Functional Analysis Of Salt-responsive Gene TaERF5in Wheat

Global demand for food is facing unprecedented challenges. Food production will need to increase38%by2025if the current global food supply is to be maintained. There is an urgent need to reusedegraded lands, in addition to increasing the area of land under cultivation. However, an estimated15%of the total land area of the world has been degraded by soil salinization and erosion. Hence, for solvingsuch problems, issues of knowing the mechanism of plant stress response, enhancing productivity byreusing degraded lands become important.In this study, we identified a salt-responsive gene TaERF5. Linkage mapping and associate analysiswere employed to explore the relationship between TaERF5and important agronomic traits; possiblefunctions of TaERF5were verified by investigating expression pattern under different abiotic stress andtransformation of rice. The main results as follows:1. One novel gene TaERF5was obtained from the wheat full-length cDNA library constructed by our labthrough homology analysis with other salt responsive genes, then orthologous gene TaERF5-A,TaERF5-B, TaERF5-D from A, B and D genomes of Chinese Spring were cloned.2. TaERF5contained an AP2/ERF domain; it belonged to B4subgroup of ERF subfamily. To identify thesubcellular localization, TaERF5-GFP was transiently expressed in onion epidermis which showed thatTaERF5was localized in nuclei.3. TaERF5showed different expression patterns in tissues of root, stem and leaves. The expression levelwere: leave>root>stem; Expression of TaERF5can be induced by high salinity, osmotic stress, abscisicacid（ABA）, MeJA and ethylene（ET）; Under long-term salt treatment, TaERF5was up-regulated inroots of four wheat varieties except for that of CDH, in which, TaERF5exhibited a lower expressionlevel than control; All these have led to the hypothesis that TaERF5may participate in differentsignaling pathways that mediate biotic and abiotic stresses.4. Numerous haplotypes of TaERF5existed in di/polyploidy wheat. There were10haplotypes forTaERF5-A;3SNP and1InDel made TaERF5-B two haplotypes;2SNP formed3haplotypes ofTaERF5-D. Phylogenetic tree showed the three homologs of TaERF5quite different. Evolutionrelationship among haplotypes within each subgenome was also presented.5.‘Chinese Spring’ nulli-tetrasomic lines and linkage genetic population were employed to ascertain thechromosomal location of TaERF5. Result showed that TaERF5-B was located on wheat chromosome2B,between markers Xwmc223and Xgwm388with the genetic distance of3.8cM and5.7cM, respectively.Genes or QTL conferring traits of grain weight, heading date and disease resistant reported previously inthis genetic region.6. The association analysis showed TaERF5-B significant related to the tiller number, plant height, headingdate, mature date and thousand grain weight. Contribution of haplotypes to phenotypes differedsignificantly（p<0.01）. In contrast to B_Hap I, the B_Hap II plants manifested as less tiller, reducedplant height, higher thousand grain weight and shorter growth period. These results showed thatTaERF5-B was a pleiotropic gene and played important roles in different processes involved in wheat development.7. TaERF5-B was introduced into rice variety Nipponbare（Oryza sativa L. ssp. Japonica）by usingAgrobacterium tumefaciens-mediated trasnformation. Functional analysis indicated TaERF5-B wasinvolved in salt-responsive.