SCIENCE AND AGRO STUDIES

Heterothallism:- > A. F. Blakeslee, an American Geneticist, in 1904 made an important observation with Mucor, which resulted in the discovery of Heterothallism. > Blakeslee observed, that while some isolates of Mucor formed sporangia as well as zygospores (e.g., M. tenuis), some others failed to form the zygospores and reproduced only by sporangiospores. > When he grew these non-sexually reproducing isolate with other similar isolates, zygospores appeared in the region where the hyphae of the different isolates came in contact with each other. > Blakeslee coined the terms homothallism and heterothallism to explain this phenomenon. The homothallic species were those that produced zygospores independently, while heterothallic species required the presence of the opposite mating type. > M. hiemalis, M. mucedo, Rhizopus nigricans are examples of heterothallic species. Since the two mating types were morphologically indistinguishable, Blakeslee designated them as the (+) and ...