May 19th, 2015
Presenter: Judith Brown, University of Arizona
Moderator: Julius E. Fajardo, USDA Office of Pest Management Policy
This webinar is hosted by USDA Office of Pest Management Policy and APS with support from the National Plant Disease Recovery System (NPDRS)
The webinar addresses an exotic seed borne virus, Cowpea mild mottle virus (CPMMV) that infects a wide range of cultivated legumes that poses a threat to U.S. soybean production. The virus causes severe mosaic and/or necrotic symptoms in leaves, stems, and pods in many bean (Phaselous species), cowpea (Vigna species), and soybean (Glycine max) varieties grown in the Americas. CPMMV is believed to have been introduced first into South America from western Africa where it is presumed to be endemic, from where it spread into the Caribbean region. In the U.S. mainland, an isolate has been detected using Next-Generation Sequencing (Illumina) in DNA extracts of the whitefly vector Bemisia tabaci (Genn.) in Florida during 2014.
Currently, no monitoring is carried out to study the potential for, or to detect actual, introductions of CPPMV into the USA. Because it has not been found yet in the US mainland, no specific expertise exists to detect the virus visually, and no molecular detection assays are available. To avoid a disastrous introduction and subsequent spread, there is a need to develop accurate diagnostics, apply diagnostics to determine the extent of the seed borne nature of the virus in legume species, and ultimately to develop training materials, and train diagnosticians and legume growers who may encounter this disease on beans, cowpea, and soybean in particular, whether transmitted by the whitefly vector and/or through the seed.
Also, efforts should be pursued to fully characterize the strain(s) occurring in Puerto Rico, and more recently, in Florida, and elsewhere (potentially) in legume growing areas of the USA, particularly where the whitefly vector prevails. If introduced into the U.S. mainland, CPMMV has potential to spread through seed in certain and perhaps all legumes (a poorly studied aspect), on infected ornamental or vegetable transplants, and by the viruliferous whitefly, Bemisia tabaci (Genn.) sibling species complex, itself if previously associated with a virus-infected host.
About the Presenter:
Judith Brown is a APS Fellow and a pioneer in the study of the molecular epidemiology of whitefly-transmitted viruses in the US and worldwide. Judy’s research focuses on virus-vector complexes globally, and was the first to recognize members of the genus, Begomovirus as ‘emerging viruses’, a concept that until then had been applied primarily to human viruses. She is a world authority on whitefly-transmitted viruses (DNA and RNA) of cotton-vegetable systems, whitefly vector biotypes and their impact on virus spread. Her recent research also involves identifying effectors of insect vector-pathogen interactions and abatement using RNAi for citrus greening/tomato vein-greening. She is also applying Next generation sequencing to support molecular epidemiological studies and management of the Cotton leaf curl virus complex in Pakistan and India, Cocao swollen shoot virus in west Africa. Judy’s program has integrated and extended research findings from virus diseases in Arizona and US crops, with her international work on whitefly, psyllid, leafhopper, and mealybug-transmitted viruses in field and greenhouse grown crops.