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Black dot disease of potato, caused by Colletotrichum coccodes (Wallr.) Hughes, is widely distributed in the United States. However, little is known regarding the population biology of this fungus. A total of 370 single-spore isolates of C. coccodes were collected from naturally infected potato plants in nine states and analyzed using amplified fragment length polymorphism (AFLP) markers and three primer pairs, yielding 190 polymorphic bands with 90.7 % polymorphism. The isolates were assigned to four vegetative compatibility groups (AFLP/VCG): AFLP/VCG1, AFLP/VCG2, AFLP/VCG4/5, and AFLP/VCG6/7. No isolates tested belonged to AFLP/VCG3. The United States C. coccodes population structure was confirmed with a high differentiation value ( G = 0.30) among VCGs. AFLP/VCG2 was the dominant group in the population ( n = 262) and was the most frequent AFLP/VCG among states, fields, farms, and plants. However, in several instances, more than one AFLP/VCG was isolated from the same plant, field, farm, and state, indicating variability within the C. coccodes population in the United States. A geographic pattern was found for isolates originating from Texas, Montana, North Dakota, and Wisconsin. Diversity within states accounted for 73 % of the total genetic diversity, and among populations accounted for 27 %. These results suggest that several AFLP/VCGs are widely distributed in the United States and that they form a single large population of C. coccodes. [ABSTRACT FROM AUTHOR]

Cotton root rot, caused by the soilborne fungus Phymatotrichopsis omnivora, is one of the most destructive plant diseases occurring throughout the southwestern United States. This disease has plagued the cotton industry for over a century, but effective practices for its control are still lacking. Recent research has shown that a commercial fungicide, flutriafol, has potential for the control of cotton root rot. To effectively and economically control this disease, it is necessary to identify infected areas within fields so that site-specific technology can be used to apply fungicide only to the infected areas. The objectives of this study were to evaluate unsupervised classification applied to multispectral imagery, unsupervised classification applied to the normalized difference vegetation index (NDVI)and six supervised classification techniques, including minimum distance, Mahalanobis distance, maximum likelihood and spectral angle mapper (SAM), neural net and support vector machine (SVM),for mapping cotton root rot from airborne multispectral imagery. Two cotton fields with a history of root rot infection in Texas, USA were selected for this study. Airborne imagery with blue, green, red and near-infrared bands was taken from the fields shortly before harvest when infected areas were fully expressed in 2011. The four-band images were classified into infected and non-infected zones using the eight classification methods. Classification agreement index values for infected area estimation between any two methods ranged from 0.90 to 1.00 for both fields, indicating a high degree of agreement among the eight methods. Accuracy assessment showed that all eight methods accurately identified root rot-infected areas with overall accuracy values from 94.0 to 96.5 % for Field 1 and 93.0 to 95.0 % for Field 2. All eight methods appear to be equally effective and accurate for detection of cotton root rot for site-specific management of this disease, though the NDVI-based classification, minimum distance and SAM can be easily implemented without the need for complex image processing capability. These methods can be used by cotton producers and crop consultants to develop prescription maps for effective and economical control of cotton root rot. [ABSTRACT FROM AUTHOR]

Fusarium crown rot (FCR), caused by Fusarium pseudograminearum and F. culmorum, reduces wheat ( Triticum aestivum L.) yields in the Pacific Northwest (PNW) of the US by as much as 35%. Resistance to FCR has not yet been discovered in currently grown PNW wheat cultivars. Several significant quantitative trait loci (QTL) for FCR resistance have been documented on chromosomes 1A, 1D, 2B, 3B, and 4B in resistant Australian cultivars. Our objective was to identify QTL and tightly linked SSR markers for FCR resistance in the partially resistant Australian spring wheat cultivar Sunco using PNW isolates of F. pseudograminerarum in greenhouse and field based screening nurseries. A second objective was to compare heritabilities of FCR resistance in multiple types of disease assaying environments (seedling, terrace, and field) using multiple disease rating methods. Two recombinant inbred line (RIL) mapping populations were derived from crosses between Sunco and PNW spring wheat cultivars Macon and Otis. The Sunco/Macon population comprised 219 F:F lines and the Sunco/Otis population comprised 151 F:F lines. Plants were inoculated with a single PNW F. pseudograminearum isolate (006-13) in growth room (seedling), outdoor terrace (adult) and field (adult) assays conducted from 2008 through 2010. Crown and lower stem tissues of seedling and adult plants were rated for disease severity on several different scales, but mainly on a numeric scale from 0 to 10 where 0 = no discoloration and 10 = severe disease. Significant QTL were identified on chromosomes 2B, 3B, 4B, 4D, and 7A with LOD scores ranging from 3 to 22. The most significant and consistent QTL across screening environments was located on chromosome 3BL, inherited from the PNW cultivars Macon and Otis, with maximum LOD scores of 22 and 9 explaining 36 and 23% of the variation, respectively for the Sunco/Macon and Sunco/Otis populations. The SSR markers Xgwm247 and Xgwm299 flank these QTL and are being validated for use in marker-assisted selection for FCR resistance. This is the first report of QTL associated with FCR resistance in the US [ABSTRACT FROM AUTHOR]

