油菜素内酯对低氧胁迫下黄瓜幼苗叶片线粒体、叶绿体超微结构及光合的影响

Effects of brassinolide on the leaf mitochondria and chloroplast ultrastructure and photosynthesis of cucumber seedlings under hypoxia stress

在水培条件下,研究24-表油菜素内酯(EBR)对低氧胁迫下黄瓜幼苗叶片叶绿体和线粒体超微结构及光合的影响.结果表明:与正常通气条件相比,低氧胁迫下表观量子效率(AQY)和羧化效率(CE)显著降低,而光补偿点(LCP)、暗呼吸速率(Rd)和CO2补偿点(CCP)显著升高;低氧胁迫并添加油菜素内酯处理下,CE与低氧胁迫处理相比显著提高29.4%,而LCP和Rd分别显著下降15.0%和14.4%.光响应Pn-PPFD曲线和CO2响应Pn-Ci曲线表明,低氧胁迫下净光合速率(Pn)增幅降低,而添加油菜素内酯有利于Pn增幅的提高.低氧胁迫下叶绿体和线粒体结构受到伤害,而油菜素内酯可以缓解低氧胁迫对黄瓜幼苗叶绿体和线粒体超微结构的不良影响,使叶片维持较好的光合性能.

A hydroponic experiment was conducted to investigate the effects of 24-epibrassinolide（EBR） on the leaf mitochondria and chloroplast ultrastructure and photosynthesis of cucumber seedlings under hypoxia stress.Under the stress,the apparent quantum yield（AQY） and carboxylation efficiency（CE） decreased significantly,while the light compensation point（LCP）,dark breathing rate（Rd）,and CO2 compensation point（CCP） had a significant increase.The application of EBR increased the CE significantly by 29.4%,and decreased the LCP and Rd significantly by 15.0% and 14.4%,respectively.The light response curve（Pn-PPFD） and CO2 response curve（Pn-Ci） indicated that under hypoxia stress,the increment of net photosynthetic rate（Pn） decreased,while EBR addition enhanced the increment of the Pn.Hypoxia stress damaged the mitochondria and chloroplast ultrastructure,while EBR could alleviate the damages in chloroplast and mitochondria under hypoxia stress,and keep the leaves in a higher photosynthetic performance.