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以‘长富2号’苹果为试验材料,采用RT-PCR的方法,从其芽中克隆得到INDETERMINATE DOMAIN(IDD)转录因子基因MdIDD7,其开放阅读框长度为1 626 bp,编码541个氨基酸。序列比对和结构域分析表明,该转录因子含有1个核定位信号和4个高度保守的锌指蛋白结构域。系统进化树分析表明,MdIDD7与白梨(Pyrus×bretschneideri,XP_009364602.1)、桃(Prunus persica,XP_007225628.1)和梅(Prunus mume,XP_008220893.1)聚在一起。实时荧光定量PCR表明,MdIDD7在‘长富2号’不同组织(茎、叶、花、果和芽)中均有表达,其中芽的表达量最高。花后40~60 d,MdIDD7在易成花品种‘烟富6号’芽中表达量显著高于难成花品种‘长富2号’。“小年”树顶芽组织中MdIDD7的表达量显著高于“大年”树。在花芽诱导前期,外源GA处理诱导MdIDD7下调表达,而蔗糖处理诱导其上调表达,说明MdIDD7响应激素和糖信号,促进苹果成花。
The cDNA sequence of MdIDD7, an INDDERMINATE DOMAIN (IDD) transcription factor, was cloned from its bud by RT-PCR using ’Changfu 2’ apple as experimental material. The open reading frame of MdIDD7 was 1 626 bp, encoding 541 amino acids. Sequence alignment and domain analysis showed that the transcription factor contains one nuclear localization signal and four highly conserved zinc finger protein domains. Phylogenetic tree analysis showed that MdIDD7 was clustered with Pyrus × bretschneideri (XP_009364602.1), Prunus persica (XP_007225628.1) and Prunus mume (XP_008220893.1). Real-time PCR showed that MdIDD7 was expressed in different tissues (stem, leaf, flower, fruit and bud) of Changfu 2, and the highest expression of bud was found in MdIDD7. The expression level of MdIDD7 was significantly higher in ’Fuyan 6’ buds of easy-flowering varieties 40 ~ 60 d after flowering than in ’Changfu No.2’. The expression of MdIDD7 in the apical bud tissue of the “small year” was significantly higher than that of the “big year” tree. In the early stage of flower bud induction, exogenous GA treatment induced MdIDD7 down-regulated expression, while sucrose treatment induced up-regulated expression, indicating that MdIDD7 responded to hormones and sugar signals and promoted apple blossom.