Biological control of potato common scab by plant-beneficial bacteria

Potato common scab in an important disease caused by several Streptomyces species that reduces potato tuber quality and market value. Management of common scab is difficult, and no conventional method can reliably control this disease. An alternative approach is the use of plant-beneficial bacteria as biocontrol agents, whose application in the field can significantly reduce common scab incidence and severity. This review begins with the description of the potato common scab disease, the diversity of scab-causing Streptomyces species and their phytotoxins and pathogenicity determinants. Then, we describe the diversity of bacterial strains successfully used to date to suppress potato common scab under controlled and field conditions, their biocontrol mechanisms and the factors influencing the biocontrol success. Finally, we discuss the use of phenazine-producing Pseudomonas spp. as biocontrol agents of potato common scab, an attractive approach supported by ten years of continuous research in our laboratory.