|Holland, Jim - Jim|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/15/2005
Publication Date: 11/10/2005
Citation: Jines, M., Goodman, M., Holland, J.B., Robertson, L. 2005. Dissection of quantitative trait loci (qtl) associated with gray leaf spot resistance and maturity in maize. Agronomy Abstracts.
Technical Abstract: Abstract Gray Leaf Spot (GLS) is recognized as one of the most significant yield-limiting diseases of maize worldwide and has the potential to threaten maize production. Breeding for resistance provides the best preventive measure against the disease. However, associations between GLS and maturity could hinder the overall breeding effort by increasing maturity while selecting for GLS resistance. One-hundred and forty-three S4:5 recombinant inbred lines (RILs) were developed from single seed descent from a cross between NC300, an all-tropical, temperate adapted line, and B104, a stiff-stalk line. The RILs were topcrossed to the Lancaster tester, FR615xFR697, and subdivided randomly into two sets. The two sets were grown at three western North Carolina locations for two years. Phenotypic data recorded on the topcrosses were used to estimate the genetic correlation between maturity and GLS resistance. Composite interval mapping was used to map genomic regions associated with each trait. QTL associated with GLS resistance were identified at individual environments on chromosomes 1, 4, and 8. One QTL located on chromosome 4 was associated with GLS resistance from the combined analysis across environments and explained 24.5% of the phenotypic variation on an entry-mean basis. A multi-locus model was constructed that involved four marker main effects and a significant epistatic interaction. The multi-locus model explained 35.0% of the phenotypic variation of entry means. The genetic correlation between GLS resistance and days to fifty-percent pollen shed (DTP) in this population was 0.46. A genomic region significantly associated with DTP corresponded to a region associated with GLS resistance on chromosome 8. Further, linked GLS resistance and DTP QTLs occurred together on chromosomes 1, 4, and 8. These experiments demonstrated that GLS resistance and DTP are somewhat correlated and share similar genomic regions.