Brief Summary of Minutes of Annual Meeting

Bill Wintermantel welcomed the group to the Salinas, CA USDA station and explained a bit about the group and its purpose. Introductions were made, and the agenda was discussed. Bill Wintermantel gave an overview of curly top work in California. 2013 was the worst year for the disease in tomatoes in the Central Valley of California since the 1990s, even surpassing 2001 in severity. Agriculture in the valley has changed over the past decade, and this may have impacted disease development. Tomatoes are transplanted now instead of direct seeded; there are higher acreages of tomatoes and very few sugarbeets. Curly top levels were very high in mid March in the foothills. The leafhopper distribution, although showing some migration patterns as expected, was much more random and populations were not just found closest to the foothills, suggesting that some leafhoppers may be overwintering in the valley or were moving very early. Weedy fields could be serving as source plants. All plants tested using standard primers for BSCTV and BMCTV, the two species dominating infections in California production for the past two decades, tested positive for BMCTV  including weeds, tomatoes, sugarbeets etc. However, bands were consistently weak, and sequencing suggests a variant that is distinct, but amplifies with BMCTV primers. In contrast, sampling of sugarbeet in Idaho, resulted in a mix of BSCTV and BMCTV. Curly top infection of commercial melon was found for the first time in over a decade. Bills lab is developing VIGS to induce resistance in tomatoes. The resistance works for at least 35 days. There are initial symptoms, some at 8 days post infection, less at 14 days, and almost none at 24 days post infection. The system includes multiple regions of virus and works against both BSCTV and BMCTV. A patent application has been submitted. Jorge Achata presented his PhD research looking at mutation rate and mutation hot spots of curly top virus using ion torrent deep sequencing. He presented a discussion of the difficulties with the machine providing high numbers of indels and described the DIs (defective interfering molecules) found. Alex Karasev gave an overview of curly top in Idaho. BSCTV, BMCTV and BCTV are the most important viruses in the state and sugarbeet and bean are the most important virus hosts. He showed that the disease rating system in sugarbeets does not reflect virus titer using a recombinant antisera to curly top that his group produced. He made infectious clones of BCTV and BSCTV and used both to screen sugarbeet germplasm, finding that some curly top resistant sugarbeet lines were susceptible to the virus derived from the clone, but induced generally lower disease ratings. Alex, working with Imad Eujayl (ARS, Kimberly, ID) has identified some resistant tomatoes and sugarbeet lines. He found that beans were susceptible to virus derived from BSCTV and BCTV clones and that the size of the cloned BSCTV 1.8 genomes was more infectious than the BSCTV 1.2 genomes. He also did tissue printing to localize virus and found it around vascular bundle. Stephen Peinado presented his MS research on the result of mixed infections of Pepper curly top virus and BSCTV in pepper and sugarbeets. He showed that host influenced whether the viruses competed or reacted synergistically. In sugarbeets, both viruses decreased slightly, while in pepper, PeCTV increased and BSCTV decreased. Li Fang presented an overview of the current status of curly top virus taxonomy followed by a summary of the disease problems in the Central Valley of CA in 2013. She has monitored leafhoppers for curly top virus titer and strain since 2002. She has found some important recombinants that appear to be stable in the environment, ie. LH71, which has components of PeCTV (rep) and BMCTV/BSCTV (CP), as well as a second emergent variant, pCO95 for which sequence of an isolate was deposited in Genbank many years ago by Drake Stenger. LH71 was common in California during 2013. In severe curly top years, large numbers of leafhoppers are collected early during the year (March) and are found to contain virus. She can use her information on curly top hot spot locations to determine the optimal locations and times to spray insecticide. In March 2013, she found BMCTV and BSCTV in leafhoppers; 84% had BMCTV and 42% had both BMCTV and BSCTV. 63% had strong signal by PCR. Testing tomatoes gave similar results; in Fresno area, around half had BMCTV and half BSCTV, and in Merced 85% was BMCTV. Sequence analysis of limited isolates of the BSCTV determined that much of this was actually the LH71. In contrast to the past 10 years, cucurbits, melons, and watermelon had high levels of infection. She also found eggplant infected for the first time, which had mild symptoms. Rebecca Creamer presented research on the bacterial endosymbionts of the beet leafhopper. Three different endosymbionts were identified, Sulcia muelleri, an alpha-proteobacter and a beta-proteobacter. The bacteria were all localized to the gut. GroEL was identified and sequenced and shown to be produced by the Sulcia endosymbiont. GroEL was localized to the gut only, while virus could be detected using confocal microscopy to both the head and the gut. Bob Hammon sent a summary of his results on management of curly top virus in tomatoes in western Colorado. Carl Strausbaugh sent his poster on the use of Poncho Beta and foliar insecticides in sugarbeets in Idaho. While Poncho Beta-treated seed was very effective in controlling disease in resistant sugarbeet, the addition of foliar insecticides extended the control. There was an extensive discussion as to the proposed lumping of all curtoviruses into a single species and the renaming of all curtoviruses. The group consensus was that we did not agree with the renaming of the viruses as Beet curly top virus A-H and preferred strain designations which retained the historical and commonly used names. Bill noted that in discussions with Judy Brown, the A-H designations were to be replaced by designations reflecting currently recognized names; however, the group expressed concern that there was not widespread notification that the nomenclature was to be changed and did not as a whole agree with the proposal. Alex Karasev agreed to write a letter to the ICTV expressing the groups concerns. Research questions concerning curly top research that were raised by the attendees. " Can functional disease prediction systems be established for southern Idaho and Central Valley of California? " Sequence of the beet leafhopper would be highly desired. There was a brief discussion as to the 2014 meeting location and Alex Karasev agreed to host the meeting in Moscow, ID.

Collaborative curly top projects for 2012-13 were carried out between Rebecca Creamer and Robert Gilbertson (Li-Fang), and among CDFA (Jennifer Willems), Bill Wintermantel, and Robert Gilbertson (Li Fang). Cooperative projects were carried out between Carl Strausbaugh, and Bill Wintermantel and between Carl Strausbaugh and Alex Karasev.

The group did not publish a report together.