How the plasma membrane senses external heat-stress signals to communicate with chloroplasts to orchestrate thermotolerance remains elusive. We identified a quantitative trait locus, Thermo-tolerance 3 ( TT3 ), consisting of two genes, TT3.1 and TT3.2 , that interact together to enhance rice thermotolerance and reduce grain-yield losses caused by heat stress. Upon heat stress, plasma membrane–localized E3 ligase TT3.1 translocates to the endosomes, on which TT3.1 ubiquitinates chloroplast precursor protein TT3.2 for vacuolar degradation, implying that TT3.1 might serve as a potential thermosensor. Lesser accumulated, mature TT3.2 proteins in chloroplasts are essential for protecting thylakoids from heat stress. Our findings not only reveal a TT3.1-TT3.2 genetic module at one locus that transduces heat signals from plasma membrane to chloroplasts but also provide the strategy for breeding highly thermotolerant crops.

中文翻译：

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水稻一个基因座的基因模块保护叶绿体以增强耐热性

质膜如何感知外部热应激信号以与叶绿体交流以协调耐热性仍然难以捉摸。我们确定了一个数量性状基因座，耐热性 3(TT3)，由两个基因组成，TT3.1和TT3.2，它们相互作用以增强水稻的耐热性并减少由热应激引起的谷物产量损失。在热应激下，质膜定位的 E3 连接酶 TT3.1 易位到内体，TT3.1 泛素化叶绿体前体蛋白 TT3.2 进行液泡降解，这意味着 TT3.1 可能作为一种潜在的热传感器。叶绿体中积累较少的成熟 TT3.2 蛋白对于保护类囊体免受热应激至关重要。我们的发现不仅揭示了一个TT3.1-TT3.2在一个基因座上的基因模块将热信号从质膜传递到叶绿体，但也为培育高耐热作物提供了策略。