IDENTIFICATION OF CYCLO(L-PRO-D-TYR) FROM BACILLUS AMYLOLIQUEFACIENS Y1 EXHIBITING ANTIFUNGAL ACTIVITY AGAINST FUSARIUM GRAMINEARUM TO CONTROL CROWN ROT IN WHEAT

In this study, evidence for antagonism of antifungal metabolites produced by Bacillus amyloliquefaciens Y1 was described, as they actively inhibit growth of Fusarium graminearum under in vitro and in vivo condition. The culture supernatant and crude butanol extract inhibit the mycelial growth of F. graminearum. In addition, an antifungal compound was purified from the metabolites of Y1 and identified as cyclo(L-Pro-D-Tyr) using H-1 and C-13 NMR spectroscopic analysis. For the first time, cyclo (L-Pro-D-Tyr) displayed potent antifungal activity against F. graminearum under in vitro condition. The hyphae of this fungal pathogen became deformed with cyclo(L-Pro-D-Tyr). Exposure of F. graminearum to various concentrations of cyclo(L-Pro-D-Tyr) on wheat seeds significantly inhibit fungal colonization. Furthermore, during in vivo wheat pot experiment, Y1 results in 27% higher total yield and showed a protective effect against F. graminearum by reducing low discoloration symptoms on stems. The grain yield per pot was five times higher compared to control pots (water only) infected with F. graminearum. To our knowledge, the antifungal activity of the cyclo(L-Pro-D-Tyr) is reported for the first time against the plant pathogenic fungus F. graminearum. The present study demonstrated the potential of B. amyloliquefaciens Y1 as a biocontrol agent against the wheat crown rot fungal pathogen as well as a plant growth promoter for wheat.