Transgenic rice plants with an antisense gene inserted via Agrobacterium tumefaciens were used to explore the impact of the reduction of Rubisco activase (RCA) on Rubisco and photosynthesis. In this study, transforma...Transgenic rice plants with an antisense gene inserted via Agrobacterium tumefaciens were used to explore the impact of the reduction of Rubisco activase (RCA) on Rubisco and photosynthesis. In this study, transformants containing 15% to 35% wild type Rubisco activase were selected, which could survive in ambient CO2 concentration but grew slowly compared with wild type controls. Gas exchange measurements indicated that the rate of photosynthesis decreased sig- nificantly, while stomatal conductance and transpiration rate did not change; and that the intercellular CO2 concentration even increased. Rubisco determination showed that these plants had approximately twice as much Rubisco as the wild types, although they showed 70% lower rate of photosynthesis, which was likely an acclimation response to the reduction in Rubsico activase and/or the reduction in carbamylation.展开更多
A full-length cDNA clone corresponding to a putative phosphatidylinositol-specific phospholipase C (PI- PLC) was isolated from Arabidopsis thaliana by screening a cDNA library and using RT-PCR strategy. The cDNA, des-...A full-length cDNA clone corresponding to a putative phosphatidylinositol-specific phospholipase C (PI- PLC) was isolated from Arabidopsis thaliana by screening a cDNA library and using RT-PCR strategy. The cDNA, des-ignated AtPLC6, encodes a putative polypeptide of 578 amino acid residues with a calculated molecular mass of 66251.84 D and a pI of 7.24. The sequence analysis indicates that the polypeptide contains X, Y, EF-hand and C2 domains. The overall structure of putative AtPLC6 protein, like other plant PI-PLCs, is most similar to that of mammalian PLCd. The recombinant AtPLC6 protein expressed in E. coli was able to hydrolyze phosphatidylinositol 4,5-biophosphate (PIP2) to generate inositol 1,4,5-trisphate (IP3) and 1,2-diacylglycerol (DAG). The protein hydrolyzes PIP2 in a Ca2+-dependent manner and the optimum concentration of Ca2+ is 10 mmol/L. These results suggested that AtPLC6 gene encodes a genuine PI-PLC. Northern blot analysis showed that the AtPLC6 gene is expressed at low level in all examined tissues, such as roots, stems, leaves, flowers, siliques and seedlings under normal growth conditions. The gene is strongly induced under low temperature and weakly induced under various stresses, such as ABA, high-salt stress and heat. These results sug-gested that AtPLC6 might be involved in the signal-trans- duction pathways of cold responses of the plants.展开更多
基金Project supported by the National Natural Science Foundation ofChina (No. 39970440) Doctoral Foundation of Ministry of Edu-cation of China (No. 20020335043) and the National Basic Re-search Program (973) of China (No. G1999011706)
文摘Transgenic rice plants with an antisense gene inserted via Agrobacterium tumefaciens were used to explore the impact of the reduction of Rubisco activase (RCA) on Rubisco and photosynthesis. In this study, transformants containing 15% to 35% wild type Rubisco activase were selected, which could survive in ambient CO2 concentration but grew slowly compared with wild type controls. Gas exchange measurements indicated that the rate of photosynthesis decreased sig- nificantly, while stomatal conductance and transpiration rate did not change; and that the intercellular CO2 concentration even increased. Rubisco determination showed that these plants had approximately twice as much Rubisco as the wild types, although they showed 70% lower rate of photosynthesis, which was likely an acclimation response to the reduction in Rubsico activase and/or the reduction in carbamylation.
文摘A full-length cDNA clone corresponding to a putative phosphatidylinositol-specific phospholipase C (PI- PLC) was isolated from Arabidopsis thaliana by screening a cDNA library and using RT-PCR strategy. The cDNA, des-ignated AtPLC6, encodes a putative polypeptide of 578 amino acid residues with a calculated molecular mass of 66251.84 D and a pI of 7.24. The sequence analysis indicates that the polypeptide contains X, Y, EF-hand and C2 domains. The overall structure of putative AtPLC6 protein, like other plant PI-PLCs, is most similar to that of mammalian PLCd. The recombinant AtPLC6 protein expressed in E. coli was able to hydrolyze phosphatidylinositol 4,5-biophosphate (PIP2) to generate inositol 1,4,5-trisphate (IP3) and 1,2-diacylglycerol (DAG). The protein hydrolyzes PIP2 in a Ca2+-dependent manner and the optimum concentration of Ca2+ is 10 mmol/L. These results suggested that AtPLC6 gene encodes a genuine PI-PLC. Northern blot analysis showed that the AtPLC6 gene is expressed at low level in all examined tissues, such as roots, stems, leaves, flowers, siliques and seedlings under normal growth conditions. The gene is strongly induced under low temperature and weakly induced under various stresses, such as ABA, high-salt stress and heat. These results sug-gested that AtPLC6 might be involved in the signal-trans- duction pathways of cold responses of the plants.
