Bacterial canker disease is a major limiting factor in the growing of cherry and other Prunus species worldwide. At least five distinct clades within the bacterial species complex Pseudomonas syringae are known to be causal agents of the disease. The different pathogens commonly coexist in the field. Reducing canker is a challenging prospect as the efficacy of chemical controls and host resistance may vary against each of the diverse clades involved. Genomic analysis has revealed that the pathogens use a variable repertoire of virulence factors to cause the disease. Significantly, strains of P. syringae pv. syringae possess more genes for toxin biosynthesis and fewer encoding type III effector proteins. There is also a shared pool of key effector genes present on mobile elements such as plasmids and prophages that may have roles in virulence. By contrast, there is evidence that absence or truncation of certain effector genes, such as hopAB, is characteristic of cherry pathogens. Here we highlight how recent research, underpinned by the earlier epidemiological studies, is allowing significant progress in our understanding of the canker pathogens. This fundamental knowledge, combined with emerging insights into host genetics, provides the groundwork for development of precise control measures and informed approaches to breed for disease resistance.
Bibliographical noteFunding Information:
The authors acknowledge BBSRC for funding this work (BB/P006272/1). They also thank Penny Greeves for generating the disease cycle graphic in Figure?2. This review builds upon the extensive work that has been conducted by various research groups across the world on bacterial canker in the last century. Without prolonged study, diseases of perennial crops cannot be well characterized. The dedication of many researchers over the years to studying the epidemiology of these diseases provides the groundwork for genomic analyses today.
© 2020 The Authors. Plant Pathology published by John Wiley & Sons Ltd on behalf of British Society for Plant Pathology
ASJC Scopus subject areas
- Agronomy and Crop Science
- Plant Science