低温条件下中国野生拟南芥种群中CBF3与ROS浓度的相关性

Association of CBF3 Expression and ROS Content Under Low Temperature among Natural Populations of Arabidopsis thaliana in China

活性氧(ROS)是植物光合作用和呼吸作用的副产物,环境胁迫可加速植物体内ROS的产生,造成植物细胞膜的过氧化,同时给光反应中心II带来光伤害。RFOs是植物体内的1类寡聚糖家族,其对环境胁迫的响应很可能与清除过剩的ROS相关。前期的研究显示,由于中国长江流域野生拟南芥(Arabidopsis thaliana)种群中CBF3基因的变异,种群的冰冻耐受性和体内RFOs含量的积累普遍低于Col生态型。研究表明,长江流域种群中ROS代谢通路在低温处理后的表达与Col生态型相比发生了明显的分化,并且植物体内ROS的浓度增高;而将Col生态型中能正常响应环境冷信号的CBF3基因转入长江流域种群后,转基因植株的冰冻耐受性得到显著提高,体内RFOs积累亦增加,而ROS浓度显著降低。这些结果说明,低温条件下CBF3很可能通过直接调控植物体内RFOs的生物积累来参与调控下游过剩ROS的清除过程。中国长江流域野生拟南芥种群低温条件下体内ROS浓度的升高,很可能是由于种群中CBF3基因发生了自然变异从而丧失了冷响应能力造成的。

Reactive oxygen species （ROS）, a by-product of photosynthesis and respiration, is increased under many stress conditions, which would result in the peroxidation of the cytomembrane and damage of the photosystem II reaction center. Soluble carbohydrates such as raffinose family oligosaccharides （RFOs） could respond to stress and might be involved in scavenging hydroxyl radicals. Previous work demonstrated that the freezing tolerance and RFO content of populations of Arabidopsis thaliana along the Yangtze River in China were decreased as compared to the Col wild type because of a natural variation of C-repeat binding factor 3 （CBF3）. In this study, we examined the transcription profile of 4 populations along the Yangtze River under cold conditions and found a different pathway of scavenging hydroxyl radicals in these 4 populations as compared with the Col ecotype. Also the concentration of ROS was greater in these 4 popula- tions than in the Col ecotype. When the cold-inducible allele of CBF3 from the Col ecotype was transformed into the CQtlx population, from the highest warmest habitat with the lowest freezing tolerance, the freezing tolerance of transgenic plants was improved significantly as compared with non-transgenic CQtlx plants. At the same time, the concentration of RFOs was increased, but that of ROS was decreased. Thus, under cold conditions, CBF3 could induce synthesis of RFOs, probably to scavenge hydroxyl radicals. The higher concentration of ROS and lower freezing tolerance in populations along the Yangtze River as compared with the Col ecotype might be explained at least in part by the natural variation of CBF3 in these populations.