Biochemical changes in recombinant inbred lines of soybean (Glycine max L. Merr.) under storage-related stresses

Soybean is a major crop that is rich in proteins, lipids, and isoflavones. Although the seeds are widely used for food and industrial purposes, soybean is recognized as a crop that does not store well, as storage conditions greatly affect seed quality. In this study, we selected 10 recombinant inbred lines (RILs) of soybean that are either sensitive or tolerant to storage, and examined the biochemical characteristics of the lines and their parents under storage-related stresses. The germination rates of all of the lines in the tolerant group were higher than those of the sensitive group for all storage conditions. Malondialdehyde (MDA) content was higher in the sensitive group than in the tolerant group, with the MDA content typically increasing under long-term storage conditions. Superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities were also more affected by long-term storage, but not by higher temperatures. Isoflavones were also assayed and it was found that the aglycones (except glycitein) increased with an increase of storage temperature. Malonyl isoflavone glucosides tended to decrease under long-term storage and high temperature conditions, suggesting that malonyl glucosides are converted to their aglycones. These results illustrate the mechanisms underlying storage-related stresses and the importance of screening for lines that can tolerate environmental stresses.