SOYBEAN LIPOXYGENASE MUTANTS AND SEED LONGEVITY

Lipid peroxidation and the generation of free radicals may contribute to seed deterioration. Lipoxygenase (LOX) is thought to be a major contributor to lipid peroxidation and free radical generation. This investigation was initiated to determine whether inactivation of one or two of the three LOX isozymes would alter soybean [Glycine max (L.) Merr.] seed storability. Seed from three soybean near-isogenic LOX null isolines and 'Century' were produced at Lexington, KY, in 1991, stored at 120 g kg(-1) seed moisture and 30 degrees C, sampled periodically for 155 d, and tested for seed vigor and viability. Embryonic axes excised from deteriorated seeds were tested for LOX activity, total and free fatty acid content, and production of six-carbon aldehydes. Century and all the LOX genotypes had high initial seed quality and lost germination and vigor (accelerated aging and cold tests) in a similar manner during storage. As seed vigor and viability declined during storage, there was a concurrent rise in free fatty acid content and E-2-hexenal formation for all genotypes. Free linoleic and linolenic acids and E-2-hexenal were inversely related to seed vigor as measured by accelerated aging and cold tests (r greater than or equal to 0.71), and this relationship did not vary among LOX isolines. Seed from the LOX mutants did not show greater or less longevity in the same storage environment. Thus, the loss of one or two of the three LOX isozymes had no effect on soybean seed deterioration.