野生大豆GsGST19基因的克隆及其转基因苜蓿的耐盐碱性分析

Isolation of GsGST19 from Glycine soja and Analysis of Saline-Alkaline Tolerance for Transgenic Medicago sativa

谷胱甘肽S-转移酶对植物抵御逆境胁迫和解除细胞毒素起着重要作用。本研究从野大豆盐碱胁迫基因表达谱中筛选并克隆得到GsGST19基因,将其转化苜蓿,获得超量表达的转基因苜蓿,并对转基因苜蓿进行耐盐碱性分析。结果显示在正常培养条件下,转基因苜蓿株系19-4和19-9的GST酶活性分别是非转基因株系的1.52倍和1.49倍。在100mmol L-1 NaHCO3处理14d后转基因株系生长状态良好,而非转基因对照株系明显萎蔫、失绿、甚至死亡;转基因株系的丙二醛含量和相对质膜透性显著低于非转基因株系(P<0.05),而叶绿素含量和根系活力显著高于非转基因对照(P<0.05),说明超量表达GsGST19基因增强了苜蓿的耐盐碱能力。

Alfalfa （Medicago sativa L.） is one of the most important leguminous forage crops worldwide. Saline-alkaline stress significantly limits the productivity of alfalfa due to its adverse effects on growth, formation of nodules, and symbiotic nitro- gen-fixation capacity, and resulting in the formation of reactive oxygen species （ROS）. To protect plants from the toxicity of reac- tive oxygen, aerobic organisms are equipped with an array of defense mechanisms, including one based on glutathione S-transferases （GSTs）. Glutathione S-transferases （GSTs） are ubiquitous enzymes that play a key role in stress tolerance and cel- lular detoxification. The GST gene GsGST19 isolated from wild type soybean （Glycine soja） under saline-alkaline stress was transformed into alfalfa （Medicago sativa L.）. Transgenic alfalfa plants showed 0.52-0.49 times higher levels of GST activity than wild type plants. Transgenic alfalfa grew well in the conditions of 100 mmol L-i NaHCO3, while wild type plants exhibited dis- coloration and stunted growth, or even death. There were significantly changes in malondialdehyde content and relative mem- brane permeability caused by saline-alkaline stress in non-transgenic lines compared to transgenic lines （P〈0.05）. Moreover, compared with non-transgenic, transgenic alfalfa had higher levels of chlorophyll content and root activity under saline-alkali stress conditions. The results indicated that the zene GsGST19 could enhance resistance to saline-alkaline in alfalfa.