嘌呤合成途径基因VAL1超表达水稻光合调控生理机制研究

Study on the Physiological Mechanism of Photosynthetic Regulation of VAL1 Overexpression in Rice(Oryza sativa L.)

以提高作物产量为目的的高光效研究已成为作物育种学和栽培学共同关注的热点问题.针对寡日照限制我国特别是西南地区水稻产量提升这一问题,以前期研究获得的嘌呤合成途径基因(VAL1)水稻植株(VAL1-OE)为材料,从确定光能利用效率提升的限制因子入手,利用其光合色素质量分数和光合速率均显著提高这一特点,开展水稻光合调控生理机制研究.结果表明:VAL1-OE水稻叶片叶绿体发育和光合相关基因,如捕光复合体II叶绿素a/b结合蛋白基因(LhcpII),编码PS I P700叶绿素a脱辅基蛋白A1基因(psaA),PS II D1蛋白基因(psbA),细胞色素f脱辅基蛋白基因(petA),细胞色素b6-f复合体小亚基基因(petG),核酮糖-1,5-二磷酸羧化酶/加氧酶大亚基基因(rbcL),核酮糖-1,5-二磷酸羧化酶/加氧酶小亚基基因(RbcS)和叶绿体ATP合成酶α亚基基因(atpA),这些编码基因转录水平均显著上调.此外,VAL1-OE水稻叶片比叶质量、光合色素质量分数显著增高.在低光和高光条件下,电子传递速率(ETR)、净光合速率(A)和光能利用效率(LUE)均显著高于野生型水稻叶片,但VAL1-OE水稻单株面积较低,干物质累积和产量未显著增加.研究结果显示:超表达VAL1水稻优化叶片光能吸收、电子传递和碳同化是提高光合作用和光能利用效率的关键.光合面积较小成为制约VAL1超表达水稻获得更多干物质累积和产量的主要因素.以VAL1超表达水稻为基础,在实现高光合能力的同时,培育高叶面积表型材料,提高光合作用面积是进一步提高该水稻材料干物质累积量和产量的突破口.

The study of high light efficiency for the purpose of improving crop yield has become a hot issue of common concern in crop breeding and cultivation.Aiming at the problem of rice yield improvement in China,especially in southwest China,this project uses the chloroplast gene(VAL1)overexpression rice plant(VAL1-OE)obtained in the previous study as the material,starts from determining the restriction factor of light energy utilization efficiency,and uses the characteristics of significantly increased photosynthetic pigment content and photosynthetic rate to study the physiological mechanism of rice photosynthetic regulation.The experimental results showed that leaf chloroplast development and photosynthesis-related genes of VAL1-OE rice,such as the light-harvesting chlorophyll a/b binding protein of PSII gene(LhcpII),P700 chlorophyll a A1 decoprotein gene(psaA),PS II D1 protein gene(psbA),cytochrome f gene(petA),cytochrome b6-f complex subunit gene(petG),riboketo-1,5-diphosphate carboxylase/Oxygenase large subunit gene(rbcL),ribotose-1,5-diphosphate carboxylase/oxygenase small subunit gene(RbcS),and chloroplast ATP synthetaseαsubunit gene,their transcription levels were significantly upregulated.In addition,the leaf mass per unit area and the photosynthetic pigment content of VAL1-OE rice leaves were significantly increased.Under both low and high light conditions,the electron transfer rate(ETR),net photosynthetic rate(A)and light energy utilization efficiency(LUE)were significantly higher than those of wild-type rice.However,the total leave area per plant of VAL1-OE rice is low.The dry matter accumulation and yield of VAL1-OE rice were not increased significantly.The results show that the optimization of leaf light energy absorption,electron transport and carbon assimilation in VAL1 overexpression rice is the key to improve photosynthesis and light energy use efficiency.The small photosynthetic area has become the main factor restricting the accumulation of more dry matter and higher yield of VAL1 overexpression rice.Based on VAL1 overexpression rice,while achieving high photosynthetic capacity,selecting the phenotypic materials with high leaf area to increase the photosynthetic area is a breakthrough to further improve the dry matter accumulation and yield of this rice material.