A spontaneous mutation in MutL-Homolog 3 (HvMLH3) affects synapsis and crossover resolution in the barley desynaptic mutant des10

Authors Organisations
  • Isabelle Colas(Author)
    The James Hutton Institute
  • Malcolm Macaulay(Author)
    The James Hutton Institute
  • James D. Higgins(Author)
    University of Leicester
  • Dylan Phillips(Author)
  • Abdellah Barakate(Author)
    The James Hutton Institute
  • Markus Posch(Author)
    College of Life Sciences, Dundee
  • Susan J. Armstrong(Author)
    University of Birmingham
  • F. Chris H. Franklin(Author)
    University of Birmingham
  • Robbie Waugh(Author)
    The James Hutton Institute
  • Luke Ramsay(Author)
    The James Hutton Institute
Type Article
Original languageEnglish
Pages (from-to)693-707
Number of pages14
JournalNew Phytologist
Volume212
Issue number3
Early online date08 Jul 2016
DOI
Publication statusPublished - 13 Oct 2016
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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.

Keywords

  • MutL-Homolog 3 (MLH3), barley (Hordeum vulgare), crossover, meiosis, recombination, super resolution microscopy