Overexpression of OsLTSD2 decreases cold tolerance in rice

As one of the three major food crops, rice (Oryza sativa L.) originated in temperate and tropical regions. Its geographical and production distribution is restricted by low temperatures. This study aimed to elucidate the effects of OsLTSD2 (Low-temperature Stress Regulated DUF829 protein) overexpression (OE) on rice under low-temperature (LT) stress. This study investigated the survival rates, agronomic traits and stress-related physiological-biochemical indices of wild-type and OsLTSD2 OE plants under LT stress to validate the impact of OsLTSD2 OE on cold tolerance. Abscisic acid (ABA) phenotype experiments and transcriptome data were further analysed to elucidate the molecular mechanisms underlying OsLTSD2-mediated cold-stress regulation in rice. OsLTSD2 is located in the cell membrane and its expression can be affected by temperature stress. OE of OsLTSD2 negatively regulated cold tolerance and reducing sensitivity to exogenous ABA. Meanwhile, it resulted in more severe damage of cell membranes in rice under LT, and the reactive oxygen species-scavenging system also exhibited similarly impaired performance. Transcriptome analysis identified that the expression of genes involved in DNA replication, cell cycle and stress response was significantly downregulated in OE lines. Our findings indicate that OsLTSD2 negatively regulates cold tolerance in rice through impairing cell membrane stability, reducing sensitivity to exogenous ABA and modulating cell cycle stability.