Project description:In rice (Oryza sativa L.), chilling-induced male sterility increased when plants experienced low water temperature (Tw, 18 °C for 14 days) before panicle initiation. The number of mature pollen grains after chilling at the booting stage (12 °C for 5 days) was only approximately 45% of total pollen grains in low-Tw plants, whereas it was approximately 71% in normal-Tw plants (Tw not controlled; approximately 23 °C under air temperature of 26 °C/21 °C, day/night). Microarray and quantitative PCR analyses showed that many stress-responsive genes (including OsFKBP65 and genes encoding a large heat shock protein OsHSP90.1, heat-stress transcription factors, and many small heat shock proteins) were strongly up-regulated by chilling in normal-Tw spikelets, but were not or rather down-regulated by chilling in low Tw spikelets. OsAPX2 and genes encoding some other antioxidative enzymes were also significantly down-regulated by low Tw in the chilled spikelets. In low-Tw plants, lipid peroxidation products (malondialdehyde equivalents) were significantly increased in the spikelets after chilling, and ascorbate peroxidase activity in the chilled spikelets was significantly lower than that in normal-Tw plants. Our data suggest that an OsFKBP65-related chilling response, which protects proteins from oxidative damage, is indispensable for chilling tolerance but is lost in low-Tw spikelets.
