GRP genes in potato genome and their expression response to phytohormone and Ralstonia solanacearum

Cell wall glycine‐rich proteins (GRPs) play important roles in plant growth and development, as well as in the effective prevention of plant diseases. Although members of the GRP family have been identified in several plants, a comprehensive analysis of GRPs has not been reported in Solanaceae plants. In this study, 43 GRPs were identified from Solanum tuberosum (named StGRPs), Solanum lycopersicum, Capsicum annuum and Nicotiana attenuata. The comparative study of these GRPs showed that they were conservative in physical properties, structures of genes and motifs. The expression patterns of Solanum tuberosum StGRPs under biotic and abiotic stress were analysed and presented very diverse profiles in responding to ABA, IAA, GA3, high salinity, pathogen and heat stress. Some StGRPs were preferentially and specifically expressed during the development of petioles and tubers, in which the expression of StGRPs was more sensitive to ABA confirmed by qRT‐PCR analysis. The strongly up‐regulated expression of StGRP1 induced by Ralstonia solanacearum indicated the positive role involved in the resistance against the bacterial wilt pathogen. Tissue localization analyses by Digoxin/fluorescence in situ hybridization indicated that the expression of StGRP1 was vascular‐specific and associated with cell wall thickening in vascular bundles and interfascicular fibres after R. solanacearum inoculation. These findings may provide a new insight into the roles of GRPs in adaptation to diverse stresses and in resistance to R. solanacearum in potatoes.