Abstract: DELLA protein is a key negative regulation factor of gibberellins（GAs）signal transduction pathway. A whole cDNA sequence of DELLA protein gene，named PaGAI，was cloned from Prunus avium L. tender leaves using RT-PCR and RACE-PCR. The cDNA of PaGAI had a length of 2 310 bp and contain an opening-reading frame（ORF）of 1 788 bp，which was supposed to encode a 595 amino-acid residues polypeptide of 64 kD. Bioinformatics analysis showed that the protein encoded by PaGAI had a conservative structural domain of DELLA protein. It had two strict conservative amino acid domains DELLA and VHYNP in the N terminal and three repression regions of VHVID，RVER and SAW in the C terminal. PaGAI，with high homologous with the DELLA proteins in some other plants，and showed the highest homology of 84% with Malus domestica. The prokaryotic expression system of pGEX-4T-1/PaGAI was constructed and transformated into E. coli BL21，and the protein expression was induced by 0.5 mmol · L-1 IPTG and a 91 kD fusion protein was detected by SDS-PAGE. Semi-quantitative RT-PCR analysis showed that PaGAI widely expressed in flower，fruit，leaf and phloem，and PaGAI in the expression of flower and phloem is much stronger than in fruit and leaf.

Key words: Prunus avium, DELLA protein, gene cloning, prokaryotic expression