异源表达棉花S-腺苷甲硫氨酸脱羧酶(Gh SAMDC1)基因提高了拟南芥抗盐能力

Ectopic expression of S-adenosylmethionine decarboxylase(GhSAMDC1) in cotton enhances salt tolerance in Arabidopsis thaliana

以转GhSAMDC1基因拟南芥研究了过量表达GhSAMDC1基因对拟南芥幼苗抗盐能力的影响,以及内源多胺、过氧化氢(H2O2)、丙二醛(MDA)、叶绿素含量(Chl)、离子渗透率、抗氧化酶(SOD、CAT、POD)活性和表达量在盐胁迫下的变化。结果表明,过量表达GhSAMDC1基因能够减少拟南芥内源腐胺(Put)含量,增加亚精胺(Spd)和精胺(Spm)含量。盐胁迫下,转基因株系亚精胺合酶(AtSPDS1、AtSPDS2)和精胺合酶(AtSPMS)基因表达量明显高于野生型,Spd和Spm含量进一步增加,H2O2、MDA、Chl以及离子渗透率显著降低;与野生型相比,过氧化物酶(POD)活力无明显差异,但超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活力明显增加,其表达水平与活力变化趋势基本一致。因此,盐胁迫下,GhSAMDC1基因通过提高Spd和Spm合成相关基因的表达,增加了转基因株系Spd和Spm含量,Spd和Spm直接或间接提高抗氧化系统相关酶的活力,通过清除H2O2等活性氧的方式提高拟南芥的抗盐能力。

Transgenic Arabidopsis thaliana (GhSAMDC1) was used to study the effect of overexpression of GhSAMDC1 on salt tolerance of Arabidopsis thaliana seedlings, Contents of endogenous polyamines, hydrogen peroxide (H2O2), malondialdehyde (MDA), and chlorophyll, ion permeability, antioxidant enzymes (SOD, CAT, POD) activities and expression levels were investi- gated under salt stress. The overexpression of GhSAMDC1 decreased the content of endogenous putrescine (Put) and increased spermidine (Spd) and spermine (Spm) contents in Arabidopsis thaliana. Under salt stress, the expression levels of spermidine synthase (AtSPDS1, AtSPDS2) and spermine synthase (AtSPMS) in transgenic lines were significantly higher than those in wild type, the contents of Spd and Spm were further increased, and the contents of H2O2, MDA, chlorophyll, and ion permeability were obviously decreased. Compared with the wild type, Transgenic lines had no remarkable difference in peroxidase (POD) activity, but significantly higher superoxide dismutase (SOD) and catalase (CAT) activities, with the same change trend as their expression levels. Therefore, GhSAMDC1 increased the contents of Spd and Spm of transgenic plants by increasing the expression of genes related to Spd and Spm synthesis under salt stress, Spd and Spm directly or indirectly increased the activity of enzymes related to antioxidant system, and enhanced the salt tolerance of Arabidopsis thaliana by scavenging H2O2 and other reactive oxygen spe- cies.