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Muribasidiospora indica was identified as the causal organism associated with leaf spots of Rhus lancea in South Africa. The disease appears more commonly in the warmer provinces of South Africa (Gauteng, Free State) than in the Western Cape. The morphological identification of the causal organism was confirmed by comparing sequence data of the lar...
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... spots were diffuse, circular, confluent, red to red-purple with a narrow chlorotic margin on the adaxial surface, becoming dark red to brown/black on older leaves, up to 1.5-cm-diameter; on the abaxial surface spots were diffuse, chlorotic, later becoming dark brown (Figs 1 and 2). Leaf spots were covered (primarily on abaxial surface) with a thin hymenial layer of subcylindrical basidia (cream in appearance). ...
Citations
... In addition, sequences of all available species of Brachybasidiaceae and Graphiolaceae were added including sequences from the public catalog of the NITE Biological Resource Center collection (NBRC), Japan. GenBank accession numbers of the sequences used (Begerow et al. 2002;Boekhout et al. 2003;Cao et al. 2018;Crous et al. 2003;Kottke et al. 2010;Kruse et al. 2017;Macedo et al. 2016;Maier et al. 2006;Matheny et al. 2006;Nasr et al. 2019;Piepenbring et al. 2010Piepenbring et al. , 2012aSchoch et al. 2014;Sepúlveda et al. 2017;Tanaka et al. 2008;Wang et al. 2015;Yasuda et al. 2005) are cited in Fig. 2. ...
The Brachybasidiaceae are a family of 22 known species of plant-parasitic microfungi belonging to Exobasidiales, Basidiomycota. Within this family, species of the largest genus Kordyana develop balls of basidia on top of stomatal openings. Basidial cells originate from fungal stroma filling substomatal chambers. Species of Kordyana typically infect species of Commelinaceae. During fieldwork in the neotropics, fungi morphologically similar to Kordyana spp. were found on Goeppertia spp. (syn. Calathea spp., Marantaceae), namely on G. panamensis in Panama and on G. propinqua in Bolivia. These specimens are proposed as representatives of a genus new to science, Marantokordyana, based on the distinct host family and molecular sequence data of ITS and LSU rDNA regions. The specimens on the two host species represent two species new to science, M. oberwinkleriana on G. panamensis and M. boliviana on G. propinqua. They differ by the size and shape of their basidia, molecular sequence data of ITS and LSU rDNA regions, and host plant species. In the past, the understanding of Brachybasidiaceae at order and family level was significantly improved by investigation realized by Franz Oberwinkler and his collaborators at the University of Tübingen, Germany. On species level, however, our knowledge is still very poor due to incomplete species descriptions of several existing names in literature, scarceness of specimens, as well as sequence data lacking for many taxa and for further barcode regions. Especially species of Kordyana and species of Dicellomyces are in need of revision.
Graphical Abstract
... Few studies reported on the effect of diseases on the health of this tree. The most significant disease known is a leaf spot disease caused by the fungal pathogen Muribasidiospora indica (Crous et al. 2000(Crous et al. , 2003. A focused survey in one location for members of the latent pathogen family Botryosphaeriaceae, revealed only one species from S. lancea despite the fact that other hosts in the area were infected with more species (Jami et al. 2013). ...
This study represents the first disease report for a new malformation disease affecting the ubiquitous South African tree species Searsia lancea. This disease is known as karee malformation disease (KMD), since inflorescences and leaves are severely malformed. The observed symptoms resemble those of mango malformation disease caused by fungal species in the important pathogen genus Fusarium. Furthermore, mango is in the same family as karee. A comparative fungal survey was conducted between healthy and malformed samples of S.lancea to determine whether Fusarium species are present in these samples, or if other fungal species could be possibly associated with the disease. Insects collected from these samples were also compared. Fusarium does not appear
to be a prominent fungus in KMD symptoms, nor is it a prominent endophyte. No other fungal species that are known to cause such type of symptoms were isolated. The insect studies showed strong associations of KMD symptoms with psyllids, a group known to cause galls and vector plant pathogens that can cause symptoms similar to malformations. It is recommended that further research focus on the potential role of psyllids, along with thrips and aphids, in the formation of karee malformation disease. Lastly, considerably more fungi and insects were collected from diseased tissues than fromhealthy tissues. These different trends in fungal and insect biodiversity between healthy and malformed S.lancea indicate that malformations represent a unique niche within trees with complex interactions between plant, microbes and insects.
... S. molle is mesophyllous and evergreen (Howard and Minnich, 1989), in contrast to A. tortilis that is microphyllous and semi-deciduous losing 480% of leaves in dry winters (Milton, 1987) and R. lancea that is mesophyllous and evergreen, but sheds all its old leaves in late spring when new leaves are forming (Palmer and Pitman, 1972). Moreover, the leaves of S. molle do not appear to suffer insect or fungal damage (S.J. Milton, personal observation), whereas leaves of R. lancea are damaged by fungi (Crous et al., 2003), that may reduce their ability to compete for light. Greater photosynthetic potential may possibly explain the competitive ability of S. molle. ...
