Abstract:

AP2/ERF transcription factors widely exist in plants, and participate in various biotic and abiotic stress responses. In order to improve cotton resistance to disease and abiotic stress, the expression vector containing HhERF2 and PeDREB2a transcription factor genes, which were isolated from resistant excellent psammophyte Halimodendron halodendron and Populus euphratica respectively, and driven by rd29A promoter, was constructed and transferred into cotton (Gossypium hirsutum) by pollen-tube pathway transformation technology. After the transgenic cottons were treated with stress, the ectopic expression HhERF2 and PeDREB2a genes, and some downstream relative pathogenesis-related (PR) genes were analyzed   by Real-time PCR in transgenic cotton. The results showed that the expression of HhERF2 gene could be induced by Verticillium dahliae (Vd), drought and salt, while PeDREB2a could only be induced by drought and salt. Inoculated by Vd, the expression of some downstream relative PR genes and the enzyme activity that related to phenolic metabolism such as: PAL, SOD and POD all increased in the transgenic lines at the same times. The resistance to Vd was also enhanced in transgenic cotton. Analysis of physiological and biochemical characteristics under drought and high-salt stresses, which indicated that compared with the contrast, the soluble carbohydrates and relative water concentration in the leaves of transgenic cotton were significantly elevated, while the conductivity and malondialdehyde (MDA) content decreased significantly. These results demonstrated that transgenic cotton performed excellent tolerability to Vd, drought and high-salt stresses.

Key words: abiotic stress, biotic stress, transgenic cotton, transcription factor, Verticillium dahliae

摘要：

AP2/ERF转录因子普遍存在于植物中，并广泛参与植物对生物和非生物胁迫的响应。为了提高棉花对病害及非生物逆境的抵抗能力，将分别从抗逆性优良的沙生植物铃铛刺(Halimodendron halodendron)和胡杨(Populus euphratica)中分离的HhERF2和PeDREB2a转录因子基因构建以rd29A为启动子的表达载体，并通过花粉管通道法转化棉花。利用Real-time PCR分析胁迫处理的转基因阳性植株HhERF2和PeDREB2a基因异位表达及下游PR(pathogenesis-related protein)基因表达情况，结果表明在病原菌、干旱和盐胁迫下转基因植株体内HhERF2基因能够超表达，而PeDREB2a基因仅在干旱和盐胁迫诱导下超表达。接种大丽轮枝菌(Verticillium dahlia)后能够诱导转基因植株相关PR基因表达，同时与对照J12相比植株体内PAL、SOD和POD等酚类代谢相关酶的活性显著增加，且增强了转基因棉花对大丽轮枝菌的抵抗能力。干旱和高盐胁迫下生理生化特性分析表明，与对照相比，转基因棉花叶片中可溶性碳水化合物和相对含水量显著升高，而电导率和丙二醛(MDA)含量显著降低。因此，转基因棉花对大丽轮枝菌及干旱和高盐胁迫表现出了较强的耐受能力。

关键词: 非生物胁迫；生物胁迫；转基因棉花；转录因子；大丽轮枝菌