Briefly describe the life cycle of Rhizopus
Answers
Answer:
Rhizopus species have haploid mycelium composed of haploid, multinuclear, coenocytic hyphe. It reproduces both sexually and asexually. Life cycle is characteristic for Zygomycota and is represented in the picture below.
Sexual reproduction. When two compatible hyphe are met, growth of aerial hyphe called zygophores occurs (1). Zygophores grow towards each other and gametangia are formed at their tips (2). The two gametangia undergo plasmogamy which leads to the formation of zygote (3) which contains nuclei from both gametangia (therefore is heterokaryotic). Zygote is transformed into zygospore (also called zygosporangia) which is thick walled and helps survive harsh environmental conditions (4). In this characteristic structure, the karyogamy occurs which results in diploid nuclei (5). In favorable conditions, after meiosis, the zygospore germinates into sporangiophore which bears a sporangium. Sporangium contains numerous spores which germinate into mycelia (8). Some spores will germinate in matng type + and some in mating type - mycelium which are neccesary for the initiation of sexual process in heterothallic species. This is not the case in homothallic species, which are self-fertile.
During asexual reproduction (9), the sporangiophores with sporangia are formed directly from mycelium. All spores in these sporangia are genetically identical (sporangiospores).
Explanation:
The life cycle of rhizopus is described below :
Rhizopus can reproduce by both modes, that is, asexual as well as sexual.
Rhizopus have haploid and coenocytic hyphae. When two hyphae that are compatible meets, it results in the formation of two zygophores. Structures called gametangia are formed at the tips of each zygophores. The plasmogamy of 2 gametangia forms a zygote.
The zygote is then transformed into zygospore. The zygospore after meiosis germinates into sporangiophore which possess a sporangium.
The spores produced from the sporangium gets germinated and forms mycelia.