Lecture Notes: Zygomycota - Conjugating Fungi

Introduction

• Zygomycota: One of the five major fungal phyla.
• Common member: Rhizopus stolonifera (bread mold).
  • Grows on bread, fruits, vegetables.
  • Example: Strawberries and bread mold demonstration.

Characteristics of Zygomycota

• Saprotrophic: Live off decaying organic matter.
  • Example: Bread mold as dead organic matter.
• Opportunistic pathogens: Rarely cause diseases in humans and animals.
• Coenocytic Hyphae:
  • Lack septa; long strands with nuclei and organelles floating.
  • Haploid nuclei: One copy of each chromosome.

Reproduction in Zygomycota

Asexual Reproduction

• Occurs in favorable conditions (nutrients, temperature).
• Involves formation of sporangiofor:
  • Forms sporangium with hundreds of sporangiospores.
  • Sporangium ruptures, spores dispersed by air currents.
• Cycle: Spores land on substrate, germinate, form coenocytic hyphae, repeat.

Sexual Reproduction

• Occurs in unfavorable conditions.
• Involves opposing mating strains (+ and - strains).
  • Formation of zygosporangia:
    • Thick-walled structure with zygospores.
    • Can withstand adverse conditions, remain dormant.
• Stages:
  1. Plasmodomy: Fusion of haploid nuclei from + and - strains.
  2. Karyogamy: Nuclei fuse to form diploid nucleus.
  3. Meiosis: Diploid undergoes meiosis, forms zygospore.
  4. Germination: Haploid hyphae form, sporangiospores produced.

Key Terms

• Saprotrophic/Saprophytic: Feeding on decaying organic matter.
• Coenocytic: Hyphae without septa.
• Haploid/Diploid: Number of chromosome sets.
• Sporangiofor/Sporangium/Sporangiospores: Structures involved in asexual reproduction.
• Zygosporangia/Zygospore: Structures involved in sexual reproduction.
• Plasmodomy/Karyogamy: Processes of nuclear fusion.

Conclusion

• Overview of Zygomycota's reproductive methods.
• Encouragement to review and be familiar with the associated terms.