Open AccessEvolution of the sex-determining region inGinkgo biloba
Author(s) -
Wei Gong,
Dmitry A. Filatov
Publication year - 2022
Publication title -
philosophical transactions - royal society. biological sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.753
H-Index - 272
eISSN - 1471-2970
pISSN - 0962-8436
DOI - 10.1098/rstb.2021.0229
Subject(s) - ginkgo biloba , biology , pseudoautosomal region , ginkgo , evolutionary biology , living fossil , indel , genetics , gene , dioecy , chromosome , genome , y chromosome , plant evolution , sex linkage , recombination , molecular evolution , transcriptome , ecology , single nucleotide polymorphism , paleontology , gene expression , pollen , genotype
Sex chromosomes or sex-determining regions (SDR) have been discovered in many dioecious plant species, including the iconic ‘living fossil'Ginkgo biloba , though the location and size of the SDR inG. biloba remain contradictory. Here we resolve these controversies and analyse the evolution of the SDR in this species. Based on transcriptome sequencing data from four genetic crosses we reconstruct male- and female-specific genetic maps and locate the SDR to the middle of chromosome 2. Integration of the genetic maps with the genome sequence reveals that recombination in and around the SDR is suppressed in a region of about 50 Mb in both males and females. However, occasional recombination does occur except a small, less than 5 Mb long region that does not recombine in males. Based on synonymous divergence between homologous X- and Y-linked genes in this region, we infer that theGinkgo SDR is fairly old—at least of Cretaceous origin. The analysis of substitution rates and gene expression reveals only slight Y-degeneration. These results are consistent with findings in other dioecious plants with homomorphic sex chromosomes, where the SDR is typically small and evolves in a region with pre-existing reduced recombination, surrounded by long actively recombining pseudoautosomal regions.This article is part of the theme issue ‘Sex determination and sex chromosome evolution in land plants’.