过表达ApGSMT2和ApDMT2基因的拟南芥和玉米耐盐性分析

Salt Tolerance of Arabidopsis and Maize Overexpressing ApGSMT2 and ApDMT2 Genes

玉米是对土壤盐渍化中度敏感的作物,易受盐碱危害。甘氨酸甜菜碱作为一种主要的渗透保护物质,能够提高植物对多种非生物胁迫(如盐碱、干旱、低温等)的抗性。本工作前期从嗜盐隐杆藻中克隆得到两个参与甘氨酸甜菜碱合成的甲基转移酶基因ApGSMT2和ApDMT2,利用农杆菌介导法,将两个基因分别在拟南芥和玉米中共同过表达,获得转基因阳性株,收获T1代转基因种子,经自交后得到T2代种子。以拟南芥T2代种子为试材,设置0、50、100、150、200mmol/LNaCl处理,进行种子萌发试验,结果显示,不同盐浓度处理下,转基因拟南芥种子的萌发率显著高于未转基因对照植株,说明过表达ApGSMT2和ApDMT2基因对于提高拟南芥的耐盐性具有显著效果。进一步对T2代转基因玉米株系幼苗的耐盐性进行试验,结果表明,180mmol/LNaCl处理后,未转基因对照植株萎蔫,而转基因株系长势良好,其株高、根长、叶片相对含水量和鲜重显著高于对照,说明过表达ApGSMT2和ApDMT2基因显著提高了玉米对盐胁迫的耐受性,为利用基因工程技术创制玉米耐盐种质提供了理论依据。

Maize is a moderately sensitive crop to soil salinization and is vulnerable to saline-alkali damage.Glycine betaine(GB),as a major osmotic protective solute,has shown the ability to improve plant resistance to a variety of abiotic stresses,such as salinity,drought and low temperature.Two methyltransferase genes,ApGSMT2 and ApDMT2,which are involved in the synthesis of GB,were cloned from Aphanothece halophytica in our previous studies.The two genes were overexpressed in Arabidopsis and maize through Agrobacterium-mediated method,and the transgenic positive strains were obtained.The T 2 generation was obtained through selfing-cross from T 1 generation.With the T 2 seeds of Arabidopsis as materials,the germination test was conducted by setting the treatments of 0,50,100,150 and 200 mmol/L NaCl.The germination rate of transgenic Arabidopsis seeds was significantly higher than that of wild-type plants under various concentrations of salt treatment.It indicated that overexpressing ApGSMT2 and ApDMT2 could significantly enhance the salt tolerance of Arabidopsis.The test was further conducted on the salt tolerance of T 2 maize seedlings.Under the treatment of 180 mmol/L NaCl,the transgenic maize seedlings developed better,while the control plants wilting.The plant height,root length,leaf relative water content and fresh weight of transgenic lines were significantly higher than those of untransformed control plants.These results demonstrated that ApGSMT2 and ApDMT2 overexpression significantly increased the tolerance of Arabidopsis and maize to salt stress.