Allele-defined genome of the autopolyploid sugarcane Saccharum spontaneum L.
Аллельно-определённый геном автополиплоидного сахарного тростника Saccharum spontaneum L.
2018-10-08
SCID: 54.1/85c3xgdr
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allele-defined genomeautopolyploid sugarcanebalancing selectionchromosome rearrangementspseudo-chromosomes
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Abstract (AI)
Modern sugarcanes are polyploid interspecific hybrids, combining high sugar content from Saccharum officinarum with hardiness, disease resistance and ratooning of Saccharum spontaneum. Sequencing of a haploid S. spontaneum, AP85-441, facilitated the assembly of 32 pseudo-chromosomes comprising 8 homologous groups of 4 members each, bearing 35,525 genes with alleles defined. The reduction of basic chromosome number from 10 to 8 in S. spontaneum was caused by fissions of 2 ancestral chromosomes followed by translocations to 4 chromosomes. Surprisingly, 80% of nucleotide binding site-encoding genes associated with disease resistance are located in 4 rearranged chromosomes and 51% of those in rearranged regions. Resequencing of 64 S. spontaneum genomes identified balancing selection in rearranged regions, maintaining their diversity. Introgressed S. spontaneum chromosomes in modern sugarcanes are randomly distributed in AP85-441 genome, indicating random recombination among homologs in different S. spontaneum accessions. The allele-defined Saccharum genome offers new knowledge and resources to accelerate sugarcane improvement.
Key Findings
1
A haploid Saccharum spontaneum genome was assembled into 32 pseudo-chromosomes across eight homologous groups, containing 35,525 genes with defined alleles.
2
Disease-resistance nucleotide-binding-site genes are disproportionately concentrated in rearranged chromosomes, with 80% located in four chromosomes and 51% within rearranged regions.
3
Introgressed S. spontaneum chromosomes in modern sugarcanes are randomly distributed, indicating random recombination among homologs from different accessions; the allele-defined genome provides resources for crop improvement.
4
Resequencing 64 S. spontaneum genomes revealed balancing selection in rearranged regions, preserving their genetic diversity.
5
The reduction of S. spontaneum’s basic chromosome number from 10 to 8 resulted from ancestral chromosome fissions followed by translocations involving four chromosomes.
Research Object
the allele-defined genome of the autopolyploid sugarcane Saccharum spontaneum L., including its pseudo-chromosomes and rearranged genomic regions
Research Subject
genome structure, chromosome rearrangements, disease-resistance gene distribution, diversity under balancing selection, and recombination patterns among homologs and accessions
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2018-10-08
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