Editing Yeast (section)

== Reproduction ==
[[File:Yeast lifecycle.svg|thumb|right|250px|The yeast cell's life cycle: {{ordered list |Budding |Conjugation |Spore}}]]
{{See also|Mating of yeast}}
Yeasts, like all fungi, may have [[asexual reproduction|asexual]] and [[sexual reproduction|sexual]] reproductive cycles. The most common mode of vegetative growth in yeast is asexual reproduction by [[budding]],<ref name="Balasubramanian-2004"/> where a small bud (also known as a [[Bleb (cell biology)|bleb]] or daughter cell) is formed on the parent cell. The [[cell nucleus|nucleus]] of the parent cell splits into a daughter nucleus and migrates into the daughter cell. The bud then continues to grow until it separates from the parent cell, forming a new cell.<ref name="Yeong-2005"/> The daughter cell produced during the budding process is generally smaller than the mother cell. Some yeasts, including ''[[Schizosaccharomyces pombe]]'', reproduce by [[Fission (biology)|fission]] instead of budding,<ref name="Balasubramanian-2004"/> and thereby creating two identically sized daughter cells.

In general, under high-stress conditions such as [[nutrient]] starvation, [[haploid]] cells will die; under the same conditions, however, [[diploid]] cells can undergo sporulation, entering sexual reproduction ([[meiosis]]) and producing a variety of haploid [[spore]]s, which can go on to [[mating of yeast|mate]] (conjugate), reforming the diploid.<ref name="Neiman-2005"/>

The haploid fission yeast ''Schizosaccharomyces pombe'' is a facultative sexual microorganism that can undergo mating when nutrients are limited.<ref name="Hoffman-2015"/><ref name="Davey-1998"/> Exposure of ''S. pombe'' to hydrogen peroxide, an agent that causes oxidative stress leading to oxidative DNA damage, strongly induces mating and the formation of meiotic spores.<ref name="Bernstein-1989"/> The budding yeast ''Saccharomyces cerevisiae'' reproduces by mitosis as diploid cells when nutrients are abundant, but when starved, this yeast undergoes meiosis to form haploid spores.<ref name="Herskowitz-1988"/> Haploid cells may then reproduce asexually by mitosis. Katz Ezov et al.<ref name="Katz-2010"/> presented evidence that in natural ''S. cerevisiae'' populations clonal reproduction and selfing (in the form of intratetrad mating) predominate. In nature, the mating of haploid cells to form diploid cells is most often between members of the same clonal population and [[Outcrossing|out-crossing]] is uncommon.<ref name="Ruderfer-2006"/> Analysis of the ancestry of natural ''S. cerevisiae'' strains led to the conclusion that out-crossing occurs only about once every 50,000 cell divisions.<ref name="Ruderfer-2006"/> These observations suggest that the possible long-term benefits of outcrossing (e.g. generation of diversity) are likely to be insufficient for generally maintaining sex from one generation to the next.{{Citation needed|date=December 2019|reason=removal of citation referring to predatory publisher content}}  Rather, a short-term benefit, such as recombinational repair during meiosis,<ref name="Birdsell-2003">{{cite book|vauthors=Birdsell JA, Wills C |date=2003 |title=The evolutionary origin and maintenance of sexual recombination: A review of contemporary models |series=Evolutionary Biology Series >> Evolutionary Biology |volume=33 |pages=27–137 |veditors=MacIntyre RJ, Clegg MT |publisher=Springer |isbn=978-0306472619}}</ref> may be the key to the maintenance of sex in ''S. cerevisiae''.

Some [[Pucciniomycotina|pucciniomycete]] yeasts, in particular species of ''[[Sporidiobolus]]'' and ''[[Sporobolomyces]]'', produce aerially dispersed, asexual [[ballistospore|ballistoconidia]].<ref name="Bai-2002"/>