Abstract
BackgroundMeiosis is a specialized cell division that underpins sexual reproduction in most eukaryotes. During meiosis, interhomolog meiotic recombination facilitates accurate chromosome segregation and generates genetic diversity by shuffling parental alleles in the gametes. The frequency of meiotic recombination in Arabidopsis has a U-shaped curve in response to environmental temperature, and is dependent on the Type I, crossover (CO) interference-sensitive pathway. The mechanisms that modulate recombination frequency in response to temperature are not yet known.ResultsIn this study, we compare the transcriptomes of thermally-stressed meiotic-stage anthers from msh4 and mus81 mutants that mediate the Type I and Type II meiotic recombination pathways, respectively. We show that heat stress reduces the number of expressed genes regardless of genotype. In addition, msh4 mutants have a distinct gene expression pattern compared to mus81 and wild type controls. Interestingly, ASY1, which encodes a HORMA domain protein that is a component of meiotic chromosome axes, is up-regulated in wild type and mus81 but not in msh4. In addition, SDS the meiosis-specific cyclin-like gene, DMC1 the meiosis-specific recombinase, SYN1/REC8 the meiosis-specific cohesion complex component, and SWI1 which functions in meiotic sister chromatid cohesion are up-regulated in all three genotypes. We also characterize 51 novel, previously unannotated transcripts, and show that their promoter regions are associated with A-rich meiotic recombination hotspot motifs.ConclusionsOur transcriptomic analysis of msh4 and mus81 mutants enhances our understanding of how the Type I and Type II meiotic CO pathway respond to environmental temperature stress and might provide a strategy to manipulate recombination levels in plants.
Highlights
Meiosis is a specialized cell division that underpins sexual reproduction in most eukaryotes
Results mRNA-Seq characteristics of meiotic recombination pathway mutants Previous reports from our lab and others revealed that the increased meiotic crossover frequencies observed in Arabidopsis grown at elevated temperatures are mediated by the Type I interference sensitive pathway [2, 3]
To identify genes potentially involved in the hyperrecombinant phenotype, we collected stage 4–7 anthers that contain male meiocytes from leptotene to tetrad stage [14] from wild type (WT) (Col-0), mus81, and msh4 plants
Summary
Meiosis is a specialized cell division that underpins sexual reproduction in most eukaryotes. The frequency of meiotic recombination in Arabidopsis has a U-shaped curve in response to environmental temperature, and is dependent on the Type I, crossover (CO) interference-sensitive pathway. The mechanisms that modulate recombination frequency in response to temperature are not yet known. Meiosis consists of a pair of cell divisions that produce gametes in sexually reproducing species. Each pair of homologs must experience at least one exchange, or crossover (CO), in order to segregate properly at end of the first meiotic division. In the model plant Arabidopsis thaliana for example, meiotic recombination exhibits a U-shaped response curve corresponding to variation from low to high environmental temperatures [3]. Meiotic mechanisms begin to fail resulting in infertility [8, 9]
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