How Does Bread Mold Reproduce?

Bread mold reproduces asexually, using mitosis to form spores, and sexually. Sexual reproduction involves contact between opposite mating strains of the fungus to form a zygospore.

Bread mold, Rhizopus stolonifer, most often reproduces asexually. Reproduction begins soon after bread mold finds a suitable substrate and sends out its feeding structures, or hyphae, to absorb nutrients. The nourished fungus forms upright structures that contain the fungal spores. These spores are the product of mitosis and remain with the fungus until conditions are appropriate for their release; usually, the spores release when weather is warm and dry. The new spores now land on a new substrate, and the fungal life cycle continues.

Bread mold does not have opposite sexes as animals and some plants do, but it does have two mating strains. When the opposite strains grow near one another, special hormones cause them to touch. When they touch, the cytoplasms of their cells combine, and their nuclei meet and join together. The union of the nuclei cause the formation of a zygospore. This structure has a very thick cell wall and the ability to remain dormant; these features enable a zygospore to survive difficult conditions. When conditions are favorable, meiosis occurs within the zygospore to create spores for release by the fungus.