番茄响应高温干旱胁迫的生理生化和环状RNAs调控机制解析

Heat and drought stress is a serious problem for global agriculture. Tomato is widely grown with high commercial value, the growth and development of which was adversely affected by heat and drought stress. However, responding mechanism of tomato to compound stresses of heat and drought remains unclear. CircRNAs is new endogenous non-coding RNAs, which plays vital roles in a series of biological processes in animals and plants. Currently, little were reported on circRNAs in plants. Regulation mechanism of circRNAs in tomato at heat, drought and compound stresses has not been reported. The aim of this project is to explicit the responding mechanism of physiology, biochemistry and circular RNAs in tomato at single stress and compound stresses of heat and drought. Firstly, physiological and biochemical characteristics of tomato at compound stresses of heat and drought were studied mainly from the perspective of photosynthesis, chlorophyll fluorescence and antioxidant system. Secondly, circRNAs in tomato were identified and key circRNAs were obtained after analysis based on high throughput sequencing. Thirdly, qRT-PCR validation of key circRNAs, miRNAs and miRNAs targets were performed. The project will help us to screen and identify tolerant tomato to heat and drought stress and to reveal the potential mechanism of circRNAs post-transcriptionally in response to heat and drought stress in tomato. These will lay a foundation for genetic improvement of tomato tolerant to heat and drought stress.

高温和干旱胁迫是全球农业面临的严重问题。番茄的种植范围广泛，商业价值高。高温干旱胁迫会影响番茄的生长发育，而番茄对高温干旱复合胁迫的响应机制尚不清楚。CircRNAs是一种新型的内源非编码RNAs，对动植物的一系列生物过程起重要作用。目前，植物circRNAs的报道很少，高温、干旱及其复合胁迫下番茄circRNAs的调控机制尚不清楚。本项目旨在明确单一胁迫和高温干旱复合胁迫下番茄生理生化和circRNAs的响应机制。本项目拟从光合作用、叶绿素荧光和抗氧化系统的角度研究番茄响应高温干旱复合胁迫的生理生化特点。利用高通量测序，鉴定分析获得关键circRNAs，对关键circRNAs、miRNAs及miRNAs靶基因进行qRT-PCR验证。本项目有利于番茄耐逆材料的筛选鉴定，揭示番茄circRNAs在转录后水平响应高温干旱胁迫的潜在机制，为番茄耐逆性的遗传改良奠定基础。

我们以三个番茄品种为材料，分析了番茄在单一胁迫和高温干旱复合胁迫下的生理生化响应特征。结果发现，根据大部分生理参数可推断出三个品种对复合胁迫的敏感程度相似。因此，单一胁迫下表现敏感性不同的番茄品种对复合胁迫并未表现出不同的敏感性，这说明对复合胁迫抗性品种的选择可能与单一胁迫的抗性无关。基于大部分的生理参数，我们发现三个番茄品种在单一干旱和复合胁迫下的响应相似，说明干旱胁迫在复合胁迫中起主导作用。我们从不同角度研究了番茄对高温、干旱及其复合胁迫的生理响应机制，探讨了耐热耐旱番茄的选择方法，为番茄抗逆育种奠定了基础。同时，我们还研究了番茄在不同胁迫处理下番茄的抗氧化能力。结果发现，单一胁迫和复合胁迫番茄植株的恢复能力与活性氧清楚能力及抗氧化物质的产生密切相关。在针对前期番茄响应复合高温干旱胁迫生理机制的研究基础上，我们选择了适宜的时间点，对番茄响应不同非生物胁迫的新型非编码RNAs进行了全面鉴定，明确miRNAs和miRNAs靶基因及circRNAs调控机制。本研究共鉴定到467个circRNAs。来源于外显子的circRNAs最多，占87.82%。其中，156个circRNAs共同存在于4个文库中。与对照相比，干旱、高温和复合胁迫共引起了9、14和8个circRNAs的表达发现显著变化。总的来说，我们从多个角度阐明了番茄响应单一高温、单一干旱及其复合胁迫的潜在机制，为植物耐逆研究奠定了基础。