Editing Self-incompatibility (section)

===Cryptic self-incompatibility (CSI)===
'''Cryptic self-incompatibility (CSI)''' exists in a limited number of taxa (for example, there is evidence for CSI in ''[[Silene vulgaris]]'', [[Caryophyllaceae]]<ref>Glaettli, M. (2004). Mechanisms involved in the maintenance of inbreeding depression in gynodioecious Silene vulgaris (Caryophyllaceae): an experimental investigation. PhD dissertation, University of Lausanne.</ref>). In this mechanism, the simultaneous presence of cross and self pollen on the same stigma, results in higher seed set from cross pollen, relative to self pollen.<ref name="bateman">{{cite journal |doi=10.1038/hdy.1956.22 | vauthors = Bateman AJ |title=Cryptic self-incompatibility in the wallflower: ''Cheiranthus cheiri'' L |journal=Heredity |volume=10 |pages=257–261 |year=1956 |issue=2|doi-access=free }}</ref> However, as opposed to 'complete' or 'absolute' SI, in CSI, self-pollination without the presence of competing cross pollen, results in successive fertilization and seed set;<ref name="bateman"/> in this way, reproduction is assured, even in the absence of cross-pollination. CSI acts, at least in some species, at the stage of pollen tube elongation, and leads to faster elongation of cross pollen tubes, relative to self pollen tubes. The cellular and molecular mechanisms of CSI have not been described. {{cn|date=July 2024}}

The strength of a CSI response can be defined, as the ratio of crossed to selfed ovules, formed when equal amounts of cross and self pollen, are placed upon the stigma; in the taxa described up to this day, this ratio ranges between 3.2 and 11.5.<ref>{{cite journal | vauthors = Travers SE, Mazer SJ | title = The absence of cryptic self-incompatibility in Clarkia unguiculata (Onagraceae) | journal = American Journal of Botany | volume = 87 | issue = 2 | pages = 191–196 | date = February 2000 | pmid = 10675305 | doi = 10.2307/2656905 | name-list-style = amp | jstor = 2656905 }}</ref>