Factors affecting germination and the mode of germination of zygospores of Choanephora cucurbitarum

Treatment of zygospores of Choanephora cucurbitarum with KMnO4, NaClO or H2O2 effectively activated the spores and induced their germination. The optimum concentration of KMnO4 for activation of zygospores was 0.25 to 0.5%. Zygospores were not able to germinate in darkness even after activation by KMnO4. When zygospores from 40 to 50‐day‐old cultures were treated with 0.5% KMnO4 solution for 60 min before incubation on water agar at 24% under light, about 50% germinated in 10 days. KMnO4 treatment killed more than 99% of residual mycelial fragments, sporangiospores and sporangiola in the zygospore suspension. During germination disappearance of oil droplets in zygospores occurred prior to the cracking on zygospore wall. Both sporangial germination and mycelial germination were found. Moreover, sporangiole germination was observed for the first time.