苋菜甜菜红素合成相关基因AmMYB1的克隆及表达分析

Cloning and Expression Analysis of Betalain-related Transcription Factor Gene AmMYB1 in Amaranthus tricolor L.

应用RACE技术,从‘大红’苋菜中克隆到1条MYB基因cDNA全长序列,命名为AmMYB1(登录号为KU557504)。AmMYB1基因开放阅读框为723bp,可编码240个氨基酸。其基因组序列与cDNA比对后显示,AmMYB1基因含有1个内含子。生物信息学分析表明,AmMYB1具有2个连续的MYB结构域,是一个典型的R2R3-MYB;同源分析显示,该基因编码的氨基酸序列与甜菜红素相关BvMYB1的一致性最高,达到54%。亚细胞定位结果显示,AmMYB1蛋白定位于细胞核。实时荧光定量PCR分析表明,AmMYB1基因在‘大红’苋菜叶片红色部位的表达量高于绿色部位;在甜菜红素含量高的叶和茎中表达量明显高于根;在光照条件下表达量高于遮光处理;在红叶品种中的表达量高于绿叶品种。研究结果表明,AmMYB1基因可能是苋菜甜菜红素合成途径中重要的正调控因子。

RACE method was used to obtain the complete cDNA sequence of AmMYB1（Genbank accession No.KU557504）from ‘Dahong＇amararanth（Amaranthus tricolor L.）,which belong to MYBgene.The AmMYB1 gene contains an open reading frame of 723 bp that encodes 240 amino acids.Comparison between the cDNA and genomic DNA sequences showed that AmMYB1 gene contains one intron.Bioinformatical analysis revealed that AmMYB1 is a typical R2R3-MYB containing two consecutive MYB domains.Blast X analysis showed that AmMYB1 is relatively close to betalain biosynthesis-related BvMYB1,with an identity of 54%.Subcellular localization analysis revealed that the AmMYB1 protein was located in the nucleus.Quantitative real time PCR results showed that the expression level of AmMYB1 was significantlyhigher in the red part of leaves than that in the green part,and was also higher in the leaves and stems with high betalain concentrations than that in the roots.The expression of AmMYB1 was obviously increased when exposure to light.AmMYB1 was found to be highly expressed in the red leaf variety compared with the green leaf variety.Therefore,the AmMYB1 may play positive roles in regulating betalain biosynthesis in Amaranthus.