins were separated by 2-DE and subsequently identified by matrix assisted laser desorption/ionization time of flight-mass spectrometry, followed by homology search in EST coffee databases. Prediction tools revealed that the majority of the 195 identified proteins are involved in cell wall metabolism and in stress/defense responses. Although most of the proteins follow the classical secretory mechanism, a low percentage of them seem to result from unconventional secretion (leaderless secreted proteins). Principal components analysis revealed that the APF samples formed two distinct groups, with the temperature amplitude mostly contributing for this separation (higher or lower than 10°C, respectively). Sixty one polypeptide spots allowed defining these two groups and 28 proteins were identified, belonging to carbohydrate metabolism, cell wall modification and proteolysis. Interestingly stress/defense proteins appeared as more abundant in Group I which is associated with a higher temperature amplitude. It seems that the proteins in the coffee leaf APF might be implicated in structural modifications in the extracellular space that are crucial for plant development/adaptation to the conditions of the prevailing environment. This is the first detailed proteomic study of the coffee leaf apoplastic fluid (APF) and of its modulation by the greenhouse conditions. The comprehensive overview of the most abundant proteins present in the extra-cellular compartment is particularly important for the understanding of coffee responses to abiotic/biotic stress. This article is part of a Special Issue entitled: Environmental and structural proteomics. Copyright © 2014 Elsevier B.V. All rights reserved.

Revealing catastrophic failure of leaf networks under stress

PubMed Central

Brodribb, Timothy J.; Bienaimé, Diane; Marmottant, Philippe

2016-01-01

The intricate patterns of veins that adorn the leaves of land plants are among the most important networks in biology. Water flows in these leaf irrigation networks under tension and is vulnerable to embolism-forming cavitations, which cut off water supply, ultimately causing leaf death. Understanding the ways in which plants structure their vein supply network to protect against embolism-induced failure has enormous ecological and evolutionary implications, but until now there has been no way of observing dynamic failure in natural leaf networks. Here we use a new optical method that allows the initiation and spread of embolism bubbles in the leaf network to be visualized. Examining embolism-induced failure of architecturally diverse leaf networks, we found that conservative rules described the progression of hydraulic failure within veins. The most fundamental rule was that within an individual venation network, susceptibility to embolism always increased proportionally with the size of veins, and initial nucleation always occurred in the largest vein. Beyond this general framework, considerable diversity in the pattern of network failure was found between species, related to differences in vein network topology. The highest-risk network was found in a fern species, where single events caused massive disruption to leaf water supply, whereas safer networks in angiosperm leaves contained veins with composite properties, allowing a staged failure of water supply. These results reveal how the size structure of leaf venation is a critical determinant of the spread of embolism damage to leaves during drought. PMID:27071104

Revealing catastrophic failure of leaf networks under stress.

PubMed

Brodribb, Timothy J; Bienaimé, Diane; Marmottant, Philippe

2016-04-26

The intricate patterns of veins that adorn the leaves of land plants are among the most important networks in biology. Water flows in these leaf irrigation networks under tension and is vulnerable to embolism-forming cavitations, which cut off water supply, ultimately causing leaf death. Understanding the ways in which plants structure their vein supply network to protect against embolism-induced failure has enormous ecological and evolutionary implications, but until now there has been no way of observing dynamic failure in natural leaf networks. Here we use a new optical method that allows the initiation and spread of embolism bubbles in the leaf network to be visualized. Examining embolism-induced failure of architecturally diverse leaf networks, we found that conservative rules described the progression of hydraulic failure within veins. The most fundamental rule was that within an individual venation network, susceptibility to embolism always increased proportionally with the size of veins, and initial nucleation always occurred in the largest vein. Beyond this general framework, considerable diversity in the pattern of network failure was found between species, related to differences in vein network topology. The highest-risk network was found in a fern species, where single events caused massive disruption to leaf water supply, whereas safer networks in angiosperm leaves contained veins with composite properties, allowing a staged failure of water supply. These results reveal how the size structure of leaf venation is a critical determinant of the spread of embolism damage to leaves during drought.

Thin Layer Chromatography-Bioautography and Gas Chromatography-Mass Spectrometry of Antimicrobial Leaf Extracts from Philippine Piper betle L. against Multidrug-Resistant Bacteria.

PubMed

Valle, Demetrio L; Puzon, Juliana Janet M; Cabrera, Esperanza C; Rivera, Windell L

2016-01-01

This study isolated and identified the antimicrobial compounds of Philippine Piper betle L. leaf ethanol extracts by thin layer chromatography- (TLC-) bioautography and gas chromatography-mass spectrometry (GC-MS). Initially, TLC separation of the leaf ethanol extracts provided a maximum of eight compounds with R f values of 0.92, 0.86, 0.76, 0.53, 0.40, 0.25, 0.13, and 0.013, best visualized when inspected under UV 366 nm. Agar-overlay bioautography of the isolated compounds demonstrated two spots with R f values of 0.86 and 0.13 showing inhibitory activities against two Gram-positive multidrug-resistant (MDR) bacteria, namely, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. The compound with an R f value of 0.86 also possessed inhibitory activity against Gram-negative MDR bacteria, namely, carbapenem-resistant Enterobacteriaceae-Klebsiella pneumoniae and metallo-β-lactamase-producing Acinetobacter baumannii. GC-MS was performed to identify the semivolatile and volatile compounds present in the leaf ethanol extracts. Six compounds were identified, four of which are new compounds that have not been mentioned in the medical literature. The chemical compounds isolated include ethyl diazoacetate, tris(trifluoromethyl)phosphine, heptafluorobutyrate, 3-fluoro-2-propynenitrite, 4-(2-propenyl)phenol, and eugenol. The results of this study could lead to the development of novel therapeutic agents capable of dealing with specific diseases that either have weakened reaction or are currently not responsive to existing drugs.

Thin Layer Chromatography-Bioautography and Gas Chromatography-Mass Spectrometry of Antimicrobial Leaf Extracts from Philippine Piper betle L. against Multidrug-Resistant Bacteria

PubMed Central

Valle, Demetrio L.; Puzon, Juliana Janet M.; Cabrera, Esperanza C.

2016-01-01

This study isolated and identified the antimicrobial compounds of Philippine Piper betle L. leaf ethanol extracts by thin layer chromatography- (TLC-) bioautography and gas chromatography-mass spectrometry (GC-MS). Initially, TLC separation of the leaf ethanol extracts provided a maximum of eight compounds with R f values of 0.92, 0.86, 0.76, 0.53, 0.40, 0.25, 0.13, and 0.013, best visualized when inspected under UV 366 nm. Agar-overlay bioautography of the isolated compounds demonstrated two spots with R f values of 0.86 and 0.13 showing inhibitory activities against two Gram-positive multidrug-resistant (MDR) bacteria, namely, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. The compound with an R f value of 0.86 also possessed inhibitory activity against Gram-negative MDR bacteria, namely, carbapenem-resistant Enterobacteriaceae-Klebsiella pneumoniae and metallo-β-lactamase-producing Acinetobacter baumannii. GC-MS was performed to identify the semivolatile and volatile compounds present in the leaf ethanol extracts. Six compounds were identified, four of which are new compounds that have not been mentioned in the medical literature. The chemical compounds isolated include ethyl diazoacetate, tris(trifluoromethyl)phosphine, heptafluorobutyrate, 3-fluoro-2-propynenitrite, 4-(2-propenyl)phenol, and eugenol. The results of this study could lead to the development of novel therapeutic agents capable of dealing with specific diseases that either have weakened reaction or are currently not responsive to existing drugs. PMID:27478476

Visceral leishmaniasis with Roth spots

PubMed Central

Meena, Jagdish; Juneja, Monica; Mishra, Devendra; Vats, Pallavi; Pawaria, Arti

2014-01-01

Visceral leishmaniasis (VL) is caused by the protozoan parasite Leishmania donovani and transmitted by the bite of infected sandfly Phlebotomus argentipes. The protozoa is obliged intracellularly and causes a wide spectrum of clinical syndromes: VL (‘kala azar’), cutaneous leishmaniasis and mucocutaneous leishmaniasis (espundia). Kala azar is the most aggressive form and if untreated causes high mortality. Here, we describe a case of VL that presented to us with high-grade fever and found to have Roth spots that were resolved after 15 days of therapy. PMID:25988048

Characterization of a commercial multileaf collimator used for intensity modulated radiation therapy.

