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

Advantages of meiosis
Some material was recently added that equates the increased production of sexual offspring in (one group of) facultative apomicts under stress conditions with meiosis as a DNA repair mechanism. I think that is quite a stretch. Any number of other mechanisms are possible, such as for example a less vigorous nucellus that isn't large enough for aposporous initials to arise, a genetic mechanism that is triggered in response to stress that has had an advantage through natural selection because sexually produced offspring have had better chances of survival in stressful (changing) conditions ... This is a much less well-understood phenomenon than the current text indicates, and I consider it quite misleading. I've also removed the statement about Boechera holboellii on the grounds that this species might be unusual in its behaviour; what would be needed here is a general survey of the behaviour of large numbers of apomictic species. Sminthopsis84 (talk) 00:49, 2 November 2012 (UTC)

inducing synthetic apomixis into food crops
I think we should add this section

proposals and research into creating genetically modified food plants that exhibit apomixis exist. The advantage of this over normal hybrids is that as clones, the daughter plants would be identical to the parent plants, which is not always true with commercial hybrid strains and hence the farmer needs to buy new seed from the company at every planting

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3747320/

"Box 4. Apomixis

One way to minimize the problems associated with gene flow is to introduce sterility, such that pollen cannot transmit information. Richard Jefferson has high hopes for an accessible, cheap way for farmers to produce genetically superior seeds, called apomixis.

But similar concepts have been floated before. The controversial terminator technology prevented gene flow, but it also outraged activists because it kept farmers from reusing seed.

Unlike terminator, apomixis is “germinator” technology—avoiding fertilization altogether by producing seeds without pollination. In effect, seeds can be natural clones of the mother, instead of a genetic exchange between mother and father. Therefore, hybrid quality can be maintained as farmers use seed year after year.

Although apomixis occurs naturally in about 400 plant species, Jefferson believes that it can be successfully developed as a useful trait in other crop plants. To ensure its widespread availability, Jefferson and collaborators pledged not to create restrictive patent rights that could block the development of apomixis."

http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.0000008

Vmaldia (talk) 16:05, 20 February 2014 (UTC)

Weird redirect
Why does "androgenetic" redirect to this page? That's just *weird*! Wahrmund (talk) 16:17, 28 January 2016 (UTC)
 * Hatnote added. A search of scholar.google.com indicates that the word when not paired with "alopecia" means male apomixis, so there is no way to build a disambiguation page for "androgenetic". Sminthopsis84 (talk) 15:37, 29 January 2016 (UTC)