Progress 11/04/20 to 09/30/21
Outputs
Target Audience:The target audiences by our research and extension efforts were the grape and wine communities, including grape growers, vineayrd managers, vintners, wine makers, service providers, as well as IMP specialists and extension educators. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Opportunities for training and professional developement were provided to temporary staff who learned and contributed to the identification of TCAH on yellow sticky card, and the identification of plant species in vineyard ecosystems. How have the results been disseminated to communities of interest?Results were disseminated to grape and wine communities through oral presentation of research progress. What do you plan to do during the next reporting period to accomplish the goals?We are planning on completing the work on (i) the comparative efficacy of GRBV transmission by two distinct population of the TCAH, and (ii) gut content analyses to advance our understanding of the landscape movement of TCAH populations, and initiating work to characterize TCAH endosymbionts
Impacts
What was accomplished under these goals?
Grapevine red blotch virus (GRBV) is the causal agent of red blotch disease and a new threat to grape production in New York and beyond. The three-cornered alfalfa hopper (TCAH) is a vector of GRBV but no information is available on transmission mode. By analogy with other members in the family Geminiviridae, we hypothesized circulative, nonpropagative transmission. Time course experiments revealed GRBV in dissected guts, hemolymph and heads with salivary glands following a 5-, 8- and 10-day exposure to infected grapevines, respectively. After a 15-day acquisition on infected grapevines and subsequent transfer on alfalfa, a non-host of GRBV, the virus titer decreased over time in adult insects, as shown by qPCR. Snap bean proved to be a feeding host of S. festinus and a pseudo-systemic host of GRBV following Agrobacterium tumefaciens-mediated delivery of an infectious clone. The virus was efficiently transmitted by S. festinus from infected snap bean plants to excised snap bean trifoliates (90%) or grapevine leaves (100%) but less efficiently from infected grapevine plants to excised grapevine leaves (10%) or snap bean trifoliates (67%). Transmission of GRBV also occurred transstadially but not via seeds. This study demonstrated circulative, nonpropagative transmission of GRBV by S. festinus with an extended acquisition access period compared with other viruses in the family Geminiviridae and marked differences in transmission efficiency between grapevine, the natural host, and snap bean, an alternative herbaceous host. Two distinct genotypes of the TCAH have been identified but no information is available on their comparative transmission ability or efficiency. Transmission assays are under way to determine whether there is a differential transmission efficiency of GRBV between the two populations of the TCAH. Characterizing the transmission mode and differential transmission by distinct TCAH genotypes is critical for effective disease management. Little is understood about the landscape-level movement of the TCAH; yet virus spread is occurring although grape is not a reproductive host and the treehoppers are only found in vineyards during brief summer months. Analyzing the molecular gut content could highlight feeding preferences in a vineyard ecosystem and advance our understanding of the TCAH ecology to help elucidate patterns in landscape-level movements and host plant associations. These data could be helpful in informing optimal disease management tactics. We placed yellow sticky cars in numerous diseased vineyards and caught TCAH. Concurrently, we collected samples of many leguminuous plants in riparian areas or in close proximity to diseased vineyards. DNA was isolated from the TCAH and plant samples and analysed by PCR using primers specific to plant-derived internal transcribed spacer (ITS) sequences and the chloroplast trnL and trnF genes. PCR amplicons were sequenced. Analyses of sequences obtained from plant genesand plant genes in the insect gut are under way.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Flasco, M., Hoyle, V., Cieniewicz, E.J., Roy, B.G., McLane, H.L., Perry, K.L., Loeb, G., Nault, B., Heck M. and Fuchs, M. 2021. Grapevine red blotch virus is transmitted by the three-cornered alfalfa hopper in a circulative, nonpropagative transmission mode with unique attributes. Phytopathology, 111: 1851-1861, https://doi/org/10/1094/phyto-02-21-0061-r
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