Advances in understanding the plant-Ralstonia solanacearum interactions: Unraveling the dynamics, mechanisms, and implications for crop disease resistance

Plant diseases caused by various pathogenic microorganisms can cause substantial reductions in agricultural crop yield and quality, resulting in significant economic losses and posing a threat to global food security. Understanding the mechanisms of plant - pathogen interactions is essential for developing genetic strategies to safeguard crops against disease. Ralstonia solanacearum, a soil-borne pathogen of significant importance, has emerged as a prominent model for studying plant-pathogenic bacteria due to its extensive genetic diversity, prolonged environmental persistence, unusually broad host range, and notably, its considerable impact on agriculture. To successfully invade and propagate in plants, R. solanacearum employs diverse extracellular pathogenic factors and intracellular type III effectors (T3Es) to evade or disrupt plant immunity. In response, plants have evolved dual-layered innate immune detection-and-response systems, represented by pattern-triggered immunity (PTI)—mediated by cell-surface pattern recognition receptors (PRRs)—and effector-triggered immunity (ETI)—mediated by intracellular nucleotide-binding and leucine-rich repeat receptors (NLRs). Over the past three decades, many factors contributing to the dynamic interactions between R. solanacearum and susceptible host plants have been identified. This comprehensive overview aims to summarize the current understanding of known R. solanacearum extracellular virulence factors and plant immunity suppressing T3E signaling pathways, as well as host plant PRRs and their target PAMPs (pathogen-associated molecular patterns), and plant NLR-mediated recognition of avirulent T3Es that govern plant host – R. solanacearum interactions. Additionally, we highlight current endeavors aimed at applying this knowledge to developing enhanced plant disease resistance tools, address prevailing challenges, and provide insights into future research perspectives.