|Ryder, Edward - COLLABORATOR-USDA,ARS|
Submitted to: American Society of Horticulture Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 24, 2003
Publication Date: October 20, 2003
Citation: Grube, R.C., Ryder, E.J., Wintermantel, W.M., Aburomia, R. Resistance to soilborne tombusviruses within lactuca sativa: genetic control, mechanisms, and potential for reliable and long-term disease control. American Society Of Horticulture Science Meeting. 2003. HortScience. v. 38(5). p. 677-678. Technical Abstract: At least two tombusviruses, tomato bushy stunt and lettuce necrotic stunt viruses, cause the disease lettuce dieback. In commercial lettuce fields in California and Arizona, symptoms have been observed only on romaine and leaf lettuce cultivars, and never on modern crisphead (iceberg) cultivars. Over 100 Lactuca cultivars and plant introduction (PI) accessions were evaluated for resistance in field experiments. Consistent with observations in commercial fields, all modern crisphead cultivars were asymptomatic (resistant) and all modern romaine cultivars were susceptible. Both resistant and susceptible accessions were identified among modern leaf lettuce cultivars, heirloom crisphead cultivars, and romaine-like PI accessions. The romaine PI 491224 was used in the development of resistant romaine breeding lines (Grube and Ryder 2003). Focusing on two genotypes that fail to develop symptoms in infested fields, the modern crisphead cv. Salinas and the romaine PI 491224, our objectives was to determine the inheritance of resistance in these genotypes and to determine whether the viral pathogen systemically infects asymptomatic accessions under field and laboratory conditions. Preliminary data suggest that the asymptomatic response of PI 491224 is conferred by a dominant allele at a single locus. We will discuss the implications of our results on the potential for the long-term control of lettuce dieback through the use of resistant cultivars.