An investigation on the effects of photoperiod, aging and culture media onvegetative growth and sporulation of rice blast pathogen pyricularia oryzae

Abstract

Pyricularia oryzae (Tel. Magnaporthegrisea) is currently used as a fungal model for plantmicrobeinteraction studies as well as an indicative model for anticancer drug discovery. Thepresent study introduces the optimal condition in which P. oryzae grows and sporulates beston common culture media. We have considered three fungal culture media, i.e. PDA, PCA andWA, based on which P. oryzae sporulation inducers like rice polish, rice extract or rice leafsegments could be added, and evaluated both for vegetative growth and sporulation. Threelight regimens, i.e. continuous light, 16.8 hr light/darkness, and continuous darkness wereapplied in combination with nine synthetic culture media. Mycelial growth was measuredafter 11 days, but sporulation was tracked on the 10th, 20th, and 30th day after incubation at26oC. The findings indicate that PDA culture medium could provide the best medium for P.oryzae vegetative growth, regardless of light condition. However, P. oryzae could sporulatewhen light was provided either continuously or at intervals. A combination of 16.8 hr light/darkness intervals and adding rice materials to culture media could induce P. oryzae for abetter sporulation. RPCA can be used as the best culture medium for P. oryzae in order toobtain a high number of conidia under light alterations. Moreover, aging increases the totalnumber of conidia.