63 research outputs found

    Morphological and habitat differentiation between diploids and tetraploids of a Drakensberg near-endemic taxon, Rhodohypoxis baurii var. platypetala (Hypoxidaceae)

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    DATA AVAILABILITY STATEMENT: Flow cytometric fcs files for ploidy levels are available at https://osf.io/ e8k2g/?view_only=566e3f2f38194a42ae0c33f8c6e39559.Environmental factors may shape the spatial distribution of ploidy levels. Here, we undertook a cytogeographical study of Rhodohypoxis baurii var. platypetala (Hypoxidaceae), a Drakensberg near-endemic taxon. We addressed the following questions: (1) Are there mixed-ploidy populations or is each population represented by a single ploidy level? (2) Is there a pattern in the environmental distribution of ploidy levels? (3) Are there specific environmental variables associated with each ploidy level locality? (4) Are plant traits similar or different within and among ploidy levels across populations that experience different environmental factors? We measured leaf and flower traits of individuals that were sampled for flow cytometry from 17 populations across the KwaZulu-Natal and Free State provinces in South Africa. We extracted daily climate data for 13 variables and collected soil samples to evaluate pH and nutrient properties to characterize the sampled populations to test for relationships with ploidy level distributions. Twelve populations were found to contain only diploids, four populations contained only tetraploids, and only one population was ‘mixed ploidy’ (both diploid and triploid individuals present). There was an overlap in the altitudinal range of diploid and tetraploid populations, but diploids reached the highest altitudes recorded for the current study. We also found that R.baurii var. platypetala occurs in acidic soils and that tetraploids occurred in soils with marginally higher nitrogen and phosphorus than soils where diploids occur. Tetraploids generally occurred in warmer conditions, in drier soils, and possessed broader leaves and larger flowers than diploids. Our study suggests that soil factors and temperature at a small (within localities) spatial scale likely shape ploidy level distributions in the Drakensberg grasslands.The University of the Witwatersrand FriedelSellschop Award and the National Research Foundation.https://onlinelibrary.wiley.com/journal/14429993Plant Production and Soil SciencePlant ScienceSDG-15:Life on lan

    Death of endemic Virgilia oroboides trees in South Africa caused by Diaporthe virgiliae sp. nov.

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    Numerous dead and dying individuals of the Western Cape endemic tree Virgilia oroboides (Fabaceae) were recently observed within a South African national botanical garden. Root-rot fungi and fungi symbiotic with bark beetles (Curculionidae; Scolytinae) from diseased trees were assessed for their respective roles in V. oroboides mortality. Disease progression was also monitored over 1 year. Fungi were isolated from surface sterilized bark and root samples from diseased trees and provisionally identified using data from the internal transcribed spacer regions (ITS1, ITS2), including the 5 8S rRNA gene (ITS). Pathogenicity of selected fungi towards V. oroboides was tested under field conditions. The pathogenicity of various bark beetle-associated Geosmithia (Hypocreales: Hypocreomycetidae) spp. from V. oroboides were similarly assessed. The only fungus consistently isolated from lesions on the roots and bark of declining V. oroboides, and never from healthy individuals, represented an undescribed Diaporthe (Diaporthales, Diaporthaceae) species that was characterized using molecular (using data from the ITS marker and part of the b-tubulin gene, TUB), cultural and morphological characters. It is an aggressive pathogen of V. oroboides, newly described here as Diaporthe virgiliae sp. nov. Trees of all ages are susceptible to this pathogen with subsequent bark beetle attack of mature trees only. All Geosmithia spp. from beetles and/or infected trees were nonpathogenic towards V. oroboides. Diaporthe virgiliae caused a severe decline in the health of the monitored V. oroboides population over a period of only 1 year and should be considered as a significant threat to these trees.DST/NRF Centre of Excellence in Tree Health Biotechnology (CHTB).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-3059hb201

    Revision of the enigmatic South African Cryptolaryngini (Coleoptera, Curculionidae), with description of a new genus and twenty-two new species

