Allopolyploidization from two dioecious ancestors leads to recurrent evolution of sex chromosomes and reversion to autosomes

ID: 613 / 431

Category: Abstract

Track: Pending

Proposed Symposium Title: Allopolyploidization from two dioecious ancestors leads to recurrent evolution of sex chromosomes and reversion to autosomes


Li He1,#,*, Yuàn Wang1,#, Yi Wang1,2, Ren-Gang Zhang3, Yuán Wang1, Elvira Hörandl4, Judith E. Mank5, Ray Ming6

Affiliations: 1Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, China 2Laboratory of Systematic Evolution and Biogeography of Woody Plants, School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, China 3Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China 4Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Göttingen, Germany 5Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada 6Centre for Genomics and Biotechnology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China *Corresponding Author: E-mail: #Contributed equally to this study.


Polyploidization presents an unusual challenge for species with sex chromosomes, as it can lead to complex combinations of sex chromosomes that disrupt reproductive development. This is particularly true for allopolyploidization between species with different sex chromosome systems. Here we assemble haplotype-resolved chromosome-level genomes of a female allotetraploid weeping willow (Salix babylonica) and a male diploid Salix dunnii using Hi-C and PacBio HiFi reads. We use phylogenomics of nuclear and plastid genomes to show that weeping willow arose from crosses between a female ancestor from the Salix clade, having XY sex chromosomes on chromosome 7, and a male ancestor from the Vetrix clade, having ancestral XY sex chromosomes on chromosome 15. Our analysis reveals that weeping willow has one pair sex chromosomes, ZW on chromosome 15, that derive from the ancestral XY sex chromosomes in the Vetrix-clade male ancestor. Moreover, the ancestral X chromosomes on chromosome 7 from the Salix-clade female ancestor have reverted to autosomal inheritance. Taken together, our results point to the rapid evolution and reversion of sex chromosomes following allopolyploidization in weeping willow.

Symposia selection: 14, ,

Key words: Degeneration, dioecy, inversion, polyploid, Salix, sex determination system