Data from: Parasites and competitors suppress bacterial pathogen synergistically due to evolutionary trade-offs

Parasites and competitors are important for regulating pathogen densities and subsequent disease dynamics. It is, however, unclear to what extent this is driven by ecological and evolutionary processes. Here we used experimental evolution to study the eco-evolutionary feedbacks between Ralstonia solanacearum bacterial pathogen, Ralstonia-specific phage parasite and Bacillus amyloliquefaciens competitor bacterium in the laboratory and plant rhizosphere. We found that while the phage had a small effect on pathogen densities on its own, it considerably increased the R. solanacearum sensitivity to antibiotics produced by B. amyloliquefaciens. Instead of density effects, this synergy was due to phage-driven increase in phage resistance that led to trade-off with the resistance to B. amyloliquefaciens antibiotics. While no evidence was found for pathogen resistance evolution to B. amyloliquefaciens antibiotics, the fitness cost of adaptation (reduced growth) was highest when the pathogen had evolved in the presence of both parasite and competitor. Qualitatively similar patterns were found between laboratory and greenhouse experiments even though the evolution of phage resistance was considerably attenuated in the tomato rhizosphere. These results suggest that evolutionary trade-offs can impose strong constraints on disease dynamics and that combining phages and antibiotic-producing bacteria could be an efficient way to control agricultural pathogens.

寄生虫与竞争者对于调控病原菌密度及后续疾病动态具有关键作用。然而，目前尚不清楚该调控过程在多大程度上由生态与进化进程驱动。本研究采用实验进化方法，在实验室环境与植物根际中探究了青枯雷尔氏菌（Ralstonia solanacearum）病原菌、青枯雷尔氏菌专一性噬菌体（Ralstonia-specific phage）寄生菌与解淀粉芽孢杆菌（Bacillus amyloliquefaciens）竞争者之间的生态-进化反馈效应。研究发现，尽管噬菌体单独作用时仅对病原菌密度产生微弱影响，但其可显著提升青枯雷尔氏菌对解淀粉芽孢杆菌所产抗生素的敏感性。该协同效应并非通过密度调控实现，而是源于噬菌体诱导的噬菌体抗性增强，这一过程引发了与解淀粉芽孢杆菌抗生素抗性之间的适应性权衡。尽管未观测到病原菌进化出针对解淀粉芽孢杆菌抗生素的抗性，但当病原菌同时暴露于寄生菌与竞争者共存的环境时，其适应的适合度代价（生长速率降低）达到最高水平。实验室与温室实验的定性结果保持一致，尽管在番茄根际中噬菌体抗性的进化过程被显著削弱。本研究结果表明，进化权衡可对疾病动态施加极强的约束，而联合使用噬菌体与产抗生素细菌或可成为防控农业病原菌的高效策略。