Genome Wide Identification Of Foxtail Millet WRKY Genes And Functional Characterization Of Gene SiWRKY89

Drought is one of the major abiotic stress factors influencing crop production.Foxtail millet(Setaria italica)has many advantages such as drought resistance and barren tolerance,which is an excellent germplasm to investigate drought-resistant genes.WRKY transcription factors are known to play key roles in plant defense against various abiotic stresses.In this study,a genome wide identification of foxtail millet WRKY genes was performed and the function of gene SiWRKY89 was analyzed through phenotypic analysis of SiWRKY89 transgenic Arabidopsis against drought stress.The main results are as following:1.The current study identified 103 WRKY transcription factor-encoding genes in the S.italica genome.The genes were named SiWRKY1 to SiWRKY103 according to their order on the chromosomes.A comprehensive expression analysis of SiWRKY genes among four different tissues was performed using publicly available RNA sequencing data.A total of 32 SiWRKY genes were more highly expressed in root tissue than in other tissues.2.The subcellular localization of SiWRKY89 protein was observed in the nucleus.The promoter region of SiWRKY89 gene included cis-acting elements,such as ABRE、ARE、MBS、WUN-motif、Aux RR-core,which possibly participate in abiotic stress response.The expression of SiWRKY89 was found in roots,leaves,stems and flowers.The expression of SiWRKY89 was induced by 20% PEG6000,15μMABA and150 m M Na Cl.Phenotypic analysis of SiWRKY89 transgenic Arabidopsis against drought stress showed that root length in transgenic plants were higher than those in WT.The transgenic plants remained green when withdrawing water for one weeks,while the wild type plant died.Our results suggest that overexpression of SiWRKY89 improved the tolerance to drought stress in transgenic plants.3.The Illumina sequencing was used to isolate its target genes.The sequencing results showed that 481 genes were up-regulated and 635 genes were down-regulated.The expression of DREB1 and DREB2A was greatly increased and the W-box element was identified in their promoters.Our results suggest SiWRKY89 may play a role in transgenic Arabidopsis against drought stress by regulating the expression of DREB1 and DREB2A.