The pathways of whole-genome duplications, diploidization, and descending dysploidy in the Biscutelleae (Brassicaceae)

HUANG, Yile. The pathways of whole-genome duplications, diploidization, and descending dysploidy in the Biscutelleae (Brassicaceae). In ANANI, Hussein, Terezie MALÍK MANDÁKOVÁ, Xinyi GUO, Manuel PORETTI, Christian PARISOD and Martin LYSÁK. Polyploidy 2023. 2023.

Basic information

• Original name: The pathways of whole-genome duplications, diploidization, and descending dysploidy in the Biscutelleae (Brassicaceae)
• Name (in English): The pathways of whole-genome duplications, diploidization, and descending dysploidy in the Biscutelleae (Brassicaceae)
• Authors: HUANG, Yile.
• Edition: Polyploidy 2023, 2023.

Other information

• Type of outcome: Conference abstract
• Confidentiality degree: is not subject to a state or trade secret

Abstract

In plants, whole-genome duplications (WGDs) are often characterized by genome-wide diploidization including descending dysploidy, i.e., chromosomal rearrangements that reduce chromosome number and genome size. However, the genomic basis and evolutionary significance of chromosomal restructuring remain poorly understood. Phylogenetic and comparative genomic analyses revealed that the Biscutelleae consist of one diploid (Megadenia), one neotetraploid (Heldreichia), and three mesotetraploid (Biscutella, Lunaria, and Ricotia) genera, with the ancestral tetraploid genomes arising from independent WGD events involving closely related diploid genomes. Here, we sequenced, analyzed and compared genomes of four Biscutella species (Buckler Mustards) differing by genome sizes (0.7 to 1.1 Gbp) and chromosome numbers (n = 6 and 8). Genome sequence data with long-range scaffolding combined with molecular cytogenetics provided accurate assemblies and annotations at the chromosome level. Highly reshuffled Biscutella genomes have descended from two ancPCK-like ancestral genomes via allopolyploidy followed by extensive descending dysploidy (n = 16 → n = 6 and 8). Such genome restructuring mediating descending dysploidies and speciation appeared to be predominantly non-random, with large chromosomal segments conserved as duplicates, while others exhibited considerable turnover. Our results provide new insights into the role of dysploid changes in plant genome evolution, speciation, and diversification.

Abstract (in English)

In plants, whole-genome duplications (WGDs) are often characterized by genome-wide diploidization including descending dysploidy, i.e., chromosomal rearrangements that reduce chromosome number and genome size. However, the genomic basis and evolutionary significance of chromosomal restructuring remain poorly understood. Phylogenetic and comparative genomic analyses revealed that the Biscutelleae consist of one diploid (Megadenia), one neotetraploid (Heldreichia), and three mesotetraploid (Biscutella, Lunaria, and Ricotia) genera, with the ancestral tetraploid genomes arising from independent WGD events involving closely related diploid genomes. Here, we sequenced, analyzed and compared genomes of four Biscutella species (Buckler Mustards) differing by genome sizes (0.7 to 1.1 Gbp) and chromosome numbers (n = 6 and 8). Genome sequence data with long-range scaffolding combined with molecular cytogenetics provided accurate assemblies and annotations at the chromosome level. Highly reshuffled Biscutella genomes have descended from two ancPCK-like ancestral genomes via allopolyploidy followed by extensive descending dysploidy (n = 16 → n = 6 and 8). Such genome restructuring mediating descending dysploidies and speciation appeared to be predominantly non-random, with large chromosomal segments conserved as duplicates, while others exhibited considerable turnover. Our results provide new insights into the role of dysploid changes in plant genome evolution, speciation, and diversification.