PubMed

Low, D A; Sohn, J W; Klein, E E; Markman, J; Mutic, S; Dempsey, J F

2001-05-01

The characteristics of a commercial multileaf collimator (MLC) to deliver static and dynamic multileaf collimation (SMLC and DMLC, respectively) were investigated to determine their influence on intensity modulated radiation therapy (IMRT) treatment planning and quality assurance. The influence of MLC leaf positioning accuracy on sequentially abutted SMLC fields was measured by creating abutting fields with selected gaps and overlaps. These data were also used to measure static leaf positioning precision. The characteristics of high leaf-velocity DMLC delivery were measured with constant velocity leaf sequences starting with an open field and closing a single leaf bank. A range of 1-72 monitor units (MU) was used providing a range of leaf velocities. The field abutment measurements yielded dose errors (as a percentage of the open field max dose) of 16.7+/-0.7% mm(-1) and 12.8+/-0.7% mm(-1) for 6 MV and 18 MV photon beams, respectively. The MLC leaf positioning precision was 0.080+/-0.018 mm (single standard deviation) highlighting the excellent delivery hardware tolerances for the tested beam delivery geometry. The high leaf-velocity DMLC measurements showed delivery artifacts when the leaf sequence and selected monitor units caused the linear accelerator to move the leaves at their maximum velocity while modulating the accelerator dose rate to deliver the desired leaf and MU sequence (termed leaf-velocity limited delivery). According to the vendor, a unique feature to their linear accelerator and MLC is that the dose rate is reduced to provide the correct cm MU(-1) leaf velocity when the delivery is leaf-velocity limited. However, it was found that the system delivered roughly 1 MU per pulse when the delivery was leaf-velocity limited causing dose profiles to exhibit discrete steps rather than a smooth dose gradient. The root mean square difference between the steps and desired linear gradient was less than 3% when more than 4 MU were used. The average dose per MU was greater and less than desired for closing and opening leaf patterns, respectively, when the delivery was leaf-velocity limited. The results indicated that the dose delivery artifacts should be minor for most clinical cases, but limit the assumption of dose linearity when significantly reducing the delivered dose for dosimeter characterization studies or QA measurements.

Ehrlichiosis

MedlinePlus

... cause a number of serious diseases worldwide, including Rocky Mountain spotted fever and typhus . All of these diseases are spread ... cases. Sometimes, the disease may be mistaken for Rocky Mountain spotted fever. The symptoms are often mild, but people are ...

7 CFR 51.1521 - U.S. No. 1.

Code of Federal Regulations, 2010 CFR

2010-01-01

...; which are free from decay and sunscald, and free from damage caused by broken skins, heat injury, growth cracks, sunburn, split pits, hail marks, drought spots, gum spots, russeting, scars, other disease...

7 CFR 51.1304 - U.S. No. 2.

Code of Federal Regulations, 2010 CFR

2010-01-01

... end, or broken skins. The pears shall also be free from serious damage caused by bruises, russeting, limbrubs, hail, scars, cork spot, drought spot, sunburn, sprayburn, stings or other insect injury, disease...

7 CFR 51.1301 - U.S. Extra No. 1.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., internal breakdown, scald, freezing injury, worm holes, black end, hard end, drought spot, and free from injury caused by russeting, limbrubs, hail, scars, cork spot, sunburn, sprayburn, stings or other insect...

Emittance Growth in the DARHT-II Linear Induction Accelerator

DOE PAGES

Ekdahl, Carl; Carlson, Carl A.; Frayer, Daniel K.; ...

2017-10-03

The dual-axis radiographic hydrodynamic test (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT-II LIA, we measure an emittance higher than predicted by theoretical simulations, and even though this accelerator produces submillimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell codes. Finally,more » the simulations establish that the most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.« less

Emittance Growth in the DARHT-II Linear Induction Accelerator

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

Ekdahl, Carl; Carlson, Carl A.; Frayer, Daniel K.

The dual-axis radiographic hydrodynamic test (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT-II LIA, we measure an emittance higher than predicted by theoretical simulations, and even though this accelerator produces submillimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell codes. Finally,more » the simulations establish that the most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.« less

Utilization of fluidized bed material as a calcium and sulfur source for apples

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

Korcak, R.F.

1984-01-01

Fluidized bed material (FBM), a dry, high Ca, alkaline waste product which results from combining coal and limestone, was used as a Ca or S source or lime substitute in an established apple orchard (Malus domestica Borkh., cv. York Imperial) over a four year period. Treatment comparisons were made between FBM was applied at one or two times (1x or 2x) the soil lime requirement and CaCO/sub 3/ applied at the lime requirement (1x). Additionally, FBM 1x was compared to a combination treatment consisting of CaCO/sub 3/ plus gypsum to apply similar amounts of Ca and S. All treatments weremore » also compared to an untreated control. No significant treatment comparisons were noted on leaf Ca levels, however, leaf Mg significantly decreased when FBM applied at the 1x or 2x level compared to CaCO/sub 3/ 1x. When FBM was compared with CaCO/sub 3/ plus gypsum there was a significant decrease in leaf Ca with FBM but no difference in leaf Mg. These effects were probably due to either a solubility difference between nutrients or to actual amount of Mg applied by the different sources. Leaf S levels were unaffected by treatments. Yields, fresh fruit weight and the incidence of cork spot were little affected by treatments. Soil extractable Mg, 1N NH/sub 4/Ac, was not a good prediction of leaf Mg content or Mg added to the soil. Only soil Al was significantly reduced, compared to the control, by the treatments among the metals studied (Zn, Mn, Cu, Cd, Pb and Al). FBM applied at twice the lime requirement (wt. basis) resulted in similar soil pH to CaCO/sub 3/ applied at the lime requirement. 14 references, 6 figures, 1 table.« less

Sclerotinia homoeocarpa Overwinters in Turfgrass and Is Present in Commercial Seed

PubMed Central

Rioux, Renée A.; Shultz, Jeanette; Garcia, Michelle; Willis, David Kyle; Casler, Michael; Bonos, Stacy; Smith, Damon; Kerns, James

