Abstract:

Using low-acid small fruit variety‘Changyecheng’and high-acid large fruit variety ‘Daguo Jincheng’both mutated from Jiangjin sweet orange as materials，two AREB（ABA responsive element binding）/ABFs（ABRE binding factors）transcription factors，i.e. CsAREB1 and CsAREB2 were analyzed by bioinformatics and expression analysis. In addition，the contents of endogenous hormones including ABA，IAA，GA and ZR in different stages of fruit development were determined with Enzyme Linked Immunosorbent Assay. The results showed that the Open Reading Frames（ORFs）of CsAREB1 and CsAREB2 contained 1 338 bp and 1 347 bp，encoding a protein of 445 and 448 amino acid residues，respectively. CsAREB1 and CsAREB2 predominantly expressed in leaves，flowers and fruits. During the fruit development，the expression level of CsAREB1 showed an increasing pattern in‘Changyecheng’and an increasing firstly and then decreasing pattern in‘Daguo Jincheng’，and the expression of CsAREB2 in both cultivars showed an increasing pattern. These two genesexpressed morehighly in‘Changyecheng’than in‘Daguo Jincheng’in division stage，conversely in rind and no significant difference in the pulp during expanding stage. The expression of CsAREB1 and CsAREB2 were induced by exogenous ABA. The contents of IAA，GA，ZR and the ratio of IAA，GA，ZR to ABA in‘Daguo Jincheng’were higher than those in‘Changyecheng’in division and expanding stage，however，an opposite trend was observed in flesh tissue in division stage. During fruit development，the expression levels of CsAREB1 were positively related to the content of endogenous ABA in fruit，while not to other and CsAREB2phytohormones. This study showed that CsAREB1 and CsAREB2 were regulated by ABA，and play a potential role in citrus fruit volume through the regulation of ABA.

Key words: citrus；">ABA；AREB/ABFs factor；fruit development；gene expression