A simplified spore-drop technique for rapid isolation of rice blast pathogen Magnaporthe oryzae from the infected rice leaf

Single spore isolation from a diseased sample is an essential step in obtaining a pure culture of a fungal pathogen. Rice blast disease caused by Magnaporthe oryzae is an inferior saprophytic competitor, and therefore, many fast-growing fungal or bacterial contaminants are predominant during its isolation. For isolation of M. oryzae, several methods are being followed; however, they are complex and often lead to contamination. In the present study, we have standardized an efficient method for rapid isolation of M. oryzae from the blast disease infected rice-leaf using single spore isolation by spore-drop technique. Following the spore-drop technique, pure culture for an isolate of M. oryzae was obtained quickly with the least contamination (4%), whereas the conventional spore-dilution and leaf-press method recorded 26.12 and 45.50% contamination, respectively. The spore-drop approach has yielded the single spore isolates in the shortest time (10 days) and can be used for regular rice blast pathogen isolation. This method can also be used for other sporulating pathogens successfully.