Improving yield and quality of bean seed protein and the development of superior populations for cooperative utilization in breeding programs; progress report, 1975

COMPARISONS BETWEEN HIGH AND LOW PROTEIN SELECTIONS INDICATE THAT THE PRIMARY EFFECT OF SELECTION IS MANIFESTED THROUGH CHANGES IN THE AMOUNT OF GL GLOBULIN FRACTION. THIS FRACTION IS THE MAJOR CONSTITUENT OF BEAN SEED PROTEIN, BUT IS POOR IN METHIONINE. THEREFORE, SELECTION FOR HIGH PROTEIN OFTEN RESULTS IN ACCOMPANYING LOW PERCENTAGE METHIONINE LEVELS. THERE ARE EXCEPTIONS TO THIS NEGATIVE ASSOCIATION, AS BEST EXEMPLIFIED BY BBL240, WHICH IS HIGH IN BOTH PERCENTAGE OF PROTEIN AND METHIONINE AND BY PROMISING SELECTIONS. SOME DIFFERENCES ARE SHOWN IN THE STRUCTURE OF ONE OF THE POLYPEPTIDES THAT CONSTITUTE THE GL GLOBULIN THAT ARE DUE TO A SINGLE GENE (LIKELY A STRUCTURAL GENE). THE EFFECTS OF THIS GENE ON THE QUALITY (AMINO ACID COMPOSITION) OF THE GL FRACTION ARE BEING STUDIED, SINCE BBL (HIGH METHIONINE) CARRIES A VARIANT ALLELE. CONSIDERABLE VARIABILITY IN TANNIN LEVELS OF DIFFERENT STRAINS HAVE BEEN FOUND. HIGH PROTEIN/METHIONINE STRAINS HAVE BEEN INTERCROSSED TO HIGH YIELDING, ADAPTED, AND DISEASE RESISTANT GERM PLASM TO FORM THE FIRST GENERATION OF A COMPOSITE OPEN POPULATION THAT INCLUDES APPROXIMATELY 50 ACCESSIONS. ONE CYCLE OF RECURRENT SELECTION FOR HIGH YIELD (FAMILY BASIS) AND HIGH PROTEIN (INDIVIDUAL PLANTS) HAS BEEN COMPLETED, WITH THE SELECTED LINES HAVING; 1) INTERCROSSED TO FORM THE SECOND COMPOSITE OPEN POPULATION GENERATION AND; 2) SENT TO COOPERATORS IN PUERTO RICO, COLOMBIA, AND BRAZIL FOR FURTHER EVALUATION.