Location: Sunflower Research
2013 Annual Report
QTLs controlling disease incidence in the field and greenhouse and yield were identified in two 94-entry pinto bean RIL populations (AP630 and AP647) generated from crosses between AN-37 and P02630 and AN-37 and P02647 pinto bean breeding lines respectively. Heritability estimates in AP630 were low for traits like lodging (0.23), days to maturity (0.21), plant canopy height (0.25) and field disease incidence (0.23), whereas traits like yield, seed weight and the straw test had moderately high heritability estimates of 0.53, 0.74 and 0.46 respectively. Higher heritability estimates for seed weight (0.88), days to flowering (0.74) and maturity (0.72) were observed in the AP647 population suggesting relatively more genetic control of these traits than yield (0.58), disease incidence (0.49) or lodging (0.46); respectively. The two populations were also screened with the BARCBean6K 3 Beadchip consisting of a total of 5,398 bead-types. Genotyping resulted in an average hybridization rate of 45% for the AP630 and 44% for AP647 population. A final total of 1024 SNP markers were polymorphic and were mapped in AP630 and 1016 markers were polymorphic and were mapped in the AP647 population.
The final map assembly of the AP630 population resulted in 11 linkage groups corresponding to the 11 chromosomes of P. vulgaris. The average marker distance was estimated at 1.2 cM however there were regions of both high and low recombination on some linkage groups. The maximum distance between adjacent markers was approximately 22 cM on Pv04. The integrated map of AP630 covered a total of 1183 cM. The total map distance for AP647 was 953 cM represented on 11 linkage groups corresponding to 11 bean chromosomes with an average marker distance of 1.0 cM. Both high and low recombination regions were observed in AP647 and the maximum distance between two loci was 45 cM on Pv01.
Eight traits namely yield, white mold disease incidence, 100 seed weight, days to flowering, days to maturity, plant height, lodging, and greenhouse disease severity (straw test) were analyzed through the multiple QTL model. Thirty six QTL were identified in AP630 in different years for seven traits (white mold disease incidence, seed yield, days to flowering, days to maturity, 100 seed weight, lodging and the straw test) and these QTL were located on 10 chromosomes. LOD scores ranged from the threshold of 2.5 to 10.5.
Fourteen QTL spread across 10 chromosomes were identified in AP647 in different years associated with seed yield, the greenhouse straw test, 100 seed weight, and number of days to maturity, number of days to flowering and plant canopy height. LOD scores ranged from 2.5 to 6.9 for these traits. Six new QTL for yield were identified on Pv01, Pv02, Pv03, Pv05 and Pv09 explaining 11 to 30% of total variation. Seven new QTL for white mold were identified on Pv01, Pv04, Pv07 and Pv08 and two were validated on Pv02 and Pv03 accounting for 19 to 41% of phenotypic variation.