INBREEDING EFFECTS ON RESISTANCE AND TRANSMISSION-RELATED TRAITS IN THE<i>SILENE–MICROBOTRYUM</i>PATHOSYSTEM

Premise: Ex situ cultivation is important for plant conservation, but cultivation in small populations may result in genetic changes by drift, inbreeding, or unconscious selection. Repeated inbreeding potentially influences not only plant fitness, but also floral traits and interactions with pollinators, which has not yet been studied in an ex situ context. Methods: We studied the molecular genetic variation of Digitalis lutea from a botanic garden population cultivated for 30 years, a frozen seed bank conserving the original genetic structure, and two current wild populations including the source population. In a common garden, we studied the effects of experimental inbreeding and betweenpopulation crosses on performance, reproductive traits, and flower visitation of plants from the garden and a wild population. Results: Significant genetic differentiation was found between the garden population and the wild population from which the seeds had originally been gathered. After experimental selfing, inbreeding depression was only found for germination and leaf size of plants from the wild population, indicating a history of inbreeding in the smaller garden population. Moreover, garden plants flowered earlier and had floral traits related to selfing, whereas wild plants had traits related to attracting pollinators. Bumblebees visited more flowers of outbred than inbred plants and of wild than garden plants. Conclusions: Our case study suggests that high levels of inbreeding during ex situ cultivation can influence reproductive traits and thus interactions with pollinators. Together with the effects of genetic erosion and unconscious selection, these changes may affect the success of reintroductions into natural habitats.

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Quantitative disease resistance in wild Silene vulgaris to its endemic pathogen Microbotryum silenes‐inflatae

Hood,

Nelson,

Cho

et al. 2023

Ecology and Evolution

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The evolution of disease resistances is an expected feature of plant–pathogen systems, but whether the genetics of this trait most often produces qualitative or quantitative phenotypic variation is a significant gap in our understanding of natural populations. These two forms of resistance variation are often associated with differences in number of underlying loci, the specificities of host–pathogen coevolution, as well as contrasting mechanisms of preventing or slowing the infection process. Anther‐smut disease is a commonly studied model for disease of wild species, where infection has severe fitness impacts, and prior studies have suggested resistance variation in several host species. However, because the outcome of exposing the individual host to this pathogen is binary (healthy or diseased), resistance has been previously measured at the family level, as the proportion of siblings that become diseased. This leaves uncertain whether among‐family variation reflects contrasting ratios of segregating discrete phenotypes or continuous trait variation among individuals. In the host Silene vulgaris, plants were replicated by vegetative propagation in order to quantify the infection rates of the individual genotype with the endemic anther‐smut pathogen, Microbotryum silenes‐inflatae. The variance among field‐collected families for disease resistance was significant, while there was unimodal continuous variation in resistance among genotypes. Using crosses between genotypes within ranked resistance quartiles, the offspring infection rate was predicted by the parental resistance values. While the potential remains in this system for resistance genes having major effects, as there were suggestions of such qualitative resistance in a prior study, here the quantitative disease resistance to the endemic anther‐smut pathogen is indicated for S. vulgaris. The variation in natural populations and strong heritability of the trait, combined with severe fitness consequences of anther‐smut disease, suggests that resistance in these host populations is highly capable of responding to disease‐induced selection.

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INBREEDING EFFECTS ON RESISTANCE AND TRANSMISSION-RELATED TRAITS IN THESILENE–MICROBOTRYUMPATHOSYSTEM

Cited by 34 publications

References 41 publications

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References

Continuous inbreeding affects genetic variation, phenology, and reproductive strategy in ex situ cultivated Digitalis lutea

Quantitative disease resistance in wild Silene vulgaris to its endemic pathogen Microbotryum silenes‐inflatae

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