Transmission electron microscopy was used to confirm the presence of picorna-like virus particles presumed to be Homalodisca coagulata virus-1 (HoCV-1) in the midgut region of adult glassy-winged sharpshooters (GWSS). In addition, we offer a reverse transcription polymerase chain reaction (RT-PCR) assay for the detection of this virus with a sensitivity of ∼95 genome equivalents. A survey employing this assay in conjunction with GWSS samples collected throughout the United States including California, Hawaii, Florida Georgia, and the Carolinas revealed a fairly widespread pattern of distribution, although potentially restricted to temperate regions, areas with elevated host densities, or to populations of a common origin. The virus was found to naturally infect adults regardless of host plant and was not specific to a particular lifestage or sex. Examination of alternate leafhopper species further demonstrated that, although infection is not ubiquitous to all sharpshooter genera, HoCV-1 is not limited to Homalodisca vitripennis (= H. coagulata). [ABSTRACT FROM AUTHOR]

Presents a list of events significant in the field of plant molecular biology. International Conference on Plant Diseases in France in December 2003; Agricultural Microbes Genome II Conference in California in January 2004; Maize Genetics Conference in Mexico in March 2004; Plant Senescence in Massachusetts in June 2004.

The article reports on the danger brought by huanglongbing, a serious disease affecting the citrus industry in the U.S. It cites that the greening disease is a bacterial infection spreading from tree to tree thru citrus psyllids that cause tiny green fruits, thinning branches and dying of the plants. Moreover, the Agricultural Bioterrorism Protection Act approved by President George W. Bush has ordered the U.S. Department of Agriculture (USDA) to include plant pathogens on the selected agent list. In addition, a survey from the Reunion Islands reveals that 65% of citrus trees have been killed by huanglongbing within seven years of planting.

The article reports on the broad host range of Phytophthora ramorum (P. ramorum), a fungal pathogen, ravaging larch plantations in Great Britain. It mentions that a widespread dieback and mortality of mature and juvenile Japanese larch, Larix kaempferi, were observed in September 2009 in plantations across southwest England and are believed to be associated with infection by P. ramorum. A historical overview of the spread of the species, not only in Great Britain but also in other countries including the U.S., is provided. It also notes the measures taken by the British Forestry Commission and other concerned private sectors to prevent further geographical spread of the species.

The article reports on the research conducted by Kevin Eggan of the Harvard Stem Cell Institute and Christopher Henderson of Columbia University on the genetic reprogramming of skin cells of elderly patients in the U.S. It reveals that skin cells from an elderly patient with amyotrophic lateral sclerosis (ALS) have been reprogrammed to generate motor neurons, the type of nerve cells that die as the disease progresses. It is the first time that researchers have induced pluripotent stem (iPS) cell line from a patient with genetic illness and result reveals that iPS cells can be made even from octogenarians with a chronic neuro-degenerative disease. Presented are the details of the study.

The article presents a study of Thomas Boller and fellows in the U.S. that clarify the contribution of pathogen associated molecular patterns (PAMP) to disease resistance, and how PAMP trigger resistance in plants. Boller and his co-member have investigated the role of plant flagellin in bacterial resistance. They examine and pre-treated Arabidopsis thaliana leaves with flg22 peptide and FLS2, a toll-like receptor that detect flagellin. The study shows that PAMP trigger plants resistance.

Sickly plants have fooled botanists into incorporating the symptoms of their ailments into species descriptions, researchers say. The discovery raises the prospect that some plants currently classified as separate species are really just unhealthy samples of other groups. "We need to continually validate the accuracy of species descriptions," says botanist Michael Hood of the University of Virginia, Charlottesville, Virginia. The disease discovery throws fresh light on a major problem area in taxonomy, botanists say.

Concerns over homeland security have put U.S. plant-disease scientists in the spotlight, and they are enjoying more money and greater visibility as a result. But the attendant bureaucracy and costly security measures already have some of them asking if all the attention is a blessing or a curse. Plant pathology has been a poor relation of human health science, commanding only a tiny fraction of the government funding that biomedical research attracts.