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YHem1是一个由拟南芥HemA1启动子(一种光响应型启动子)控制的酿酒酵母菌5–氨基乙酰丙酸(ALA)合酶基因(Hem1)。将该基因转化番茄植株,可以提高叶片内源ALA含量及其代谢能力,增加叶绿素含量和抗氧化酶活性,并降低O2-产生速率和丙二醛(MDA)含量。200mmol·L-1NaCl处理,降低了野生型番茄叶片ALA合成与代谢能力和叶绿素含量,同时诱导叶片O2-产生速率、H2O2和丙二醛(MDA)含量上升,而超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)等抗氧化酶活性则逐渐降低。盐胁迫也导致转YHem1番茄ALA合成与代谢能力、叶绿素含量和抗氧化酶活性下降,但其降幅明显低于野生型。盐处理10d后,转基因番茄植株保持着较高的生物学积累量和较低的盐胁迫抑制程度,说明转入YHem1基因可以提高番茄耐盐性。此外,转基因番茄叶片H2O2含量始终保持较高水平,暗示其可能作为一种信号分子参与细胞生理调节。
YHem1 is a S. cerevisiae 5-aminolevulinic acid (ALA) synthase gene (Hem1) controlled by the Arabidopsis HemA1 promoter, a light-responsive promoter. Transgenic tomato plants could increase endogenous ALA content and metabolism, increase chlorophyll content and antioxidant enzyme activity, decrease O2-producing rate and MDA content. 200mmol·L-1 NaCl decreased ALA biosynthesis, metabolism and chlorophyll content in leaves of wild-type tomato leaves, at the same time induced the increase of O2- production rate and the content of H2O2 and malondialdehyde (MDA) in leaves, while the superoxide dismutase (SOD) CAT activity, POD activity and APX activity decreased gradually. Salt stress also led to the synthesis and metabolism of ALA in tomato, and the chlorophyll content and antioxidant enzyme activity of YHem1 tomato decreased, but the decrease was significantly lower than that of wild type. After 10 days of salt treatment, the transgenic tomato plants maintained high biological accumulation and lower inhibition of salt stress, indicating that the introduction of YHem1 gene can improve the salt tolerance of tomato. In addition, the content of H2O2 in transgenic tomato leaves always maintained a high level, suggesting that it may serve as a signaling molecule involved in cell physiological regulation.