期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：42
DOI：10.1073/pnas.2025711118
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Plants’ adaptations to and divergence in arid deserts have long fascinated scientists and the general public. Here, we present a genomic analysis of two congeneric desert plant species that clarifies their evolutionary history and shows that their common ancestor arose from a hybrid polyploidization, which provided genomic foundations for their survival in deserts. The whole-genome duplication was followed by translocation-based rearrangements of the ancestral chromosomes. Rapid evolution of genes in these reshuffled chromosomes contributed greatly to the divergences of the two species in desert microhabitats during which gene flow was continuous. Our results provide insights into plant adaptation in the arid deserts and highlight the significance of polyploidy-driven chromosomal structural variations in species divergence.
Deserts exert strong selection pressures on plants, but the underlying genomic drivers of ecological adaptation and subsequent speciation remain largely unknown. Here, we generated de novo genome assemblies and conducted population genomic analyses of the psammophytic genus
Pugionium (Brassicaceae). Our results indicated that this bispecific genus had undergone an allopolyploid event, and the two parental genomes were derived from two ancestral lineages with different chromosome numbers and structures. The postpolyploid expansion of gene families related to abiotic stress responses and lignin biosynthesis facilitated environmental adaptations of the genus to desert habitats. Population genomic analyses of both species further revealed their recent divergence with continuous gene flow, and the most divergent regions were found to be centered on three highly structurally reshuffled chromosomes. Genes under selection in these regions, which were mainly located in one of the two subgenomes, contributed greatly to the interspecific divergence in microhabitat adaptation.
