Light, temperature, and aging dependent vegetative growth and sporulation of Colletotrichum gloeosporioides on different culture media

Abstract

The fungal organism Colletotrichum gloeosporioides is the causative agent of anthracnose disease of Citrus fruits. It is recently introduced as a potential producer of anticancer metabolite paclitaxel. Here, we introduce the optimal conditions for growth and sporulation of C. gloeosporioides. We have considered four fungal culture media, that is potato dextrose agar (PDA), carnation leaf agar (CLA), potato carrot agar (PCA) and water agar (WA), based on which sporulation inducers like Watman or Fabriano filter papers could be added, and evaluated both for vegetative growth and sporulation. Three light regimens, i.e. continuous light, 16/8 hrs light/darkness, and continuous darkness were applied in combination with the culture media. All experiments were tracked on 7th, 15th, 21st, and 30th day after incubation. At 28°C, PDA and PCA culture media, under continuous light, provided the best condition for C. gloeosporioides maximal growth. Decreasing light periods decreased the fungal growth. Furthermore, fungal sporulation showed a high dependence on light, temperature and culture medium in use. Under 16/8 h light/darkness interval at the same temperature C. gloeosporioides sporulation was at its maximum on Fabriano paper placed on PDA medium. At a lower temperature, that is 22°C, C. gloeosporioides sporulation on the same culture media was highly defected. Furthermore, aging generally increased the fungal sporulation. Key words: Colletotrichum gloeosporioides, citrus, growth, conidiation, development.