Screening And Functional Analysis Of Low Phosphorus-stress Responsive Genes For Wheat

Five wheat varieties widely used in Huanghuai region of China,which include:Zhengmai 9023(ZM9023)、 Jimai 17(JM17)、 Xiaoyan54(XY54)、 Xinong979(XN979)、Yunong 202(YN202),were employed to identify the low phosphorus responsive genes of wheat by using cDNA-AFLP.The main results as following:The cDNA-AFLP profiling of 5 varieties of wheat roots exposed in different phosphorus concentrations were conducted by using 216 pairs of selective primer combinations.More than 120 differentially expressed fragments were selected for consequently cloning andsequencing.Finally,total 18 candidate genes which were manifestly responsive to lowphosphorus stress were obtained.The Blast X was used for gene homology analysis of selected candidate genes.Major types of highly homologous proteins as follows: Acidic ribosomal protein P1a-like,Cysteine protease,Adenosine monophosphate deaminase,Ribosomal protein S20,GTP super family of enzymes,peroxidase 12,aspartate aminotransferase 1 superfamily,salt stress induced protein,GTP enzyme activator protein,auxin transport into similar carrier component4.ATen candidate genes were selected for qRT-PCR analysis,indicating that their expression abundance patterns were consistent withthe results fromcDNA-AFLP screening experiments.Based on the information of wheat genome sequence and transcriptome profiling,full-length c DNA sequences of TaTEF1 and TaPOX12 genes were cloned from wheat variety ZM9023.The TaTEF1 gene encodes a TEF-protein with an ORF(open reading frame length)of 1321 bp and molecular weight of encoded the protein of 49.17 KD,containing 447 amino acids.The putative protein possesses the signal peptide,phosphorylationand glycosylation sites,implying TaTEF gene mightily belongs to the Ras like GTPase superfamily.The TAPOX12 gene’s open reading frame is 1190 bp,encoding 366 amino acids,the putative TaPOX12 protein molecular weight was 42.17 KD,andcontainsphosphorylation,glycosylation sites.Tapox12 gene has heme binding sites located between 50-300 amino acid residues,which were found in the plant peroxidase like superfamilyand also contains a special secretory peroxidase domain.TaTEF1 and TaPOX12 gene were predicted respectively with the function of the signal transmission and metabolism of cell defensive.Hence,TaTEF and TaPOX12 gene probably could play important roles in enhancingresistance to low phosphrusstress of wheat.Relative expressions of TaRBPMS-like and TaLC1314 genes in the five tested varieties in normal phosphorus and low phosphorus regimes with different time course(7d,14 d,21d,24 h after low phosphate treatment)were analyzed.TaRBPMS-like and TaLC1314 genes in different varieties were showed an up-regulation.After phosphate were re-supplied,there presented a down-regulation.The results indicated that the expressions of these two candidate genes were significantly regulated by the phosphorus conditions.Whilethe expression patterns of these two candidate genes in the roots of different wheat varieties exposed to low phosphorus stresswere different,which indicated that different wheat genotypes might have different mechanisms for low phosphorus reaction.TaLC1314 encoded protein might involve in the process of plant growth and development with function of β-1,3 – glucanase.TaRBPMS-like encoded protein was predicted with RNA binding protein function.These two candidate genes could involve in the regulation mechanism of phosphorus stress and deseve for further investigation.