棉铃发育响应花铃期水分逆境的生理机制研究

Greenhouse effects exacerbate the risk of agriculture suffered from short-term extreme climate stress. Recently, drought or waterlogging becomes more frequent during the flowering and boll- forming period, resulting in that cotton yield and fiber quality deteriorated; meanwhile, the flowering and boll forming period is the critical stage to cotton boll development and the most sensitive time to water stress. Water stress experiments are designed using cotton cultivars with different water stress sensitivity to investigate the relationships between “four systems” which are comprised of (1) the subtending leaf to cotton boll, which can afford 60%-87% photosynthate to its subtended boll; (2) capsule wall, which is carbohydrates source for cotton seed and fiber; (3) cottonseed, which is the matter source of fiber development; and (4) cotton fiber, which is come from epidermal cells. And by cooperative analysing the ource-sink relationships and the responses of “four systems” to cotton plant water content, this study will identify the key matters and key metabolic pathways which are sensitive to water stress. Besides, this study will reveal the mutual linkage mechanism among “four systems” under water stress and simultaneously confirm “main system” and “key factors” (key material and key enzymes) which obviously affect seed cotton weight per boll and boll (seed, fiber) quality.Through comparing the differences in mRNA and protein levels for key enzyme between different cultivars, this study will reveal the molecular mechanism of "main system" and "key factors" in response to water stress. The findings will provide a theoretical basis for exploring the soil water regulation pathways on cotton yield and quality formation and would help to develop effective techniques in cotton cultivation.

温室化效应加剧农业遭受短期极端气候胁迫的风险，棉花生产中表现为因花铃期干旱或涝渍频发而产量品质降低。花铃期是棉铃发育和产量品质形成关键期，对水分最为敏感。本项目基于对水分逆境敏感性差异显著品种的花铃期土壤水分试验，在以蔗糖代谢为核心的光合产物形成运转中，从棉铃对位叶(60%-87%光合产物供给棉铃)-铃壳(棉籽纤维发育物质源)-棉籽(纤维发育载体)-纤维(种皮细胞突起)“四大系统”关系着手，协同分析“四大系统”间的源库关系及对棉株水分的响应，明确对水分逆境敏感的关键物质和关键代谢路径，揭示“四大系统”在水分逆境下的相互联动机制，确定影响铃重与棉铃（棉籽、纤维）品质的“主要系统”和“关键因子（关键物质和关键酶）”，并在mRNA和蛋白质水平上比较关键酶表达品种间差异，揭示“主要系统”和“关键因子”主要生理代谢响应水分逆境的分子机制。研究结果将为探索水分逆境下提高棉花产量品质的调控途径提供依据。

温室化效应下棉花花铃期水分逆境频发而导致产量品质降低，亟需研究基于棉铃发育水分生理的防灾减损调控技术。本项目基于耐旱、干旱敏感品种花铃期水分试验(CK-SRWC(75±5)%，渍水3、6天-SRWC100%，干旱-SRWC (60±5)%、(45±5)%)，以蔗糖代谢为核心协同研究棉铃发育四大系统-棉铃对位叶、铃壳、棉籽、纤维响应水分逆境的生理机制表明：.①干旱或渍水6天显著降低棉铃生物量及籽棉产量，干旱的作用更明显。.②干旱提高棉铃对位叶GhSPS1、GhSUSA、GhSUSB、GhSUS2表达及SPS、SuSy活性而促进蔗糖生成，降低GhSWEET10表达而抑制蔗糖转运，最终蔗糖增加；增加铃壳SPS、SuSy活性而促进蔗糖生成，并抑制蔗糖转运，最终蔗糖增加。蔗糖、SuSy为棉铃对位叶及铃壳碳代谢响应干旱的关键物质、关键酶。.③干旱提高棉仁GhINV1表达及acid/alkaline-INV活性而促进蔗糖分解为己糖，但降低PFK、PK活性而抑制己糖向丙酮酸转化，阻碍己糖参与油分、蛋白质合成；降低GhPEPC1、GhDGAT表达及PEPCase、DGAT活性而抑制乙酰辅酶A、三酰甘油产生，降低油分含量；但提高GhGS、GhGOGAT表达及GS、GOGAT活性而促进谷氨酸生成，增加蛋白质含量。蔗糖及SPS和alkaline-INV、PEPCase和DGAT、GS和GOGAT分别为棉仁糖代谢、油分、蛋白质合成响应干旱的关键物质及关键酶。.④干旱降低纤维伸长期GhCesA6、GhXXT1、GhGATL9、GhGATL10、GhSuSy表达及SuSy活性而抑制初生壁组分合成，其中且对纤维素合成阻碍最严重，降低GhEG6、GhXTH8、GhPE3、GhEXPA8、GhEXPA4表达及EG、XTH活性而降低纤维细胞壁松弛性，纤维变短；干旱降低加厚期SPS活性而抑制蔗糖合成，降低GhSuSy表达及SuSy活性而抑制蔗糖向UDPG转化，增加GhLAC表达及β-1,3-GS活性而促进木质素及β-1,3葡聚糖累积，共同影响纤维素合成而降低比强度。纤维素和SuSy、蔗糖和SuSy分别是纤维伸长、加厚发育响应干旱的关键物质和关键酶。.⑤干旱影响铃重的主控系统为棉铃对位叶，上述关键物质和关键酶是各系统响应干旱的主控因子。.研究结果可为探索水分逆境下棉花优质高产协同提高的调控途径提供依据。