花铃期增温与土壤干旱耦合影响棉纤维发育及纤维品质形成的生理生态机制研究

It is predicted that global warming will cause the mean air temperature to increase to 1.8-4.0℃. These changes would pose a challenge to agricultural production. In the last 5 decades, the duration of the maximum daily temperature over 38℃ was more than 20 days in cotton belt of China, and soil drought also occurs simultaneously and frequently. These phenomena have serious impacts on lint yield and fiber quality. However, most previous research has been conducted based on a single climatic factor(only temperature or water), which can’t report the direct and combined effect of temperature and water on cotton. Hence, this study will concentrate on the effects of the elevated temperature combined with soil drought on the physiological and ecological mechanism of cotton fiber development and fiber quality formation. In this study, temperature-tolerant cotton cultivar and temperature-sensitive cotton cultivar will be used, and the experimental temperature will be 3℃ higher than the ambient temperature. By analyzing the relationships among "substance metabolism - fiber secondary wall thickening characteristics - fiber quality formation", the key carbohydrates and the key enzymes mediating the response of fiber development to the elevated temperature combined with soil drought will be identified. Besides, varietal difference of two cotton cultivars with different temperature sensitivity will be revealed. The purpose of the research is to clarify the effect of elevated temperature combined with soil drought on the mechanism in molecular ecology of the key physiological processes during fiber development through gene expression and proteomic analysis. These findings would provide reference information for the research on effects of global warming on cotton production and would be helped to develop effective techniques in cotton cultivation.

温室化效应（未来温度将增加1.8-4.0℃）的加剧使农业遭受极端气候胁迫的风险加大。近50年来我国棉区花铃期38℃以上高温持续20天以上，同时常伴有干旱发生，严重影响棉花生产。以往的研究多在环境温度或土壤水分单因素下进行，难以衡量温度与水分耦合对棉花的直接影响。本研究选择纤维发育温度敏感、弱敏感品种设置花铃期增温3℃左右与土壤干旱耦合试验，从“纤维发育物质代谢——纤维次生壁特性——纤维品质形成”之间关系入手，研究纤维发育的物质代谢和纤维品质形成的生理生态机制，明确花铃期增温、土壤干旱、增温与土壤干旱耦合对其作用效应，筛选对花铃期增温与土壤干旱耦合敏感的纤维发育关键物质和关键酶，并弄清纤维发育关键物质变化在不同温度敏感性品种之间的差异，在mRNA和蛋白质水平上阐明纤维发育关键生理过程响应花铃期增温与土壤干旱耦合的分子机制。研究结果将为探索全球气候变暖对棉花生产影响以及棉花优质栽培提供依据。

用温度敏感(苏棉15号)、弱敏感(PHY370WR)品种进行花铃期增温(2.5-2.7℃)与干旱(对照SRWC(75±5)%、轻旱(60±5)%、重旱(45±5)%)耦合试验，研究棉铃发育生理机制，为评估高温和干旱对棉花生产影响及优质栽培提供了依据。.1. 增温、干旱及其耦合下铃数、铃重、产量及纤维长度降低；比强度在增温下升高，干旱、增温-干旱耦合下降低。①纤维伸长：增温下GhKT-1、GhPEPC上调表达使K+、苹果酸含量增加，干旱、增温-轻旱耦合下GhPEPC上调表达使PEPC活性和苹果酸含量升高，因起主导作用的GhSUT-1下调表达降低了SuSy活性和蔗糖含量，纤维快速伸长期缩短，纤维变短；增温-重旱耦合下GhSUT-1、GhKT-1基因表达较增温-轻旱显著下调，纤维缩短。②纤维加厚：增温下GhSPSs上调表达提高了SPS活性，但起主导作用的GhSuSys和β-1,3-glucanase基因下调使SuSy活性和蔗糖含量降低，纤维素快速累积期缩短，合成受阻；干旱、增温-干旱耦合下GhSuSys、GhSPSs、β-1,3-glucanase下调表达，SuSy、SPS活性和蔗糖含量降低，GhCalS-5上调表达使碳流向利于β-1,3-葡聚糖合成，纤维素含量和纤维生物量降低，并随SRWC降低而降低。③增温-干旱耦合下，纤维伸长主要受蔗糖调控，SuSy是关键酶，GhSUT-1为关键基因；纤维加厚受蔗糖、纤维素和β-1,3-葡聚糖的共同调控，SuSy和SPS是关键酶，GhSuSy-A、GhSuSy-B和GhSPS-1、GhSPS-3为关键基因。.2. 增温下棉仁脂肪量降低、蛋白质量增加，干旱、增温-干旱耦合则相反。增温-干旱耦合：①GhSuSy、GhSPS、GhInv表达下调，GhPEPC-1、GhDGAT-1表达上调，促进三酰甘油合成，脂肪含量增加；脂肪累积主要受己糖调控，PEPC和DGAT是关键酶，GhPEPC-1和GhDGAT-1为关键基因。②增温-轻旱下蛋白质含量变化较小，增温-重旱下GhGS、GhGOGAT表达下调，GS、GOGAT活性降低，游离氨基酸和蛋白质含量减少；蛋白质累积主要受游离氨基酸调控，GS和GOGAT是关键酶，GhGS和GhGOGAT为关键基因。.3. 纤维发育关键物质和棉籽脂肪、蛋白质对增温-干旱耦合的响应，温度敏感较弱敏感品种的变幅显著增大。