摘要
用经转入磷酸烯醇式丙酮酸羧化酶 (PEPC)、丙酮酸磷酸二激酶 (PPDK )、NADP 苹果酸酶 (NADP ME)、PEPC +PPDK等酶的基因的水稻株系及原种为材料 ,研究了光氧化条件下的叶绿素荧光特性和膜脂过氧化。光氧化处理后 ,与原种相比 ,转C4光合酶基因特别是转PEPC和转PEPC +PPDK基因水稻株系的PSⅡ原初光化学效率 (Fv/Fm)、PSⅡ在照光下的实际光化学效率 (PSⅡ )和光化学猝灭 (qP)下降的比原种少 ,而非光化学猝灭 (qN)增加的比原种多 ,说明在光氧化条件下 ,转C4光合酶基因水稻株系吸收的光能中有较多的光能转化为化学能 ,过剩的光能通过热耗散而减轻光破坏 ;同时转C4光合酶基因水稻株系诱导产生的的内源活性氧清除酶系超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)、过氧化物酶 (POD)的活性比原种高 ,从而有效清除水稻叶片内的活性氧 (O- ·2 、H2 O2 ) ,使活性氧积累比原种少 ,因而膜脂过氧化产物丙二醛(MDA)产生较少。表明转C4光合酶基因特别是转PEPC和转PEPC +PPDK基因水稻株系耐光氧化能力较强。在光氧化条件下 ,它们的叶绿素和蛋白质含量下降较少 ,表现出耐光氧化特性。
The characteristics of chlorophyll fluorescence and the performance of membrane lipid peroxidation in progenies of transgenic rice plants with maize PEPC, PPDK, NADP ME and PPDK+PEPC genes under photooxidation were studied by comparison with untransformed rice plants ( Oryza sativa L. subsp. japonica Kitaake). After being subjected to photooxidation inducing treatment, Fv/Fm which reflects the primarily photochemical efficiency of PSⅡ, actually photochemical efficiency of PSⅡunder light (PSⅡ) and photochemical quenching (q P) in transgenic rice plants (especially in transgenic rice plants with maize PEPC and PPDK+PEPC genes) decreased less than those in untransformed rice (Fig.2A, B and C), while the non photochemical quenching (q N) increased more (Fig.2D), which suggested that more light energy absorbed by transgenic rice plants was converted into chemical energy and the excessive light energy was dissipated as heat, resulting in the alleviation of photodamage. Meantime, the higher activities of enzymes scavenging active oxygen such as superoxide dismutase (SOD) (Fig.4A), catalase (CAT) (Fig.4B) and peroxidase (POD) (Fig.4C) in transgenic rice plants led to a lesser accumulation of endogenous active oxygen (O -· 2,H 2O 2) (Fig.3A and B). As a result, the malondialdehyde (MDA, a product of membrane lipid peroxidation) content (Fig.3C) was less than that in untransformed rice, and the chlorophyll and protein contents in transgenic rice plants (especially in transgenic rice plants with maize PEPC and PPDK+PEPC genes) decreased less than those of untransformed rice, which showed that there was a stronger tolerance in transgenic rice plants to photooxidation. This work provided the experimental evidence that new varieties with photooxidation tolerant germplasm can be created by introducing the desired germplasm using biotechnology.
基金
国家重点基础研究发展规划项目 (G19980 10 10 0 )资助