2014-01-01

Dollar spot is the most economically important disease of amenity turfgrasses in the United States, yet little is known about the source of primary inoculum for this disease. With the exception of a few isolates from the United Kingdom, Sclerotinia homoeocarpa, the causal agent of dollar spot, does not produce spores. Consequently, it was assumed that overwintering of this organism in soil, thatch, and plant debris provides primary inoculum for dollar spot epidemics. Overwintering of S. homoeocarpa in roots and shoots of symptomatic and asymptomatic creeping bentgrass turfgrass was quantified over the course of a three-year field experiment. Roots did not consistently harbor S. homoeocarpa, whereas S. homoeocarpa was isolated from 30% of symptomatic shoots and 10% of asymptomatic shoots in the spring of two out of three years. The presence of stroma-like pathogen material on leaf blades was associated with an increase in S. homoeocarpa isolation and colony diameter at 48 hpi. Commercial seed has also been hypothesized to be a potential source of initial inoculum for S. homoeocarpa. Two or more commercial seed lots of six creeping bentgrass cultivars were tested for contamination with S. homoeocarpa using culture-based and molecular detection methods. A viable, pathogenic isolate of S. homoeocarpa was isolated from one commercial seed lot and contamination of this lot was confirmed with nested PCR using S. homoeocarpa specific primers. A sensitive nested PCR assay detected S. homoeocarpa contamination in eight of twelve (75%) commercial seed lots. Seed source, but not cultivar or resistance to dollar spot, influenced contamination by S. homoeocarpa. Overall, this research suggests that seeds are a potential source of initial inoculum for dollar spot epidemics and presents the need for further research in this area. PMID:25333928

Mapping of leaf rust resistance genes and molecular characterization of the 2NS/2AS translocation in the wheat cultivar Jagger

USDA-ARS?s Scientific Manuscript database

Winter wheat cultivar 'Jagger' was recently found to have an alien chromosomal segment 'VPM1' that should carry Lr37, a gene conferring resistance against leaf rust caused by Puccinia triticina, and this cultivar was also reported to have the wheat gene Lr17 against leaf rust. Both Lr17 and Lr37 wer...

Monitoring Phytophthora ramorum in soil, leaf litter, rain traps, and watercourses in an historical cornish garden

Treesearch

David Lockley; Judith Turner; Gillian Humphries; Phil Jennings

2008-01-01

Phytophthora ramorum was identified as the cause of a leaf blight on rhododendrons in an historic garden in Cornwall in 2003. A programme of measures was set in place to eradicate the disease from the garden and several sites were selected to monitor the effect of these measures on the recovery of P. ramorum from soil, leaf litter...

Mapping of SnTox3-Snn3 as a major determinant of field susceptibility to Septoria nodorum leaf blotch in the SHA3/CBRD x Naxos population

USDA-ARS?s Scientific Manuscript database

Parastagonospora nodorum is a necrotrophic pathogen of wheat, causing Septoria nodorum blotch (SNB) affecting both the leaf and glume. P. nodorum is the major leaf blotch pathogen on spring wheat in Norway. Resistance to the disease is quantitative, but several host-specific interactions between nec...

Stomatal Conductance, Plant Species Distribution, and an Exploration of Rhizosphere Microbes and Mycorrhizae at a Deliberately Leakimg Experimental Carbon Sequestration Field (ZERT)

NASA Astrophysics Data System (ADS)

Sharma, B.; Apple, M. E.; Morales, S.; Zhou, X.; Holben, B.; Olson, J.; Prince, J.; Dobeck, L.; Cunningham, A. B.; Spangler, L.

2010-12-01

One measure to reduce atmospheric CO2 is to sequester it in deep geological formations. Rapid surface detection of any CO2 leakage is crucial. CO2 leakage rapidly affects vegetation above sequestration fields. Plant responses to high CO2 are valuable tools in surface detection of leaking CO2. The Zero Emission Research Technology (ZERT) site in Bozeman, MT is an experimental field for surface detection of CO2 where 0.15 ton/day of CO2 was released (7/19- 8/15/2010) from a 100m horizontal injection well, HIW, 1.5 m underground with deliberate leaks of CO2 at intervals, and from a vertical injector, VI, (6/3-6/24/2010). The vegetation includes Taraxacum officinale (Dandelion), Dactylis glomerata (Orchard Grass), and other herbaceous plants. We collected soil and roots 1, 3 and 5 m from the VI to determine the responses of mycorrhizal fungi and rhizosphere microbes to high CO2. Mycorrhizal fungi obtain C from root exudates, increase N and P availability, and reduce desiccation, while prokaryotic rhizosphere microbes fix atmospheric N and will be examined for abundance and expression of carbon and nitrogen cycling genes. We are quantifying mycorrhizal colonization and the proportion of spores, hyphae, and arbuscules in vesicular-arbuscular mycorrhizae (VAM) in cleared and stained roots. Stomatal conductance is an important measure of CO2 uptake and water loss via transpiration. We used a porometer (5-40°C, 0-90% RH, Decagon) to measure stomatal conductivity in dandelion and orchard grass at 1, 3, and 5 m from the VI and along a transect perpendicular to the HIW. Dandelion conductance was highest close to the VI and almost consistently higher close to hot spots (circular regions with maximum CO2 and leaf dieback) at the HIW, with 23.2 mmol/m2/s proximal to the hot spot, and 10.8 mmol/m2/s distally. Average conductance in grass (50.3 mmol/m2/s) was higher than in dandelion, but grass did not have high conductance near hot spots. Stomata generally close at elevated CO2. Dandelion leaves near hot spots undergo rapid color change from green to red before senescing to a desiccated brown, while xeromorphic grass leaves do not. Species-specific differences in leaf survival following exposure to CO2 may be linked to species-specific differences in stomatal conductance, and to rhizosphere and mycorrhizal responses. Initial survey results of plant species distribution suggest a shift from a dandelion-grass to a grass-dominated community over hot spots. Sudden and long-term shifts in species composition have important ecological implications and may provide a means of surface detection of upwelling CO2.

Emittance Growth in the DARHT-II Linear Induction Accelerator

NASA Astrophysics Data System (ADS)

Ekdahl, Carl; Carlson, Carl A.; Frayer, Daniel K.; McCuistian, B. Trent; Mostrom, Christopher B.; Schulze, Martin E.; Thoma, Carsten H.

2017-11-01

The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. Some of the possible causes for the emittance growth in the DARHT LIA have been investigated using particle-in-cell (PIC) codes, and are discussed in this article. The results suggest that the most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.

Gas exchange recovery following natural drought is rapid unless limited by loss of leaf hydraulic conductance: evidence from an evergreen woodland.

PubMed

Skelton, Robert P; Brodribb, Timothy J; McAdam, Scott A M; Mitchell, Patrick J

2017-09-01

Drought can cause major damage to plant communities, but species damage thresholds and postdrought recovery of forest productivity are not yet predictable. We used an El Niño drought event as a natural experiment to test whether postdrought recovery of gas exchange could be predicted by properties of the water transport system, or if metabolism, primarily high abscisic acid concentration, might delay recovery. We monitored detailed physiological responses, including shoot sapflow, leaf gas exchange, leaf water potential and foliar abscisic acid (ABA), during drought and through the subsequent rehydration period for a sample of eight canopy and understory species. Severe drought caused major declines in leaf water potential, elevated foliar ABA concentrations and reduced stomatal conductance and assimilation rates in our eight sample species. Leaf water potential surpassed levels associated with incipient loss of leaf hydraulic conductance in four species. Following heavy rainfall gas exchange in all species, except those trees predicted to have suffered hydraulic impairment, recovered to prestressed rates within 1 d. Recovery of plant gas exchange was rapid and could be predicted by the hydraulic safety margin, providing strong support for leaf vulnerability to water deficit as an index of damage under natural drought conditions. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Tomato chocolate spot virus, a member of a new torradovirus species that causes a necrosis-associated disease of tomato in Guatemala.

