桑树MaGPX家族基因的克隆及表达分析

Gene Cloning and Expression Analysis of the MaGPX Family in Morus alba L.

谷胱甘肽过氧化物酶(Glutathione peroxidases,GPXs)是植物细胞清除活性氧的重要酶类之一,与植物的抗逆性紧密相关。该研究以桑树(Morus alba L.)‘红果2号’为材料,利用RT-PCR方法克隆了桑树MaGPX基因家族6个成员。生物信息学分析表明,MaGPX蛋白序列具有植物GPX的典型结构域和Cys残基,并与拟南芥(Arabidopsis thaliana)AtGPX蛋白序列具有较高的相似性。亚细胞定位结果表明,MaGPX1/2/3/6可能定位在细胞膜、细胞质和细胞核,MaGPX4定位在叶绿体,MaGPX5可能定位在细胞膜,暗示桑树MaGPX成员具有功能的分化。qRT-PCR分析表明,MaGPX基因家族各成员在芽、叶、根、雄花、雌花以及果实中均有表达,其中MaGPX 1/3/5在根以及雄花中高表达,MaGPX 2在雄花中高表达,MaGPX 4在叶和雄花中高表达,MaGPX 6在果实中高表达;MaGPX各成员的表达受干旱胁迫诱导,各成员对干旱胁迫的响应随着处理时间和胁迫程度的变化而有所不同,其中MaGPX 1、MaGPX 2和MaGPX 3可能在清除活性氧和维持细胞内氧化还原平衡中发挥重要作用。该研究结果为桑树MaGPX基因家族的生理功能研究奠定了良好基础。

Glutathione peroxidases(GPXs)are one of the crucial enzymes scavenging reactive oxygen species in plant cells and closely related to plant stress tolerance.In this study,six MaGPX genes of mulberry(Morus alba L.)were cloned from‘Hong guo 2’by RT-PCR.Bioinformatics analysis indicated that the MaGPX protein sequences had a typical domain of plant GPXs and Cys residue,with a high similarity to the AtGPX from Arabidopsis thaliana.The subcellular localization results indicated that MaGPX1,MaGPX2,MaGPX3 and MaGPX6 were possibly located in the plasma membrane,cytosol and nucleus,while MaGPX4 was chloroplastic isoenzyme and MaGPX5 was potentially active in the plasma membrane,suggesting that MaGPX might have diversified function.The qRT-PCR results showed that MaGPX genes were detected in shoots,leaves,roots,staminate flowers,pistillate flowers and fruits.MaGPX1,MaGPX3 and MaGPX5 were highly expressed in roots and staminate flowers.MaGPX2 transcripts were high in staminate flowers.MaGPX4 showed the high transcription levels in leaves and staminate flowers.Transcripts of MaGPX 6 were mainly accumulated in fruits.The expression of MaGPX genes was induced by drought stress and the expression levels varied with treatment time and stress degree.MaGPX 1,MaGPX2 and MaGPX3 might play a significant role in scavenging ROS and maintaining intracellular redox balance.These results will contribute greatly to further study of the physiological function of MaGPX genes in Morus alba L.