Genetic improvement of protein quality in edible beans with adaptation to Manitoba.

Protein quality in beans is limited by the suboptimal levels of sulphur-containing amino acids, methionine (Met) and cysteine (Cys). The germplasm line SMARC1N-PN1 lacks major seed storage polypeptides. This leads to increased total Cys (up to 70%) and Met content (about 10%) and decreased levels of S-methylcysteine as compared with the corresponding wild-type line. A cross was made between SMARC1N-PN1 (S) and the navy cultivar Morden003 (M) to generate an F2:8 population of 185 recombinant inbred lines (RIL). Protein profiles classified them into four groups according to genetic inheritance at the phaseolin and lectin loci. Lines were tested under field conditions and their amino acid concentrations were evaluated. Some SS lines were characterized by a 50% increase in Cys concentration as compared with Morden003. This was apparent at the London site, under non-sulphate fertilized conditions, but less so at the Morden site, where sulphate fertilizer is routinely applied, with an increase of 10-20%. The significance of these results will be discussed.