Cloning And Expression Of Three Water-stress Related Genes In Wheat

Drought is one of important limiting factors which influence plant growth and development. Based on the study of gene expression profile response to water-stress, three water-induced genes were cloned, and their expression patterns under the drought- and salt (NaCL)- stresses, as well as the ABA treatment, were studied. The main results showed as follows:1 A full-length cDNA, encoding a leucine-rich repeats of ribonuclease inhibitor protein was cloned by using RACE (rapid amplification of cDNA ends) technology from the Drought wheat cultivar Luohan No.2 and termed as TaLRR1, Sequence analysis showed that the full-length cDNA of TaLRR1 was 2657 bp,which including the 47 bp of 5′UTR, 1314 bp of 3′UTR and 1296 bp of ORF (open reading frame) encoding 431 amino acid residues of this gene is about 45.79KD.The analysis of the deduced amino acid sequence of TaLRR1 showed that it included a typical Leucine rich repeat N-terminal domain and a LRR_RI (leucine-rich repeats ribonuclease inhibitor) domain, and the TaLRR1 protein was acidulous with pI of 5.69 and without any obvious hydrophobic or hydrophilic domain. The 3D struction analysis showed that the TaLRR1 was constructed by alpha helixes, beta strands and random loops, and can wrap around in a curved, right-handed solenoid with a pair of extended side arms.2 A cDNA including 689bp in length termed as TaDHD1 were isolated, and which is, encoding 185 amino acid residues of this gene is about 18.91KD .A cDNA integrate 3'end,and which is 619 bp in length was cloned, named TaDHD2. Phylogenetic anlaysis showed TaDHD1 was higher similarity with TaWZY1-1, and TaDHD2 was closely related to TaWZY1-2 , CAA62449,CAA54705,CAA62448, which indicated TaDHD1 and TaDHD2 are two new genes encoding dehydrin in wheat.3 Luohan No.2 with the drought resistance phenotype and Chinese Spring were as the material,expression patterns of cloned genes under various abiotic stresses were studied via semi-RT-PCR, the results showed the expression of TaLRR1 was induceded under drought- and NaCl-stress in Luohan No.2, and the expression of the gene was only induceded by drought-stress in Chinese spring, and it was not expressed under ABA in two tested varieties, which showed that TaLRR1 is related to drought-stree,but not regulated by ABA. The expression of TaDHD1 was induceded under different abiotic stresses in Luo han No.2, but not in Chinese Spring, which might imply that TaDHD1 is involved in more strong resistance with drough in Luohan No.2. The expression of TaDHD2 was induceded under different abiotic stresses in two varieties, and the results indicated that the gene of TaDHD2 not only subject to regulation by ABA-stress , but also related to drought, salt. The results obtained in this study will be helpful for further elucidating molecular mechanism of drought tolerance in Luohan No. 2 and molecular breeding of drought resistant in wheat.