菊花TAS3 tasi-RNA靶基因CmARF4的鉴定及表达分析.

The study aimed to verify if the auxin response factor CmARF4 was a target gene of TAS3 tasi-RNA in Chrysanthemum morifolium, and to explore its expression characteristics.[Methods] The full-length of CmARF4 was obtained by high fidelity PCR using chrysanthemum variety ’Jinba’ as plant material, and the cleavage site of TAS3 tasi-RNA in the CmARF4 gene was confirmed through 5’ RLM-RACE PCR reactions. The relative expression levels of CmARF4 in different tissues and in response to auxin and salt treatment of chrysanthemum variety ’Jinba’ were detected by qPCR.[Results] CmARF4 was a target gene of TAS3,and its cleavage site was located between the 10th and 11th bases of the 5’ end of TAS3. The CmARF4 had an open reading frame(ORF) of 2 322 bp encoding 773 amino acids. The predicted protein molecular weight was 85.7×10³,and the theoretical isoelectric point(pI) was 6.44. Phylogenetic analysis showed that it had the closest relationship with ARF4 from Cynara cardunculus with an identity of 78.63%. CmARF4 gene had the highest expression level in bud and ray-florets during vegetative period and flowering period, followed by that in stem, respectively. Subcellular localization analysis indicated that CmARF4 protein was located in the nucleus. The CmARF4 gene had no transcriptional activity in the yeast system. The expression level of CmARF4 gene increased significantly at 12 h under 5 μmol·L-1 naphthalic acetic acid(NAA) treatment, and kept increase under 15 μmol·L-1 NAA. Under treatment with 200 mmol·L-1 NaCl, the expression level of CmARF4 increased to the highest level at 1 h, and then gradually decreased.[Conclusions] The CmARF4 gene is the target gene of TAS3 tasi-RNA in chrysanthemum. The transcription level of CmARF4 is induced by auxin and salt treatment. [ABSTRACT FROM AUTHOR]