Following the Formation of Synaptonemal Complex Formation in Wheat and Barley by High-Resolution Microscopy
Wheat and barley have large genomes of 15 Gb and 5.1 Gb, respectively, which is much larger than the human genome (3.3 Gb). The release of their respective genomes has been a tremendous advance the understanding of the genome organization and the ability for deeper functional analysis in particular meiosis. Meiosis is the cell division required during sexual reproduction. One major event of meiosis is called recombination, or the formation of crossing over, a tight link between homologous chromosomes, ensuring gene exchange and faithful chromosome segregation. Recombination is a major driver of genetic diversity but in these large genome crops, the vast majority of these events is constrained at the end of their chromosomes. It is estimated that in barley, about 30% of the genes are located within the poor recombining centromeric regions, making important traits, such as resistance to pest and disease for example, difficult to access. Increasing recombination in these crops has the potential to speed up breeding program and requires a good understand of the meiotic mechanism. However, most research on recombination in plant has been carried in Arabidopsis thaliana which despite many of the advantages it brings for plant research, has a small genome and more spread out of recombination compare to barley or wheat. Advance in microscopy and cytological procedures have emerged in the last few years, allowing to follow meiotic events in these crops. This protocol provides the steps required for cytological preparation of barley and wheat pollen mother cells for light microscopy, highlighting some of the differences between the two cereals.
Key words3D microscopy Barley Meiosis Synapsis Wheat
The research leading to these results has received funding from the European Community’s Seventh Framework Programme FP7/2007-2013 under grant agreement no. 222883 MeioSys and ERC advanced grant “Shuffle” (Project ID: 669182). Use of the OMX microscope was supported by the Euro-BioImaging PCS and through the MRC Next Generation Optical Microscopy Award (Ref: MR/K015869/1) and part of this work was performed in the frame of the Proof of Concept Studies (PCS) for the ESFRI research infrastructure project Euro-BioImaging at the PCS facility OMX (WTB Dundee). L.R. and R.W. were funded from the Scottish Government’s Rural and Environment Science and Analytical Services Division Work Program 5.2. B.D. was funded by INRA and Auvergne and his training at the James Hutton Institute was supported by a funding from INRA-DARESE (Direction de l’Action Régionale, de l’Enseignement Supérieur et de l’Europe) in the course of EIR-A (Ecole Internationale de Recherche d’Agreenium). S.M. was funded by Biotechnology and Biological Science Research Council EASTBIO PhD studentship program and M.A. was supported by the European Community’s Seventh Framework Programme FP7-PEOPLE-2013-ITN COMREC- 606956.
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