Cytosolic HSC70s repress heat stress tolerance and enhance seed germination under salt stress conditions
Cytosolic HSC70s repress heat stress tolerance and enhance seed germination under salt stress conditions
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胞浆 HSC70 抑制热应激耐受性并增强盐胁迫条件下的种子发芽
DOI：
10.1111/pce.14009
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Yamaguchi‐Shinozaki Kazuko
中科院分区：
文献类型：
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作者：
Zhao Huimei;Jan Asad;Ohama Naohiko;Kidokoro Satoshi;Soma Fumiyuki;Koizumi Shinya;Mogami Junro;Todaka Daisuke;Mizoi Junya;Shinozaki Kazuo;Yamaguchi‐Shinozaki Kazuko
热休克因子A1(HsfA1)家族蛋白是拟南芥热应激反应转录级联反应的主要调节因子。虽然已知70 kDa热休克蛋白参与抑制HsfA1活性，但它们调节HsfA1活性的机制尚不清楚。在此，我们报道了HSC70-1、HSC70-2和HSC70-3三种胞质Hsp70在正常和应激条件下的生理功能。HSC70基因在整个幼苗中都有表达，在正常和逆境条件下，HSC70蛋白存在于细胞质和细胞核中，HsfA1和hsc70-1/2/2双突变体和hsc70-1/2/3三重突变体表现出比野生型(WT)更高的耐热性。转录分析表明，在正常生长条件下，hsc70-1/2/3突变体中热应激反应HsfA1下游基因上调，表明这些HSC70冗余地作为HsfA1活性的抑制因子。此外，在高盐胁迫条件下，hsc70-1/2/3植株在萌发阶段表现出比对照植株更严重的生长延迟，并且许多在萌发过程中表达抑制的种子特异性簇2基因在hsc70-1/2/3植株中表达，这表明这些hsc70还通过抑制簇2基因的表达而在高盐条件下种子向幼苗的发育转换中发挥作用。
Heat shock factor A1 (HsfA1) family proteins are the master regulators of the heat stress‐responsive transcriptional cascade in Arabidopsis. Although 70 kDa heat shock proteins (HSP70s) are known to participate in repressing HsfA1 activity, the mechanisms by which they regulate HsfA1 activity have not been clarified. Here, we report the physiological functions of three cytosolic HSP70s, HSC70‐1, HSC70‐2 and HSC70‐3, under normal and stress conditions. Expression of theHSC70genes was observed in whole seedlings, and the HSC70 proteins were observed in the cytoplasm and nucleus under normal and stress conditions, as were the HsfA1s.hsc70‐1/2double andhsc70‐1/2/3triple mutants showed higher thermotolerance than the wild‐type (WT) plants. Transcriptomic analysis revealed the upregulation of heat stress‐responsive HsfA1‐downstream genes inhsc70‐1/2/3mutants under normal growth conditions, demonstrating that these HSC70s redundantly function as repressors of HsfA1 activity. Furthermore,hsc70‐1/2/3plants showed a more severe growth delay during the germination stage than the WT plants under high‐salt stress conditions, and many seed‐specific cluster 2 genes that exhibited suppressed expression during germination were expressed inhsc70‐1/2/3plants, suggesting that these HSC70s also function in the developmental transition from seed to seedling under high‐salt conditions by suppressing the expression of cluster 2 genes.