Comparative analysis on root exudate and rhizosphere soil bacterial assembly between tomatoes and peppers infected by Ralstonia

Abstract

Background: The rhizosphere environment regulated by root secretory activity and rhizosphere microbial interactions plays an essential role in resisting soil-borne diseases, while the host species is an important factor that affects the composition of root exudates and rhizosphere microbiomes. However, few studies have been done on the characteristics of root exudates and bacterial communities in terms of composition, diversity, and functional potential when host plants of different species are subjected to the same disease. Results: In this study, we examined the rhizosphere soil bacteria and root exudates of both healthy and diseased tomatoes and peppers employing metabolomics and amplicon techniques. Our findings indicated that variations existed in both root exudates and the bacterial community among different host species and health states. The diversities of both rhizosphere metabolites and bacterial communities were significantly reduced in different diseased plants. Although pepper and tomato resisted the invasion of Ralstonia by recruiting different potentially beneficial bacteria, their rhizosphere bacterial communities had the same functional potential. In comparison to diseased rhizosphere soil, healthy rhizosphere soil had many more functional pathways associated with disease suppression and plant growth. Conclusions: This study highlighted the crucial role of host plants in shaping the rhizosphere environment and revealed the variation characteristics of root exudates and rhizosphere bacteria of different host plants induced by the same disease. Graphical Abstract: (Figure presented.)