Improved methodology for the isolation of false smut pathogen Ustilaginoidea virens of rice

Abstract

Rice false smut is an emerging disease of rice caused by Ustilaginoidea virens (Cooke) Takashi. Along with yield loss, the pathogen affects the quality of the grains and produces mycotoxins also. Isolation of the pathogen is difficult due to its slow growing nature which often leads to the contamination. Hence, an improved methodology for the isolation was developed. For this, first the infected rice smut balls were taken and sterilized for 2 min in 1% (v/v) sodium hypochloride solution followed by washing three times (1 min each) with sterilized distilled water. Then, the smut balls were halved using a sterilized scalpel and spores from the inner surface of the ball were dusted onto the Petri plates containing ampicillin added potato sucrose agar (PSA). The plates were incubated at 27 °C ± 1 °C for 7 days after which white fungal colonies appeared were transferred in the PSA plates. The pathogen U. virens was further confirmed morphologically and through internal transcribed spacer (ITS) region amplification with 98–100% sequence homology. The developed methodology is comparatively faster with 80–85% success and will be helpful for the pathogen characterization, and understanding the biology of the pathogen.