大气CO2浓度升高对宁夏枸杞糖代谢的影响机制

The effect of elevated CO2 concentration on plant photosynthesis, biomass allocation, and fruit quality etc. is affected by various factors that their effect mechanism is more complexity, and different plant species shows different response to elevated CO2 concentration. Our former study showed that elevated CO2 concentration increased the vegetative growth and photosynthesis of Lycium barbarum, and increased the photosynthate accumulation in the fruit, but decreased the content of soluble sugar and Lycium barbarum polysaccharides. So how the photosynthate was accumulated and metabolized need to be studied further. Based on the preliminary study, we plan to use the open-top-chambers to simulate the controlled environment, and measure the contents of soluble sugar, fructose, sucrose, etc. in the fruit and leaf of Lycium barbarum under the CO2 elevation condition. We will also measure the enzymes activity related to glycometabolism and analyze the sugar accumulation characteristics. Using transcriptome sequencing technique we will identify the differential expression genes f enzymes related to glycometabolism. All of these measurements and analyses will try to elucidate the molecular mechanisms of CO2 elevation effects on glycometabolism in Lycium barbarum, as well as the effects of climate change on fruit quality formation of the woody plants. This will provide experimental evidence for cultivation and breeding of non-wood product forests.

大气CO2浓度升高对植物光合作用、生物产量分配、果实品质等的影响受多种因素影响，机理比较复杂，不同类型植物对CO2浓度升高的响应不同。我们研究发现：大气CO2浓度升高促进宁夏枸杞的营养生长与光合作用，果实中的光合产物分配增多，但可溶性糖、枸杞多糖等的含量降低，这些光合产物（糖类）在叶、果实中如何积累与代谢需深入研究。本项目在前期研究基础上，采用开顶气室（OTC）系统模拟环境，以宁夏枸杞为研究对象，测定种植在大气CO2浓度升高环境下宁夏枸杞叶片、果实中可溶性糖、果糖、蔗糖等糖分含量及其代谢相关酶活性变化，分析CO2浓度升高处理下宁夏枸杞的糖分积累与代谢变化；采用高通量转录组测序技术，筛选参与糖代谢相关酶的差异表达基因，构建基因调控网络，从分子水平阐明大气CO2浓度升高对宁夏枸杞糖代谢的影响机制，揭示气候变化对木本植物果实品质形成的影响机理，为经济林栽培与育种应对气候变化提供理论指导与参考。

大气CO2浓度升高对植物光合作用、生物产量分配、果实品质等的产生影响，机理比较复杂，不同类型植物对CO2浓度升高的响应不同。项目组前期研究发现：大气CO2浓度升高促进宁夏枸杞的营养生长与光合作用，果实中的光合产物分配增多，但可溶性糖、枸杞多糖等的含量降低，这些光合产物（糖类）在叶、果实中如何积累与代谢还需深入研究。本项目在前期研究的基础上，采用开顶气室（OTC）系统控制模拟环境CO2浓度，以宁夏枸杞为研究对象，测定种植在大气CO2浓度升高环境下宁夏枸杞叶片、果实中可溶性糖、果糖、蔗糖等糖分含量及其代谢相关酶活性变化，结果表明：宁夏枸杞叶片和果实的糖含量在长期高CO2浓度处理下均有降低的趋势；果实中的转化酶活性升高、蔗糖合成酶和蔗糖磷酸合成酶活性降低，果糖、葡萄糖和蔗糖含量降低；果实中的枸杞多糖等主要活性物质含量降低，CO2浓度升高对宁夏枸杞的糖分积累与代谢有显著影响。对果实转录组测序分析，获得了73个在CO2浓度升高处理下显著表达的差异基因，筛选到了三个（LBGAE、LBGALA和LBMS）差异基因在CO2浓度升高处理下的果实糖代谢通路中显著表达，进一步克隆其cDAN序列，获得长度分别为1837 bP、1233 bP和2449 bP，分别编码411、410和571个氨基酸；多重序列比对及进化树构建分析表明三个基因与茄科家族的辣椒（CaPsicum annuum）、 马铃薯（Solanum tuberosum）、番茄（Solanum lycoPersicum ）及烟草（Nicotiana tabacum）同源性较高；qRT-PCR定量分析表明，三个基因均在CO2浓度升高处理120天的果实中显著表达，分析三个基因参与的代谢通路与调控网络，发现这些基因主要参与与半乳糖、蔗糖、葡萄糖、果糖及中间产物丙酮酸等的转化合成有关的代谢通路，初步表明基因LBGAE、LBGALA和LBMS为宁夏枸杞响应CO2浓度升高调控糖代谢的关键基因。