Cloning And Functional Analysis Of Stress Associated Protein Gene TaSAP17 From Wheat(Tricticum Aestivum L.)

Common wheat(Tricticum aestivum L.)is one of the most important food crops.It plays an important role in the food security.However,the global climate change and unreasonable irrigation lead to increasingly serious soil salinization.The growth and productivity of wheat and other crops were severely restricted by the severe soil salinization.Therefore,utilizing biotechnology explores wheat stress-tolerance gene resources and cultivating new wheat varieties are the important approaches to break the salinization restriction.As a kind of multigene family,stress associated protein(SAP)widely exists in the process responding to a variety of biotic and abiotic stresses.Presently,SAPs are poorly known in common wheat.Because SAPs play an important role in plants,we retrieved the SAP genes in wheat by Hidden Markov Model.We selected TaSAP17 as a target gene because it obviously responded to stresses by using real-time quantitative PCR analysis.The main results are as follows:1.A stress associated protein gene TaSAP17 was cloned.The putative TaSAP17 has two AN1 domain and two conserved C2H2 motifs,the specific structures of the SAP gene superfamily.Three copies of TaSAP17,originated from the A,B and D genomes,have the same gene structure,each containing two exons and one intron.The sequence similarities of three copies in cDNA and amino acid were as high as 98.35% and 99.03%,respectively.2.Expression pattern analysis showed that TaSAP17-D expressed in the different period of wheat growth and organization.The expression level of TaSAP17-D was the highest in seedling stage leaf and the lowest in stem internodes.TaSAP17-D could respond to the high salt,exogenous ABA,cold and PEG.Among them,the strongest response is to high salt stress.The expression levels of TaSAP17-D in salt-tolerant genotype ‘Taishan 23' were higher than that in salt-sensitive genotype ‘Nongda 20074' under salt-stress condition.Subcellular localization demonstrated that TaSAP17-D was present in the nucleus,cytoplasm and cell membrane.3.TaSAP17-D can enhance the salt tolerance of transgenic Arabidopsis,the survival rate,cell membrane stability,free proline content and SPAD value are higher than that of wild type(WT),osmotic potential and leaf water loss rate are lower than that of WT.4.TaSAP17-D has no transcriptional activation capability.Seven candidate proteins probably interacting with TaSAP17-D were identified via screening the yeast library constructed with the full-length cDNA of wheat.In conclusion,TaSAP17-D can enhance the salt tolerance of transgenic Arabidopsis.Therefore,it could be used as candidate gene to improve the tolerance to salt stress in crops.