美洲黑杨对冬季水淹及后期恢复的性别特异性响应

Previous studies have confirmed that poplars (Populus spp.) are ideal candidate species for the construction of ecological protection forest in the water-level-fluctuation zone in the Three Gorges Reservoir. However, adaptable mechanisms of poplars in response to reversal of flooding times in winter season is not clear. Poplars are dioecious plants. The males and females in a dioecious plant developed different strategies in response to environmental stresses. In the present study, male clones (P. deltoides CL.'Juba') and female clones (P.deltoides CL. 'Danhong'), originated from same parents, will be used as materials to test their individual repsones to winter flooding and post-flooding recovery. Sex-specific physiological, biochemical, and ultrastructural changes of both males and females at different recovery phases after different winter flooding durations will be investigated. Further molecular mechanisms involved will be elucidated based on proteomic approach, using protein samples extracted from leaf and chloroplast, respectively. The aims of this study are to compare different responsive strategies developed by males and females in P.deltoides. We mainly focus on the sex-related photosynthetic responses and molecular mechanisms between male and female in a dioecious plant after winter flooding stress. This research intends to elucidate adaptable mechanisms in woody plants in response to reversal of flooding times in winter season, and to provide certain theoretical basis and scientific instructions for the construction of ecological protection forest in the water-level-fluctuation zone in the Three Gorges Reservoir. It will further clariy the sex-specific responses in a dioecious plant to winter flooding and post flooding recovery on the molecular level, and provide some clues about screening and clone of anti-flooding genes in woody plants.

前期研究证实，杨树是三峡水库消落区生态防护林建设的适宜树种，但对其在三峡水库消落区反季节水淹后的适应机制并不清楚。杨树是雌雄异株植物，雌雄植株在应对环境胁迫时采用不同的应对策略。本项目拟以美洲黑杨的雌株丹红杨、雄株巨霸杨为研究对象，运用植物生理学及蛋白质组学的研究方法，结合亚细胞超微结构分析，模拟在三峡水库水位变动条件下，对比分析在经历不同时间的冬季水淹后，雌雄植株在不同恢复生长期的生长发育、生理生化、亚细胞超微结构、叶片全蛋白质组和叶绿体蛋白质组等方面的响应差异，从而揭示经历冬季水淹胁迫后雌雄植株在不同恢复生长期的应对策略及雌雄植株光合响应差异的分子机制。研究成果试图阐明木本植物对三峡水库消落区反季节水淹的适应机制，为消落区生态防护林建设提供理论依据与科学指导；并在分子水平上揭示雌雄异株植物在冬季水淹胁迫后的性别特异性响应机理，为木本植物抗水淹基因的筛选和克隆提供线索。

本项目在形态、生理、超微结构及蛋白质组学方面开展了美洲黑杨雌雄植株对冬季水淹及后期恢复的性别特异性研究。结果表明雌雄植株都具备较强的耐水淹能力。水淹持续时间对植株的形态发育、生理指标和超微结构影响不显著，表明雌雄植株对冬季水淹持续时间并不敏感。就光合作用和叶绿素荧光而言，雄株比雌株更耐冬季水淹。水淹胁迫下雌株比雄株表现出更严重的氧化伤害，而雄株具有更有效的抗氧化酶系统来清除或控制活性氧簇物质的含量。雌雄植株在植株生长、生理及超微机构方面都表现出较强而且类型的恢复能力，不过就叶片色素含量而言，雄株具备更强的恢复能力。通过iTRAQ分析，共鉴定到5776个蛋白。正常水分条件下的，雌雄植株之间有204个差异表达蛋白。水淹胁迫下，雌雄植株之间有298个差异表达蛋白。雌株水淹后出现347个差异表达蛋白，其中有253个蛋白表达下调，94个蛋白表达上调。雄株水淹后，出现171个差异表达蛋白。其中有114个蛋白表达下调，57个蛋白表达上调。在恢复生长期，未水淹的雌雄植株之间有168个差异表达蛋白。水淹后的雌雄植株经过生长恢复后，雌雄植株之间有175个差异表达蛋白。水淹后的雌株经过生长恢复后，与对照相比，有165个差异表达蛋白。其中有54个蛋白表达下调，111个蛋白表达上调。雄株经过生长恢复后，与对照相比，有448个差异表达蛋白。其中有222个蛋白表达下调，226个蛋白表达上调。在这些差异表达蛋白主要参与了能量生产与转化过程，氨基酸运输代谢，核苷酸转运和代谢，碳水化合物运输代谢，辅酶的转运代谢，脂质转运与代谢，转录、复制、翻译、重组和修复过程，翻译后修饰和蛋白折叠，次生代谢物的生物合成、转运和催化，信号传导，防御机制反应等。通过本项目研究增加了杨树对冬季水淹胁迫适应的理解，也有效的阐释了雌雄植株在休眠期的冬季水淹及后期恢复的性别特异性差异。本项目的研究成果表明美洲黑杨雌雄植株均可作为三峡水库消落区防护林建设的优选树种。