Tolerância a seca e resistência a murcha bacteriana (Ralstonia solanacearum): aspectos moleculares e fisiológicos em plantas hospedeiras

Abstract

Plants are sessile organisms and often face a wide range of abiotic and biotic stresses, including pathogens, pests and climate change. These factors can have a considerable impact on the productivity of plant species, particularly those of economic importance. In order to improve crop resistance to these stresses, it is essential to understand plant response strategies. Genes that encode transcription factors (TFs) participate directly in the regulation of environmental conditions and pathogen pressure. In this study, we investigated the molecular and biochemical interactions between the biotic stress response pathways of bacterial wilt (Ralstonia solanacearum) and the abiotic stress of water deficit, using tobacco and tomato plants. To understand whether TF MYB (NbPHAN gene) associated with drought tolerance in Nicotiana benthamiana would also influence bacterial wilt resistance, we used TRV (Tobacco rattle virus) vectors for gene silencing by VIGS (virus-induced post- transcriptional silencing), developing a pathosystem in tobacco plants. The results revealed correlations between the response pathways to these stresses, indicating complex interactions between biotic and abiotic stresses. The silencing of the NbPHAN gene in tobacco plants negatively affected bacterial wilt and drought resistance. Similarly, contrasting tomato genotypes for resistance to R. solanacearum were subjected to drought by treatment with polyethylene glycol (PEG) nutrient solution. Our data showed that water deficit reduced growth, photosynthetic activity and water-to-biomass conversion efficiency in both varieties. It was observed that the effects on rearrangement of root architecture, on biomass production and on photosynthetic characteristics were analogous to other pathosystems with use of resistant genotype. However, despite similarities in responses, no direct associations were found between bacterial wilt resistance and drought tolerance. These results highlight the complexity of interactions between abiotic and biotic stresses in plants and provide important insights for the development of crops that are more resistant to multiple stresses. Future studies in this sense are essential for a deeper understanding of these processes.