OAT ENDOSPERM CELL-WALLS .1. ISOLATION, COMPOSITION, AND COMPARISON WITH OTHER TISSUES

To test the hypothesis that the composition of oat endosperm cell wall s would vary with the total great beta-glucan content, endosperm walls were isolated from two cultivars of oats previously identified as con taining high and low levels of beta-glucan (Marion and OA516-2, respec tively). Oat endosperm cell walls were isolated by a modification of a method developed for wheat endosperm walls. In this modification, a s lurry of anion exchange resin beads was used to take out cell walls fr om the bran (aleurone, pericarp, and testa) that were not removed usin g the original procedure, and cytoplasmic starch and protein were remo ved by ''washing'' the cell walls with 1% sodium dodecyl sulfate in 70 % ethanol. In both cultivars, beta-glucan was the major endospermic ce ll wall polysaccharide, constituting approximately 85% of the wall. De spite the major difference in the beta-glucan content of the two culti vars, determined on a great basis, this difference was not reflected i n the composition of isolated endosperm walls. The beta-glucan content and monosaccharide composition were similar for the two types of wall s. There were, however, differences in the phenolic acid content of th e walls between the two cultivars, with those from OA516-2 having a hi gher total phenolic acid content than those from Marion. Preliminary a nalyses indicate that oat endosperm cell walls are composed primarily of beta-glucan and arabinoxylan, with a small amount of cellulose and glucomannan. Phenolic acids and a small amount of protein, determined as amino acids, are also present in the cell wall.