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    SUPPLEMENTARY MATERIAL : Supp. file 1. Uncorrected p-distances between specimens based on COI and EF1. https://DOI.org/10.5852/ejt.2023.877.2151.9151The weevil genus Cryptolarynx Van Schalkwyk, 1966 is endemic to the Northern and Western Cape provinces of South Africa. The two previously known species of the genus, C. vitis (Marshall, 1957) and C. estriatus (Marshall, 1957), have an aberrant globular body and head shape, which has made it difficult to place the genus into the classification systems of the Curculionoidea. This paper presents the description of 21 new species of Cryptolarynx from South Africa (C. subglaber Haran sp. nov., C. squamulatus Haran sp. nov., C. muellerae Haran sp. nov., C. hirtulus Haran sp. nov., C. robustus Haran sp. nov., C. namaquanus Haran sp. nov., C. carinatus Haran sp. nov., C. variabilis Haran sp. nov., C. pyrophilus Haran sp. nov., C. pilipes Haran sp. nov., C. armatus Haran sp. nov., C. falciformis Haran sp. nov., C. oberprieleri Haran sp. nov., C. spinicornis Haran sp. nov., C. cederbergensis Haran sp. nov., C. homaroides Haran sp. nov., C. marshalli Haran sp. nov., C. endroedyi Haran sp. nov., C. oberlanderi Haran sp. nov., C. san Haran sp. nov., and C. luteipennis Haran sp. nov.) and of one new genus and species, Hadrocryptolarynx major Haran gen. et sp. nov., also from South Africa. A redescription of the genus Cryptolarynx is provided to incorporate the characters of the new species. The plant genus Oxalis (Oxalidaceae) is recorded as larval host for several species of Cryptolarynx and for Hadrocryptolarynx Haran gen. nov., as their larvae develop in the subterranean bulbs of members of the genus, and the egg, larva and pupa of C. variabilis are described. The characters of the Cryptolarynx larva confirm that Cryptolaryngini are an early-diverging group of Curculionidae, with a placement among taxa currently classified in the subfamily Brachycerinae sensu lato, and although their exact taxonomic position remains unresolved, some larval characters, and also pupal ones, suggest a close relationship between Cryptolaryngini and Stenopelmus Schoenherr. Potential use of species of Cryptolarynx in the biological control of weedy South African species of Oxalis is discussed.http;//www.europeanjournaloftaxonomy.euam2024Plant Production and Soil ScienceSDG-15:Life on lan

    New species of Ophiostomatales from Scolytinae and Platypodinae beetles in the Cape Floristic Region, including the discovery of the sexual state of Raffaelea

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    Olea capensis and Rapanea melanophloeos are important canopy trees in South African Afromontane forests. Dying or recently dead individuals of these trees are often infested by Scolytinae and Platypodinae (Curculionidae) beetles. Fungi were isolated from the surfaces of beetles emerging from wood samples and their galleries. Based on micromorphological and phylogenetic analyses, four fungal species in the Ophiostomatales were isolated. These were Sporothrix pallida and three taxa here newly described as Sporothrix aemulophila sp. nov., Raffaelea vaginata sp. nov. and Raffaelea rapaneae sp. nov. This study represents the first collection of S. pallida, a species known from many environmental samples from across the world, from Scolytinae beetles. S. aemulophila sp. nov. is an associate of the ambrosia beetle Xyleborinus aemulus. R. rapaneae sp. nov. and R. vaginata sp. nov. were associated with a Lanurgus sp. and Platypodinae beetle, respectively, and represent the first Raffaelea spp. reported from the Cape Floristic Region. Of significance is that R. vaginata produced a sexual state analogous with those of Ophiostoma seticolle and O. deltoideosporum that also grouped in our analyses in Raffaelea s. str., to date considered an asexual genus. The morphology of the ossiform ascospores and anamorphs of the three species corresponded and the generic circumscription of Raffaelea is thus emended to accommodate sexual states. The two known species are provided with new combinations, namely Raffaelea seticollis (R.W. Davidson) Z.W. de Beer and T.A. Duong comb. nov. and Raffaelea deltoideospora (Olchow. and J. Reid) Z.W. de Beer and T.A. Duong comb. nov.DST/NRF Centre of Excellence in Tree Health Biotechnology (CHTB).http://link.springer.com/journal/104822016-10-30hb201

    Repression of Sex4 and Like Sex Four2 Orthologs in Potato Increases Tuber Starch Bound Phosphate With Concomitant Alterations in Starch Physical Properties

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    To examine the roles of starch phosphatases in potatoes, transgenic lines were produced where orthologs of SEX4 and LIKE SEX FOUR2 (LSF2) were repressed using RNAi constructs. Although repression of either SEX4 or LSF2 inhibited leaf starch degradation, it had no effect on cold-induced sweetening in tubers. Starch amounts were unchanged in the tubers, but the amount of phosphate bound to the starch was significantly increased in all the lines, with phosphate bound at the C6 position of the glucosyl units increased in lines repressed in StSEX4 and in the C3 position in lines repressed in StLSF2 expression. This was accompanied by a reduction in starch granule size and an alteration in the constituent glucan chain lengths within the starch molecule, although no obvious alteration in granule morphology was observed. Starch from the transgenic lines contained fewer chains with a degree of polymerization (DP) of less than 17 and more with a DP between 17 and 38. There were also changes in the physical properties of the starches. Rapid viscoanalysis demonstrated that both the holding strength and the final viscosity of the high phosphate starches were increased indicating that the starches have increased swelling power due to an enhanced capacity for hydration

    Oxalis dreyerae (Oxalidaceae), a new species from South Africa

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    Oxalis dreyerae, a new species from the arid Richtersveld region of South Africa, is described. It is most similar to O. inconspicua from which it differs, among others, by having a larger plant body, larger and showier flowers with a broadly trumpet-shaped tube, much larger leaflets, petioles that are thicker than the peduncles, much larger lanceolate sepals and short, stubby teeth on the longer filaments. Its placement within the O. flava clade is supported by nrDNA ITS sequence evidence, which is also consistent with a close relationship to O. inconspicua. Oxalis dreyerae represents the eighth described species of Oxalis endemic to the arid Richtersveld of the Northern Cape, thus supporting the importance of the floristically diverse Gariep Centre of Endemism, of which the region forms a part.</jats:p
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