ISHS Acta Horticulturae 637: XXVI International Horticultural Congress: Advances in Vegetable Breeding
GENETIC ANALYSIS OF RESISTANCE TO LETTUCE DROP CAUSED BY SCLEROTINIA MINOR |
| Author: | R.C. Grube |
| Keywords: | Lactuca sativa, vegetable, breeding, disease, soilborne, fungus, escape mechanisms, partial resistance |
| Abstract:
Despite extensive germplasm screening, no lettuce accessions have been identified as possessing immunity to infection by Sclerotinia species. As previously reported, several genotypes have consistently shown a significant reduction in disease incidence compared with susceptible varieties following inoculation with S. minor. Many of these genotypes exhibit architectural features that may promote avoidance or escape from infection, such as upright growth and early bolting. To date, the genetic basis and mechanisms of resistance identified in lettuce remain unknown. Transfer of resistance that is due solely to avoidance into commercial cultivars without simultaneous transfer of unacceptable plant morphology may be difficult or impossible. In contrast, physiological resistance is likely to be more easily incorporated into acceptable cultivars. To facilitate the development of lettuce cultivars with S. minor resistance, we sought to ascertain the genetic basis of resistance from the primitive L. sativa accession PI 251246. Recombinant-inbred lines (RILs) were developed from a ‘Salinas’ x PI 251246 F2 population to determine the heritability and action of genes involved in resistance derived from PI 251246 and for mapping of quantitative resistance loci. Results and implications of preliminary evaluation of F2:4 RILs in a replicated field trial will be discussed. | |
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