Antisense suppression of LOX3 gene expression in rice endosperm enhances seed longevity

Lipid peroxidation plays a major role in seed longevity and viability. In rice grains, lipid peroxidation is catalyzed by the enzyme lipoxygenase 3 (LOX3). Previous reports showed that grain from the rice variety DawDam in which the LOX3 gene was deleted had less stale flavour after grain storage than normal rice. The molecular mechanism by which LOX3 expression is regulated during endosperm development remains unclear. In this study, we expressed a LOX3 antisense construct in transgenic rice (Oryza sativa L.) plants to down-regulate LOX3 expression in rice endosperm. The transgenic plants exhibited a marked decrease in LOX mRNA levels, normal phenotypes and a normal life cycle. We showed that LOX3 activity and its ability to produce 9-hydroperoxyoctadecadienoic acid (9-HPOD) from linoleic acid were significantly lower in transgenic seeds than in wild-type seeds by measuring the ultraviolet absorption of 9-HPOD at 234 nm and by high-performance liquid chromatography. The suppression of LOX3 expression in rice endosperm increased grain storability. The germination rate of TS-91 (antisense LOX3 transgenic line) was much higher than the WT (29% higher after artificial ageing for 21 days, and 40% higher after natural ageing for 12 months). To our knowledge, this is the first report to demonstrate that decreased LOX3 expression can preserve rice grain quality during storage with no impact on grain yield, suggesting potential applications in agricultural production.