Bdellovibrio bacteriovorus as a biocontrol agent against blackleg disease in potatoes

Abstract

Blackleg disease is a condition that occurs in potatoes when bacteria such as Erwinia carotovora infect the tuber. The pathogenic bacteria enter the host plant through natural pores or wounds and cause the plant tissue to macerate, the foliage to wilt, and the stems to turn dark brown/black. Symptoms of blackleg disease commonly develop while in storage and at temperatures above 25 degrees Celsius. As much as 5% of the crop production in North-Western Europe may be lost annually due to blackleg disease (Sharga and Lyon 1998). A possible method for preventing blackleg disease may be implementing biocontrol agents such as predatory bacteria. Bdellovibrio bacteriovorus is a gram negative, uniflagellated, motile, and parasitic bacterium that preys on other gram negative bacteria. Extensive research has shown that B. bacteriovorus is effective in reducing pathogenic bacteria on the host. In this study, this predatory bacterium will be inserted into potatoes to prevent blackleg disease or reduce its symptoms; we hypothesize that B. bacteriovorus will prey on the bacterium that causes blackleg disease in potatoes, reducing disease severity. Potato slices were inoculated with treatments including pathogenic E. carotovora alone, the combination of E. carotovora and B. bacteriovorus, and control treatments. The zone width of maceration was measured daily for three days per trial and there was a total of seven trials in this study. There was a significant difference in the zone width of maceration between the potato slices inoculated with the pathogen and the potato slices inoculated with the pathogen and the predatory bacterium (p=0.005). This suggests that B. bacteriovorus may be an effective treatment for reducing blackleg disease severity caused by the pathogen E. carotovora.