Submitted to: Michigan Dry Bean Digest
Publication Type: Trade Journal
Publication Acceptance Date: 2/11/1996
Publication Date: N/A
Interpretive Summary: Most of the navy beans (Phaseolus vulgaris L.) grown in the U.S. are processed in tin cans. Thus, new cultivars considered for release must meet strict industry standards for canning quality. Canning quality traits are strongly influenced by the environment. In order to identify cultivars with stability for canning traits, it is necessary to conduct evaluations over a number of locations and years. Because traditional selection strategies for canning quality are inefficient, costly, and time consuming; alternative selection strategies would be beneficial. One method currently being used by breeders to select traits that are difficult or expensive to measure is marker assisted selection (MAS). A special type of DNA marker called random amplified polymorphic DNA (RAPD) was used to mark several canning quality traits. The genetic material used for evaluation was grown in the field at two locations for two years before processing in a pilot laboratory under conditions simulating commercial canning procedures. The quality traits measured were the washed drain weight, percent solids lost, processed bean texture, the hydration coefficient, and general visual appearance. Several DNA markers were associated with each of the canning quality traits. The RAPD markers associated with general visual appearance and processed bean texture were the most useful to improve canning quality. The use of RAPD markers allows breeders to select for canning quality earlier in the breeding cycle than is the current practice. Early generation selection increases the efficiency of a breeding program and saves valuable resources because it gives the breeder criteria to eliminate inferior genotypes long before they are evaluated in costly replicated tests.
Technical Abstract: Three populations of navy bean, consisting of recombinant inbred lines, were grown at two locations for two years and were used to study canning quality. The traits measured included: visual appeal, texture, washed drained weight, hydration coefficient and percent solids lost. Heritability estimates were calculated for visual appeal (VIS), texture (TXT) and washed drained weight (WDWT) and these were moderate to high in value (0.56 to 0.82). There was a negative correlation (r= -0.26 to -0.66) between VIS and WDWT and a positive correlation (r= 0.19 to 0.66) between VIS and TXT across populations. Random amplified polymorphic DNA markers associated with quantitative trait loci 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/or population specificity was common among the marker-QTL associations identified. Coefficient of variation (R**2) 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 WDWT. Markers were identified that were associated with multiple traits and those associations supported correlations observed between phenotypic traits.