Abstract:

【Objective】The aim of this study was to clone the full length cDNA of the gene encoding SQUAMOSA promoter binding protein-like 9 (SPL9) from strawberry, to analyze its expression level at different growth stages of strawberry and the expression relationship between SPL9 and miR156, and preliminarily to elucidate the role of SPL9 gene in strawberry plant development.【Method】The fragment of SPL9 gene was amplified from strawberry leaves by RT-PCR with the degenerate primers designed according to the sequences of Malus SPL genes. The full-length cDNA of SPL9 gene was obtained with RACE. Real time RT-PCR was used to analyze the expression levels of SPL9 and miR156 in strawberry leaves.【Result】The full-length cDNA sequence of SPL9 was cloned from strawberry (Fragaria×ananassa) cultivar ‘Allstar’ and the gene product was designated as Fragaria×ananassa SPL9 (FaSPL9). The CDS length of FaSPL9 is 1143bp that encoded a predicted protein of 381 amino acid residues. The amino acid identity compared with Arabidopsis thaliana AtSPL9, Vitis vinifera VvSPL9, Poncirus trifoliate PtSPL9, Malus domestica MdSPL9 and Zea mays ZmSPL9 was 40.30%, 64.57%, 56.09%, 70.33%, and 38.35%, respectively. There are highly conserved SBP structure domain and two-way nuclear localization signal KRXXXRRRK in FaSPL9. The nucleotide sequence of FaSPL9 includes the target site of miR156. The real time RT-PCR result showed that the expression levels of FaSPL9 changed at the different development stages of strawberry plants, and the expression of FaSPL9 was strikingly complementary with the expression of miR156.【Conclusion】FaSPL9 gene was cloned from strawberry. As the target gene of miR156, FaSPL9 may play an important role in regulating the growth and development of strawberry plants.