【作者】 张丽；

【导师】 赵明；

【作者基本信息】 中国农业大学 ， 作物栽培学与耕作学， 2004， 硕士

【摘要】 本研究利用C₃植物、C₄植物、旱稻与稗草等的杂交后代的材料，进行光合速率的测定，进一步分析植株在光能吸收传递、气孔调节、羧化反应等生理特性，研究高光效的生理机制。主要结果如下： 1．对C₃、C₄植物的光合速率进行了系统的比较，明确C₄植物在光合速率的优势。各个时期C₄植物的光合速率的平均值均高于C₃植物，各个时期C₄植物表现出的光合速率的优势随着植株的衰老而降低，在生长旺盛期，C₄植物的光合速率的优势达到30％以上。C₃、C₄植物都是一个分类群体，其光合速率的表现也存在很大的差异，如长芒稗等就表现绝对高的光合速率，而同样条件下水稗（C₄植物）的光合速率的优势不明显。环境胁迫影响植物的光合作用，从而影响到光合速率的表达。 2．PEPCase是C₄植物固定CO₂的关键酶，RuBPCase是植物同化CO₂的关键酶。C₄植物中的PEPCase活性和RuBPCase活性显著高于C₃植物，并且C₄植物中PEPCase／RuBPCase显著高于C₃植物。C₄植物固定、同化CO₂能力强，其中以长芒稗、高粱为最优。 3．气孔特性调节光合作用效率，气孔特性的改善对光合作用的提高有至关重要的影响。C₄植物长芒稗、玉米等气孔较大，但单位面积气孔数少，水稻及其杂交后代的气孔器大小显著小于C₄植物，而YGFL的气孔器大小略大于其母本。杂交后代的气孔密度有超亲特性，不同程度的高于各亲本。 选择光合性能优势突出的C₄植物材料（如长芒稗、高粱等），用于转基因或传统育种来改良我国旱稻或水稻，有效改善旱稻或水稻的光合生理特性，提高光合速率。更多还原

【Abstract】 Terrestrial plants are classified into three major photosynthetic types, namely, C3, C4 and Crassulacean acid metabolism (CAM) plants, according to the mechanism of their photosynthetic carbon assimilation. C4 plants have CO2 concentrating mechanism and higher photosynthetic efficiency than C3 plants, especially under high light intensity, high temperature, high oxygen partial pressure and drought conditions. Since the discovery of the C4 pathway, it has been postulated that the transfer of C4 traits to C3 plants should improve the photosynthetic performance of C3 plants. Initially, conventional hybridization between C3 and C4 plants was carried out. This approach was available only in several plant genera and most C3-C4 hybrids were infertile. Another approach that has been adopted in the last ten years involves the use of recombinant DNA technology.Our objective was to provide the mechanism of high photosynthetic efficiency of C4 plants. We studied on net photosynthesis, key enzyme activities, stomata conductance and chlorophyll fluorescence parameters in C3 plants, C4 plants and rice-Echinochloa rusgalli hybrids. The major results were as follows:1.Compared with C3 plants, C4 plants have higher photosynthetic rate. In different periods, photosynthetic rate is higher than C3 plants and the advantage decreases with the plants maturing. In rapid growing period C4 plants’ advantage of photosynthesis is over 30%. C4 plants are a family, so their photosynthetic rate is different such as Echinochloa rusgalli has highest photosynthetic rate than any other plants. But some C4 plants even tower than some C3 plants in the same environmental condition. And as the environment is changed, the photosynthesis are also changed.2.Phosphoewo/pyruvate carboxylase (PEPC) is the key enzyme of photosynthetic carbon assimilation in C4 plants and C3 plants also have PEPC. But PEPC activity is lower in C3 plant. C4 plants concentrate CO2 around Rubisco through the use of dual carboxylation pathways, first by CO2 fixation with PEPCase and secondarily by Rubisco. Because C4 plants, such as maize, are capable of concentrating CO2 at the Rubisco active site, they have many desirable agronomic traits. And the RuBPCase activity in C4 plants is higher than in C3 plants because ofconcentrating CO2 at the site. The value of PEPCase/RuBPCase dedicates the C4 photosynthetic capacity and is higher in C4 plants than in C3 plants.3. Stomata characteristic is very important to improve photosynthetic capacity. The stomata of C4 plants such as Echinochloa rusgalli, maize, are larger than C3 plants such as rice and stomata density of C4 plants is less than C3 plants. Stomata of rice and its progenies of hybrids are smaller than C4 plants, but the stomata of progenies of hybrids (YFGL) are less larger than their mother. Stomata density of progenies of hybrids (YFGL) is higher than their parents, so it is possible to select plants of high photosynthetic capacity in progenies of YFGL. Using conventional hybridization or transgenic technology to improve photosynthetic capacity ofrice in our country, it is important to choose correct C4 plants which have high photosynthetic capacityand water use efficiency such as Echinochloa rusgalli and sorghum.更多还原