Distinguished Positive Reactions of Macrophomina phaseolina (Tassi) Goid Host Plants, Laboratory Media, and Potting soil

Abstract

Fourteen isolates of Macrophomina phaseolina (Tassi) Goid the causal of charcoal rot, were isolated from different hosts dominated at different locations in Egypt. Macromorphological features of isolates were compared by growing on different agar media at 28±2ºC. Colony appearance, growth rate, aerial mycelia, and production of sclerotia were assessed. Four isolates were scored as fast grow with cod No. M4, M9, M12, M15 and three as slow grow, i.e., M1, M2, M13. The best media for growth were Lima bean Agar (LBA), Czapek's Dox Agar (CZA), Potato Dextrose Agar (PDA), Corn Agar (CA), and potato-sucrose agar (PSA) respectively. The colony characteristic of color was of black dense, light black dense, light grey and dark brown. The best media for sclorotia formation were LBA and PDA media for the isolates M4, M7, M9, M11, M14, M15. Pathogenicity experiments showed that M. phaseolina isolates were able to cause root rot and hypocotyl discoloration of hosts. Three fungal isolates appeared to be less virulent i.e., M2, M3 and M8 whereas two isolates i.e., M11and M15 were scored, highly virulent or drastically virulent to beans, cantaloupe, tomato, cotton and sunflower plants. No relationship between the morphological characteristics and pathogenicity of the isolates. In addition, protein analysis assay of M. phaseolina revealed different numbers of separated bands (1-10) that protein profiling for isolates of M. phaseolina was not related to their virulence, host variety or location. In a greenhouse study, different soil types and bean were used for pathogenicity test of the fungus. Disease severity ranged from 21.3-44.0 %.