Apparent Epigenetic Meiotic Double-Strand-Break Disparity in Saccharomyces cerevisiae: A Meta-Analysis

Abstract

Previously published, and some unpublished, tetrad data from budding yeast (Saccharomyces cerevisiae) are analyzed for disparity in gene conversion, in which one allele is more often favored than the other (conversion disparity). One such disparity, characteristic of a bias in the frequencies of meiotic double-strand DNA breaks at the hotspot near the His4 locus, is found in diploids that undergo meiosis soon after their formation, but not in diploids that have been cloned and frozen. Altered meiotic DNA breakability associated with altered metabolism-related chromatin states has been previously reported. However, the above observations imply that such differing parental chromatin states can persist through at least one chromosome replication, and probably more, in a common environment. This conclusion may have implications for interpreting changes in allele frequencies in populations.

Molecular mechanisms for environmentally induced plasticity in the positioning of meiotic recombination at hotspots

“…Third, the poised epigenetic states provide a potential mechanism for the observation that prior environmental conditions can affect the frequency distribution of recombination in subsequent meiosis (27), although at present we cannot tell if the genetic imprinting that we observed extends over multiple, mitotic cell divisions.…”

“…Differences in parental mating type and the freezing of diploids each affect the activity of hotspots in subsequent meiosis, which suggests that there is epigenetic imprinting (21,27).…”

Diverse DNA Sequence Motifs Activate Meiotic Recombination Hotspots Through a Common Chromatin Remodeling Pathway

“…We also observed hotspot motif-dependent changes in chromatin structure, relative to the basal recombination control, prior to meiosis for all other DNA sequence-dependent hotspots (Figure 3 and Figure S1). We speculate that changes in such poised epigenetic states might contribute to the modulation of hotspot positioning or strength that are induced by differences in mating type (Parvanov et al 2008), auxotrophies and nutritional states (Abdullah and Borts 2001; Cotton et al 2009), temperature (Fan et al 1995; Zhang et al 2017), and prior freezing (Stahl et al 2016). The fact that transcription factors of fission yeast and budding yeast respond to such intracellular and environmental cues, and that they are rate-limiting for hotspot recombination at their DNA binding sites (there is a protein dose-dependent response) (White et al 1991; Kon et al 1997), supports this idea.…”

Exploring impact of recombination landscapes on breeding outcomes

“…It might be that presence of inter-parental DNA sequence polymorphism in DSB vicinity causes the DSB to be repaired as a CO rather than an NCO ( 17 ). Alternatively, the forming GCs might be repaired back to the state of the original DNA segment ( 18 ). Regardless of the mechanism, these observations imply that most of the meiotic recombination-generated genetic variation in plants comes from COs.…”