PubMed

Batuman, O; Kuo, Y-W; Palmieri, M; Rojas, M R; Gilbertson, R L

2010-06-01

Tomatoes in Guatemala have been affected by a new disease, locally known as "mancha de chocolate" (chocolate spot). The disease is characterized by distinct necrotic spots on leaves, stems and petioles that eventually expand and cause a dieback of apical tissues. Samples from symptomatic plants tested negative for infection by tomato spotted wilt virus, tobacco streak virus, tobacco etch virus and other known tomato-infecting viruses. A virus-like agent was sap-transmitted from diseased tissue to Nicotiana benthamiana and, when graft-transmitted to tomato, this agent induced chocolate spot symptoms. This virus-like agent also was sap-transmitted to Datura stramonium and Nicotiana glutinosa, but not to a range of non-solanaceous indicator plants. Icosahedral virions approximately 28-30 nm in diameter were purified from symptomatic N. benthamiana plants. When rub-inoculated onto leaves of N. benthamiana plants, these virions induced symptoms indistinguishable from those in N. benthamiana plants infected with the sap-transmissible virus associated with chocolate spot disease. Tomatoes inoculated with sap or grafted with shoots from N. benthamiana plants infected with purified virions developed typical chocolate spot symptoms, consistent with this virus being the causal agent of the disease. Analysis of nucleic acids associated with purified virions of the chocolate-spot-associated virus, revealed a genome composed of two single-stranded RNAs of approximately 7.5 and approximately 5.1 kb. Sequence analysis of these RNAs revealed a genome organization similar to recently described torradoviruses, a new group of picorna-like viruses causing necrosis-associated diseases of tomatoes in Europe [tomato torrado virus (ToTV)] and Mexico [tomato apex necrosis virus (ToANV) and tomato marchitez virus (ToMarV)]. Thus, the approximately 7.5 kb and approximately 5.1 kb RNAs of the chocolate-spot-associated virus corresponded to the torradovirus RNA1 and RNA2, respectively; however, sequence comparisons revealed 64-83% identities with RNA1 and RNA2 sequences of ToTV, ToANV and ToMarV. Together, these results indicate that the chocolate-spot-associated virus is a member of a distinct torradovirus species and, thus, another member of the recently established genus Torradovirus in the family Secoviridae. The name tomato chocolate spot virus is proposed.

Immune Thrombocytopenia as a Consequence of Rocky Mountain Spotted Fever.

PubMed

Baldeo, Cherisse; Seegobin, Karan; Zuberi, Lara

2017-01-01

Primary immune thrombocytopenia (ITP) - also called idiopathic thrombocytopenic purpura or immune thrombocytopenic purpura - is an acquired thrombocytopenia caused by autoantibodies against platelet antigens. It is one of the more common causes of thrombocytopenia in otherwise asymptomatic adults. Rocky Mountain spotted fever (RMSF) is a potentially lethal, but curable, tick-borne disease. We present a case of ITP that was triggered by RMSF.

Nest reuse by Northern Spotted Owls on the east slope of the Cascade Range, Washington

Treesearch

Stan G. Sovern; Margaret Taylor; Eric D. Forsman

2011-01-01

During a long-term demography study of Northern Spotted Owls (Strix occidentalis caurina) in the eastern Cascade Range of Washington State in 1989 to 2008, we documented 276 nests of Northern Spotted Owls at 73 different territories. Of these nests, 90.2% were on platforms, mostly in clumps of deformed limbs caused by dwarf mistletoe (primarily...

High seroprevalence of antibodies against spotted fever and scrub typhus bacteria in patients with febrile Illness, Kenya.

PubMed

Thiga, Jacqueline W; Mutai, Beth K; Eyako, Wurapa K; Ng'ang'a, Zipporah; Jiang, Ju; Richards, Allen L; Waitumbi, John N

2015-04-01

Serum samples from patients in Kenya with febrile illnesses were screened for antibodies against bacteria that cause spotted fever, typhus, and scrub typhus. Seroprevalence was 10% for spotted fever group, <1% for typhus group, and 5% for scrub typhus group. Results should help clinicians expand their list of differential diagnoses for undifferentiated fevers.

CLD1/SRL1 modulates leaf rolling by affecting cell wall formation, epidermis integrity and water homeostasis in rice.

PubMed

Li, Wen-Qiang; Zhang, Min-Juan; Gan, Peng-Fei; Qiao, Lei; Yang, Shuai-Qi; Miao, Hai; Wang, Gang-Feng; Zhang, Mao-Mao; Liu, Wen-Ting; Li, Hai-Feng; Shi, Chun-Hai; Chen, Kun-Ming

2017-12-01

Leaf rolling is considered as one of the most important agronomic traits in rice breeding. It has been previously reported that SEMI-ROLLED LEAF 1 (SRL1) modulates leaf rolling by regulating the formation of bulliform cells in rice (Oryza sativa); however, the regulatory mechanism underlying SRL1 has yet to be further elucidated. Here, we report the functional characterization of a novel leaf-rolling mutant, curled leaf and dwarf 1 (cld1), with multiple morphological defects. Map-based cloning revealed that CLD1 is allelic with SRL1, and loses function in cld1 through DNA methylation. CLD1/SRL1 encodes a glycophosphatidylinositol (GPI)-anchored membrane protein that modulates leaf rolling and other aspects of rice growth and development. The cld1 mutant exhibits significant decreases in cellulose and lignin contents in secondary cell walls of leaves, indicating that the loss of function of CLD1/SRL1 affects cell wall formation. Furthermore, the loss of CLD1/SRL1 function leads to defective leaf epidermis such as bulliform-like epidermal cells. The defects in leaf epidermis decrease the water-retaining capacity and lead to water deficits in cld1 leaves, which contribute to the main cause of leaf rolling. As a result of the more rapid water loss and lower water content in leaves, cld1 exhibits reduced drought tolerance. Accordingly, the loss of CLD1/SRL1 function causes abnormal expression of genes and proteins associated with cell wall formation, cuticle development and water stress. Taken together, these findings suggest that the functional roles of CLD1/SRL1 in leaf-rolling regulation are closely related to the maintenance of cell wall formation, epidermal integrity and water homeostasis. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Insights on the development, kinetics, and variation of photoinhibition using chlorophyll fluorescence imaging of a chilled, variegated leaf.

PubMed

Hogewoning, Sander W; Harbinson, Jeremy

2007-01-01

The effect of chilling on photosystem II (PSII) efficiency was studied in the variegated leaves of Calathea makoyana, in order to gain insight into the causes of chilling-induced photoinhibition. Additionally, a relationship was revealed between (chilling) stress and variation in photosynthesis. Chilling treatments (5 degrees C and 10 degrees C) were performed for different durations (1-7 d) under a moderate irradiance (120 micromol m-2 s-1). The individual leaves were divided into a shaded zone and two illuminated, chilled zones. The leaf tip and sometimes the leaf base were not chilled. Measurements of the dark-adapted Fv/Fm were made on the different leaf zones at the end of the chilling treatment, and then for several days thereafter to monitor recovery. Chilling up to 7 d in the dark did not affect PSII efficiency and visual appearance, whereas chilling in the light caused severe photoinhibition, sometimes followed by leaf necrosis. Photoinhibition increased with the duration of the chilling period, whereas, remarkably, chilling temperature had no effect. In the unchilled leaf tip, photoinhibition also occurred, whereas in the unchilled leaf base it did not. Whatever the leaf zone, photoinhibition became permanent if the mean value dropped below 0.4, although chlorosis and necrosis were associated solely with chilled illuminated tissue. Starch accumulated in the unchilled leaf tip, in contrast to the adjacent chilled irradiated zone. This suggests that photoinhibition was due to a secondary effect in the unchilled leaf tip (sink limitation), whereas it was a direct effect of chilling and irradiance in the chilled illuminated zones. The PSII efficiency and its coefficient of variation showed a unique negative linearity across all leaf zones and different tissue types. The slope of this curve was steeper for chilled leaves than it was for healthy, non-stressed leaves, suggesting that the coefficient of variation may be an important tool for assessing stress in leaves.

