Molecular Characterization And Function In Abiotic Stress Tolerance For Cytokinin Response Factor TaARR193,Calmodulin TaCaM12 And TaPC And Transcription Factor TaNF-YB3;1 In Wheat (Triticum Aestivum L.)

As critical abiotic stresses,N and P deprivations as well as drought and high salinity lead to serious limitation on crop growth and development,and yield formation capacity.In this study,the molecular characterization and function in mediating stress tolerance on a set of genes,including a cytokinin response regulator gene TaARR193,calmodulin genes TaCaM12 and TaPC and NF-Y transcription family gene TaNF-YB3;1 were investigated.The main results are as follows:1.Based on the root cDNA libraries constructed in the laboratory that enrich differential genes upon N and P deprivations,three genes showing differentially expressed including a cytokinin response regulatory factor gene TaARR193,two calmodulin-associated genes TaCaM12 and TaPC were obtained and subjected to further analysis.The full-length cDNA sequences of above genes are1647,602 and 1095 bp which encode amino acids of 520,202 and 349,respectively.Prediction analysis on TaARR193,TaCaM12 and TaPC revealed that they are localized in positions of extracellular,cytoplasmic and vacuolar membranes,respectively.Under starvation of N and P,the expression pattern of TaARR193 was shown to be upregulated in roots.Under N deprivation condition,the expression level of TaCaM12 and TaPC was shown to be gradually increased along with the treatment progression.2.Based on the use of DNA recombination approach,the lines of tobacco fused TaARR193,TaCaM12 and TaPC were generated.Under N-and P-starvation conditions,compared with wild type(WT),the lines with TaARR193 overexpression showed improved phenotypes,increased leaf area and dry fresh weight,and enhanced activities of antioxidant enzymes.In contrast,the lines with TaARR193 knockdown exhibited alleviated growth,lowered dry and fresh weights,reduced chlorophyll content,and decreased activities of the antioxidant enzymes.Compared with WT,the lines overexpressing TaPC showed enlarged leaves,increased fresh weight and root system whereasthe lines with this gene knockdown lowered plant growth largely.3.The expression patterns of a suited of genes encoding phosphate transporter,nitrate transporter,nitrate reductase,nitrite reductase,and nitrogen assimilation-associated genes were assessed in the lines transformed by TaARR193.The results showed that part of the examined genes exhibited modified transcription,showing upreguated expression in the lines with TaARR193 overexpression and downregulated in the lines with TaARR193 knockdown.Similarly,a set of genes encoding antioxidant enzymes such as superoxide dismutase(SOD),catalase(CAT),and peroxidase(POD)showed upregulated expression in TaARR193 overexpression lines and downregulated expression in TaARR193 knockdown lines.These results indicated that TaARR193 regulates plant N-and P-deprivation tolerance via its role in regulating transcription of the genes associated with N and P absorption as well as antioxidant enzymes.4.The wheat NF-YB family transcription factor gene TaNF-YB3;1 is highly homologous to its counterparts in various plant species.Under drought and exogenous ABA treatments,the transcript abundance of TaNF-YB3;1 was shown to be significantly upregulated in roots and leaves.The lines with TaNF-YB3;1 overexpression showed improved growth feature under drought conditions,displaying increased biomass,leaf water retention capacity,antioxidative enzyme activity and osmotic stress-induced substance.These results have shown that TaNF-YB3;1 acts as one critical regulator in mediating plant drought tolerance through the ABA-dependent pathway,which regulates the transcription of downstream stress defensive genes.