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Widespread coexistence of self-compatible and self-incompatible phenotypes in a diallelic self-incompatibility system in Ligustrum vulgare (Oleaceae)

Citation

De Cauwer, Isabelle et al. (2021), Widespread coexistence of self-compatible and self-incompatible phenotypes in a diallelic self-incompatibility system in Ligustrum vulgare (Oleaceae), Dryad, Dataset, https://doi.org/10.5061/dryad.pvmcvdnmb

Abstract

The breakdown of self-incompatibility (SI) in angiosperms is one of the most commonly observed evolutionary transitions. While multiple examples of SI breakdown have been documented in natural populations, there is strikingly little evidence of stable within-population polymorphism with both inbreeding (self-compatible) and outcrossing (self-incompatible) individuals. This absence of breeding system polymorphism corroborates theoretical expectations that predict that in/outbreeding polymorphism is possible only under very restricted conditions. However, theory also predicts that a diallelic sporophytic SI system should facilitate the maintenance of such polymorphism. We tested this prediction by studying the breeding system of Ligustrum vulgare L., an insect pollinated hermaphroditic species of the Oleaceae family. Using stigma tests with controlled pollination and paternity assignment of open-pollinated progenies, we confirmed the existence of two self-incompatibility groups in this species. We also demonstrated the occurrence of self-compatible individuals in different populations of Western Europe arising from a mutation affecting the functioning of the pollen component of SI. Our results show that the observed low frequency of self-compatible individuals in natural populations is compatible with theoretical predictions only if inbreeding depression is very high.

Methods

This dataset contains phenotypic and genotypic data collected in an experimental population of Ligutrum vulgare. The species has a rare mating system, a sporophytic diallelic self-incompatibility system (only two compatibility groups, named GA and GB can be observed in natura). This was confirmed using two approaches : (1) stigma tests, where stigmas collected on all individuals in the experimental population were tested with self-pollen, pollen from a GA tester genotype and pollen from a GB tester genotype and (2) paternity analysis on offspring produced by open-pollination in the experimental population.

Phenotypic data (i.e. results from stigma tests) was collected on 125 adult shrubs.

Genotypic data corresponds to multilocus nuclear microsatellite data, obtained for 125 adults and 1209 offspring from the experimental population (5 nuclear microsatellites).

Usage Notes

Column names and contents of the 3 sub-datasets are described below.

-> Sub-data-set 1 : Adult_Phenotypes.txt

ID : Name of the plant
Pop : Full name of the population of origin
Pop_ID : Identifier of the population of origin
Region : Region of the population of origin
Country : Country of the population of origin
Phenotype : Results of the stigma tests, with four possible outcomes (GA : incompatible from the GA group, GB : incompatible from the GB group, GA-SF : self-compatible from the GA group and NT : not tested)

-> Sub-data-set 2 : Adult_Genotypes.txt

ID : Name of the plant
Pop : Full name of the population of origin
Pop_ID : Identifier of the population of origin
Region : Region of the population of origin
Country : Country of the population of origin
Lv01 to Lv19 : diallelic genotypes for the five nuclear microsatellites that were used in the study - missing data is coded as "000"

-> Sub-data-set 3 : Offspring_Genotypes.txt

Offspring_ID : Name of the offspring
Mother_ID : Name of the mother plant (i.e. plant on which the offspring was collected)
Tissue : Type of tissue that was used for DNA extractions (either "Embryo" or "Leaf" tissue)
Lv01 to Lv19 : diallelic genotypes for the five nuclear microsatellites that were used in the study- missing data is coded as "000"