The meiotic recombination is a conserved process that leads to an exchange of parental genetic material during gametes formation and increases genetic diversity in organisms. This process is initiated by Spo11, an endonuclease that introduces meiotic double-strain-breaks (DSBs) that are repaired on the homologous chromatid.
Unfortunately, the frequency of meiotic recombination is not uniform in the genome creating genomic regions with very low frequency (“cold regions“). These cold regions are present in every eukaryotic organism and their size can be dramatically large in large genomes such in plants.
Because genetic exchanges in these cold regions are very rare, the selection of genetic traits in these regions can be very difficult if not impossible. In plant breeding the amplitude of the problem can be dramatic as large regions of the chromosomes almost never recombine.
SpiX technology modulates the process of homologous recombination in the genome by increasing its frequency in cold regions. By stimulating the process in regions of rare exchange, SpiX can unlock unexplored genetic diversity.
SpiX technology is a fusion protein constituted by two domains:
- Targeting domain
- Recombination domain
The initial work on the technology was done in yeast using GAL4-BD, the DNA binding domain of the transcription factor GAL4. We can now use more precise targeting systems such as Zinc-Fingers, TALE and Cas9.
The recombination domain is constituted by the endogenous Spo11 protein. When the targeting domain brings Spo11 to the site, the endonuclease introduces a double-strand-break and recruits other proteins that together constitute the natural machinery leading to the meiotic recombination.
Sarno et al. Programming sites of meiotic crossovers using Spo11 fusion proteins. Nucleic Acids Research. 2017 Aug 24.
Nicolas A. Modulating and targeting meiotic double-strand breaks in Saccharomyces cerevisiae. Methods Mol Biol. 2009;557:27-33. doi: 10.1007/978-1-59745-527-5_3.
Murakami et al. Locally, meiotic double-strand breaks targeted by Gal4BD-Spo11 occur at discrete sites with a sequence preference. Mol Cell Biol. 2009 Jul;29(13):3500-16. doi: 10.1128/MCB.00088-09.
Robine et al. Genome-wide redistribution of meiotic double-strand breaks in Saccharomyces cerevisiae. Mol Cell Biol. 2007 Mar;27(5):1868-80.
Peciña et al. Targeted stimulation of meiotic recombination. Cell. 2002 Oct 18;111(2):173-84.
Features of SpiX
- Targeting of meiotic recombination using the natural machinery of the organism
- Meiotic recombination is targeted efficiently in cold regions containing the sequence recognized by the targeting module
- SpiX can be used in a Spo11 +/+ background
- High flexibility of targeting (transcription factors, ZFs, TALEs, Cas9)
- Accelerate plant breeding (e.g. break linkage drag)
- Increase genetic diversity of germplasm
- Facilitate the isolation of genetic traits
We have collaborations to apply SpiX in rice, maize and wheat. In parallel, we improve the technology and develop new methods in model organisms such as Saccharomyces cerevisiae and Arabidopsis thaliana.