气候变暖下青杨雌雄植株对植食性昆虫的防御响应研究

The growth and development processes of plant can be modified by climate warming, and result in the change of structure and function of plant community, even of ecosystem. Dioecy is reported about 6% of angiosperm species, and it is an essential group that can not be ignored in terrestrial ecosystem. Populus cathayana Rehd. is a widely distributed dioecious tree species in China and plays important roles in maintaining ecological stability and forest restoration. Previous studies focus on the ecophysiological responses of dioecious plant to abiotic stress, however, few study has been putted on the defense responses to biotic stress under global warming. In this project, to investigate the defense responses of dioecious plant to insect herbivore under elevated temperature, P. cathayana has been chosen as a model plant, for evaluating under warming (1) sexual differences in defense to insect herbivore in P. cathayana; (2) the relationship between defense and growth of P. cathayana females and males. The results reported here can provide models on sexual anti-insect defense of dioecious species and plant how to integrate among growth, reproduction and defenses under warming, and also can contribute to understand population maintenance and forest ecosystem of Populus plantation construction under future climate warming.

气候变暖会直接影响物种的生长发育过程，进而影响群落乃至生态系统结构和功能。雌雄异株植物在植物界中约占6％左右，是陆地生态系统的重要组成部分。青杨是我国广泛分布的雌雄异株植物，对维持生态系统稳定性和森林恢复具有重要意义。先前关于雌雄异株植物的研究主要集中在其对非生物环境胁迫后的响应与适应，而对该类植物在气候变暖下对生物因子的响应的研究依然较少。本项目拟以青杨为模式材料，比较增温下青杨雌雄植株对其植食性昆虫的防御响应差异，其目的是(1)揭示气候变暖下雌雄青杨对植食性昆虫的物理和化学防御响应差异，(2)探讨气候变暖背景下雌雄植株对昆虫的防御机制与生长的关系，为杨树人工林培育和构建提供建议。这些研究结果为气候变暖下探讨植物在性别水平上的防御机制及植物生长、繁殖与防御机制的关系提供理论依据，也为未来气候变暖下杨树种群维持乃至杨树人工林生态系统的构建提供参考。

气候变暖会直接影响物种的生长发育过程，进而影响种群、群落乃至生态系统的结构和功能。雌雄异株植物是植物类群中重要的组成部分，青杨是我国广泛分布的雌雄异株植物，在维持生态系统的稳定性和森林恢复方面至关重要。先前关于雌雄异株杨树的研究主要集中在其对非生物环境胁迫后的响应与适应，而对气候变暖下该类植物如何响应生物因子的研究还较少。本项目研究了温度增加及增温下水分变化对雌雄杨树的防虫机理及雌雄植株之间的防虫能力与生长的关系。结果发现：[1]增温降低了青杨雌株和雄株叶片的防虫能力，且改变了青杨性别间叶片防虫的模式。在对照（未增温）下，雌株的抗虫能力高于雄株，但增温下雌株的抗虫能力低于雄株。[2]增温下不同性别杨树的生长和防虫能力与水分息息相关。水分充足时，增温显著提高了雌株的生长和光合能力，而对雄株的生长有限；水分缺乏时，增温降低了雌株和雄株的生长。防御方面，水分缺乏下，雌株的抗虫能力总是低于雄株。总的来说，夏季的增温导致的干旱显著降低了杨树雌株的生长和防虫能力，且增加了性别间生长或防御的差异。[3]雌雄之间的物理防御和化学防御与生长的关系受到温度影响。这些结果从生理生态的角度阐明了气候变暖下青杨雌雄植株之间的防御变化及机理，能为探讨植物在性别水平上的防御机制及植物生长、繁殖与防御的关系对温度的响应提供理论依据，也为未来气候变暖下杨树种群动态及虫害预警提供参考。