应答非生物胁迫的甘蔗硫氧还蛋白基因ScTRXh2的克隆

Cloning of a novel thioredoxin gene( ScTRXh2),responsive to abiotic stresses,in sugarcane

从甘蔗蔗茎cDNA文库中获得1个TRXⅠ类第3亚组成员的硫氧还蛋白家族基因全长cDNA序列,命名为ScTRXh2(登录号:KF921298).该基因全长752 bp,开放阅读框长381 bp,5'非翻译区长57 bp,3'非翻译区长314 bp,编码126个氨基酸残基,氨基酸序列与拟南芥TRXs具有高度同源性.实时定量PCR检测显示,该基因在甘蔗中为组成型表达,叶片和蔗茎中的表达量显著高于根和芽.在H2O2和PEG逆境胁迫下,甘蔗ScTRXh2基因的应答模式基本相同,呈现初期(3 h)略微下调,早中期(6 h或12 h)表达量明显上调,中后期(24、48、72 h)显著下调并维持基本稳定的低水平表达.甘蔗ScTRXh2基因对NaCl胁迫的应答较快,虽然也呈现中期(12 h)表达量显著上调,后期(24、48、72 h)显著下调并维持基本稳定的低水平表达,但表达模式与H2O2和PEG胁迫应答有明显不同,表现在胁迫初期(3 h)基因表达显著下调.上述结果提示,甘蔗ScTRXh2基因积极应答非生物逆境H2O2、PEG和NaCl的胁迫,在应答的基因表达谱模式上存在一些差异.

A full-length cDNA sequence of thioredoxin gene with a length of 752 bp and open reading frame （ORF） 381 bp, desig- nated as ScTRXh2 （ C, enBank Accession No. KF921298）, was isolated from sugarcane stem full-length cDNA library. The ScTRXh2 was predicted to encode 126 amino acid residues, and its deduced amino acid sequence shared a high degree of homology with Arabi- dops/s TRXs. The length of 5＇ non-translated region and 3＇ non-translated region were 57 bp and 314 bp, respectively. The expres- sion profdes of ScTRXh2 detected by real-time qPCR in different sugarcane organs showed to be a constitute expression, and the ex- pression levels in leave and stems were significant higher than those in roots and buds. The expression profiles of ScTRXh2 respon- sive to H2O2 and PEG stresses detected by Q-PCR were similar, which is slightly down-regalated at initial stage （3 h）, sign/ficantly up-regulated at early to middle stages （6 h or 12 h ） and significantly down-regtdated with a steadily low expression at middle to later stages （ 12 h, 24 h, 48 h and 72 h for H2O2 stress or 24, 48 and 72 h for PEG stress）. Though the expression profiles of ScTRXh2 appearing to be significantly up-regulated at middle stage （ 12 h） and significantly down-regalated with a steadily low expression at later stages （24 h, 48 h and 72 h）, the expression of ScTRXh2 responsive to NaCI stress was faster than that in H2O2 or PEG stress and the expression profi/e was obviously different with a significantly up-regulated at initial stage （3 h）. It was suggested that the ScTRXh2 gene was actively responsive to the abiotic stresses of H2O2, PEG and NaCl, but there was difference in the responsive rapidness and the expression profiles.