Invasion of ecosystems by woody alien plant species is a widespread phenomenon. Interspecific competition has often been suggested as a mechanism for replacement of one species by another, but this is rarely tested. We investigated the potential of an invasive alien tree to transform vegetation by quantifying the relative abilities of the alien tree Schinus molle and dominant native trees Acacia tortilis and Rhus lancea to compete for light when growing in association within a South African semi-arid savanna. Due to dispersal of its fruits by birds, seedlings of S. molle establish under tree canopies. Using canopy symmetry as an index of ability to compete for light, we found that the alien S. molle consistently out-competes the dominant native tree species. The results also show that pod production of A. tortilis was higher when it grew alone compared to when it grew with S. molle or R. lancea. The percentage of dead branches was higher on A. tortilis trees growing in association with the S. molle. The outcome is that the alien tree will gradually increase in abundance, changing woodland structure and ecosystem processes. Our findings provide evidence for the role of competition in the process of alien plant invasions. We suggest that S. molle, previously considered a benign naturalized species in South Africa, should be declared a noxious weed in some parts of that country.
... Kamat & Rajendren was recently reported from South Africa for the first time, causing a prominent leaf spot on native Rhus lancea (Crous et al. 2003). ...
The genus Quambalaria consists of plant-pathogenic fungi causing disease on leaves and shoots of species of Eucalyptus and its close relative, Corymbia. The phylogenetic relationship of Quambalaria spp., previously classified in genera such as Sporothrix and Ramularia, has never been addressed. It has, however, been suggested that they belong to the basidiomycete orders Exobasidiales or Ustilaginales. The aim of this study was thus to consider the ordinal relationships of Q. eucalypti and Q. pitereka using ribosomal LSU sequences. Sequence data from the ITS nrDNA were used to determine the phylogenetic relationship of the two Quambalaria species together with Fugomyces (= Cerinosterus) cyanescens. In addition to sequence data, the ultrastructure of the septal pores of the species in question was compared. From the LSU sequence data it was concluded that Quambalaria spp. and F. cyanescens form a monophyletic clade in the Microstromatales, an order of the Ustilaginomycetes. Sequences from the ITS region confirmed that Q. pitereka and Q. eucalypti are distinct species. The ex-type isolate of F. cyanescens, together with another isolate from Eucalyptus in Australia, constitute a third species of Quambalaria, Q. cyanescens (de Hoog & G.A. de Vries) Z.W. de Beer, Begerow & R. Bauer comb. nov. Transmission electron-microscopic studies of the septal pores confirm that all three Quambalaria spp. have dolipores with swollen lips, which differ from other members of the Microstromatales (i.e. the Microstromataceae and Volvocisporiaceae) that have simple pores with more or less rounded pore lips. Based on their unique ultrastructural features and the monophyly of the three Quambalaria spp. in the Microstromatales, a new family, Quambalariaceae Z.W. de Beer, Begerow & R. Bauer fam. nov., is described.
The genus Muribasidiospora producing muriform basidiospores belongs to Exobasidiaceae. Three species, Muribasidiospora hesperidium, M. indica and M. celtidis, have been recorded. Muribasidiospora gordoniae, which causes a prominant red leaf spot disease on Gordonia axillaris, is a new species in Taiwan based on the host and its morphology. Additionally, analysis of the internal transcribed region (ITS1-5.8S rDNA-ITS2) reveals M. gordoniae is closely related to the genus Exobasidium, especially those species of it occurring on Camellia species.
Novel species of microfungi described in the present study include the following from Australia: Bagadiella victoriae and Bagadiella koalae on Eucalyptus spp., Catenulostroma eucalyptorum on Eucalyptus laevopinea, Cercospora eremochloae on Eremochloa
bimaculata, Devriesia queenslandica on Scaevola taccada, Diaporthe musigena on Musa sp., Diaporthe acaciigena on Acacia retinodes, Leptoxyphium kurandae on Eucalyptus sp., Neofusicoccum grevilleae on Grevillea aurea, Phytophthora
fluvialis from water in native bushland, Pseudocercospora cyathicola on Cyathea australis, and Teratosphaeria mareebensis on Eucalyptus sp. Other species include Passalora leptophlebiae on Eucalyptus leptophlebia (Brazil), Exophiala tremulae
on Populus tremuloides and Dictyosporium stellatum from submerged wood (Canada), Mycosphaerella valgourgensis on Yucca sp. (France), Sclerostagonospora cycadis on Cycas revoluta (Japan), Rachicladosporium pini on Pinus monophylla (Netherlands),
Mycosphaerella wachendorfiae on Wachendorfia thyrsifolia and Diaporthe rhusicola on Rhus pendulina (South Africa). Novel genera of hyphomycetes include Noosia banksiae on Banksia aemula (Australia), Utrechtiana cibiessia on Phragmites australis
(Netherlands), and Funbolia dimorpha on blackened stem bark of an unidentified tree (USA). Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.
