水稻OsJAZ家族基因在碱胁迫应答中的功能及其调控机制

JASMONATE ZIM-domain（JAZ）family proteins are involved in crucial regulator of jasmonate (JA) signaling pathway, and play important roles in plant response to abiotic stresses. Rice genome contains 15 JAZ gene family members, which have been implicated in response to low temperature, drought and salinity stresses in recent studies. However, the role of OsJAZ genes in response to alkaline stress still remains unknown. Our preliminary experimental results indicated that alkaline stress impacted on the expression of OsJAZ genes in rice. Therefore, we firstly analyzed the expression pattern of 15 OsJAZ genes under alkaline stress, and clarify the expression response of each OsJAZ gene to alkaline stress. Subsequently, those OsJAZ gene(s) response to alkaline stress will be selected and subjected to transgenic overexpression or suppression, and the difference of plant growth and physiological changes under alkaline stress, such that to reveal the role of the genes in alkaline stress-tolerance of rice plants. Finally, the regulation network of OsJAZs gene was explored under alkaline stress through transcriptome sequencing and protein interaction. These studies will further illuminate the function and regulation mechanism of OsJAZ family gene in alkali stress. With above research, it is expected to deepen the understanding of alkaline tolerant mechanism for us, and also provide new theoretical basis on the development of new rice varieties for saline-akaline tolerance in molecular genetic improvement.

JAZ(JASMONATE ZIM-domain)蛋白家族是茉莉酸（JA）信号通路中的重要调控因子，在植物抗逆反应中起重要作用。水稻共有15个JAZ家族成员(OsJAZs)，近年的研究证明该家族基因参与调控对低温、干旱、盐胁迫的应答。但关于OsJAZ基因在水稻碱胁迫应答中的作用尚无报道。申请者前期研究显示，碱胁迫处理能够影响水稻OsJAZs基因表达。因此，本项目首先通过碱胁迫处理分析15个水稻OsJAZs基因表达模式，明确OsJAZs基因对碱胁迫的响应；然后克隆响应碱胁迫的OsJAZ基因，深入解析OsJAZs基因的耐碱功能；最后，通过转录组测序及蛋白质互作研究，探索碱胁迫条件下水稻OsJAZs基因的调控网络，进一步阐明水稻OsJAZ家族基因在碱胁迫应答中的功能及其调控机制，为解析水稻的耐碱机制、培育耐碱水稻新品种提供科学支撑。

土壤盐碱化日益严重，已引发全球性的关注。随着科学技术的发展，这些盐碱地被视为珍贵的土地资源。我国东北地区的盐碱地为苏打盐碱类型，土壤盐化与碱化相伴而生, 除了含有较高的有害盐分，还具有较高 pH (>8.5)，而高 pH对植物的伤害远高于盐离子伤害，可直接损伤植物根系，影响根系对水分和矿质营养的吸收，最终降低作物产量。长期的研究与实践表明，盐碱地种植水稻是解决盐碱地区阻碍耕地种植及限制粮食生产的有效途径，所以研究水稻的耐盐碱机制对合理开发利用盐碱地具有重要作用。JAZ(Jasmonate ZIM-domain)蛋白是茉莉酸(Jasmonate, JA)信号通路中的一个重要转录调节因子，在植物抗逆反应中起重要作用。水稻基因组中共含有15个JAZ家族成员(OsJAZs)，研究表明该家族基因参与调控对低温、干旱、盐胁迫的应答，但对碱胁迫的应答作用尚无报道。本研究分析了14个水稻OsJAZs基因表达模式，证实了水稻OsJAZs家族基因能够响应碱胁迫，尤其OsJAZ5、OsJAZ9、OsJAZ11等基因在碱胁迫下能够高水平表达。克隆了OsJAZ2、OsJAZ5、OsJAZ9、OsJAZ11、OsJAZ12五个相应碱胁迫的OsJAZ基因，分别构建了全编码区序列过表达、JASMONATE ZIM-domain 功能域缺失过表达和OsJAZ基因敲除的突变株系。对部分突变株系进行耐碱表型鉴定显示，过表达碱胁迫响应的OsJAZ基因的株系TS21663则提高了水稻的耐碱性，而OsJAZ敲除株系21662则表现为耐碱胁迫能力下降，说明OsJAZs家族基因具有调控水稻耐碱作用。在本项目的支持下解析了外源茉莉酸甲酯对水稻耐碱性的调控作用，该研究表明碱胁迫提高了水稻内源茉莉酸甲酯含量和茉莉酸信号应答基因OsJAmyb和OsOMT的表达水平，外源茉莉酸甲酯预处理通过调控水稻内源IAA的合成缓解了碱胁迫对水稻幼苗生长的抑制、根系的损伤，提高了水稻幼苗的耐碱能力，也揭示了茉莉酸与生长素两信号途径在调控水稻耐碱机制中存在相互作用。本研究丰富了对水稻耐碱机理的认知，也进一步补充了茉莉酸对水稻耐碱功能的调控作用，为深入揭示水稻的耐碱机制、培育耐碱水稻新品种提供科学支撑。