Abstract
Postharvest lipid degradation is a major factor contributing to quality loss, off-flavors, and reduced shelf life in stored rice grains. We investigated whether inducing secondary dormancy using abscisic acid (ABA) can stabilize lipid metabolism in rice. Non-dormant japonica (Nanjing 46) and indica (Fengliangyou) rice grains were induced into secondary dormancy with ABA (800 and 1500 mg/L, respectively), then subjected to accelerated aging (35 °C, 75 ± 2 % RH, up to 45 days). Lipid metabolism was assessed by enzyme assays, UHPLC–MS/MS lipidomics, and RNA-seq. Dormancy induction significantly suppressed the activities of lipase, phospholipase D, and lipoxygenase, resulting in lower rates of lipid hydrolysis and oxidative deterioration. Lipidomic profiling revealed delayed degradation of triacylglycerols and membrane phospholipids (phosphatidylcholine and phosphatidylethanolamine), while transcriptomic analysis showed coordinated downregulation of lipid degradation genes (OsLOX1, OsPLDalpha3). This multi-level suppression led to decreased accumulation of free fatty acids, lipid peroxides, and volatile aldehydes associated with rancid off-flavors. These findings provide new insights into dormancy-mediated lipid regulation and suggest a novel physiological strategy to enhance the storage stability and sensory quality of rice and other lipid-rich cereals.
