Cloning and Expression Analysis of Auxin Response Factor Gene (CsARF1) in Tea Plant (Camellia sinensis [L.] O. Kuntze)

Abstract

Auxin response factors (ARFs) are transcription factors that bind to TGTCTC auxin response elements in promoters of early/primary response genes and regulate the expression of auxin response genes. The full-length cDNA of one ARF gene named CsARF1 (GenBank accession number JX307853) was firstly cloned from tea plant (Camellia sinensis [L.] O. Kuntze) by SMART-RACE-PCR. The results indicated that the full-length cDNA of CsARF1 was 3222 bp containing 2463 bp ORF which encoded 820 amino acid residues with a putative molecular mass of 49.35 kD. The soluble protein encoded by CsARF1 functioned in the cytoplasm and consisted of an amino-terminal DNA-binding domain (B3), a carboxy-terminal dimerization domain (IAA_ARF), and a Gln, Ser and Leu-rich middle region, which is proposed to function as an activation domain. Blast and phylogenetic analysis showed that the protein encoded by CsARF1 shared the highest identity (83%) with ARF8 in Vitis vinifera, and had close genetic relationship with ARF8 in Solanum lycopersicum. The expression analysis of CsARF1 conducted by qRT-PCT during the different phases of bud dormancy and bud break indicated that CsARF1 had a marked rise in the expression level at deep dormant stage and sprouting stage, demonstrating that CsARF1 is relevant to the regulation of tea plant bud dormancy and bud break.