不同盐碱胁迫下棉花离子组响应特征与离子稳态机制研究

Salt salinity is one of the most serious abiotic stresses of crop plants worldwide. Physiological response and salt tolerance mechanism for different crop species were varied under different salinity and alkalinity stress. The present research, however, mainly focus on the NaCl stresses. Xinjiang is the major cotton producing region in China. In Xinjiang, the characteristics of soil salinization are widespread distribution, high salt content, and various types. Understanding the salt tolerance mechanism of cotton under different salinity and alkalinity stress is very important for improving cotton salt tolerance. Maintain ion homeostasis in tissue is one of the important mechanisms for crop salt tolerance. Ion homeostasis is the result of interactions of all elements, but the most studies mainly focus one or few mineral elements and the response of other elements to salt stress and the interaction between elements and salt stress are still largely unknown yet. Ionomics provides an important way to quantitative analysis ion characteristics of crop and to reveal the ion homeostasis mechanism under salt stress. The objective of this study is (1) to investigate ionomic responses of cotton under different salinity and alkalinity stress, (2) to determine the relationship between ionomic and physiological metabolism of cotton, and (3) to explore the molecular mechanism of Na+ transport regulation in cotton plant and to reveal the ion homeostasis mechanism of cotton under different salinity and alkalinity stress. This research may provide the theoretical basis for ion regulation and fertilization management of cotton in saline soil. Furthermore, it can also be useful for salt tolerance variety breeding of cotton.

土壤盐渍化是限制作物生产最严重的非生物胁迫因素之一。作物对不同类型盐碱胁迫存在不同的生理响应和耐盐机制，而目前的研究主要关注NaCl胁迫。新疆是我国棉花主产区，也是我国盐渍土分布最广，积盐最重，盐碱化类型最多的地区。研究揭示不同盐碱胁迫下棉花的耐盐机制，对于提高棉花耐盐性有重要的科学意义。维持细胞内离子稳态是作物重要的耐盐机制之一。离子稳态是所有元素共同作用的结果，但目前大部分研究只针对一种或几种矿质元素，而其它元素对盐胁迫的响应及其与盐胁迫的相互作用还未被完全阐明。离子组学为定量分析作物离子组特征，揭示盐胁迫下作物离子稳态机制提供了重要的研究途径。本项目通过研究不同盐碱胁迫下棉花离子组响应特征，阐明棉花离子组和生理代谢的关系，探讨棉花Na+转运调控的分子机理，揭示不同盐碱胁迫下棉花离子稳态机制，为盐渍土壤棉花的离子调控和合理施肥提供理论依据，也可为棉花耐盐品种选育提供参考。

盐胁迫限制作物产量和土地利用，是对环境资源和人类健康的主要威胁。碱性盐胁迫与中性盐胁迫有很大区别，分别称为碱胁迫和盐胁迫。同时，土壤盐化和碱化现象在自然盐碱土壤中经常同时发生（复合盐碱胁迫）。维持细胞内离子稳态是作物的重要耐盐机制之一，离子稳态是众多元素共同作用的结果。研究揭示不同盐碱胁迫（盐、碱、复合盐碱）下棉花离子组响应特征及离子稳态机制，对于深入认识棉花耐盐机理和提高棉花耐盐性具有重要意义。研究表明复合盐碱胁迫对棉花生长的抑制作用大于盐胁迫或碱胁迫。盐胁迫（NaCl、Na2SO4）对棉花地上部的抑制作用大于根系，碱胁迫（NaHCO3和Na2CO3）对地上部和根系均有显著的抑制作用。盐胁迫的主要危害是渗透胁迫，碱胁迫是氧化胁迫。盐胁迫显著抑制P素吸收以及K、Mg向茎、叶的转运；碱胁迫和复合盐碱胁迫碱胁迫则限制更多元素的吸收及转运，P、K、Ca、Mg、Zn、Cu、B吸收和转运均受到明显的抑制。耐盐品种根系K含量较高，地上部Na含量较低。耐盐品种在盐胁迫下叶片中积累更多的Cu、Mo、Si、P和B；碱胁迫下则积累更多的Cu、Fe、B、Zn和Si。说明，耐盐品种具有更强的矿质元素转运能力，将大部分元素转运到地上部，以维持体内的离子平衡。盐胁迫下，棉花叶片Na+调控相关基因（GhSOS1、GhNHX1、GhHKT和GhAKT1）表达量均高于碱胁迫。耐盐品种GhSOS1基因相对表达量表现为碱胁迫>盐胁迫>复合盐碱胁迫，而盐敏感品种表现为盐胁迫>碱胁迫>复合盐碱胁迫。GhNHX1基因相对表达量，耐盐品种为盐胁迫>碱胁迫>复合盐碱胁迫，盐敏感品种为碱胁迫>盐胁迫>复合盐碱胁迫。耐盐品种GhSOS1和GhNHX1基因相对表达量均高于盐敏感品种。说明不同盐碱胁迫尤其是碱胁迫和复合盐碱胁迫下，耐盐品种GhSOS1和GhNHX1基因的过量表达可促进Na+外排与区隔化。不同盐胁迫胁迫下，耐盐品种与离子转运相关基因（ABC 转运蛋白、Eam-like转运蛋白家族、POT家族等）上调表达，盐敏感品种下调或不表达；同时，盐胁迫下基因表达的上调幅度大于碱胁迫。表明碱胁迫对离子运输功能的影响大于盐胁迫，耐盐品种具有较强的离子转运能力。