转YHem1 番茄植株耐盐性的研究

 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产生速率和丙二醛（MDA）含量。200 mmol ·L^-1 NaCl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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10 d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。

Studies on Salt Tolerance in Tomato Plants by Transformation of YHem1

YHem1 was a Saceharomyces cerevisiae Hem1 gene，controlled by an Athaliana HemA1 promoter（a light responsive promoter）. When YHem1 was transformed into tomato plants，the leaf endogenous ALA content，the capacities for ALA biosynthesis and catabolism，the chlorophyll content and the antioxidant enzyme activities were all improved，while the superoxide anion（）production rate and the malondialdehyde（MDA）content were depressed significantly. Treatment by 200 mmol · L^-1 NaCl solution dramatically decreased the ALA biosynthetic and catabolic capacities，and the chlorophyll content in the wild type of tomato plants. It also induced increase of the production rate and the H₂O₂ and MDA content，but inhibited the activities of superoxide dismutase（SOD），catalase（CAT），peroxidase （POD）and ascorbic peroxidase（APX）. In the transgenic plants，the ALA metabolic capacities，the chlorophyll content and the antioxidant enzyme activities were also affected by salt stress，but the impacted seriousness was much lower than that in the wild type. Ten days after salt treatment，the transgenic plants kept higher biomass with less salt-induced inhibition，compared with the wild type，which suggested that the YHem1 transformation into tomato might improve its salt tolerance. Additionally，the H₂O₂ content was generally  higher in transgenic plants than in the WT，either under salt stress or not，which implied that H₂O₂ might be a molecular signal involved in cellular regulation.