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植物多肽激素是一类经剪切后形成具有特殊功能的成熟的多肽。以‘嘎拉’苹果(Malus×domestica‘Royal Gala’)为研究试材,初步探讨多肽激素C-TERMINALLY ENCODED PEPTIDE1(CEP1)调控根系生长发育的机理,为苹果多肽激素的研究奠定基础。扩增获得多肽激素基因MdCEP1(MDP0000886459),其开放阅读框为366 bp,编码121个氨基酸。进化树分析表明,苹果MdCEP1与白梨的PbCEP1亲缘关系最近。表达分析显示MdCEP1在苹果根和茎中表达量最高,在叶和果实中相对较低;基因表达响应显示MdCEP1表达受到生长素的调控,低浓度生长素明显上调,而高浓度生长素显著抑制MdCEP1表达。外施人工合成小肽MdCEP1p~(Hyp)对拟南芥根系发育起到明显抑制作用,主根变短,侧根数减少。在拟南芥中异位表达MdCEP1,同样表现出主根变短,侧根数减少。qRT-PCR分析结果显示,外源MdCEP1p~(Hyp)处理和过表达MdCEP1均明显抑制了拟南芥根系生长素合成与转运相关基因的表达。研究结果表明MdCEP1在根系生长发育过程中起到了负调控作用。
Plant polypeptide hormones are a class of mature polypeptides that have been cleaved to form specific functions. Using ’Galas’ apple (Malus × domestica’Royal Gala’) as research material, we initially discussed the mechanism of CEP-TERMINALLY ENCODED PEPTIDE1 (CEP1) regulating the growth and development of roots and laid the foundation for the research of apple polypeptide hormones. The polypeptide hormone gene MdCEP1 (MDP0000886459) was amplified and the open reading frame was 366 bp encoding 121 amino acids. Phylogenetic tree analysis showed that the relationship between apple MdCEP1 and Pb pearPCEP1 was the closest. Expression analysis showed that the expression of MdCEP1 was the highest in apple roots and stems and relatively low in leaves and fruits. The gene expression response showed that MdCEP1 expression was regulated by auxin, and auxin at low concentration was significantly up-regulated, while that at high concentration of auxin significantly inhibited MdCEP1 expression. Artificial synthesis of small peptides MdCEP1p ~ (Hyp) on root development of Arabidopsis played a significant inhibitory effect, the main root becomes shorter, fewer lateral roots. Ectopic expression of MdCEP1 in Arabidopsis also showed shorter main roots and fewer lateral roots. qRT-PCR analysis showed that exogenous MdCEP1p ~ (Hyp) treatment and overexpression of MdCEP1 significantly inhibited the expression of genes related to root auxin synthesis and transport in Arabidopsis thaliana. The results showed that MdCEP1 played a negative regulatory role in root growth and development.