Genetic basis of tristyly in tetraploid<i>O</i><i>xalis alpina</i>(Oxalidaceae)

The floral polymorphism tristyly involves three style morphs with a reciprocal arrangement of stigma and anther heights governed by two diallelic loci (S and M). Tristyly functions to promote cross-pollination, but modifications to stamen position commonly cause transitions to selfing. Here, we integrate whole-genome sequencing and genetic mapping to investigate the genetic architecture of the M locus and the genetic basis of independent transitions to selfing in tristylous Eichhornia paniculata. We crossed independently derived semi-homostylous selfing variants of the long- and mid-styled morph fixed for alternate alleles at the M locus (ssmm and ssMM, respectively), and backcrossed the F to the parental ssmm genotype. We phenotyped and genotyped 462 backcross progeny using 1450 genotyping-by-sequencing (GBS) markers and performed composite interval mapping to identify quantitative trait loci (QTL) governing style-length and anther-height variation. A QTL associated with the primary style-morph differences (style length and anther height) mapped to linkage group 5 and spanned ~13-27.5 Mbp of assembled sequence. Bulk segregant analysis identified 334 genes containing SNPs potentially linked to the M locus. The stamen modifications characterizing each selfing variant were governed by loci on different linkage groups. Our results provide an important step towards identifying the M locus and demonstrate that transitions to selfing have originated by independent sets of mating-system modifier genes unlinked to the M locus, a pattern inconsistent with a recombinational origin of selfing variants at a putative supergene.

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“…; Weller et al . ) and Pontederiaceae (Gettys & Wofford ; S.C.H. Barrett & R. Arunkumar, unpublished data).…”

Section: Introductionmentioning

confidence: 97%

The genetic architecture of tristyly and its breakdown to self‐fertilization

et al. 2016

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“…Plants with at least one dominant S ‐allele are S‐morph and those that are homozygous recessive at this locus are either M‐morph ( ssMM , ssMm ) or L‐morph ( ssmm ). Several variations of this basic model of inheritance occur (reviewed in Barrett, ), including polysomic inheritance (Weller et al ., ), linked or unlinked loci, and apparent dominance reversals.…”

Section: Genetic Architecturementioning

confidence: 99%

‘A most complex marriage arrangement’: recent advances on heterostyly and unresolved questions

2019

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Summary Heterostylous genetic polymorphisms provide paradigmatic systems for investigating adaptation and natural selection. Populations are usually comprised of two (distyly) or three (tristyly) mating types, maintained by negative frequency‐dependent selection resulting from disassortative mating. Theory predicts this mating system should result in equal style‐morph ratios (isoplethy) at equilibrium. Here, I review recent advances on heterostyly, focusing on examples challenging stereotypical depictions of the polymorphism and unresolved questions. Comparative analyses indicate multiple origins of heterostyly, often within lineages. Ecological studies demonstrate that structural components of heterostyly are adaptations improving the proficiency of animal‐mediated cross‐pollination and reducing pollen wastage. Both neutral and selective processes cause deviations from isoplethy in heterostylous populations, and, under some ecological and demographic conditions, cause breakdown of the polymorphism, resulting in either the evolution of autogamy and mixed mating, or transitions to alternative outcrossing systems, including dioecy. Earlier ideas on the genetic architecture of the S‐locus supergene governing distyly have recently been overturned by discovery that the dominant S‐haplotype is a hemizygous region absent from the s‐haplotype. Ecological, phylogenetic and molecular genetic data have validated some features of theoretical models on the selection of the polymorphism. Although heterostyly is the best‐understood floral polymorphism in angiosperms, many unanswered questions remain.

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Generation of genomic resources and phylogenetic contributions in Oxalis from desert fog oases in Peru

Gaspar,

Song,

et al. 2024

J of Systematics Evolution

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Several species in the genus Oxalis occupy Peruvian fog oases (Lomas) with a significant habitat‐adapted and endemic diversity. Acknowledging this aspect, the genus Oxalis is a conceivable group for evolutionary and biogeographic hypothesis testing; however, molecular resources for the genus still need improvement. We conducted a genome skimming approach to assemble new plastomes from 18 accessions (six species) of Oxalis collected in Lomas locations in Peru. These complete plastomes of Oxalis species (several reported for the first time) present a highly conserved composition. Our phylogenetic results were congruent with previous section‐based backbone phylogenies of Oxalis; however, a closer look at the phylogeny of sect. Carnosae revealed nonmonophyletic arrangements involving Oxalis megalorrhiza and Oxalis bulbocastanum individuals. We also propose a set of three hypervariable plastid regions as potential molecular markers. Likewise, an array of primers for nuclear simple sequence repeat markers based on the most widely distributed species, O. megalorrhiza, were listed and evaluated for their transferability to the other species under examination. These new genomic resources represent a significant development for future population, phylogenetic, and biogeographic studies in Oxalis.

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Genetic basis of tristyly in tetraploidOxalis alpina(Oxalidaceae)

Cited by 3 publications

References 33 publications

The genetic architecture of tristyly and its breakdown to self‐fertilization

The genetic architecture of tristyly and its breakdown to self‐fertilization

‘A most complex marriage arrangement’: recent advances on heterostyly and unresolved questions

Generation of genomic resources and phylogenetic contributions in Oxalis from desert fog oases in Peru

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