TaCML36, a wheat calmodulin-like protein, positively participates in an immune response to Rhizoctonia cerealis

Abstract

Sharp eyespot, mainly caused by the soil-borne fungus Rhizoctonia cerealis, affects wheat (Triticum aestivum L.) production worldwide. In this study, we isolated TaCML36 gene encoding a wheat calmodulin-like protein, and studied its defense role in protection against R. cerealis. Transcription of TaCML36 was significantly elevated by both R. cerealis infection and exogenous ethylene treatment. Transcription was higher in resistant wheat lines than in susceptible ones. There were copies of TaCML36 on chromosomes 5A, 5B, and 5D. The TaCML36 protein is composed of 183 amino acids and contains two calcium-binding EF-hand domains. Subcellular localization assays in wheat indicated that TaCML36 localizes in both the cytoplasm and nucleus. Virus-induced gene silencing and disease assessment indicated that compared to the controls, TaCML36-silenced wheat plants displayed significantly reduced resistance to R. cerealis and had greater fungal biomass, suggesting that knockdown of TaCML36 impaired host resistance. Knockdown of TaCML36 also significantly repressed expression of pathogenesis-related genes such as Chitinase 1, PDF35, and PR17C, the ethylene response factor-encoding gene TaPIE1, and ethylene biosynthesis gene ACO2. Collectively, our results suggest that TaCML36 positively participates in the innate immune response to R. cerealis infection by modulating expression of defense-associated genes possibly in the ethylene signaling pathway. Keywords: Calmodulin-like protein, Defense-associated gene, Ethylene signaling, Sharp eyespot, Triticum aestivum