Background

Global warming threatens rice growth and reduces yields. Proline plays important roles in plant abiotic stress tolerance. Previous research demonstrated that engineering proline metabolism-related genes can enhance tolerance to freezing and salinity in Arabidopsis. OsProDH encodes a putative proline dehydrogenase and is a single copy gene in rice. However, whether OsProDH plays roles in abiotic stress in rice remains unknown.

Findings

Quantitative RT-PCR analysis revealed that OsProDH transcript contents were relatively higher in leaf blade and root tissues and the high temperature treatment repressed expression of OsProDH. The predicted OsProDH protein localized in mitochondria. Using the Oryza sativa ssp. japonica cultivar KY131, we generated OsProDH overexpression (OE) lines and knockout mutant lines using the CRISPR/Cas9 (CRI) system. Overexpression of OsProDH decreased proline content, while mutation of OsProDH increased proline content compared with that of KY131. The CRI and OE lines were respectively more resistant and sensitive to heat stress than KY131. Heat stress induced proline accumulation and mutation of OsProDH led to proline overproduction which reduced H₂O₂ accumulation in the seedlings.

Conclusions

OsProDH negatively regulates thermotolerance in rice. Our study provides a strategy to improve heat tolerance in rice via manipulating proline metabolism.

中文翻译：

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OsProDH通过调节脯氨酸代谢和清除活性氧来负调节水稻的耐热性。

背景

全球变暖威胁水稻生长并降低单产。脯氨酸在植物非生物胁迫耐受性中起重要作用。先前的研究表明，工程化脯氨酸代谢相关基因可以增强拟南芥对冻结和盐度的耐受性。OsProDH编码一个假定的脯氨酸脱氢酶，是水稻中的单拷贝基因。然而，OsProDH是否在水稻非生物胁迫中发挥作用尚不清楚。

发现

定量RT-PCR分析显示，叶片和根部组织中OsProDH转录物含量相对较高，并且高温处理抑制了OsProDH的表达。预测的OsProDH蛋白位于线粒体中。使用Oryza sativa ssp。粳稻品种KY131，我们使用CRISPR / Cas9（CRI）系统生成了OsProDH过表达（OE）系和敲除突变体系。OsProDH的过表达降低了脯氨酸的含量，而OsProDH的突变与KY131相比，脯氨酸含量增加。与KY131相比，CRI和OE线分别更耐高温。热胁迫诱导脯氨酸的积累和OsProDH的突变导致脯氨酸的过量生产，从而减少了幼苗中H ₂ O _2的积累。

结论

OsProDH负面调节水稻的耐热性。我们的研究提供了通过控制脯氨酸代谢来提高水稻耐热性的策略。