A MITE variation-associated heat-inducible isoform of a heat-shock factor confers heat tolerance through regulation of JASMONATE ZIM-DOMAIN genes in rice

第一作者：Nai Wu

第一单位：华中农业大学

通讯作者：Lizhong Xiong

 Abstarct 

背景+问题：High temperature causes huge yield loss in rice. Heat-shock factors(Hsfs) are key transcription factors regulating the expression of heat stress-responsive genes, but natural variation and functional characterization of Hsfs have been seldom reported. 

每年高温会导致水稻产量的巨大损失。热休克因子（Hsf）是调控植物热响应基因表达的关键转录因子，但是其自然变异和功能鉴定缺很少被报道。

结果1-GWAS鉴定热响应候选基因位点HTG3：A significant heat response locus was detected by genome-wide association study (GWAS) using green leaf area as an indicative trait. A miniature inverted-repeat transposable element (MITE) in the promoter of a candidate gene HTG3 (heat-tolerance gene on chromosome 3) was found to be significantly associated with heat-induced expression of HTG3 and heat tolerance (HT). 

本文中，作者以绿叶面积作为指示性性状，通过全基因组关联分析（GWAS）在水稻中鉴定到了一个热响应的位点。候选基因HTG3是水稻3号染色体上的热耐受性基因，其启动子上的一个转座子元件MITE的插入与HTG3基因的热诱导表达和水稻植株的热耐受性显著相关。

结果2-HTG3a异构体：The MITE-absent variant has been selected in heat-prone rice-growing regions. HTG3a, an alternatively spliced isoform encoding a functional Hsf, positively regulated HT at both vegetative and reproductive stages based on the results of HTG3a over-expression and knockout rice lines. 

在温度较高的水稻种植区，缺乏MITE的变体受到了选择。HTG3a是HTG3基因的一种可变剪切异构体，编码一个功能性的Hsf，HTG3a过表达和敲除株系中的试验结果表明其在营养和生殖生长阶段均能够正调控热耐受性。

结果3-HTG3下游基因：The HTG3-regulated genes were enriched for heat shock proteins and jasmonic acid signaling. Two heat-responsive JASMONATE ZIM-DOMAIN (JAZ) genes were confirmed to be directly up-regulated by HTG3a, and one of them, OsJAZ9, positively regulates HT. 

受到HTG3调控的基因富集于热休克蛋白和茉莉酸信号转导途径。进一步的试验表明，HTG3a能够直接上调两个热响应JAZ基因的表达，并且其中之一OsJAZ9能够正调控热耐受性。

结论：We conclude that HTG3 plays an important role in HT through the regulation of JAZs and other heat-responsive genes. The MITE-absent allele may be valuable for HT breeding in rice.

综上，本文的研究结果揭示了HTG3基因通过对JAZs基因和其他热响应基因的调控在水稻的热耐受性中发挥重要作用。另外，MITE缺失的等位基因在将来的水稻高温耐受性育种中具有潜在应用价值。

** 熊立仲 **

doi: https://doi.org/10.1111/nph.18068

Journal: New Phytologist

Published date: March 04, 2022​