Levels of Crotonaldehyde and 4-hydroxy-(E)-2-nonenal and Expression of Genes Encoding Carbonyl-Scavenging Enzyme at Critical Node During Rice Seed Aging

摘要

The critical node (CN) is an important stage during seed aging, which is related to effective genebank conservation. Previous studies have demonstrated that proteins undergo carbonylated modification at the CN in rice, indicating oxidative damage. However, the levels of reactive carbonyl species (RCS) and the associated scavenging system at the CN are largely unknown. In this study, we optimized methods for the extraction and analysis of RCS from dry rice embryos. In order to acquire seeds at the CN, rice seeds were subjected to natural conditions for 7, 9, 11 and 13 months, and the seed germination rates were reduced to 90%, 82%, 71% and 57%, respectively. We chose the stage with seed germination rate of 82% as the CN according to the rice seed vigor loss curve. The levels of crotonaldehyde and 4-hydroxy-(E)-2-nonenal (HNE) were significantly increased at the CN. In addition, genes encoding carbonyl-scavenging enzyme, including OsALDHs and OsAKRs, were significantly down-regulated at the CN, and reductions in the expression of OsALDH2-2, OsALDH2-5, OsALDH3-4, OsALDH7, OsAKR1 and OsAKR2 in particular could be responsible for RCS accumulation. Thus, the accumulations of crotonaldehyde and HNE and down-regulation of genes encoding carbonyl-scavenging enzyme might be related to an accelerating loss of seed viability at the CN.