Isolation and Characterization of HaRAN1 Encoding A Small G Protein in Haloxylon ammodendron

Haloxylon ammodendron(C.A.Mey.)Bunge,a stem-assimilating,xero-halophytic and halophytic desert shrub distributing naturally in the desert of north-west in China,where represents one of the harshest ecosystems on earth,combining drought,extreme temperatures and high salt.One TDF(transcript-derived fragment)encoding amino acids of RAN(small GTPase)protein,was obtained in H.ammodendron under drought stress by using cDNA-AFLP.Full-length gene HaRAN1,1 083 bp,was cloned by 5'-RACE and 3'-RACE,which contained an ORF encoding a 221 amino acids protein with four binding GTP/GDP conserved domains.Blast analysis showed that HaRAN1 have 95%～96% homologous to mono-and dico-tyledon(populus,arabidopsis,wheat and rice,et al.),and 88% homologous to human and fungi,et al.Semi-quantitative RT-PCR showed the expression of HaRAN1 was induced significantly under drought,PEG and NaCl stress.The results suggested this protein encoded by HaRAN1 has very high homology among species and may play an important role in H.ammodendron response to extreme desert environments.