关键词: 蜡梅, 小GTP结合蛋白, 基因表达, 花发育, 非生物胁迫

Abstract:

In this study，we cloned a small GTP binding protein gene（CpRAC1）by randomly sequencing from cDNA library of Chimonanthus praecox flowers. The cDNA full length of CpRAC1 gene was 1 089 bp，which contained an opening reading frame of 597 bp and encoded a protein of 198 amino acids residues. Bioinformatic analysis showed that there was no signal peptide or trans-membrane domain existed in CpRAC1 protein. Sequence alignment and phylogenetic analysis indicated that CpRAC1 protein，belonged to the typeⅠplant Rac protein，which contained the Rho superfamily conversed domain and had the high identity with other Rac proteins in different plants. The qRT-PCR demonstrated that CpRAC1 expressed in different tissues（root，stem，leaf，petal，stamen and pistil）and had the highest expression level in stamen. However，no transcripts of CpRAC1 were detected in the early stage of flower development，and then the expression level increased gradually along with the flower development. And the expression level reached its peak at the wither period. The expression of CpRAC1 was down-regulated under cold，hot，salt，CuSO4，drought and ABA stresses but up-regulated by H2O2 treatment. We speculated CpRAC1 may play impotant roles in flower development and abiotic stress response.

Key words: Chimonanthus praecox, small GTP binding protein, gene expression, flower development, abiotic stress