新疆枣树高温胁迫下生理与基因表达响应机理研究

The jujube (Ziziphus jujuba Mill.), a member of family Rhamnaceae, is a major fruit, plays an important role in poverty alleviation in four southern Xinjiang Districts, the planting area and yield of jujube in Xinjiang rank first in China. But recently, the effects of extreme weather such as high temperature on jujube caused abnormal growing and bad quality of fruits. Nowadays few studies has been reported on studying the effects of high temperature stress on physiological characteristics and molecular response mechanism of jujube.In this study, we choose two jujube varieties, one grown in high temperature zone and another grown in normal temperature zone, to study leaf anatomical structure and other physiological indexes of jujube under high temperature stress. To understand the molecular mechanism of response to high temperature stress in jujube, we also study the response pattern of endogenous genes of jujube under different temperature treatment by using high throughput sequencing, screen the specific candidate genes related to high temperature stress, clone the full-length related genes and structural functional analysis, and find out the dynamic expression rules of these genes under different temperature treatment. So, from two levels, physiological biochemistry and transcriptional gene level, we could study the response mechanism of jujube under high temperature stress, and set up some methods for reducing the loss of productivity on jujube cultivation, and give suggestion and molecular evidences for cultivating heat resistant jujube variety resources.

新疆红枣面积和产量均居全国第一位，是南疆四地州农民脱贫致富的重要支柱产业。但近年来新疆极端高温天气频发，对枣树的生长和结果危害严重。目前关于枣在高温胁迫下的生理特性和分子应答机制鲜有报道。本研究拟以耐热性明显不同的2个枣品种为材料，从生理生化角度探讨枣在高温胁迫下叶片解剖结构及生理指标等变化；利用高通量测序技术取得枣在高温胁迫条件下差异表达的mRNA，筛选枣应答高温胁迫相关的特异性候选基因，并进行相关基因的全长克隆和结构功能解析，摸清它们在温度差异处理条件下的动态表达规律，以期在全基因组范围内了解枣在转录水平应答高温胁迫的分子机制，为减少枣树高温胁迫损失、培育耐热枣品种资源提供新思路、理论依据和生理分子指标。

新疆红枣面积和产量均居全国第一位，是南疆四地州农民脱贫致富的重要支柱产业。但近年来新疆极端高温天气频繁发生，对枣树的生长和结果危害严重。本项目以课题组在吐鲁番极端高温区筛选的枣耐热和热敏感材料为研究对象，通过对其生理指标研究发现耐热枣品种‘HR’叶片细胞膜稳定性较热敏感枣‘HS’强，细胞膜损坏程度小，叶片受高温伤害的程度轻。耐热枣的脯氨酸含量、过氧化氢酶活性在高温胁迫期间始终高于热敏感枣。通过转录组测序及生物信息学分析，在耐热枣品种‘HR’和热敏感枣‘HS’中总共分别鉴定出6887和5077个DEGs。GO和KEGG富集分析表明，这些DEGs在氧化还原过程、胁迫应答、水分缺失应答、热响应、碳代谢、蛋白质内质网加工和植物激素信号转导显著富集。在HSP家族中鉴定出4个HSP90s、2个HSP70s和18个sHSPs；在转录因子中鉴定出1个转录因子（HSFC1）在‘HR’中表达显著高于‘HS’，1个转录因子NAC2（LOC107421097）基因在‘HR’热胁迫各时间点均高表达；在‘HR’和‘HS’两者中，鉴定出4个编码泛素蛋白连接酶基因（LOC107414605，LOC107432264，LOC107418004，LOC107428857）在高温胁迫下的表达均受到抑制，这些基因可能在枣树响应高温胁迫过程中发挥重要作用。紧接着我们从耐热枣品种‘HR’幼苗叶片中克隆到1个ZjWRKY43基因，并成功构建了其沉默表达载体TRV-ZjWRKY43，通过对高温胁迫不同时间下沉默植株生理指标的研究表明，ZjWRKY43基因沉默后枣耐热性降低。项目执行期间，共计发表研究性论文5篇，其中SCI文章3篇。