Genes affecting starch biosynthesis exert pleiotropic effects on the protein content and composition of pea seeds

We have used a series of near-isogenic mutant pea lines defective in starch biosynthesis to identify genes that exert pleiotropic effects on the protein content and composition of the pea seed. The total protein contents of the flours obtained from the dry seed of these lines, determined using a new method based on amino acid analysis and validated by near-infrared reflectance spectroscopy, ranged fi om 19 to 28% of dry matter. Modifications in the legumin (11S)/vicilin (7S) ratios were confirmed by analytical ultracentrifugation and accompanied by compensatory increases in the albumin (2S-4S) content, Improving the albumin fraction of plant protein can be used to improve its nutritional value. There is additional variability in the solubility profiles for the protein in these lines. This variability has implications for the functional properties, processing behaviour, potential industrial applications, digestibility and nutritional value of the different pea meal and the protein ti actions derived therefrom. Digestibility of the protein in meal and in air-classified and extruded products from selected lines will be compared in nutritional evaluation trials with poultry to assess the suitability of these products for incorporation into animal diets. (C) 2001 Society of Chemical Industry.