title: A spontaneous mutation in MutL-Homolog 3 (HvMLH3) affects synapsis and crossover resolution in the barley desynaptic mutant des10.
abstract: Although meiosis is evolutionarily conserved, many of the underlying mechanisms show species-specific differences. These are poorly understood in large genome plant species such as barley (Hordeum vulgare) where meiotic recombination is very heavily skewed to the ends of chromosomes. The characterization of mutant lines can help elucidate how recombination is controlled. We used a combination of genetic segregation analysis, cytogenetics, immunocytology and 3D imaging to genetically map and characterize the barley meiotic mutant DESYNAPTIC 10 (des10). We identified a spontaneous exonic deletion in the orthologue of MutL-Homolog 3 (HvMlh3) as the causal lesion. Compared with wild-type, des10 mutants exhibit reduced recombination and fewer chiasmata, resulting in the loss of obligate crossovers and leading to chromosome mis-segregation. Using 3D structured illumination microscopy (3D-SIM), we observed that normal synapsis progression was also disrupted in des10, a phenotype that was not evident with standard confocal microscopy and that has not been reported with Mlh3 knockout mutants in Arabidopsis. Our data provide new insights on the interplay between synapsis and recombination in barley and highlight the need for detailed studies of meiosis in nonmodel species. This study also confirms the importance of early stages of prophase I for the control of recombination in large genome cereals.
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Colas
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Macaulay
authors.affiliation: University of Leicester, Adrian Building, University Road, Leicester, LE1 7RH, UK.
authors.forename: James D
authors.initials: JD
authors.lastname: Higgins
authors.affiliation: Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, SY23 3DA, UK.
authors.forename: Dylan
authors.initials: D
authors.lastname: Phillips
authors.affiliation: Division of Plant Sciences, University of Dundee at The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Abdellah
authors.initials: A
authors.lastname: Barakate
authors.affiliation: Light Microscopy Facility, College of Life Sciences, Dundee, DD1 5EH, UK.
authors.forename: Markus
authors.initials: M
authors.lastname: Posch
authors.affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Armstrong
authors.affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: F Chris H
authors.initials: FC
authors.lastname: Franklin
authors.affiliation: Division of Plant Sciences, University of Dundee at The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Claire
authors.initials: C
authors.lastname: Halpin
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK. Robbie.Waugh@hutton.ac.uk.|Division of Plant Sciences, University of Dundee at The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK. Robbie.Waugh@hutton.ac.uk.
authors.forename: Robbie
authors.initials: R
authors.lastname: Waugh
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK. Luke.Ramsay@hutton.ac.uk.
authors.forename: Luke
authors.initials: L
authors.lastname: Ramsay
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D023902:Chromosome Pairing / Q000235:genetics*; D020090:Chromosome Segregation / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics; D003433:Crosses, Genetic; D003434:Crossing Over, Genetic; D053843:DNA Mismatch Repair / Q000235:genetics; D017343:Genes, Plant; D059765:Homologous Recombination / Q000235:genetics; D001467:Hordeum / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins
keywords: MutL-Homolog 3 (MLH3); barley (Hordeum vulgare); crossover; meiosis; recombination; super resolution microscopy