Sweetpotato (Ipomoea batatas) storage root breakdown in plant beds is regularly seen in commercial sweetpotato production and leads to decreased productivity of sprouts for field planting. Cultivar differences and abiotic factors such as soil temperature, soil moisture, and poor drainage may drive physiological changes in storage roots. Biotic factors such as soilborne pathogens and endophytic bacteria and fungi may also play a role in the premature breakdown of bedding roots. Previous research has shown that Erwinia spp., Fusarium spp. and Sclerotium rolfsii have been implicated in root rots and wilting of the sprouts.
In Australia and Papua New Guinea, it is unclear which of these microorganisms are associated with or cause the breakdown of sweetpotato storages roots. In Bundaberg, QLD, we collected sweetpotato storage roots and sprouts from healthy and diseased plants across three farms, representing a total of seven cultivars (Beauregard, Bellevue, Bonita, Eclipse, Orleans, Murasaki, and Northern Star).
Plant specimens were sub-sampled, sectioned, and plated onto growth media. Pure cultures were obtained and have been frozen for future DNA extraction, PCR, and sequencing, to identify cultures to species level. Representative fungi and bacteria will be examined for their role in storage root breakdown, by conducting a pathogenicity test confirming Koch's postulates in the glasshouse.
Understanding what microorganisms are present in the storage roots has implications for both plant disease management and biosecurity. This study aims to create a better understanding of plant pathogens that may impact sweetpotato production both in Australia and PNG, minimise yield losses associated with plant disease in the plant beds.
For more information, please email the Graduate Research School or phone on 0746 31 1088.