水稻抽穗后剑叶衰老过程中光合关键酶的基因表达

Gene Expression of Key Enzymes for Photosynthesis During Flag Leaf Senescence of Rice After Heading

协优 930 8、培矮 6 4s/ 9311和汕优 6 3三个超级高产水稻品种抽穗后 ,剑叶中光合速率减小、叶绿素含量下降、SOD活力降低和MDA含量上升的幅度不同 ,显示它们开花结实过程中叶片衰老的速度不同 ,以汕优 6 3衰老最快 ,协优 930 8最慢 ,培矮 6 4s/ 9311居中。Northern杂交和免疫定量研究表明 ,汕优 6 3和培矮6 4s/ 9311剑叶rbcS(Rubisco小亚基基因 )和rca(Ru bisco活化酶基因 )mRNA的表达随抽穗后天数的增加而下降 ,而协优 930 8在抽穗后第 10天才开始下降 ;Rubisco和Rubisco活化酶蛋白含量的下降趋势与rbcS和rcamRNA的变化趋势相似。因此 ,水稻抽穗后剑叶衰老过程中光合能力的下降与光合关键酶基因(rbcS和rca)

Some senescence-associated characteristics in physiology and molecular biology of the flag leaves of three superhigh-yield rice cultivars, Xieyou 9308, Peiai64s/9311 and Shanyou 63 were investigated after heading. The results showed that photosynthetic rate, chlorophyll contents, superoxide dismutase (SOD) activity decreased, while the malondialdehyd (MDA) contents increased during senescence (Figs.1,2). Xieyou 9308 kept highest chlorophyll contents and SOD activities after heading, while Shanyou 63 had lowest. However, the former showed lowest MDA contents and the latter highest. Northern hybridization was performed to examine photosynthetic genes (rbcS and rca) expression after heading (Fig.4). The results were illustrated in Fig. 4A (rbcS mRNAs) and B (rca mRNAs). Both rbcS and rca mRNAs declined in flag leaves of Shanyou 63 and Peiai64s/9311 after heading, and the declination in Xieyou 9308 happened 10 d after heading. The results that these changes are directly correlated with the decrease in abundance of Rubisco and Rubisco activase (Fig.3) suggested that the decline of photosynthetic ability of flag leaf after heading could be attributed to the fall of the level of rbcS and rca transcript.