ALA对枣树盐胁迫的缓解效应及其作用机理研究

Xinjiang is the largest saline soil region in China,but at the same time it is an advantageous region for Zizyphus jujuba Mill, whose growth, development and the improvement of its quality of production is severely restricted by soil salinity stress, resulting in significant economic losses. How to mitigate the adverse effects of salt stressing environment of the jujube trees and to improve the jujube stress resistance is the core issue of Xinjiang's jujube industry. Therefore, in-depth understanding of salt damage mechanism and research on the relationship between salt threat and jujube tree growth and adaptability is, on the one hand, an important guarantee of realizing a sustainable development of red jujube industry in Xinjiang and, on the other hand, has a very positive social and economic value and ecological realities of significance from the perspective of highly efficient use of saline land and abandoned farmland. By probing into exogenous 5-Aminolevulinic acid (ALA) and its effectiveness on plant shape, cell membrane permeability, chlorophyll content, proline content, index of salt injury, cell ultrastructure, ion absorption and micro field distribution, enzyme activity ，the expression of miRNA and regulation of target gene with different salt tolerance of Zizyphus jujuba Mill. under salt stress in order to seek how exogenous 5-Aminolevulinic acid(ALA) actually works to alleviate salt stress, this research project hopes to play a constructive role to develop and utilize the saline-alkali soil, to improve productivity of Zizyphus jujuba Mill. And to gain reasonable ecological and economical benefit from out of the saline-alkali fields.

新疆是我国最大的盐土区，同时也是红枣产业发展的优势区域，土壤盐分胁迫严重制约着红枣的生长发育及产量品质的提高，从而造成重大的经济损失。如何减轻盐胁迫环境对枣树的不良影响和提高枣树的抗逆性是当前新疆红枣产业的核心问题之一。因此，深入了解盐害机理，开展盐胁迫与枣树生长适应性关系的研究一方面是实现新疆红枣产业可持续发展的重要保障，另一方面从高效利用盐碱地、弃耕地角度来看亦具有十分积极的社会经济价值和生态现实意义。本项目通过外源ALA对耐盐性不同的枣树品种在盐胁迫下植株形态、细胞膜透性变化、叶绿素含量、脯氨酸含量、盐害指数、细胞超微结构、离子吸收和微域分布、酶活性等生理指标以及miRNA表达的变化及其对靶基因调控的研究，探索和阐明外源ALA对枣树盐胁迫的缓解效应与机理，以期为开发利用盐碱地、提高枣树生产力、合理获取盐碱地生态效益和经济效益发挥建设性作用。

新疆是枣树主要栽培区域。新疆生态环境脆弱，土壤和水分含盐量高制约着枣树的优质生产，酸枣是新疆枣树生产上枣品种主要的砧木，利用外源物质提高酸枣的耐盐性，从而提高接穗品种耐盐性是重要的生产措施。ALA因其绿色无残留的特点表现出其在农业中的潜在应用价值，但其作用机制还不明确。本项目研究ALA（5-氨基乙酰丙酸）浸种对NaCl胁迫下酸枣种子萌发及芽苗保护酶活性和丙二醛含量的影响；探索ALA对酸枣水培幼苗在处理后第3天和第6天的光合气体交换参数、渗透调节物质、根系活力和保护酶活性等指标的影响，筛选出不同程度NaCl胁迫下ALA缓解效果最佳的处理浓度；以赞皇大枣和酸枣为材料，研究喷施ALA对NaCl胁迫下枣树光合特性、生理生化指标、保护酶活性以及ASA-GSH循环系统相关指标测定和分析，探究ALA对NaCl胁迫的缓解作用及筛选不同NaCl胁迫下适宜的ALA处理浓度；研究NaCl胁迫下外源ALA对酸枣幼苗生长发育、抗逆性、叶绿素合成代谢及光合能力的影响，利用RNA-Seq技术对NaCl胁迫下外源ALA处理后酸枣幼苗叶片进行转录组学分析。通过项目的研究可以得出：外源ALA可以有效缓解盐胁迫下对酸枣植株幼苗光合作用的伤害，酸枣幼苗在NaCl浓度为100 mmol•L-1，ALA浓度为75 mg•L-1缓解效果最好，且处理后第3天缓解效果优于处理后第6天；2年生赞皇大章和酸枣150 mg•L-1浓度的ALA具有更好的缓解效应。本研究明确了外源ALA喷施或浸种可以提高赞皇大枣、酸枣等的耐盐碱能力，确定了ALA提高枣树耐盐性的最佳使用浓度，从生理层面和转录组水平上探究了外源ALA调控酸枣幼苗抗盐性的机制，为通过基因工程技术提高枣树耐盐性提供理论基础，为开发利用盐碱地、提高枣树生产力、合理获取盐碱地生态效益和经济效益发挥建设性作用。