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Plants producing 2n gametes and clonal seeds

A group of researchers coordinated by Dr Raphael Mercier has characterized a set of meiotic genes whose inhibition results in the production of diplogametes and apomictic plants of interest for the seed industry.

Methods for obtaining plants producing 2n gametes and clonal seeds. © INRA
Updated on 12/08/2016
Published on 08/26/2013

2n gametes, also known as diplogametes, are gametes having the somatic chromosome number rather than the gametophytic chromosome number. They have been shown to be useful for the genetic improvement of several crops (e.g. potato). In particular, the production of diplogametes allows crosses between plants of different ploidy level, for instance crosses between tetraploid crop plants and their diploid wild relatives, in order to use their genetic diversity in plant breeding programs. Fertilization involving 2n gametes can be also used to produce synthetic vigorous tetraploid or triploid individuals, whose sterility is a suited character in some species (e.g. seedless banana, watermelon, etc.). In addition, 2n gametes can be used to produce innovative powerful mapping populations (WO2006/094773). Clonal 2n gametes are also essential for apomixis, the clonal reproduction through seeds.

Researchers steered by Dr Raphael Mercier have discovered a gene implicated in the formation of 2n gametes in plants. They have found that inactivation of this gene results in the skipping of the second meiotic division. This generates diploid male and female spores, giving rise to viable diploid male and female gametes, which are SDR gametes (Second Division Restitution). This gene will be hereinafter designated OSD1, for Omission of Second Division (WO2010/079432; d’Erfurth et al., 2009).
The researchers have further found that by combining the inactivation of OSD1 with the inactivation of two other genes - one (SPO11-1) which encodes a protein necessary for efficient meiotic recombination in plants and whose inhibition eliminates recombination and pairing, and another (REC8) which encodes a protein necessary for the monopolar orientation of the kinetochores during meiosis and whose inhibition modifies the chromatid segregation - resulted in a genotype in which meiosis is totally replaced by mitosis without affecting subsequent sexual processes. This genotype will be called hereinafter MiMe for “Mitosis instead of Meiosis". This replacement of meiosis by mitosis results in apomeiotic gametes, retaining all the parent’s genetic information (WO2010/079432; d’Erfurth et al., 2009).

The apomeiotic gametes produced by the MiMe mutant can be used, in the same way as the SDR 2n gametes, for producing polyploid plants, or for crossing plants of different ploidy level. Most importantly, they are also of interest for the production of apomictic plants, i.e. plants which are able to form seeds that are genetic clones of the maternal parent (WO2012/075195; Marimuthu et al., 2011).
These results - obtained on the plant model Arabidopsis thaliana - and industrial applications are protected under two patent applications (WO2010/079432, WO2012/075195) with INRA Transfert entitled to grant licences for commercial applications to the plant breeding industry.

Contact(s)
Scientific contact(s):

  • Raphaël MERCIER UMR INRA-AgroParisTech, Institut Jean-Pierre Bourgin
Scientific leader, Inra transfert:
Claire NODET (+33 1 42 75 93 44)
Associated Division(s):
Plant Biology and Breeding, Science for Food and Bioproduct Engineering
Associated Centre(s):
Versailles-Grignon

References

  • d’Erfurth, I.,et al., (2009). Turning meiosis into mitosis. PLoS biology, 7(6), e1000124. doi:10.1371/journal.pbio.1000124
  • Marimuthu MP et al. (2011). Synthetic clonal reproduction through seeds. Science, 331(6019), 876. doi:10.1126/science.1199682
  • Crismani W, et al., (2012). Tinkering with meiosis. J. Exp. Bot. 2012 Nov 7. doi:10.1093/jxb/ers314