Ninety-eight percent of the navy beans (Phaseolus vulgaris) grown in the US are processed. Thus, new cultivars considered for release must meet industry standards. Canning quality behaves as a classical QTL which precludes its selection and evaluation in early generations. Such delays add a measure of inefficiency to a breeding program. Indirect selection for canning quality using molecular markers could increase efficiency. RAPD markers are more useful than RFLP's, in Phaseolus, due to a simpler protocol and a higher level of polymorphism within genetically related cultivars. Three populations of RIL's, derived from crosses between cultivars with standard and sub-standard canning quality, were screened to identify markers associated with canning quality. Material for evaluation was grown at two locations, in three replications and processed, in the Food Science Processing Lab, following industry standards. Quality traits measured were: processed texture, color and appearance. Associations of putative markers with canning quality were identified using ANOVA and Mapmaker programs
Three populations of navy bean (Phaseolus vulgaris L.), consisting of recombinant inbred lines, were grown at two locations for 2 years and were used to study canning quality. The traits measured included visual appeal (VIS), texture (TXT), and washed drained mass (WDM). Genotype mean squares were significant for all three traits across populations, although location and year mean squares were higher. We found a positive correlation (r = 0.19 to 0.66) between VIS and TXT and a negative correlation (r = -0.26 to -0.66) between VIS and WDM and between TXT and WDM (r = -0.53 to -0.83) in all three populations. Heritability estimates were calculated for VIS, TXT, and WDM, and these values were moderate to high (0.48 to 0.78). Random amplified polymorphic DNA markers associated with quantitative trait loci (QTL) for the same canning quality traits were identified and studied in each population. Marker-QTL associations were established using the general linear models procedure with significance set at P=0.05. Location and population specificity was common among the marker-QTL associations identified. Coefficient of determination (R2) values for groups of markers used in multiple regression analyses ranged from 0.2 to 0.52 for VIS, 0.11 to 0.38 for TXT, and 0.25 to 0.38 for WDM. Markers were identified that were associated with multiple traits and those associations supported correlations between phenotypic traits. MAS would offer no advantage over phenotypic selection for the improvement of negatively associated traits.