Pre-treatment of salicylic acid enhances resistance of soybean seedlings to Fusarium solani

Sudden death syndrome of soybean is largely caused by Fusarium solani (F. solani). Salicylic acid (SA) has been reported to induce resistance in plants against many pathogens. However, the effect of exogenous SA application on F. solani infection of soybean is less reported. This study investigated the effect of foliar application of SA on soybean seedlings before F. solani infection. Seedlings were sprayed with 200 mu M SA and inoculated with F. solani after 24 h of last SA application. After 3 days post-inoculation, seedlings treated with 200 mu M SA showed significantly fewer disease symptoms with increased endogenous SA level, SA marker genes expression and antioxidant activities in the SA-treated seedlings more than the untreated control seedlings. Furthermore, the decrease in hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels was observed in the SA-treated plants as compared to the untreated plants. Analysis of the effect of SA application on F. solani showed that the mycelia growth of F. solani was not affected by SA treatment. Further investigation in this study revealed a decreased in F. solani biomass content in the SA treated seedlings. Results from the present study show that pretreatment of 200 mu M SA can induce resistance of soybean seedlings against F. solani infection.