Chromosomal regions associated with dollar spot resistance in colonial bentgrass.

摘要

Interspecific hybridization between colonial bentgrass and creeping bentgrasses may be a useful approach for introducing resistance to Sclerotinia homoeocarpa, the causal agent of dollar spot disease, into creeping bentgrass. An interspecific backcross population of 271 genotypes was evaluated for dollar spot in a 2-year field study, and 11% of the genotypes were resistant to dollar spot. In the subset of the backcross population used for genetic linkage mapping, some resistant plants were identified, but no quantitative trait locus (QTL) was detected. A model of qualitative 3-gene recessive epistasis for dollar spot resistance in colonial bentgrass was proposed, and the limitations of QTL analysis to detect genomic regions conferring multigenic qualitative traits were examined. In the simulations, monogenic traits and 2-gene recessive epistatic traits were readily detectable by QTL analysis, whereas for 3-gene recessive epistasis, a QTL was not detectable. As an alternative to QTL analysis, screening of resistant plants from the backcross population for genomic regions held in common suggests that linkage groups 2A₁ and 3A₁ are possibly genomic locations of dollar spot resistance in colonial bentgrass.