Talk:Apomixis

I think apomixis is used with all organisms, not just plants. Parthenogenesis also. Actually parthenogenesis and apogamy are types of apomixis!

While apomixis may also be used for other organisms, it is primarily used in reference to plants. While I cannot speak in regards to usage in other organisms, I do know a bit about its usage in botany.

Unfortunately, the wide-range of overlapping and redundant terminology, along with differences in usage between disciplines, has caused considerable confusion in many terms relating to asexual reproduction. However, in apomixis literature, parthenogenesis, defined as the development of an embryo in the absence of fertilization, is considered one of the required components of apomixis, and not a type thereof. By definition, apomixis, which in plants is defined as reproduction through seed in the absence of fertilization, requires parthenogenesis in all its forms. However, the apomictic process in plants is considered to require two other components, namely 1) absent or abnormal meiosis and 2) initiation of endosperm development, either through fertilization (called pseudogamy due to the fertilization only of the polar nuclei) or spontaneously.

In plants, such a distinction between apomixis and parthenogenesis is important, as some species are also capable of producing haploid offspring through seed - which occurs in the presence of meiosis alongside parthenogenesis. This is often also considered a form of apomixis. Unfortunately, such a consideration does not reconcile with the requirement that apomixis have absent or abnormal meiosis. This contradiction unfortunatley represents actual contradiction in the literature, largely divided between genetics/ecology subdisciplines. Regardless, parthenogenesis is required in apomixis, but is not a type thereof.

Depending on which source you choose to use, apogamy could refer either to asexual reproduction as a whole, to apomixis in particular, or to a subtype of apomixis (sporophytic apomixis/adventitious embryony). In reality, however, this term is not used in plant apomixis literature.

When I have more time, I will clean up this article, as much of the information currently does not reflect the terminology used for apomixis in plants, despite the current plant focus. Ultiam 04:00, 24 April 2007 (UTC)

Hi Ultiam!

I agree entirely, this article is a mess. It is such a mess that I don't feel that I have time to clean it up completely either, perhaps over the next few months. I've recently been working through the whole terminology tangle for an article (Talent, N. (2009). "Evolution of gametophytic apomixis in flowering plants: an alternative model from Maloid Rosaceae". Published online 5 Mar 2009 Theory in Biosciences. It was rather nice to see that the tangle is not just due to silliness, but due to the extreme difficulty of the subject. Winkler 1908 found that he had to replace the term apogamy with a new one (apomixis) because of confusion (apogamy is still used in ferns). We are having a similar problem now with "gametophytic apomixis" because the division between it and adventitious embryony is artificial ...

It's nice to find someone else who cares and understands this material! Nadiatalent (talk) 13:30, 13 April 2009 (UTC)

Please do clean up if you have time!

I found very very few google hits to terms like 'prickle pollination' (Gynogenesis, apparently), androgenesis, 'monohaploid' and 'double haploid' (currently trying to understand some potato breeding literature). I for one would really appreciate some work on these articles. You guys are the experts and its confusing for you! Think about people trying to learn this stuff from scratch! ;-) All the best, --Dan|^(talk) 13:38, 27 April 2009 (UTC)

Hi Dan,

I don't know about prickle pollination either, I suspect that it might be used for more than just gynogenesis, perhaps including parthenocarpy. Monohaploid would seem to be the product of halving a diploid (i.e. it is monoploid, and originated by haploidy), see the ploidy page under "polyhaploidy and dihaploidy". For Double haploid I've added a redirect to Doubled haploidy. See also the previously mentioned part of the ploidy page, some modern plant breeders have forgotten that good old terminology and use dihaploid instead, which is totally ambiguous. Over to you to suggest whether a redirect would be useful for monohaploid. Nadiatalent (talk) 13:10, 14 June 2009 (UTC)

In this paragraph, the sentence begining with "thus" is a non-sequitur. It does not follow logically from what cam before, as "thus" would imply.

In botany, apomixis was defined by Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization.[1] This definition notably does not mention meiosis. Thus "normal asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet, or replacement of the flower by bulbils are types of apomixis.

68.194.106.90 (talk) 19:19, 26 May 2011 (UTC)Comma Service