Elucidation of defense-related signaling responses to spot blotch infection in bread wheat (Triticum aestivum L.).

PubMed

Sahu, Ranabir; Sharaff, Murali; Pradhan, Maitree; Sethi, Avinash; Bandyopadhyay, Tirthankar; Mishra, Vinod K; Chand, Ramesh; Chowdhury, Apurba K; Joshi, Arun K; Pandey, Shree P

2016-04-01

Spot blotch disease, caused by Bipolaris sorokiniana, is an important threat to wheat, causing an annual loss of ~17%. Under epidemic conditions, these losses may be 100%, yet the molecular responses of wheat to spot blotch remain almost uncharacterized. Moreover, defense-related phytohormone signaling genes have been poorly characterized in wheat. Here, we have identified 18 central components of salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and enhanced disease susceptibility 1 (EDS1) signaling pathways as well as the genes of the phenylpropanoid pathway in wheat. In time-course experiments, we characterized the reprogramming of expression of these pathways in two contrasting genotypes: Yangmai #6 (resistant to spot blotch) and Sonalika (susceptible to spot blotch). We further evaluated the performance of a population of recombinant inbred lines (RILs) by crossing Yangmai#6 and Sonalika (parents) and subsequent selfing to F10 under field conditions in trials at multiple locations. We characterized the reprogramming of defense-related signaling in these RILs as a consequence of spot blotch attack. During resistance to spot blotch attack, wheat strongly elicits SA signaling (SA biogenesis as well as the NPR1-dependent signaling pathway), along with WRKY33 transcription factor, followed by an enhanced expression of phenylpropanoid pathway genes. These may lead to accumulation of phenolics-based defense metabolites that may render resistance against spot blotch. JA signaling may synergistically contribute to the resistance. Failure to elicit SA (and possibly JA) signaling may lead to susceptibility against spot blotch infection in wheat. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

Heterochrony underpins natural variation in Cardamine hirsuta leaf form

PubMed Central

Cartolano, Maria; Pieper, Bjorn; Lempe, Janne; Tattersall, Alex; Huijser, Peter; Tresch, Achim; Darrah, Peter R.; Hay, Angela; Tsiantis, Miltos

2015-01-01

A key problem in biology is whether the same processes underlie morphological variation between and within species. Here, by using plant leaves as an example, we show that the causes of diversity at these two evolutionary scales can be divergent. Some species like the model plant Arabidopsis thaliana have simple leaves, whereas others like the A. thaliana relative Cardamine hirsuta bear complex leaves comprising leaflets. Previous work has shown that these interspecific differences result mostly from variation in local tissue growth and patterning. Now, by cloning and characterizing a quantitative trait locus (QTL) for C. hirsuta leaf shape, we find that a different process, age-dependent progression of leaf form, underlies variation in this trait within species. This QTL effect is caused by cis-regulatory variation in the floral repressor ChFLC, such that genotypes with low-expressing ChFLC alleles show both early flowering and accelerated age-dependent changes in leaf form, including faster leaflet production. We provide evidence that this mechanism coordinates leaf development with reproductive timing and may help to optimize resource allocation to the next generation. PMID:26243877

Validation of GEOLAND-2 Spot/vgt Albedo Products by Using Ceos Olive Methodology

NASA Astrophysics Data System (ADS)

Camacho de Coca, F.; Sanchez, J.; Schaaf, C.; Baret, F.; Weiss, M.; Cescatti, A.; Lacaze, R. N.

2012-12-01

This study evaluates the scientific merit of the global surface albedo products developed in the framework of the Geoland-2 project based on SPOT/VEGETATION observations. The methodology follows the OLIVE (On-Line Validation Exercise) approach supported by the CEOS Land Product Validation subgroup (calvalportal.ceos.org/cvp/web/olive). First, the spatial and temporal consistency of SPOT/VGT albedo products was assessed by intercomparison with reference global products (MODIS/Terra+Aqua and POLDER-3/PARASOL) for the period 2006-2007. A bulk statistical analysis over a global network of 420 homogeneous sites (BELMANIP-2) was performed and analyzed per biome types. Additional sites were included to study albedo under snow conditions. Second, the accuracy and realism of temporal variations were evaluated using a number of ground measurements from FLUXNET sites suitable for use in direct comparison to the co-located satellite data. Our results show that SPOT/VGT albedo products present reliable spatial and temporal distribution of retrievals. The SPOT/VGT albedo performs admirably with MODIS, with a mean bias and RMSE for the shortwave black-sky albedo over BELMANIP-2 sites lower than 0.006 and 0.03 (13% in relative terms) respectively, and even better for snow free pixels. Similar results were found for the white-sky albedo quantities. Discrepancies are larger when comparing with POLDER-3 products: for the shortwave black-sky albedo a mean bias of -0.014 and RMSE of 0.04 (20%) was found. This overall performance figures are however land-cover dependent and larger uncertainties were found over some biomes (or regions) or specific periods (e.g. winter in the north hemisphere). The comparison of SPOT/VGT blue-sky albedo estimates with ground measurements (mainly over Needle-leaf forest sites) show a RMSE of 0.04 and a bias of 0.003 when only snow-free pixels are considered. Moreover, this work shows that the OLIVE tool is also suitable for validation of global albedo products.

Genomic and phenotypic characterization of Xanthomonas cynarae sp. nov., a new species that causes bacterial bract spot of artichoke (Cynara scolymus L.).

PubMed

Trébaol, G; Gardan, L; Manceau, C; Tanguy, J L; Tirilly, Y; Boury, S

2000-07-01

A bacterial disease of artichoke (Cynara scolymus L.) was first observed in 1954 in Brittany and the Loire Valley, France. This disease causes water-soaked spots on bracts and depreciates marketability of the harvest. Ten strains of the pathogen causing bacterial spot of artichoke, previously identified as a member of the genus Xanthomonas, were characterized and compared with type and pathotype strains of the 20 Xanthomonas species using a polyphasic study including both phenotypic and genomic methods. The ten strains presented general morphological, biochemical and physiological traits and G+C content characteristic of the genus Xanthomonas. Sequencing of the 165 rRNA gene confirmed that this bacterium belongs to the genus Xanthomonas, and more precisely to the Xanthomonas campestris core. DNA-DNA hybridization results showed that the strains that cause bacterial spot of artichoke were 92-100% related to the proposed type strain CFBP 4188T and constituted a discrete DNA homology group that was distinct from the 20 previously described Xanthomonas species. The results of numerical analysis were in accordance with DNA-DNA hybridization data. Strains causing the bacterial bract spot of artichoke exhibited consistent determinative biochemical characteristics, which distinguished them from the 20 other Xanthomonas species previously described. Furthermore, pathogenicity tests allowed specific identification of this new phytopathogenic bacterium. Thus, it is concluded that this bacterium is a new species belonging to the genus Xanthomonas, for which the name Xanthomonas cynarae is proposed. The type strain, CFBP 4188T, has been deposited in the Collection Française des Bactéries Phytopathogènes (CFBP).

Leaf shrinkage with dehydration: coordination with hydraulic vulnerability and drought tolerance.

