Genomic evidence for supergene control of Darwin's 'complex marriage arrangement' - the tristylous floral polymorphism

Xue, H.; Gong, Y.; Wright, S. I.; Barrett, S. C. H.

doi:10.1101/2024.01.15.575583

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bioRxiv · 10.1101/2024.01.15.575583

Genomic evidence for supergene control of Darwin's 'complex marriage arrangement' - the tristylous floral polymorphism

Xue, H.·Gong, Y.·Wright, S. I.·Barrett, S. C. H.

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Abstract

Tristyly is a polymorphism characterized by three flower morphs with reciprocal stigma and anther heights controlled by two epistatically interacting diallelic loci (S and M), hypothesized to be supergenes. Chromosome-level genome assemblies of Eichhornia paniculata identified the S- and M-loci. The S-locus is a supergene consisting of two divergent alleles: The S-allele (2.51Mb) with three S-allele specific genes hemizygous in most S-morph plants and the s-allele (596kb) with five s-allele specific genes. Two of the S-allele specific genes, LAZY1-S and HRGP-S, were specifically expressed in styles and stamens, respectively, making them tristyly candidate genes. The M-locus contained one gene (LAZY1-M), homologous to LAZY1-S, that was present in the M-allele but absent from the m-allele. Estimates of allele ages are consistent with the prediction that the S-locus evolved before the M-locus. Re-use of the same gene family highlights the potential role of gene duplication in the evolution of epistatic multilocus polymorphisms.

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Xue, H., Gong, Y., Wright, S. I., Barrett, S. C. H.. 2024-01-17. Genomic evidence for supergene control of Darwin's 'complex marriage arrangement' - the tristylous floral polymorphism. https://doi.org/10.1101/2024.01.15.575583

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