National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, China.
Rice Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China.
Int J Mol Sci. 2024 Oct 20;25(20):11291. doi: 10.3390/ijms252011291.
Low temperatures cause serious threat to rice seed emergence, which has become one of the main limiting factors in the production of direct seeding rice. It is of great importance to study the genes controlling low-temperature tolerance during seed germination and to mine the possible regulatory mechanism for developing new rice varieties with immense low-temperature germination ability. In the current research study, two types of mutants of and , derived from the WT (wild type) ZH11, were used for the analysis of low-temperature germinability. The results showed that the and mutants displayed no significant difference in germination rate with ZH11 at room temperature, but the mutants showed significantly lower germination rates, germination potential and germination index, and slowed seedling growth in the simulated direct seeding experiments at low temperatures compared to ZH11. Additionally, the activity of POD, SOD, CAT, and anti-superoxide anion radial activity were significantly reduced, but the levels of MDA and HO were significantly higher in the and mutant seeds that were germinated at low temperatures compared to ZH11. Further analysis revealed that the levels of total active GA, especially GA4 and GA7, were significantly lower in the and mutants than that in ZH11 during low-temperature germination. Based on qRT-PCR analysis, the expression levels of some GA synthesis-related genes were higher, whereas some were lower in the and mutants than those in ZH11, however, the GA metabolism-related genes and and the GA signaling negative regulator gene were significantly up-regulated in both and mutants at several time points during low-temperature germination. This may explain the lower GA levels in the and mutants. Furthermore, the interaction between the OsNAL11 and OsGASR9 proteins was confirmed by Y2H, LUC, and Co-IP assays. This study provides preliminary insights into the regulatory mechanism of the and genes, which control the low-temperature germination of rice seeds by affecting the GA pathway. Our study will provide the basis for further mining the molecular mechanisms of low-temperature germination in rice and valuable theoretical reference for breeding varieties with strong low-temperature germinability.
低温对水稻种子萌发造成严重威胁，成为直播稻生产的主要限制因素之一。研究控制种子萌发期低温耐受性的基因，挖掘具有巨大低温萌发能力的新水稻品种的可能调控机制，具有重要意义。本研究以 ZH11 的两种突变体 和 为材料，分析其低温萌发能力。结果表明，突变体在室温下与 ZH11 的萌发率无显著差异，但在模拟直播条件下低温萌发时，突变体的萌发率、萌发势和萌发指数显著降低，幼苗生长缓慢。此外，POD、SOD、CAT 和抗超氧阴离子自由基活性显著降低，MDA 和 HO 含量显著升高。进一步分析表明，与 ZH11 相比，低温萌发时突变体的总活性 GA，尤其是 GA4 和 GA7 的含量显著降低。基于 qRT-PCR 分析，一些 GA 合成相关基因在突变体中的表达水平高于 ZH11，而一些基因的表达水平低于 ZH11，但在低温萌发过程中的几个时间点，GA 代谢相关基因 和 以及 GA 信号负调控基因 在 和 突变体中均显著上调。这可能解释了突变体中 GA 含量较低的原因。此外，通过 Y2H、LUC 和 Co-IP 实验证实了 OsNAL11 和 OsGASR9 蛋白之间的相互作用。本研究初步探讨了 和 基因调控水稻种子低温萌发的机制，通过影响 GA 途径来控制水稻种子的低温萌发。本研究为进一步挖掘水稻低温萌发的分子机制以及培育具有较强低温萌发能力的品种提供了理论参考。
