Engineering bacteriocin-mediated resistance against plant pathogenic bacteria in plants

Abstract

ABSTRACTPseudomonas syringae(Ps) and related plant pathogenic bacteria are responsible for losses in diverse crops such as tomato, kiwifruit, pepper, olive and soybean. Current solutions, involving the use of chemicals and the introduction of resistance genes, have enjoyed only limited success and may have adverse environmental impacts. Consequently, there is a pressing need to develop alternative technologies to address the problem of bacterial disease in crops. An alternative strategy is to utilise the narrow spectrum protein antibiotics (bacteriocins) used by diverse bacteria for competition against closely related species. Here, we demonstrate that active putidacin L1 (PL1) can be expressed at high levelsin plantaand expression of PL1 provides effective resistance against diverse pathovars ofPs.Furthermore, we found that strains which evolve to become insensitive to PL1; lose their O-antigen, exhibit reduced motility and are less virulent in PL1 transgenic plants. Our results provide proof-of-principle that transgene-mediated expression of a bacteriocinin plantais an effective strategy for providing disease resistance against bacterial pathogens. Genetically modified (GM) crops expressing insecticidal proteins have proved extremely successful as a strategy for pest management; expressing bacteriocins to control bacterial disease may have a similar potential. Crucially, nearly all genera of bacteria, including many plant pathogenic species, produce bacteriocins, providing an extensive source of these antimicrobial agents.SIGNIFICANCEWith the global population to surpass 9 billion by 2050 there is a huge demand to make industrial farming as efficient as possible. A disadvantage of industrial farming is the lack of genetic diversity within crop monocultures, which make them highly susceptible to diseases caused by plant pathogenic bacteria likePseudomonas syringae. Bacteriocins are narrow spectrum protein antibiotics which are produced by all major bacterial lineages. Their main purpose is to eliminate competitor strains to establish dominance within a niche. By arming plants with bacteriocins we can increase the genetic toolbox used to engineer crops to be resistant to specific bacterial plant pathogens.