小麦核氧还蛋白基因TaNRX1的序列特征及表达分析

核氧还蛋白(nucleoredoxin,NRX)是一类广泛存在于植物中的氧化还原调控蛋白。为探讨NRX基因在小麦发育调控过程中的生物学功能,利用生物信息学及RT-PCR方法,鉴定并克隆了小麦核氧还蛋白基因 TaNRX1,将其3个部分同源基因分别命名为 TaNRX1-2AL、 TaNRX1-2BL和 TaNRX1-2DL。序列分析显示,3个部分同源基因均包含4个外显子和3个内含子,且CDS序列高度一致(98%),分别编码576、580和577个氨基酸;蛋白特性分析发现,TaNRX1包含3个TryX_like_TryX_NRX保守域,属于植物NRXI亚类;三级结构预测显示,TaNRX1可折叠形成一个C型的特定空间结构,其中包含4个由反向平行β-折叠及外围α-螺旋构成的结构单元。利用qRT-PCR技术进行的时空表达特性分析显示,在籽粒发育过程中 TaNRX1基因整体呈下调表达趋势,但在小麦品种矮抗58籽粒发育过程中有两次表达回升出现,这可能与矮抗58具有较强的抗逆特性有关;在不同组织间 TaNRX1基因存在差异表达,其中在节间和穗下节中的表达量最高,在成熟种子中的表达量最低。

Sequence Characteristics and Expression Patterns of a Nucleoredoxin GeneTaNRX1 in Wheat

Nucleoredoxins are a group of relatively uncharacterized proteins in thioredoxin family, which widely exist in plants. In order to provide information for analyzing the biological function of nucleoredoxins during the process of wheat developmental regulation, a nucleoredoxin geneTaNRX1 was identified and cloned from common wheat plants by using bioinformatic analysis and RT-PCR based cloning techniques, and three homoeologues of this gene were designated asTaNRX1-2AL,TaNRX1-2BL andTaNRX1-2DL, respectively. Sequence analysis indicated that three introns were included in this gene and the cDNA regions were highly identical(>98%) amongTaNRX1-2AL,TaNRX1-2BL andTaNRX1-2DL, which encode 576, 580 and 577 amino acids, respectively. Characterization of amino acid sequence indicated that three TryX_like_TryX_NRX conserved domains were detected inTaNRX1 and it was classified into the subgroup I of NRX family. The tridimensional structure analysis demonstrated thatTaNRX1 can fold into a C-shape spatial structure including four subunits, which were folded by anti-parallel beta-sheets and embedded in alpha-helices. The qRT-PCR based spatio-temporal expression analysis showed that theTaNRX1 is generally down-regulated during the process of grain development, while two times of increased expression were detected during the grain development in wheat variety of Aikang 58, which is probably associated with the characteristics of relatively stronger stress tolerance of this variety. Additionally,TaNRX1 is differentially expressed significantly between different tissues, which showed the highest expression level in internode and peduncle, while the lowest is in mature seeds.