海南龙血树金属硫蛋白基因DcMT3a和DcMT3b的鉴定和表达分析

Identification and Expression Analysis of Metallothionein Gene DcMT3a and DcMT3b in Dracaena cambodiana

植物金属硫蛋白通过清除活性氧参与了植物防御反应,是植物胁迫应答的关键蛋白。MT3蛋白是重要的植物金属硫蛋白之一。本研究在对海南龙血树转录组序列进行注释拼接的基础上,利用RT-PCR技术首次克隆了2个DcMT3基因,分别命名为DcMT3a和DcMT3b,GeneBank登录号分别为MF594216和MF594217。结果表明DcMT3a和DcMT3b基因分别编码65个和62个氨基酸,且均具有植物MT3蛋白的典型结构特征,即N端的4个保守性半胱氨酸(cysteine,C)和C端的6个保守性半胱氨酸。进化分析表明DcMT3a和DcMT3b与百合目植物芦笋、马蔺具有较高相似度。亚细胞定位分析发现2个DcMT3蛋白均定位于叶绿体,二级结构也都主要由α螺旋和无规则卷曲构成。表达分析表明DcMT3a和DcMT3b在海南龙血树各组织中具有不同程度的表达,其中果实中的表达量最高。此结果为深入研究植物金属硫蛋白在海南龙血树发育及血竭形成过程中的作用奠定了基础。

Plant metallothionein（MTs） are the crucial proteins for plant against（a） biotic stresses by scavenging redundancy reactive oxygen species.MT3 is one of the most important MT proteins in plant.Based on the transcriptome data from our previous study,two MT3 proteins named DcMT3a and DcMT3b are cloning from Dracaena cambodiana by RT-PCR technology.The accession number of DcMT3a and DcMT3b in Gene Bank is MF594216 and MF594217,respectively.The gene of DcMT3a and DcMT3b encoded 65 or 62 amino acids respectively.Both DcMT3a and DcMT3b protein contained two conservative structures in N-and C-terminal which separately consist of 4 or 6 cysteines.Two DcMT3 proteins are similar with the MT3 proteins from Asparagus officinali and Iris lacteal which were classified into Liliales genus.Subcellular localization and secondary structure analysis predicted that DcMT3a and DcMT3b were located on chloroplast and mostly consisted of α-helix and random coil.The expression profiles of DcMT3a and DcMT3b in root,stem,leaf,flower and fruit of D.cambodiana with RT-q PCR demonstrated that the relative expression of these two DcMT3 genes in fruit were all higher than other tissues.This study offered foundation for revealing the functions of metallothionein in developmental progress and dragon＇s blood formation from D.cambodiana.