花铃期土壤水分亏缺对陆地棉纤维伸长的影响及其生理机制

Midsummer drought is the main climatic disaster for cotton production in the Yangtse valley region. Soil water deficit usually leads to decreased fibre length and low fibre quality during flowering and boll-setting stage. Understanding how soil moisture deficit alters cotton fibre elongation would provide insight into the development of drought tolerant cotton varieties and enhancement of fibre quality in cultivation practice. Two upland cotton breeding lines with different response to water stress in fibre elongation, a drought tolerant line (A001) and a drought susceptible line (A705), will be used in pot culture experiment in greenhouse to investigate the effect of soil moisture on fiber elongation and its physiological mechanism. Three soil moisture treatment are as follows: well watered ( soil relative water content SRWC =70%-75%), low moisture deficit (SRWC=55%-60%), high moisture deficit (SRWC=40%-45%). The experimental design is a completely randomized experiment with three replications across 4 yr. Comparative growth of cotton fibre between two experimental lines will be carried out at varying soil moisture levels. Dynamic changes and differences and their relationship of fibre elongation will be investigated for osmotically active solutes(glucose, fructose, sucrose, malate), enzymes involved in osmoregulation (vacuolar invertase VIN, phosphoenolpyruvate carboxylase PEPC, plasma membrane and tonoplast H+-ATPase et al.), and cell wall loosening and extensibility factors(expansin, xyloglucan endotransglucosylase/hydrolase XTH, endo-1,4-β-glucanase ). Candidate enzyme genes up-regulated and their expression characteristics under water deficit stress will be indentified by Real-time Quantitative Polymerase Chain Reaction during the fibre elongation phase. This research will contribute to elucidate the enzymology mechanism of fibre elongation response to water deficit stress.

伏旱是长江流域棉区花铃期主要的气象灾害，盛花期土壤水分亏缺往往导致棉纤维长度下降、纤维品质变劣。本项目以两个纤维伸长对水分亏缺耐性不同的陆地棉高品质系（干旱敏感型和钝感型）为试验材料，在不同土壤水分处理条件下（正常供水、轻度水分亏缺、重度水分亏缺），观察棉纤维伸长变化的特征与差异；研究棉纤维伸长期纤维细胞渗透调节物质（蔗糖、葡萄糖、果糖、苹果酸）及其代谢与跨膜转运关键酶（VIN、PEPC、质膜质子腺苷三磷酸酶等）、细胞壁松驰和延展相关因子（expansin、XTH、1,4-β-内葡聚糖酶）的动态变化、基因型差异及与纤维伸长的关系；利用实时荧光定量PCR技术研究上述酶和功能蛋白响应土壤水分亏缺的基因表达规律。阐明陆地棉纤维伸长响应干旱胁迫的渗透调节物质变化特点及其酶学机制。研究结果将增强对植物细胞生长的认识，为陆地棉抗/耐旱品种选育、品质保优栽培提供理论基础。