Factors affecting conidial germination of Colletotrichum gloeosporioides isolated from Polystigma rubrum subsp. rubrum stromata

Abstract

Factors associated with conidial germination and germ tube length of Colletrichum gloeosporioides, a Polystigma rubrum subsp. rubrum stromata mycoparasite, have been studied in vitro. Maximal germination was obtained at 20°C and pH ranging from 6-7. An incubation period of 3-8 prior to germination, depending on temperature, was required. Germination and germ tube length decreased when conidia were exposed to sunlight or if the concentration of conidia in suspension increased. There was poor germination (2.5% after 24 h) at high relative humidity (near 100%). Stromata fragments added into conidial suspension increased germination and germ tube length. Conidia discharged from acervuli on parasited stromata kept germination viability for more than 4 months, while germination of those placed on glass slides was negligible after 4 weeks.