CaWRKY40, a WRKY protein of pepper, plays an important role in the regulation of tolerance to heat stress and resistance toRalstonia solanacearuminfection

• DOI: 10.1111/pce.12011
• Publication Date: 2012-09-20T13:03:08Z
• Authors: FENG‐FENG DANG; YU‐NA WANG; LU YU; THOMAS EULGEM; YAN LAI; ZHI‐QIN LIU; XU WANG; AI‐LIAN QIU; TING‐XIU ZHANG; JING LIN; YAN‐SHENG CHEN; DE‐YI GUAN; HAN‐YANG CAI; SHAO‐LIANG MOU; SHUI‐LIN HE
• Keywords: 2. Zero hunger; Cell Nucleus; 0301 basic medicine; Hot Temperature; Gene Expression; Cyclopentanes; Sequence Analysis, DNA; Ethylenes; Plants, Genetically Modified; Plant Leaves; 03 medical and health sciences; Plant Growth Regulators; Gene Expression Regulation, Plant; Seedlings; Onions; Ralstonia solanacearum; Oxylipins; Capsicum; Salicylic Acid; Disease Resistance; Plant Diseases; Plant Proteins; Signal Transduction

ABSTRACTWRKY proteins form a large family of plant transcription factors implicated in the modulation of numerous biological processes, such as growth, development and responses to various environmental stresses. However, the roles of the majority WRKY family members, especially in non‐model plants, remain poorly understood. We identifiedCaWRKY40from pepper. Transient expression in onion epidermal cells showed that CaWRKY40 can be targeted to nuclei and activates expression of a W‐box‐containing reporter gene.CaWRKY40transcripts are induced in pepper byRalstonia solanacearumand heat shock. To assess roles ofCaWRKY40in plant stress responses we performed gain‐ and loss‐of‐function experiments. Overexpression ofCaWRKY40enhanced resistance toR. solanacearumand tolerance to heat shock in tobacco. In contrast, silencing ofCaWRKY40enhanced susceptibility toR. solanacearumand impaired thermotolerance in pepper. Consistent with its role in multiple stress responses, we foundCaWRKY40transcripts to be induced by signalling mechanisms mediated by the stress hormones salicylic acid (SA), jasmonic acid (JA) and ethylene (ET). Overexpression ofCaWRKY40in tobacco modified the expression of hypersensitive response (HR)‐associated and pathogenesis‐related genes. Collectively, our results suggest thatCaWRKY40orthologs are regulated by SA, JA and ET signalling and coordinate responses toR. solanacearumattacks and heat stress in pepper and tobacco.