Petalomaniacs & Smuts & Polymorphism

Oxalis has some interesting peculiarities.
For fun we feature them here. Petalomaniacs and Polymorphisms and Smuts

Petalomaniacs

Doubles turn up every now and then. Most are complete and feature the petals, but occasionally plants do half a job.
If you see any Oxalis with multiple copies of the petals, Please add the entry "Petalomaniac" to the [Oxalis features] observation field.
See examples here:

Sorrel Smut

Partial petalomaniac here: https://www.inaturalist.org/observations/211454993

Polymorphism

Some species and populations have different colour morphs. In populations with different colours, please estimate or record the ratios and add it to the Colour Polymorphism project. (https://www.inaturalist.org/projects/colour-polymorphism-in-the-cape-flora)
See examples here:

Sorrel Smut

Sorrel Smut Thecaphora capensis

Sorrel Smut is a fungus that attacks the anthers, rendering the plant pollen sterile. This is essentially a plant Sexually Transmitted Disease that replaces the plant pollen with its fungal spores.
It can easily be seen by creating a "dark" tube to the flower. Careful inspection can also reveal the pollen dust on the petals. Watch out for it please, and if seen, please remember to duplicate the observation to record the fungus, and to add the interaction.
Originally thought to only infect one Oxalis species, we now know it from many more.

Sorrel Smut

Publicado el 21 de mayo de 2024 por

tonyrebelo

Comentarios

? https://www.inaturalist.org/observations/174651076
? https://www.inaturalist.org/observations/158097858
? https://www.inaturalist.org/observations/141142736
? https://www.inaturalist.org/observations/69829411
? https://www.inaturalist.org/observations/11180937
? https://www.inaturalist.org/observations/11012840

Publicado por tonyrebelo hace 4 meses

Thecaphora capensis sp. nov., an unusual new anther smut on Oxalis in South Africa
F Roets, L L Dreyer, M J Wingfield, D Begerow 2008
PMID: 20396584 PMCID: PMC2846123 DOI: 10.3767/003158508X387462

Abstract
The smut genus Thecaphora contains plant parasitic microfungi that typically infect very specific plant organs. In this study, we describe a new species of Thecaphora from Oxalis lanata var. rosea (Oxalidaceae) in the Cape Floristic Region of South Africa. Molecular phylogenetic reconstructions based on large subunit ribosomal DNA sequence data confirmed the generic placement of the fungus and confirmed that it represents an undescribed species for which the name T. capensis sp. nov. is provided. The closest known sister species of the new taxon is T. oxalidis that infects the fruits of Oxalis spp. in Europe, Asia and the Americas. In contrast, T. capensis produces teliospores within the anthers of its host. This is the first documented case of an anther-smut from an African species of Oxalis and the first Thecaphora species described from Africa.

Anther-smut fungal infection of South African Oxalis species: Spatial distribution patterns and impacts on host fecundity
lH.R. Curran, F. Roets, L.L. Dreyer 2009 https://doi.org/10.1016/j.sajb.2009.08.004

Abstract
The smut fungi (phylum Basidiomycota) contain various economically important virulent plant pathogens and may infect only specific plant organs such as flowers. Fungi may replace pollen of infected flowers with their own fungal spores, creating potential study systems for sexually transmitted diseases. An anther-smut fungus, Thecaphora capensis, was recently rediscovered infecting Oxalis flowers in the Greater Cape Floristic Region. This study aimed to provide insight into the ecology and spatial distribution patterns of T. capensis infection. Eight new Oxalis hosts were discovered over a wide geographic area. Two insect species were collected from infected flowers and both carried fungal spores, implicating them as fungal vectors. Host morphology and reproductive success of infected plants differed significantly to that of healthy Oxalis individuals. Nearest neighbour and Gabriel connectedness analyses revealed diseased plants to be spatially clumped, although this non-random distribution could be ascribed to clonality. We found no common tendency for diseased plants to be of a particular floral morph

Thecaphora anther-smut fungi : ecology and implications for CFR Oxalis species
2012 Curran, Helen R. (Helen Rae)
Stellenbosch : Stellenbosch University
Abstract
Only a limited number of systems involving anther-smut fungi have been studied, usually due to the economic significance of their crop plant hosts. A smut fungus of the genus Thecaphora has been discovered infecting Oxalis hosts in South Africa. This pathogenic fungus, Thecaphora capensis, produces dark-coloured spores in the anthers of host flowers, rendering it an anther-smut fungus. The host genus is the seventh largest plant genus in the Cape Floristic Region (CFR) and the largest geophytic genus of this region. Nine Oxalis species that host T. capensis have been identified across a wide distribution in the CFR of South Africa. A preliminary assessment of T. capensis infections of Oxalis was conducted in 2009, which provided a foundation for further research into the ecological and evolutionary consequences of hosting this fungus.
In this study, a comprehensive host diversity assessment was conducted to determine the extent of infected Oxalis individuals within the CFR. Three new Oxalis host species for Thecaphora capensis were discovered. This brings the total number of known hosts to twelve. The morphological and reproductive effects of the fungus were assessed on two host species (O. incarnata and O. lanata) by comparing healthy and infected individuals of these species. Infection by Thecaphora capensis had a significantly negative effect on both of these factors. Host resources appear to be co-opted for fungal spore production, since floral morphological characters of infected individuals were reduced in size. Furthermore, infection by T. capensis ensured near-universal sterility in both hosts.
Differences in floral characters and pollinator preferences for healthy Oxalis incarnata and O. lanata individuals from disease-free and diseased populations were compared to determine the evolutionary influence of Thecaphora capensis infections. It was shown that this pathogen can have a significant evolutionary influence on its hosts, showing its ability to shape flower size and pollinator activity in O. lanata, but not in O. incarnata. A need has therefore been identified to assess these evolutionary forces independently for each host and its pathogen before making erroneous assumptions for conservation practices. Plant pollinators play an integral role in plant fitness. Pollinator movements within a population are important when between-flower spore transfer by pollinators increases the likelihood of new infections. Pollinator movements may be influenced by host density and the frequency of diseased individuals, amongst other factors. Pollinators were found to mediate Thecaphora capensis spore transfers within diseased Oxalis populations. Host density and disease frequency affected the number of spores transferred under field and standardized conditions. More research is required to investigate confounding factors in these complex systems.
This study highlighted the complexities of a fungal-plant-insect relationship, the evolutionary consequences of such fungal infections and the various factors influencing the likelihood of new infections. This research adds to the limited body of knowledge on multi-organismal interactions in the CFR and provides a base for more detailed future studies on this intriguing system.

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