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 plantmicrobe<br />interaction studies as well as an indicative model for anticancer drug discovery. The<br />present study introduces the optimal condition in which P. oryzae grows and sporulates best<br />on common culture media. We have considered three fungal culture media, i.e. PDA, PCA and<br />WA, based on which P. oryzae sporulation inducers like rice polish, rice extract or rice leaf<br />segments could be added, and evaluated both for vegetative growth and sporulation. Three<br />light regimens, i.e. continuous light, 16.8 hr light/darkness, and continuous darkness were<br />applied in combination with nine synthetic culture media. Mycelial growth was measured<br />after 11 days, but sporulation was tracked on the 10th, 20th, and 30th day after incubation at<br />26ºC. The findings indicate that PDA culture medium could provide the best medium for P.<br />oryzae vegetative growth, regardless of light condition. However, P. oryzae could sporulate<br />when light was provided either continuously or at intervals. A combination of 16.8 hr light/<br />darkness intervals and adding rice materials to culture media could induce P. oryzae for a<br />better sporulation. RPCA can be used as the best culture medium for P. oryzae in order to<br />obtain a high number of conidia under light alterations. Moreover, aging increases the total<br />number of conidia.