茄子花青素合成中SmTTG1、SmGL3和SmTT8的表达及其蛋白质间的相互作用

Cloning,Expression and Interaction of Anthocyanin-related Transcription Factors Sm TTG1,Sm GL3 and Sm TT8 in Eggplant

采用同源克隆方法从茄子(Solanum melongena L.)中分离得到3个基因,分别命名为Sm TTG1、Sm GL3和Sm TT8。序列分析表明,Sm TTG1的c DNA全长1 220 bp,开放阅读框为1 029 bp,编码342个氨基酸,与马铃薯(S.tuberosum L.)TTG1基因序列同源性达到94%,成熟蛋白等电点为4.90,具有典型的WD结构域;Sm GL3的c DNA全长2 329 bp,开放阅读框为1 887 bp,编码628个氨基酸,与马铃薯GL3基因序列相似性达到94%,蛋白等电点为5.61,有典型的HLH结构域;Sm TT8的c DNA全长2 242 bp,开放阅读框为1 896 bp,编码631个氨基酸,与马铃薯TT8基因序列同源性为85%,蛋白等电点为5.18,有典型的HLH结构域。荧光定量检测结果表明,Sm TTG1、Sm GL3和Sm TT8在茄子根、茎、叶、花、果皮和果肉中均有表达,但表达水平具有组织特异性。酵母双杂交结果表明,Sm TTG1与Sm TT8、Sm GL3之间有相互作用,并且Sm TTG1、Sm GL3和Sm TT8都与Sm MYB之间发生作用。推测Sm TTG1为WD40转录因子,Sm GL3和Sm TT8为b HLH转录因子,它们都参与调控茄子花青素的合成。

Three genes,respectively named Sm TTG1,Sm GL3 and Sm TT8 were isolated from eggplant(Solanum melongena L.)using homology-based cloning method. Sequence analysis shows that the open reading frame(ORF)of Sm TTG1 is 1 029 bp long,encoding 342 amino acids and sequence alignment reveals 94% identity with TTG1 in potato(S. tuberosum L.). Sm TTG1 protein contains four typical WD domains and protein isoelectric point is at p I 4.90. The ORF of Sm GL3 is 1 887 bp long,encoding 628 amino acids and sequence alignmentreveals 94% identity with GL3 in potato. Sm GL3 protein contains typical HLH domain and protein isoelectric point is at p I 5.61. While the ORF of Sm TT8 gene is 1 896 bp long,encoding 631 amino acids and the multiple alignment of Sm TT8 gene sequence with those of other homologues showed that it had high identity with homologous genein potato. Sm TT8 protein contains typical HLH domain and protein isoelectric point is at p I 5.18. QPCR analysis indicates that Sm TTG1,Sm GL3 and Sm TT8 are expressed in all organs of eggplants,including roots,stems,leaves,petals,peels and sarcocarp. However,the expression level of Sm TTG1,Sm GL3 and Sm TT8 are tissue-specific. Yeast two-hybrid shows that Sm TTG1 can interact with Sm GL3 and Sm TT8. Meanwhile,Sm TTG1,Sm GL3 and Sm TT8 can interact with Sm MYB. Therefore,it is speculated that Sm TTG1 is a WD40 transcription factor and Sm GL3 and Sm TT8 are b HLH transcription factors,which are involved in the biosynthesis of anthocyaninin eggplant.