PubMed

Scoffoni, Christine; Vuong, Christine; Diep, Steven; Cochard, Hervé; Sack, Lawren

2014-04-01

Leaf shrinkage with dehydration has attracted attention for over 100 years, especially as it becomes visibly extreme during drought. However, little has been known of its correlation with physiology. Computer simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll pathways outside the xylem would cause a strong decline of leaf hydraulic conductance (K(leaf)). For 14 diverse species, we tested the hypothesis that shrinkage during dehydration (i.e. in whole leaf, cell and airspace thickness, and leaf area) is associated with reduction in K(leaf) at declining leaf water potential (Ψ(leaf)). We tested hypotheses for the linkage of leaf shrinkage with structural and physiological water relations parameters, including modulus of elasticity, osmotic pressure at full turgor, turgor loss point (TLP), and cuticular conductance. Species originating from moist habitats showed substantial shrinkage during dehydration before reaching TLP, in contrast with species originating from dry habitats. Across species, the decline of K(leaf) with mild dehydration (i.e. the initial slope of the K(leaf) versus Ψ(leaf) curve) correlated with the decline of leaf thickness (the slope of the leaf thickness versus Ψ(leaf) curve), as expected based on predictions from computer simulations. Leaf thickness shrinkage before TLP correlated across species with lower modulus of elasticity and with less negative osmotic pressure at full turgor, as did leaf area shrinkage between full turgor and oven desiccation. These findings point to a role for leaf shrinkage in hydraulic decline during mild dehydration, with potential impacts on drought adaptation for cells and leaves, influencing plant ecological distributions.

Exclusion of EDNRB and KIT as the basis for white spotting in Border Collies.

PubMed

Metallinos, D; Rine, J

2000-01-01

White spotting patterns in mammals can be caused by mutations in the genes for the endothelin B receptor and c-Kit, whose protein products are necessary for proper migration, differentiation or survival of the melanoblast population of cells. Although there are many different dog breeds that segregate white spotting patterns, no genes have been identified that are linked to these phenotypes. An intercross was generated from a female Newfoundland and a male Border Collie and the white spotting phenotypes of the intercross progeny were evaluated by measuring percentage surface area of white in the puppies. The Border Collie markings segregated as a simple autosomal recessive (7/25 intercross progeny had the phenotype). Two candidate genes, for the endothelin B receptor (EDNRB) and c-Kit (KIT), were evaluated for segregation with the white spotting pattern. Polymorphisms between the Border Collie and Newfoundland were identified for EDNRB using Southern analysis after a portion of the canine gene had been cloned. Polymorphisms for KIT were identified using a microsatellite developed from a bacterial artificial chromosome containing the canine gene. Both EDNRB and KIT were excluded as a cause of the white spotting pattern in at least two of the intercross progeny. Although these genes have been implicated in white spotting in other mammals, including horses, pigs, cows, mice and rats, they do not appear to be responsible for the white spotting pattern found in the Border Collie breed of dog.

Exclusion of EDNRB and KIT as the basis for white spotting in Border Collies

PubMed Central

Metallinos, Danika; Rine, Jasper

2000-01-01

Background: White spotting patterns in mammals can be caused by mutations in the genes for the endothelin B receptor and c-Kit, whose protein products are necessary for proper migration, differentiation or survival of the melanoblast population of cells. Although there are many different dog breeds that segregate white spotting patterns, no genes have been identified that are linked to these phenotypes. Results: An intercross was generated from a female Newfoundland and a male Border Collie and the white spotting phenotypes of the intercross progeny were evaluated by measuring percentage surface area of white in the puppies. The Border Collie markings segregated as a simple autosomal recessive (7/25 intercross progeny had the phenotype). Two candidate genes, for the endothelin B receptor (EDNRB) and c-Kit (KIT), were evaluated for segregation with the white spotting pattern. Polymorphisms between the Border Collie and Newfoundland were identified for EDNRB using Southern analysis after a portion of the canine gene had been cloned. Polymorphisms for KIT were identified using a microsatellite developed from a bacterial artificial chromosome containing the canine gene. Conclusions: Both EDNRB and KIT were excluded as a cause of the white spotting pattern in at least two of the intercross progeny. Although these genes have been implicated in white spotting in other mammals, including horses, pigs, cows, mice and rats, they do not appear to be responsible for the white spotting pattern found in the Border Collie breed of dog. PMID:11178229

SU-D-201-04: Evaluation of Elekta Agility MLC Performance Using Statistical Process Control

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

Meyers, SM; Balderson, MJ; Letourneau, D

2016-06-15

Purpose: to evaluate the performance and stability of the Elekta Agility MLC model using an automated quality control (QC) test in combination with statistical process control tools. Methods: Leaf positions were collected daily for 11 Elekta units over 5–19 months using the automated QC test, which analyzes 23 MV images to determine the location of MLC leaves relative to the radiation isocenter. The leaf positions are measured at 5 nominal positions, and images are acquired at collimator 0° and 180° to capture all MLC leaves in the field-of-view. Leaf positioning accuracy was assessed using individual and moving range control charts.more » Control limits were recomputed following MLC recalibration (occurred 1–2 times for 4 units). Specification levels of ±0.5, ±1 and ±1.5mm were tested. The mean and range of duration between out-of-control and out-of-specification events were determined. Results: Leaf position varied little over time, as confirmed by very tight individual control limits (mean ±0.19mm, range 0.09–0.44). Mean leaf position error was −0.03mm (range −0.89–0.83). Due to sporadic out-of-control events, the mean in-control duration was 3.3 days (range 1–23). Data stayed within ±1mm specification for 205 days on average (range 3–372) and within ±1.5mm for the entire date range. Measurements stayed within ±0.5mm for 1 day on average (range 0–17); however, our MLC leaves were not calibrated to this level of accuracy. Conclusion: The Elekta Agility MLC model was found to perform with high stability, as evidenced by the tight control limits. The in-specification durations support the current recommendation of monthly MLC QC tests with a ±1mm tolerance. Future work is on-going to determine if Agility performance can be optimized further using high-frequency QC test results to drive recalibration frequency. Factors that can affect leaf positioning accuracy, including beam spot motion, leaf gain calibration, drifting leaves, and image artifacts, are under investigation.« less

QTL-seq approach identified genomic regions and diagnostic markers for rust and late leaf spot resistance in groundnut (Arachis hypogaea L.).

PubMed

Pandey, Manish K; Khan, Aamir W; Singh, Vikas K; Vishwakarma, Manish K; Shasidhar, Yaduru; Kumar, Vinay; Garg, Vanika; Bhat, Ramesh S; Chitikineni, Annapurna; Janila, Pasupuleti; Guo, Baozhu; Varshney, Rajeev K

2017-08-01

Rust and late leaf spot (LLS) are the two major foliar fungal diseases in groundnut, and their co-occurrence leads to significant yield loss in addition to the deterioration of fodder quality. To identify candidate genomic regions controlling resistance to rust and LLS, whole-genome resequencing (WGRS)-based approach referred as 'QTL-seq' was deployed. A total of 231.67 Gb raw and 192.10 Gb of clean sequence data were generated through WGRS of resistant parent and the resistant and susceptible bulks for rust and LLS. Sequence analysis of bulks for rust and LLS with reference-guided resistant parent assembly identified 3136 single-nucleotide polymorphisms (SNPs) for rust and 66 SNPs for LLS with the read depth of ≥7 in the identified genomic region on pseudomolecule A03. Detailed analysis identified 30 nonsynonymous SNPs affecting 25 candidate genes for rust resistance, while 14 intronic and three synonymous SNPs affecting nine candidate genes for LLS resistance. Subsequently, allele-specific diagnostic markers were identified for three SNPs for rust resistance and one SNP for LLS resistance. Genotyping of one RIL population (TAG 24 × GPBD 4) with these four diagnostic markers revealed higher phenotypic variation for these two diseases. These results suggest usefulness of QTL-seq approach in precise and rapid identification of candidate genomic regions and development of diagnostic markers for breeding applications. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Rapid green synthesis of spherical gold nanoparticles using Mangifera indica leaf

NASA Astrophysics Data System (ADS)

Philip, Daizy

2010-11-01

This paper reports the rapid biological synthesis of spherical gold nanoparticles at room temperature using fresh/dry leaf extract of Mangifera indica. This is a simple, cost-effective, stable for long time and reproducible aqueous synthesis method to obtain a self-assembly of nearly monodispersed Au nanoparticles of size ˜20 nm and 17 nm. The nanoparticles were obtained within 2 min of addition of the extract to the solution of HAuCl 4·3H 2O and the colloid is found to be stable for more than 5 months. Smaller and more uniformly distributed particles could be obtained with dried leaf extract. The nanoparticles obtained are characterized by UV-vis, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Crystalline nature of the nanoparticles in the fcc structure is confirmed by the peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes, bright circular spots in the selected area electron diffraction (SAED) and clear lattice fringes in the high-resolution TEM image. The possible biomolecules responsible for efficient stabilization are suggested by studying the FTIR spectrum of the sample. This environmentally benign method provides much faster synthesis and colloidal stability comparable to those of chemical reduction.

