High-resolution crossover mapping reveals similarities and differences of male and female recombination in maize

Penny M A Kianian,Anitha Sundararajan,Minghui Wang,Shahryar F Kianian,Joann Mudge,Yan He,Kristin Simons,Wojciech P Pawlowski,Qi Sun,Jaroslaw Pillardy,Stefanie Dukowic-Schulze,Changbin Chen,Farhad Ghavami

doi:10.1038/s41467-018-04562-5

Abstract

Meiotic crossovers (COs) are not uniformly distributed across the genome. Factors affecting this phenomenon are not well understood. Although many species exhibit large differences in CO numbers between sexes, sex-specific aspects of CO landscape are particularly poorly elucidated. Here, we conduct high-resolution CO mapping in maize. Our results show that CO numbers as well as their overall distribution are similar in male and female meioses. There are, nevertheless, dissimilarities at local scale. Male and female COs differ in their locations relative to transcription start sites in gene promoters and chromatin marks, including nucleosome occupancy and tri-methylation of lysine 4 of histone H3 (H3K4me3). Our data suggest that sex-specific factors not only affect male–female CO number disparities but also cause fine differences in CO positions. Differences between male and female CO landscapes indicate that recombination has distinct implications for population structure and gene evolution in male and in female meioses.

Highlights

Meiotic crossovers (COs) are not uniformly distributed across the genome
We found that the value of the correlation between male and female hotspots in the empirical population was not significantly different from these in resampled populations (P = 0.4970 according to the Z-test), indicating that the empirical value was representative statistically and that increasing the population size would have little effect on our conclusion
Arabidopsis[10,11,12,15], we found that over 90% of the 1165 COs were within 10 kbp of a gene, which represents a statistically significant enrichment compared to a random distribution (P = 9.201e−05 according to the Mann–Whitney–Wilcoxon test)

Summary

Introduction

Meiotic crossovers (COs) are not uniformly distributed across the genome. Factors affecting this phenomenon are not well understood. Many species exhibit large differences in CO numbers between sexes, sex-specific aspects of CO landscape are poorly elucidated. Our data suggest that sex-specific factors affect male–female CO number disparities and cause fine differences in CO positions. A lthough meiotic recombination is a key source of genetic variation, it does not affect the genome uniformly, as recombination events are unevenly distributed along chromosomes[1]. Factors affecting the location of recombination events are poorly understood. Meiotic recombination is initiated by formation of double-strand breaks (DSBs) in chromosomal

Methods

Results

Conclusion