Location: Vegetable Research
2013 Annual Report
2. Determine genetic basis of resistance to root-knot nematodes in watermelon, identify molecular markers associated with resistance, and develop resistant breeding lines.
3. Determine genetic basis of resistance to root-knot nematodes in pepper and develop resistant breeding lines.
Over 1,300 Plant introductions were screened and new sources of resistance were identified for possible use in managing the whitefly transmitted Squash Vein Yellowing Virus (SqVYV), which has caused devastating losses to the watermelon industry in Florida. Single plant selections from SqVYV resistant wild watermelon accessions were made to develop resistant watermelon germplasm. A release notice for a new germplasm line, 392291-VDR, was published. Crosses between 392291-VDR and susceptible ‘Charleston Gray’ and ‘Mickey Lee’ were made to develop populations for conducting inheritance studies.
Strategies to manage white-fly transmitted viral watermelon vine decline (WVD) including insecticide treatments and resistant pollenizers were developed and experiments were completed. Vine decline resistant pollenizers reduced WVD on the foliage and fruit of the susceptible seedless watermelon Tri-X 313 compared to the susceptible pollenizer ‘Mickey Lee’. Large scale trials conducted in fall 2012 in Immokalee, FL, confirmed these findings.
Watermelon lines were developed and selected for resistance to root-knot nematodes (RKN). The most resistant watermelon lines were evaluated as rootstocks for managing RKN in grafted seedless watermelon in field trials. Several watermelon rootstocks exhibited significantly higher resistance to RKN than squash hybrid and bottle gourd rootstocks, which are commonly used for grafted watermelon.
Homozygous lines of sweet cherry, Cubanelle, and sweet banana were selected for resistance to southern RKN, Meloidogyne incognita, and back-crossed to susceptible parents in order to recover fruit types of the original parents. The most resistant sweet cherry pepper lines are being evaluated for fruit characteristics and fruit yields in field tests.
Advanced sweetpotato breeding lines from USDA, Charleston, North Carolina, and Louisiana, entered in the Sweetpotato Collaborator’s Test were evaluated for resistance to southern RKN, M. incognita. Sweetpotato seedlings from USDA, Charleston, SC were screened for resistance to RKN in efforts to develop RKN resistant sweetpotato varieties.
The most resistant African horned cucumber (Cucumis metulifer) accessions from the U.S. Plant Introduction (PI) collection (identified in previous tests) were evaluated for resistance to RKN (M. incognita) in field tests. Ten African horned cucumber lines selected for resistance to RKN were re-evaluated as rootstocks for grafted ‘Athena’ cantaloupe in RKN-infested fields. Several C. metulifer rootstocks grafted with ‘Athena’ cantaloupe produced higher fruit yields than non-grafted ‘Athena’ and ‘Athena’ grafted on ‘Carnivor’ squash hybrid rootstock.
Kousik, C.S., Ikerd, J.L., Wechter, W.P., Harrison Jr, H.F., Levi, A. 2012. Resistance to Phytophthora fruit rot of watermelon caused by Phytophthora capsici in U.S. Plant Introductions (PI). HortScience. 47(12):1682-1689. Donahoo, R.S., Turechek, W., Thies, J.A., Kousik, C.S. 2013. Potential sources of resistance in U.S. cucumis melo PIs to crown rot caused by phytophthora capsici. HortScience. 48(2):164-170. Kousik, C.S., Adkins, S.T., Turechek, W., Webster, C.G., Roberts, P. 2012. 392291-VDR, a watermelon germplasm line with resistance to Squash vein yellowing virus (SqVYV)-caused watermelon vine decline (WVD). HortScience. 47(12):1805-1807. Kousik, C.S., Adkins, S.T., Turechek, W., Webster, C.G., Webb, S.E., Baker, C.A., Stansly, P.A., Roberts, P.D. 2013. Progress and Challenges in Managing Watermelon Vine Decline caused by whitefly transmitted Squash Vein Yellowing Virus (SqVYV). Israel Journal of Plant Science. 60(4):435-445.