Grapevine Red Blotch Virus Is Transmitted by the Three-Cornered Alfalfa Hopper in a Circulative, Nonpropagative Mode with Unique Attributes

• DOI: 10.1094/phyto-02-21-0061-r
• Publication Date: 2021-03-19T04:14:32Z
• Authors: Madison Flasco; Victoria Hoyle; Elizabeth J. Cien...; Brandon G. Roy; Heather L. McLane; Keith L. Perry; Gregory Loeb; Brian Nault; Michelle Heck; Marc Fuchs
• Keywords: Geminiviridae; Aphis; Horizontal transmission; Vine

The transmission mode of grapevine red blotch virus (GRBV, genus Grablovirus, family Geminiviridae) by Spissistilus festinus, the three-cornered alfalfa hopper, is unknown. By analogy with other members in Geminiviridae, we hypothesized circulative, nonpropagative transmission. Time-course experiments revealed GRBV dissected guts, hemolymph, and heads salivary glands after a 5-, 8-, 10-day exposure to infected grapevines, respectively. After 15-day acquisition on grapevines subsequent transfer alfalfa, nonhost GRBV, titer decreased over time adult insects, as shown quantitative PCR. Snap bean proved be feeding host S. festinus pseudosystemic Agrobacterium tumefaciens-mediated delivery an infectious clone. was efficiently transmitted from snap plants excised trifoliates (90%) or leaves (100%) but less (10%) (67%). Transmission also occurred trans-stadially not via seeds. significantly higher (i) guts hemolymph relative glands, (ii) adults emanating third compared first instars that emerged developed trifoliates. This study demonstrated extended access period viruses Geminiviridae marked differences efficiency between grapevine, natural host, bean, alternative herbaceous host.