苹果多肽激素及其编码基因MdCEP1调控拟南芥根系发育

Apple Peptide Hormone and Its Coding Gene MdCEP1 Regulate Root Development in Arabidopsis thaliana

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 peptide hormones are small cleavage products of precursor peptides. A peptide hormone gene named MdCEP1 was cloned from Malus x domestica ＇Royal Gala＇ . The mechanism of MdCEP1 on the growth and development of apple roots was discussed. The Open Reading Frame （ORF） of MdCEP1 contained 366 bp, encoding 121 amino acid residues. Phylogenetic tree indicated that MdCEP1 had the highest evolutionary relationship with PbCEP1 from pear. The qRT-PCR analysis indicated that MdCEP1 had higher expression levels in apple root and stem compared with those in fruit and leaves. Additionally, MdCEPI expression was negatively regulated by auxin concentration. The synthetic peptide MdCEPlpuyp could inhibit the development of the root system of Arabidopsis significantly. The main root was short and the number of lateral roots decreased. The ectopic expression of MdCEP1 in Arabidopsis also showed a phenotype of reduced taproot and reduced number of lateral roots. qRT-PCR analysis showed that the auxin related genes were significantly down regulated in exogenous MdCEPlpHyp treatment and over expression of MdCEP1 in Arabidopsis. The results indicated that MdCEP1 played a negative role in the growth and development of apple roots.