Transmission ratio distortion is frequent in Arabidopsis thaliana controlled crosses

Danelle K Seymour,Detlef Weigel,Burak I Arioz,Daniel Koenig,Eunyoung Chae

doi:10.1038/s41437-018-0107-9

Abstract

The equal probability of transmission of alleles from either parent during sexual reproduction is a central tenet of genetics and evolutionary biology. Yet, there are many cases where this rule is violated. The preferential transmission of alleles or genotypes is termed transmission ratio distortion (TRD). Examples of TRD have been identified in many species, implying that they are universal, but the resolution of species-wide studies of TRD are limited. We have performed a species-wide screen for TRD in over 500 segregating F2 populations of Arabidopsis thaliana using pooled reduced-representation genome sequencing. TRD was evident in up to a quarter of surveyed populations. Most populations exhibited distortion at only one genomic region, with some regions being repeatedly affected in multiple populations. Our results begin to elucidate the species-level architecture of biased transmission of genetic material in A. thaliana, and serve as a springboard for future studies into the biological basis of TRD in this species.

Highlights

At the genetic level, evolution is the change in the frequency of allelic variants in a population over time, which can be caused by several different evolutionary forces, including selection
Intercrossing was facilitated by induced male sterility which was achieved by artificial miRNA mediated knock-down of the floral homeotic gene APETALA3 (AP3) (Chae et al 2014)
The incidence of transmission ratio distortion (TRD) was surveyed in 583 F2 populations generated from naturally inbred accessions that represent much of the Eurasian genetic diversity in A. thaliana (Cao et al 2011)

Summary

Introduction

Evolution is the change in the frequency of allelic variants in a population over time, which can be caused by several different evolutionary forces, including selection. While in many cases the strength of selection is too low for these changes to be detected within a few generations, a unique opportunity to directly study such changes is offered in cases where selection coefficients are high. In such a situation, competition between alleles can be seen already in the distribution of heterozygous progeny (a/ A). Deviation from this ratio has important implications for population dynamics. Because TRD arises from the biased segregation of alleles, it has been suggested that TRD may be a major contributor to the formation of reproductive barriers (Frank 1991; Hurst and Pomiankowski 1991; Orr and Irving 2005)

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Results

Conclusion