Unraveling complex viral infections in cassava (Manihot esculenta Crantz) from Colombia.

PubMed

Carvajal-Yepes, Monica; Olaya, Cristian; Lozano, Ivan; Cuervo, Maritza; Castaño, Mauricio; Cuellar, Wilmer J

2014-06-24

In the Americas, different disease symptoms have been reported in cassava including leaf mosaics, vein clearings, mottles, ring spots, leaf distortions and undeveloped and deformed storage roots. Some viruses have been identified and associated with these symptoms while others have been reported in symptomless plants or latent infections. We observed that reoviruses associated with severe root symptoms (RS) of Cassava Frogskin Disease (CFSD) are not associated with leaf symptoms (LS) observed in the cassava indicator plant 'Secundina'. Neither were these LS associated with the previously characterized Cassava common mosaic virus, Cassava virus X, Cassava vein mosaic virus or phytoplasma, suggesting the presence of additional pathogens. In order to explain LS observed in cassava we used a combination of biological, serological and molecular tests. Here, we report three newly described viruses belonging to the families Secoviridae, Alphaflexiviridae and Luteoviridae found in cassava plants showing severe RS associated with CFSD. All tested plants were infected by a mix of viruses that induced distinct LS in 'Secundina'. Out of the three newly described viruses, a member of family Secoviridae could experimentally induce LS in single infection. Our results confirm the common occurrence of complex viral infections in cassava field-collected since the 1980s. Copyright © 2013 Elsevier B.V. All rights reserved.

Ozone affects leaf physiology and causes injury to foliage of native tree species from the tropical Atlantic Forest of southern Brazil.

PubMed

Moura, Bárbara Baêsso; Alves, Edenise Segala; Marabesi, Mauro Alexandre; de Souza, Silvia Ribeiro; Schaub, Marcus; Vollenweider, Pierre

2018-01-01

In southern Brazil, the recent increase in tropospheric ozone (O 3 ) concentrations poses an additional threat to the biodiverse but endangered and fragmented remnants of the Atlantic Forest. Given the mostly unknown sensitivity of tropical species to oxidative stress, the principal objective of this study was to determine whether the current O 3 levels in the Metropolitan Region of Campinas (MRC), downwind of São Paulo, affect the native vegetation of forest remnants. Foliar responses to O 3 of three tree species typical of the MRC forests were investigated using indoor chamber exposure experiments under controlled conditions and a field survey. Exposure to 70ppb O 3 reduced assimilation and leaf conductance but increased respiration in Astronium graveolens while gas exchange in Croton floribundus was little affected. Both A. graveolens and Piptadenia gonoacantha developed characteristic O 3 -induced injury in the foliage, similar to visible symptoms observed in >30% of trees assessed in the MRC, while C. floribundus remained asymptomatic. The underlying structural symptoms in both O 3 -exposed and field samples were indicative of oxidative burst, hypersensitive responses, accelerated cell senescence and, primarily in field samples, interaction with photo-oxidative stress. The markers of O 3 stress were thus mostly similar to those observed in other regions of the world. Further research is needed, to estimate the proportion of sensitive forest species, the O 3 impact on tree growth and stand stability and to detect O 3 hot spots where woody species in the Atlantic Forest are mostly affected. Copyright © 2017 Elsevier B.V. All rights reserved.

Isolation and Characterization of Burkholderia rinojensis sp. nov., a Non-Burkholderia cepacia Complex Soil Bacterium with Insecticidal and Miticidal Activities

PubMed Central

Fernandez, Lorena E.; Koivunen, Marja; Yang, April; Flor-Weiler, Lina; Marrone, Pamela G.

2013-01-01

Isolate A396, a bacterium isolated from a Japanese soil sample demonstrated strong insecticidal and miticidal activities in laboratory bioassays. The isolate was characterized through biochemical methods, fatty acid methyl ester (FAME) analysis, sequencing of 16S rRNA, multilocus sequence typing and analysis, and DNA-DNA hybridization. FAME analysis matched A396 to Burkholderia cenocepacia, but this result was not confirmed by 16S rRNA or DNA-DNA hybridization. 16S rRNA sequencing indicated closest matches with B. glumae and B. plantarii. DNA-DNA hybridization experiments with B. plantarii, B. glumae, B. multivorans, and B. cenocepacia confirmed the low genetic similarity (11.5 to 37.4%) with known members of the genus. PCR-based screening showed that A396 lacks markers associated with members of the B. cepacia complex. Bioassay results indicated two mechanisms of action: through ingestion and contact. The isolate effectively controlled beet armyworms (Spodoptera exigua; BAW) and two-spotted spider mites (Tetranychus urticae; TSSM). In diet overlay bioassays with BAW, 1% to 4% (vol/vol) dilution of the whole-cell broth caused 97% to 100% mortality 4 days postexposure, and leaf disc treatment bioassays attained 75% ± 22% mortality 3 days postexposure. Contact bioassays led to 50% larval mortality, as well as discoloration, stunting, and failure to molt. TSSM mortality reached 93% in treated leaf discs. Activity was maintained in cell-free supernatants and after heat treatment (60°C for 2 h), indicating that a secondary metabolite or excreted thermostable enzyme might be responsible for the activity. Based on these results, we describe the novel species Burkholderia rinojensis, a good candidate for the development of a biocontrol product against insect and mite pests. PMID:24096416

Nonlinear simulations of Jupiter's 5-micron hot spots

NASA Technical Reports Server (NTRS)

Showman, A. P.; Dowling, T. E.

2000-01-01

Large-scale nonlinear simulations of Jupiter's 5-micron hot spots produce long-lived coherent structures that cause subsidence in local regions, explaining the low cloudiness and the dryness measured by the Galileo probe inside a hot spot. Like observed hot spots, the simulated coherent structures are equatorially confined, have periodic spacing, propagate west relative to the flow, are generally confined to one hemisphere, and have an anticyclonic gyre on their equatorward side. The southern edge of the simulated hot spots develops vertical shear of up to 70 meters per second in the eastward wind, which can explain the results of the Galileo probe Doppler wind experiment.

