Molecular modeling and docking studies of phytoalexin(s) with pathogenic protein(s) as molecular targets for designing the derivatives with anti-fungal action on Alternaria spp. of Brassica

The present study used molecular modeling and docking based approaches to test some proteins viz, ABC transporter, Amr1, Betatubulin, Cutinase, Fusicoccadiene synthase and Glutathione transferase of Alternaria brassicicola as possible molecular target of phytoalexins during pathogenesis or defense response. Molecular Operating Environment (MOE) was used to predict 3D structures of above proteins which were subsequently docked with phytoalexins which included Camalexin, Brassilexin, Rutalexin and Spirobrassinin by Molegro Virtual Docker. The results of molecular docking of Spirobrassinin with the above targets showed greater affinity as revealed from binding energy in the range of -73.09 to -94.46 Kcal/mol. Accordingly five derivatives of Spirobrassinin were further designed and docked against each target proteins, so as to detect phytoalexin(s) having the antifungal potential. The molecular modeling and docking experiments identified two derivatives of Spirobrassinins, with binding energy in the range of 77.50 to -85.88 Kcal/mol respectively, which could be used for protection of Brassica plants against infection by Alternaria spp including Alternaria brassicicola and Alternaria brassicae, main pathogen of Alternaria blight in rapeseed mustard. Further studies and downstream validation would give way to use the above phytoalexin(s) as a substitute for hazardous fungicides to control plant diseases.