Systemic Resistance Induction of Tomato Plants against ToMV Virus by Surfactin Produced from Bacillus subtilis BMG02

Tomato mosaic virus (ToMV) is a major disease of tomato (Lycopersicon esculentum) which can strongly reduce tomato yields. Different efforts have been made to control tomato virus infection. Among these efforts is the use of cyclic lipopeptides. The surfactin produced by Bacillus subtilis BMG02 single overproducer strain strongly reduced (ToMV) virus symptoms and was responsible for the elicitation of Induced Systemic Resistance (ISR) in tomato. Treatment with 1000 mg surfactin used as critical antivirial concentration showed a strong symptoms reduction with complete negative ELISA results. The infected seedlings showed the ideal severe symptoms with fully positive ELISA reaction, while both healthy and infected seedlings treated with surfactin showed the same effect of strong symptoms reduction with complete negative ELISA results thus confirming the antivirial activities of surfactin. The hydrogen peroxide (H2O2), salicylic acid (SA) and jasmonic acid (JA) pathways have been proven to be involved in the tomato plant defense responses by surfactin treatment, whereas relative gene expression of phenylalanine ammonia lyase (PAL) and β 1,3- glucanase 2 (BGL2) involved in SA and JA pathways, respectively increased in treated seedlings compared to infected ones. The healthy seedlings showed very low H2O2 levels compared to infected tomato seedlings. Moreover, high levels of H2O2 were detected in treated seedlings with the same behaviour BGL2 and PAL expression levels due to the relationship between the ISR involved substrates.