Submitted to: American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/1997
Publication Date: N/A
Citation: Interpretive Summary: Most of the navy beans (Phaseolus vulgaris L.) grown in the US are processed. Thus, new cultivars considered for release must meet strict industry standards. Traits related to canning quality in bean behave in a quantitative fashion, e.g., observed differences are distributed on a continuum rather than in individual groups. Traits that behave quantitatively are known as quantitative trait loci (QTLs). Practical breeding experience indicates that QTLs are influenced strongly by the environment, thus, breeders must evaluate potential new varieties over a number of places and years. The time and cost required to select for canning quality in many environments could be reduced if selection could be practiced indirectly using a marker that is associated with the trait of interest rather than selecting for the trait itself. Since genes are composed of DNA, a complex chemical, DNA markers would be useful for indirect selection. A special type of DNA marker called random amplified polymorphic DNA (RAPD) has been used to mark QTLs in beans. An experiment was designed in which recombinant inbred lines (RILs) were developed. RILs are the best kind of genetic population to study RAPDs. Three populations of RILs derived from crosses between cultivars with acceptable and unacceptable canning quality were screened to identify RAPD markers associated with canning quality. Material for evaluation was grown at two locations and 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, color and general appearance. Associations between RAPD markers and washed drain weight, texture and general appearance were identified.
Technical Abstract: Random amplified polymorphic DNA markers associated with quantitative trait loci (QTLs) for canning quality were identified and studied in three populations of navy bean. Each population, consisting of recombinant inbred lines (RILs), was grown and evaluated at two locations for two years. The traits measured were: visual appeal, texture, washed drained weight, hydration coefficient and percent solids lost. Marker-QTL associations wer established using the General Linear Models procedure with significance set at P = 0.05. Location and/or population specificity was common among the markers identified. Coefficient of variation (R**2) values for individual markers ranged from 0.10 to 0.38 and R**2 values for groups of markers used in multiple regression analyses ranged from 0.15 to 0.74. Heritability estimates were calculated for visual appeal, texture and washed drained weight and these were moderate to high in value (0.56 to 0.82). There was a anegative correlation (r= -0.26 to -0.66) between visual appeal and washed drained weight and a positive correlation (r+ 0.19 to 0.66) between visual appeal and texture. These relationships will influence which markers and in what manner they are used for marker assisted selection. Relationships between canning quality traits should also influence which traits are used for traditional phenotypic selection.