7 public questions tagged with this topic.
In Basidiomycetes, karyogamy and meiosis occur in the basidium, usually producing four basidiospores. These spores are formed exogenously on the basidium, and the basidia are arranged in basidiocarps.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Fungi - Deuteromycetes and Economic Importance
Deuteromycetes contain fungi whose sexual stages are not known. Once the sexual stage is discovered, the fungus is transferred to the appropriate class. Production of basidiospores identifies the sexual form as a Basidiomycete.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Fungi - Phycomycetes Ascomycetes Basidiomycetes
Ascomycetes produce sexual ascospores endogenously inside sac-like asci. Basidiomycetes produce basidiospores exogenously on basidia. Both groups generally possess branched, septate mycelium.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Fungi - Phycomycetes Ascomycetes Basidiomycetes
Basidium constitutes characteristic meiosporangium of Basidiomycota, club-shaped dikaryotic cell within hymenium of gills, pores or other sporulating surfaces of mushrooms. After karyogamy, meiosis produces four haploid nuclei migrating onto sterigmata forming basidiospores externally above basidial surface. Ascus sac-like housing ascospores inside, sporangiophore supports sporangium in zygomycetes, conidiophore bears conidia asexual. Club shape maximizes spore exposure for forcible discharge using surface tension catapult mechanism called Buller's drop. Basidium morphology varies: holobasidia non-septate, phragmobasidia septate in rusts, but clavate shape conserved. Mitosome identification utilized immunofluorescence targeting iron sulfur cluster assembly proteins confirming mitochondrial evolutionary origin despite minimal proteome.
Ref: Campbell Biology 12th ed., Chapter 31: Basidium Club-Shaped Meiosporangium; NCERT Class 11 Basidiomycota Basidium; NCBI Basidium Structure
Basidiospores formation follows meiotic division within basidium after diploid nucleus formed via karyogamy. Meiosis I and II yield four haploid nuclei that migrate into sterigmata developing into basidiospores exogenously. Some species follow additional mitotic division to produce eight spores increasing output. Mitosis, binary fission and budding produce genetically identical clones without reduction, not characteristic here. Meiosis ensures genetic recombination, segregation of mating-type loci and reduction from transient diploid zygote to haploid dispersal propagules essential for Basidiomycota life cycle maintaining haploid-dominant dikaryotic mycelial phase after spore germination and dispersal.
Ref: Campbell Biology 12th ed., Chapter 31: Meiosis in Basidium Basidiospores; NCERT Class 11 Basidiospore Formation - Meiosis; NCBI Basidiosporogenesis
Basidiospores are sexual meiospores characteristic of Basidiomycota produced exogenously on club-shaped basidium functioning as meiosporangium. Following karyogamy and meiosis inside basidium, four haploid nuclei migrate into developing spore primordia on sterigmata at basidial apex. Basidium may be holobasidium non-septate or phragmobasidium septate in rusts. Ascus harbors ascospores inside, sporangium contains sporangiospores, conidiophore bears conidia asexually. Basidial position ensures forcible spore discharge via Buller's drop mechanism aiding wind dispersal from mushrooms, bracket fungi and puffballs efficiently. Detailed ascocarp development involves haploid mating, dikaryotic growth and eventual ascus formation within protective tissue layers regulating moisture.
Ref: Campbell Biology 12th ed., Chapter 31: Basidium Basidiospores Formation; NCERT Class 11 Basidiomycetes Reproduction; NCBI Basidiospore Development
Reproduction in Basidiomycetes is highly specific. After karyogamy and meiosis occur within the specialized club-shaped microscopic structure called the basidium, four haploid sexual spores are generated. The NCERT textbook distinctly specifies that these four 'basidiospores' are produced 'exogenously' (they bud outward and sit on the external surface of the basidium), unlike ascospores which are produced endogenously inside a sac.
Ref: NCERT Class 11 Biology > Chapter 2: Biological Classification > 2.3 Kingdom Fungi
