The fungi covered so far in this chapter have all been in the subdivision Agaricomycotina. These fungi follow some version of the life cycle in Figure \(\PageIndex{1}\) below.  PucciniomycotinaRust fungi are in the Pucciniomycotina. These fungi have complex life cycles that can have a variety of different spore stages that require different plant hosts. A macrocyclic life cycle (containing all of the five spore stages) of Puccinia gramminis is represented in Figure \(\PageIndex{2}\). UstilaginomycotinaSmut fungi are in the Ustilaginomycotina. These fungi often have a saptrotrophic phase where they form yeasts and a biotrophic phase during which they act as parasites. The life cycle of the corn smut fungus Ustilago maydis is shown in Figure \(\PageIndex{3}\). What is the life cycle of a Basidiomycete?Figure 8: Basidiomycete life cycle. The lifecycle of a basidiomycete has alternate generations with haploid and dikaryotic mycelia. Haploid primary mycelia fuse to form a dikaryotic secondary mycelium, which is the dominant stage of the life cycle, and produces the basidiocarp.
Which form within the Basidiomycota life cycle is diploid?The zygote is the only diploid stage in the life cycle. The zygote immediately undergoes meiosis to form four haploid nuclei, and the future basidiospores are formed as blown out structures, on the tips of sterigmata, of the basidium.
How are basidiospores formed in mushroom?In the basidium, nuclei of two different mating strains fuse (karyogamy), giving rise to a diploid zygote that then undergoes meiosis. The haploid nuclei migrate into four different chambers appended to the basidium, and then become basidiospores.
What is the relationship between a basidiocarp and a mycelium?Thus, each cell in this mycelium has two haploid nuclei, which will not fuse until formation of the basidium. Eventually, the secondary mycelium generates a basidiocarp , a fruiting body that protrudes from the ground—this is what we think of as a mushroom.
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Place the appropriate label in the correct location of the basidiomycetes reproductive cycle.
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