逆境胁迫对油菜谷胱甘肽还原酶基因表达及其酶活性的影响

Effects of diverse stresses on gene expression and enzyme activity of glutathione reductase in Brassica campestris

利用cDNA末端快速分离(RACE)技术从陇油6号油菜中克隆得到一个新的谷胱甘肽还原酶基因GR2,全长2073 bp,开放阅读框1692 bp,编码563个氨基酸,预测蛋白质分子量为60.7 kDa,等电点7.9.实时荧光定量PCR分析表明:GR2基因在油菜根、茎、叶中均有表达,其中在叶中表达量最高.GR1和GR2基因的转录以及谷胱甘肽还原酶(GR)活性受到低温、高温、干旱、高盐胁迫的诱导,表明油菜谷胱甘肽还原酶在抵御低温、高温、干旱、高盐胁迫过程中发挥重要作用.脱落酸(ABA)预处理后再进行上述胁迫处理,与单独上述胁迫相比,GR1和GR2基因的转录以及GR活性水平明显上升,表明ABA可以诱导GR1和GR2基因表达和GR酶活性.MAPKK抑制剂U0126预处理后再进行上述胁迫处理,与单独上述胁迫相比,GR1和GR2基因的转录以及GR活性水平明显下降,表明U0126对GR1、GR2基因表达以及GR酶活性有抑制作用.

A novel glutathione reductase gene （GR2） was isolated from Brassica campestris Longyou 6 by rapid isolation of cDNA ends （RACE）. The full-length of cDNA of GR2 was 2073 bp, with an open reading frame （ORF） of 1692 bp. GR2 encoded a protein of 563 amino acids with a deduced molecular mass of about 60.7 kDa and an isoelectric point of 7.9. The real-time quantitative PCR results showed that GR2 was expressed in the roots, stems and leaves in B. campestris, among which the expression of GR2 in leaves was the highest. The transcript levels of GR1 and GR2, and the enzyme activity of glutathione reductase （GR） increased in response to cold temperature, high temperature, drought stress, and salt stress. The results suggested that GR played an important role in coping with diverse stresses in B. campestris. When abscisic acid （ABA） pretreatment was applied before cold temperature, high temperature, drought stress, salt stress, the expression levels of GR1and GR2, and the activity level of GR all significantly increased compared with the single stress, which indicated that ABA could induce GR1 and GR2 gene transcription and GR activity. However, when MAPKK inhibitor （U0126） pretreatment was applied before the above stresses, the expression levels of GR1and GR2 and the activity level of GR significantly decreased compared with the single stress suggesting that U0126 inhibited GR1 and GR2 gene transcription and GR activity.