Differential Control Efficacies of Vitamin Treatments against Bacterial Wilt and Grey Mould Diseases in Tomato Plants

Abstract

Bacterial wilt and grey mould in tomato plants are economically destructive bacterial and fungal diseases caused by <i>Ralstonia solanacearum</i> and <i>Botrytis cinerea</i>, respectively. Various approaches including chemical and biological controls have been attempted to arrest the tomato diseases so far. In this study, <i>in vitro</i> growths of bacterial <i>R. solanacearum</i> and fungal <i>B. cinerea</i> were evaluated using four different vitamins including thiamine (vitamin B1), niacin (vitamin B3), pyridoxine (vitamin B6), and menadione (vitamin K3). <i>In planta</i> efficacies of the four vitamin treatments on tomato protection against both diseases were also demonstrated. All four vitamins showed different <i>in vitro</i> antibacterial activities against <i>R. solanacearum</i> in dose-dependent manners. However, treatment with 2 mM thiamine was only effective in reducing bacterial wilt of detached tomato leaves without phytotoxicity under lower disease pressure (10⁶ colony-forming unit [cfu]/ml). Treatment with the vitamins also differentially reduced <i>in vitro</i> conidial germination and mycelial growth of <i>B. cinerea</i>. The four vitamins slightly reduced the conidial germination, and thiamine, pyridoxine and menadione inhibited the mycelial growth of <i>B. cinerea</i>. Menadione began to drastically suppress the conidial germination and mycelial growth by 5 and 0.5 mM, respectively. Grey mould symptoms on the inoculated tomato leaves were significantly reduced by pyridoxine and menadione pretreatments one day prior to the fungal challenge inoculation. These findings suggest that disease-specific vitamin treatment will be integrated for eco-friendly management of tomato bacterial wilt and grey mould.