Effect of potato tuber greening on blackleg development by Dickeya solani and Pectobacterium brasiliense

Abstract

Potato (Solanum tuberosum) is a globally important crop, but its production is often threatened by pectinolytic bacteria of genus Pectobacterium and Dickeya, including Pectobacte­rium brasiliense (Pcb), and Dickeya solani (Ds), which cause two diseases, soft rot of potato tubers and blackleg of potato plants. These pathogens cause a reduction of potato yield, and significant yield losses due to tuber rot in storage. Currently, there are no effective chemical solutions to control these bacterial pathogens. This study aimed to investigate the effect of tuber greening, a process that significantly increases the content of glycoalkaloids (GAs), on the susceptibility of the potato cultivar Tajfun to infection by Pcb and Ds. Tubers were exposed to continuous artificial light for 2 weeks to induce greening. Control tubers were kept in the dark under the same environmental conditions. Then, tubers were infiltrated with Pcb and Ds under low pressure to ensure efficient bacterial penetration and planted in pots under controlled conditions. After 3 weeks phenotypic symptoms of bacterial in­fection such as wilting, overall plant vitality and stem necrosis were determined. Results showed a significant reduction in Ds infection in greened tubers compared to non-greened controls, supporting the hypothesis that greening which increases GAs levels, enhances resistance to bacterial pathogens. The response to Pcb was more variable, with some plants grown from greened tubers still exhibiting high levels of infection, suggesting that while greening may reduce susceptibility, the greater aggressiveness of Pcb may limit the pro­tective effects of greening. In conclusion, the present study showed that tuber greening could be an effective non-chemical method for controlling blackleg, particularly against Ds. However, the variable response to Pcb indicates that additional strategies are needed. Future research should focus on integrating GAs-based defenses with potato cultivars that exhibit stronger resistance to pectinolytic bacteria for improved management of blackleg.

Keywords

• bacterial pathogens
• glycoalkaloids
• pectinolytic bacteria
• plant protection
• resistance
• solanum tuberosum