|McCreight, James - Jim|
|NATWICK, ERIC - University Of California - Cooperative Extension Service|
|Wintermantel, William - Bill|
Submitted to: International Working Group on Legume and Vegetable Viruses
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2015
Publication Date: N/A
Technical Abstract: Cucurbit yellow stunting disorder virus (CYSDV), emerged in the Southwest USA in 2006, where it is transmitted by the MEAM1 cryptic species of Bemisia tabaci. The virus results in late-season infection of spring melon crops with limited economic impact; however, all summer and fall cucurbits become infected shortly after emergence due to high B. tabaci populations and abundant host plants. Vector management efforts are insufficient to reduce the impact of CYSDV on cucurbit production in the region, therefore, development of host plant resistance in melon to CYSDV and SPWF are high priorities. Melon accessions TGR 1551 (PI 482420), TGR 1937 (PI 482431) and PI 313970 are partially resistant to CYSDV, but inheritance of resistance has been reported only for TGR 1551 and PI 313970. Approx. 500 melon accessions of India origin were evaluated in Imperial Valley, CA for reaction to natural infection by CYSDV in open field tests from 2007 to 2013. Six accessions were heterogeneous for apparent resistance to CYSDV, and CYSDV resistance was confirmed in TGR 1937 and PI 614479. These accessions were crossed with CYSDV-susceptible ‘Top Mark’ and ‘Impac’, and F2 progeny and testcrosses were produced in a greenhouse. Inheritance of resistance was studied under high whitefly feeding pressure in naturally infected field tests. There were significant differences in symptom severity 10 weeks post planting (WPP) between the resistant parents and their susceptible mates. F1 generations did not significantly differ from their respective susceptible parents, indicating recessive control of resistance to CYSDV in TGR 1937 and PI 614479, and F2 and respective testcross generations confirmed recessive resistance. CYSDV titer at 10 WPP reflected differences in symptom expression. Additional studies are focused on enhancing resistance to SPWF in melon in an effort to improve opportunities for summer and fall cucurbit production in this region and other areas where melon production encounters strong disease pressure from CYSDV and high vector populations.