转苜蓿MsOr基因烟草光合-光响应和光合-CO2响应曲线特征研究

Characteristics of Photosynthetic-Light Response and Photosynthetic-CO2 Response Curves in Transgenic Alfalfa MsOr Gene Tobacco

为明确苜蓿(Medicago sativa)Orange基因的表达对植物光合作用的影响,以转Orange(MsOr)基因型烟草(TOR1与TOR2)和野生型烟草(WT)为研究材料,采用盆栽控制试验,比较研究了WT,TOR1和TOR2叶片光响应曲线和CO 2响应曲线,并测定其叶片类胡萝卜素含量。结果表明:直角双曲线修正模型可较好地拟合烟草光响应曲线和CO 2响应曲线;在一定光合有效辐射强度和CO 2浓度范围内,随光强和CO 2浓度增加,TOR1和TOR2的净光合速率均显著高于WT(P<0.05);TOR1和TOR2的最大净光合速率、光饱和点、CO 2饱和点、羧化效率、暗呼吸速率和光呼吸速率显著高于WT,而CO 2补偿点显著低于WT(P<0.05);TOR1和TOR2的叶片总类胡萝卜素含量约为WT的2倍。研究表明:苜蓿MsOr基因的表达促进了烟草植株叶片类胡萝卜素的积累,同时提高了其光能和CO 2利用能力,增强了植株对高光强、高CO 2浓度环境的适应能力。

In order to clarify the effect of alfalfa(Medicago sativa)Orange gene expression on plant photosynthesis,the leaf light response curves and CO 2 response curves of transgenic Orange(MsOr)(TOR1 and TOR2)and wild tobacco(WT)lines were analyzed through a pot experiment.The results showed that the right angle hyperbolic correction model could better fit the tobacco light response curve and CO 2 response curve than rectangular hyperbolic model and non-rectangular hyperbolic model.Over a range of photosynthetically active radiant and CO 2 concentration,the net photosynthetic rate of TOR1 and TOR2 were always significantly higher than that of WT(P<0.05)as the increase of light intensity and CO 2 concentration;maximum net photosynthetic rate,light saturation point,CO 2 saturation point,carboxylation efficiency,dark respiration rate,and photorespiration rate of TOR1 and TOR2 were significantly higher than those of WT,while the CO 2 compensation point was significantly lower than WT(P<0.05);meanwhile,the total leaf carotenoid content of TOR1 and TOR2 were about twice that of WT.These observations indicated that the expression of MsOr gene could efficiently improve tobacco plants adaptability through enhancing the leaf carotenoid content accumulation and the photosynthesis and CO 2 utilization ability under high light intensity and high CO 2 concentration condition.