Background

Signal transduction mediated by heterotrimeric G proteins, which comprise the α, β, and γ subunits, is one of the most important signaling pathways in rice plants. RGA1, which encodes the Gα subunit of the G protein, plays an important role in the response to various types of abiotic stress, including salt, drought, and cold stress. However, the role of RGA1 in the response to heat stress remains unclear.

Results

The heat-resistant mutant ett1 (enhanced thermo-tolerance 1) with a new allele of the RGA1 gene was derived from an ethane methyl sulfonate-induced Zhonghua11 mutant. After 45 °C heat stress treatment for 36 h and recovery for 7 d, the survival rate of the ett1 mutants was significantly higher than that of wild-type (WT) plants. The malondialdehyde content was lower, and the maximum fluorescence quantum yield of photosystem II, peroxidase activity, and hsp expression were higher in ett1 mutants than in WT plants after 12 h of exposure to 45 °C. The RNA-sequencing results revealed that the expression of genes involved in the metabolism of carbohydrate, nicotinamide adenine dinucleotide, and energy was up-regulated in ett1 under heat stress. The carbohydrate content and the relative expression of genes involved in sucrose metabolism indicated that carbohydrate metabolism was accelerated in ett1 under heat stress. Energy parameters, including the adenosine triphosphate (ATP) content and the energy charge, were significantly higher in the ett1 mutants than in WT plants under heat stress. Importantly, exogenous glucose can alleviate the damages on rice seedling plants caused by heat stress.

Conclusion

RGA1 negatively regulates the thermo-tolerance in rice seedling plants through affecting carbohydrate and energy metabolism.

中文翻译：

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RGA1 通过影响水稻的碳水化合物代谢和能量供应来负调节耐热性

背景

由 α、β 和 γ 亚基组成的异三聚体 G 蛋白介导的信号转导是水稻植物中最重要的信号传导途径之一。RGA1编码 G 蛋白的 Gα 亚基，在响应各种类型的非生物胁迫（包括盐、干旱和冷胁迫）中发挥着重要作用。然而， RGA1在热应激反应中的作用仍不清楚。

结果

带有RGA1基因新等位基因的耐热突变体ett1（增强耐热性1 ）源自乙烷磺酸盐诱导的Zhonghua11突变体。经过45℃热胁迫处理36 h并恢复7 d后， ett1突变体的成活率显着高于野生型（WT）植物。45℃暴露12 h后，ett1突变体中丙二醛含量较低，光系统II最大荧光量子产率、过氧化物酶活性和hsp表达高于WT植物。RNA测序结果显示，热应激下ett1中涉及碳水化合物、烟酰胺腺嘌呤二核苷酸和能量代谢的基因表达上调。碳水化合物含量和参与蔗糖代谢的基因的相对表达表明，热应激下ett1的碳水化合物代谢加速。热胁迫下， ett1突变体的能量参数，包括三磷酸腺苷 (ATP) 含量和能量电荷显着高于WT 植物。重要的是，外源葡萄糖可以减轻热应激对水稻幼苗的损害。

结论

RGA1通过影响碳水化合物和能量代谢来负调节水稻幼苗的耐热性。