Genome-Wide Comparison of Magnaporthe Species Reveals a Host-Specific Pattern of Secretory Proteins and Transposable Elements

PubMed Central

Gowda, Malali

2016-01-01

Blast disease caused by the Magnaporthe species is a major factor affecting the productivity of rice, wheat and millets. This study was aimed at generating genomic information for rice and non-rice Magnaporthe isolates to understand the extent of genetic variation. We have sequenced the whole genome of the Magnaporthe isolates, infecting rice (leaf and neck), finger millet (leaf and neck), foxtail millet (leaf) and buffel grass (leaf). Rice and finger millet isolates infecting both leaf and neck tissues were sequenced, since the damage and yield loss caused due to neck blast is much higher as compared to leaf blast. The genome-wide comparison was carried out to study the variability in gene content, candidate effectors, repeat element distribution, genes involved in carbohydrate metabolism and SNPs. The analysis of repeat element footprints revealed some genes such as naringenin, 2-oxoglutarate 3-dioxygenase being targeted by Pot2 and Occan, in isolates from different host species. Some repeat insertions were host-specific while other insertions were randomly shared between isolates. The distributions of repeat elements, secretory proteins, CAZymes and SNPs showed significant variation across host-specific lineages of Magnaporthe indicating an independent genome evolution orchestrated by multiple genomic factors. PMID:27658241

Endophytic fungi reduce leaf-cutting ant damage to seedlings

PubMed Central

Bittleston, L. S.; Brockmann, F.; Wcislo, W.; Van Bael, S. A.

2011-01-01

Our study examines how the mutualism between Atta colombica leaf-cutting ants and their cultivated fungus is influenced by the presence of diverse foliar endophytic fungi (endophytes) at high densities in tropical leaf tissues. We conducted laboratory choice trials in which ant colonies chose between Cordia alliodora seedlings with high (Ehigh) or low (Elow) densities of endophytes. The Ehigh seedlings contained 5.5 times higher endophyte content and a greater diversity of fungal morphospecies than the Elow treatment, and endophyte content was not correlated with leaf toughness or thickness. Leaf-cutting ants cut over 2.5 times the leaf area from Elow relative to Ehigh seedlings and had a tendency to recruit more ants to Elow plants. Our findings suggest that leaf-cutting ants may incur costs from cutting and processing leaves with high endophyte loads, which could impact Neotropical forests by causing variable damage rates within plant communities. PMID:20610420

A proteomic analysis of leaf sheaths from rice.

PubMed

Shen, Shihua; Matsubae, Masami; Takao, Toshifumi; Tanaka, Naoki; Komatsu, Setsuko

2002-10-01

The proteins extracted from the leaf sheaths of rice seedlings were separated by 2-D PAGE, and analyzed by Edman sequencing and mass spectrometry, followed by database searching. Image analysis revealed 352 protein spots on 2-D PAGE after staining with Coomassie Brilliant Blue. The amino acid sequences of 44 of 84 proteins were determined; for 31 of these proteins, a clear function could be assigned, whereas for 12 proteins, no function could be assigned. Forty proteins did not yield amino acid sequence information, because they were N-terminally blocked, or the obtained sequences were too short and/or did not give unambiguous results. Fifty-nine proteins were analyzed by mass spectrometry; all of these proteins were identified by matching to the protein database. The amino acid sequences of 19 of 27 proteins analyzed by mass spectrometry were similar to the results of Edman sequencing. These results suggest that 2-D PAGE combined with Edman sequencing and mass spectrometry analysis can be effectively used to identify plant proteins.

Climatic Forcing on Black Sigatoka Disease of Banana Crops in Urabá, Colombia

NASA Astrophysics Data System (ADS)

Ochoa, A.; Álvarez, P.; Poveda, G.; Buriticá, P.; Mira, J.

2012-12-01

Bananas are widely the most consumed fruit in the world and Colombia is one of the major producers and exporters of bananas worldwide. We analyzed the climatic forcing agents on banana crops in the Urabá region, the largest banana producer in Colombia. Although this crop is harvested continuously throughout the entire year, it exhibits climate driven seasonality. Black Sigatoka Disease (BSD) has been the most important threat for banana production worldwide. BSD attacks plant leaves producing small spots of dead material. When BSD is not treated, it can grow enough to damage the entire leaf, reducing both growth and developmental rates which may result in the loss of the plant. BSD is caused by Mycosphaerella fijiensis. This fungus is dispersed by wind with its inoculation occurring when there is water on the leaf. Thus, climatic variables such as wind, relative humidity of air (RH) and leaf wetness duration (LWD) all affect phenological phases of the banana crop (suckering, growing, flowering and harvesting). This study was carried out at the Cenibanano Experimental Plot located in Carepa (Urabá, Colombia) during 2007-2012. We used phytopathologic and weather data from the Cenibanano database along with climatic data from the North American Regional Reanalysis (NARR). BSD was diagnosed using the Biological Forecasting method. Results show that rainfall drives both plant and disease development rate. During wet periods the Foliar Emission Rate exceeds rates measured during dry periods. Although wetness is a positive factor for fungal reproduction (and BSD), it also heightens the chance for the plant to create more foliar tissue to fight against BSD. Hence, during wet periods the Severity Index of BSD is reduced in relation to dry periods. This effect was also observed at the inter-annual scale of the El Niño - South Oscillation (ENSO) phenomenon. During the ENSO warm/cold phase (El Niño/La Niña) rainfall anomalies in Colombia were observed as negative/positive. The Foliar Emission Rate of banana plants also reflected negative/positive anomalies which are consistent with the increase/decrease observed in the Severity Index of BSD.

Vascular Streak Dieback of cacao in Southeast Asia and Melanesia: in planta detection of the pathogen and a new taxonomy.

PubMed

Samuels, Gary J; Ismaiel, Adnan; Rosmana, Ade; Junaid, Muhammad; Guest, David; McMahon, Peter; Keane, Philip; Purwantara, Agus; Lambert, Smilja; Rodriguez-Carres, Marianela; Cubeta, Marc A

2012-01-01

Vascular Streak Dieback (VSD) disease of cacao (Theobroma cacao) in Southeast Asia and Melanesia is caused by a basidiomycete (Ceratobasidiales) fungus Oncobasidium theobromae (syn. =Thanatephorus theobromae). The most characteristic symptoms of the disease are green-spotted leaf chlorosis or, commonly since about 2004, necrotic blotches, followed by senescence of leaves beginning on the second or third flush behind the shoot apex, and blackening of infected xylem in the vascular traces at the leaf scars resulting from the abscission of infected leaves. Eventually the shoot apex is killed and infected branches die. In susceptible cacao the fungus may grow through the xylem down into the main stem and kill a mature cacao tree. Infections in the stem of young plants prior to the formation of the first 3-4 lateral branches usually kill the plant. Basidiospores released from corticioid basidiomata developed on leaf scars or along cracks in the main vein of infected leaves infect young leaves. The pathogen commonly infects cacao but there are rare reports from avocado. As both crops are introduced to the region, the pathogen is suspected to occur asymptomatically in native vegetation. The pathogen is readily isolated but cultures cannot be maintained. In this study, DNA was extracted from pure cultures of O. theobromae obtained from infected cacao plants sampled from Indonesia. The internal transcribed spacer region (ITS), consisting of ITS1, 5.8S ribosomal RNA and ITS2, and a portion of nuclear large subunit (LSU) were sequenced. Phylogenetic analysis of ITS sequences placed O. theobromae sister to Ceratobasidium anastomosis groups AG-A, AG-Bo, and AG-K with high posterior probability. Therefore the new combination Ceratobasidium theobromae is proposed. A PCR-based protocol was developed to detect and identify C. theobromae in plant tissue of cacao enabling early detection of the pathogen in plants. A second species of Ceratobasidium, Ceratobasidium ramicola, identified through ITS sequence analysis, was isolated from VSD-affected cacao plants in Java, and is widespread in diseased cacao collected from Indonesia. Published by Elsevier Ltd.

Tick Bites (For Parents)

MedlinePlus

... can carry harmful germs that cause diseases like Rocky Mountain spotted fever and Lyme disease . The deer tick is tiny, ... disease) red dots on the ankles and wrists (Rocky Mountain spotted fever) flu -like symptoms such as fever , headache , fatigue, ...