Genomics Analysis and Roles of WRKY Transcription Factors in Grapevine

WRKY transcription factors (TFs) play significant roles in plant development and defense against biotic and abiotic stresses. Norton is a grape variety of Vitis aestivalis and exhibits higher levels of resistance to pathogens than grape varieties of Vitis vinifera. Understanding on WRKY TFs will help us interpret the resistance differences between Vitis aestivalis and Vitis vinifera. In this study, 52 WRKY TFs were found and annotated in the grapevine reference genome PN40024. Cis-elements in response to different stresses were identified by using binomial analysis. Three cis-elements were identified for grape\u27s response to abscisic acid (ABA) treatment, one for Grapevine leaf rollassociated virus-3 (GLRaV-3) infection and two unknown cis-elements for heptakis (2,6-di-O-methyl)-β-cyclodextrin (DIMEB) treatment and water deficit, respectively. Frequency of each cis-element in the promoter regions of WRKY was compared between Norton and PN40024. Transcript profiling of six selected WRKY genes (WRKY9, 13, 14,18, 20, 41) was analyzed by the quantitative polymerase chain reaction (qPCR). Transcript levels of six WRKY genes are higher in mature leaves than in young leaves. Three WRKY TFs were induced in Norton in responses to powdery mildew infection, while the other three were induced in Cabernet Sauvignon. A Yeast-One-Hybrid (Y1H) assay was also conducted to analyze the interaction between WRKY TFs and promoter of EDS1 in Norton and Cabernet Sauvignon. Results showed that unknown proteins in yeast may be able to activate the promoter of EDS1. Y1H results also suggest that WRKY TFs are able to compete with these unknown proteins on binding with promoter of EDS1