Objective This study was committed to explore low-temperature germinability (LTG) related genes of rice, and clarify the molecular mechanism, which can provide theoretical foundation for genetic modification and molecular breeding of low-temperature germinability in rice.

Method Based on the acquired RNA-seq data of low-temperature germination in different rice accessions, differentially expressed genes (DEGs) were screened out. Genetic transformation materials of the chosen DEG were constructed, which were applied for the identification of gene function through seed germination trials.

Result A Yippee family member encoding gene OsYIPL1, which had a higher expression level in high LTG accessions, was chosen for further study. The results of temporal and spatial expression of OsYIPL1 showed that it was specifically expressed higher in rice anther and young embryo. Two over-expression lines of OsYIPL1, OX-1and OX-2, were acquired and the seeds from the T2 generation were applied for germination trials at normal temperature (28℃) and low temperature (13 ℃). The results showed that when the expression of OsYIPL1 was increased to 44.5 times that of the wild type (OX-1), the germination rate of its seeds at normal temperature was 18.3% higher than that of the wild type on average. When the expression of OsYIPL1 was increased to 88.9 times that of the wild type (OX-2), the germination rate of its seeds at normal temperature was 54.5% lower than that of the wild type. At low temperature, overexpression of OsYIPL1 could reduce seed germination, and the germination rates of OX-1 and OX-2 were 43.8% and 81.5% lower than those of the control on average.

Conclusion OsYIPL1 participates in regulation of rice seed germination, but the effects are obviously different at different temperatures. The underlying mechanism is waiting for further research.