Desiccation tolerance in developing soybean seeds: The role of stress proteins

The consistent correlation between desiccation tolerance in orthodox seed tissue and an accumulation ot certain "late embryogenesis abundant"" (LEAI proteins suggests that these profeins reduce desiccation-induced cellular damage. The aim of the present work was to test this hypothesis. Exogenous abscisic acid {ABAi was used lo elevate the level of heat-soluble LE.A-like proteins in axes from immature (30 da\s after tlowering: mid-development) seeds of soybean iGlxrine ttuLX [L.] MeiTill c\ Chippewa 64). .As ihe LE.A-iike proteins accumulated in response to .ABA, the leakage of all elements alter desiccation and subsequent rehydration markedly declined. Both LEAlike protein accumulation and ihe decline in desiccation-induced electrolyte leakage were apparently dependeni on the presence of ,AB.A. Both effects of AB.A were inhibited by cyclobeximide. Light microscopy revealed a marked effect ol the .AB.A on cellular integrity following desiccation. Osmotic stress also caused a decrease in desiccation-induced electrolyte leakage and stimulated the accumulation oi LE.A-like proteins. Our data are consistent with the hypothesis that the LE,Vlike proteins contribute (o the increase in desiccation tolerance in response to ,ABA. and are consistent with a general protective role for these proteins in desiccation tolerance.