Hua Bing, Chang Jiang, Xu Zhijing, Han Xiaoqian, Xu Mengyuan, Yang Meina, Yang Changxian, Ye Zhibiao, Wu Shuang
College of Horticulture, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China.
New Phytol. 2021 May;230(3):1063-1077. doi: 10.1111/nph.17216. Epub 2021 Feb 26.
Plant hormones can adjust the physiology and development of plants to enhance their adaptation to biotic and abiotic challenges. Jasmonic acid (JA), one of the immunity hormones in plants, triggers genome-wide transcriptional changes in response to insect attack and wounding. Although JA is known to affect the development of trichomes, epidermal appendages that form a protective barrier against various stresses, it remains unclear how JA interacts with developmental programs that regulate trichome development. In this study, we show that JA affects trichome length in tomato by releasing the transcriptional repression mediated by Jasmonate ZIM (JAZ) proteins. We identified SlJAZ4, a negative regulator preferentially expressed in trichomes, as the critical component in JA signaling in tomato trichomes. We also identified a homeodomain-leucine zipper gene, SlHD8, as the downstream regulator of JA signaling that promotes trichome elongation. SlHD8 is also highly expressed in trichomes and physically interacts with SlJAZ4. Loss-of-function mutations in SlHD8 caused shorter trichomes, a phenotype that was only partially rescued by methyl jasmonate treatment. Our dual-luciferase and chromatin immunoprecipitation-quantitative PCR assays revealed that SlHD8 regulates trichome elongation by directly binding to the promoters of a set of cell-wall-loosening protein genes and activating their transcription. Together, our findings define SlHD8-SlJAZ4 as a key module mediating JA-induced trichome elongation in tomato.
植物激素可以调节植物的生理和发育，以增强其对生物和非生物胁迫的适应性。茉莉酸（JA）是植物中的免疫激素之一，可触发全基因组转录变化以响应昆虫攻击和伤口。尽管已知JA会影响毛状体的发育，毛状体是形成抵御各种胁迫的保护屏障的表皮附属物，但JA如何与调节毛状体发育的发育程序相互作用仍不清楚。在本研究中，我们表明JA通过释放由茉莉酸ZIM（JAZ）蛋白介导的转录抑制来影响番茄中的毛状体长度。我们鉴定出SlJAZ4，一种优先在毛状体中表达的负调节因子，是番茄毛状体中JA信号传导的关键成分。我们还鉴定出一个同源域-亮氨酸拉链基因SlHD8，作为促进毛状体伸长的JA信号传导的下游调节因子。SlHD8也在毛状体中高度表达，并与SlJAZ4发生物理相互作用。SlHD8的功能缺失突变导致毛状体变短，茉莉酸甲酯处理只能部分挽救该表型。我们的双荧光素酶和染色质免疫沉淀-定量PCR分析表明，SlHD8通过直接结合一组细胞壁松弛蛋白基因的启动子并激活其转录来调节毛状体伸长。总之，我们的研究结果将SlHD8-SlJAZ4定义为介导番茄中JA诱导的毛状体伸长的关键模块。
