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Phoma selaginellicola was detected on wild invasive plants of Selaginella kraussiana (African club moss). Identification was made based on colony characteristics, pycnidial and conidial morphology and comparison of ITS DNA sequences. This is the first record of the species for New Zealand and a new host species.
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... forming mainly on the surface of the agar, 145 – 395 μm in diameter, solitary to occasionally in clusters of 2 – 3, with one usually non-papillate ostiole ( Fig. 2), citrine to honey in colour when young, black when older. Pycnidial walls made up of 3 – 6 layers of cells, outer layers becoming pigmented brown to black on maturity (Fig. 3). Conidial exudate was straw-coloured, visible through the aerial mycelium. Conidiogenous cells 4 – 6 × 3.5 – 5 μm, globose to bottle shape. Conidia were ellipsoidal, occasionally curved, 3.5 – 4.5 × 1.5 – 1.75 μm, average 3.9 × 1.48 μm, with 2 or 3 guttules (Fig. 4). Chlamydospores were absent. The ITS sequence was 100% identical to a sequence identified as Phoma selaginellicola in GenBank (GU237762) by Aveskamp et al. (2010). Within 14 days plants inoculated for pathogenicity testing exhibited yellowing of leaves and stems, while control plants remained green. After 3 weeks damaged and undamaged plants had 10 – 50% dieback of foliage (Fig. 5) and yellowing of cones. Samples were again taken, surface-sterilised and inoculated onto plates of PDA amended with chloramphenicol. Cultures morphologically identified as Phoma were consistently reisolated and DNA sequencing again generated ITS sequences identical to those of Phoma selaginellicola ...
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Citations
... As yet there appears to be little knowledge of naturally occurring pathogens of S. kraussiana in New Zealand or elsewhere [20]. Some fungal species with varying degrees of pathogenicity towards the species have been reported recently in collections of S. kraussiana in New Zealand [21,22], and more recently a study included a comparison with the native club mosses Lycopodium deuterodensum and Lycopodium volubile. Here, we analyse the microbial profiles of 18 samples of S. kraussiana collected from nine disjunct locations in New Zealand matched against protein databases to gain a better understanding of the plant-fungal and plant-bacteria associations. ...
... With MEGAN, we normalized counts to 186,029 paired-end assignments per sample. To examine whether data base representation might have impacted inferences made concerning the presence and absence of fungal pathogens, paired reads used in DIAMOND-MEGAN and Kaiju analyses were independently mapped using BWA [28] (default parameter settings) to the internal transcribed spacer (ITS) regions of Phoma selaginellicola and Pestalotiopsis clavispora which had previously been cultured from Selaginella kraussiana in New Zealand [21,22]. The reads were also mapped to the ITS region of Parastagonospora phoenicicola and Parastagonospora caricis, since this genus was identified in DIAMOND-MEGAN analyses of S. kraussiana. ...
... The reads were also mapped to the ITS region of Parastagonospora phoenicicola and Parastagonospora caricis, since this genus was identified in DIAMOND-MEGAN analyses of S. kraussiana. Of interest was determining whether analyses of ITS sequences would suggest the presence of Phoma and Pestalotiopsis on any of the accessions S. kraussiana, since these fungal species had previously been cultured from S. kraussiana in New Zealand [21,22]. Table S1 provides details on taxonomy assignments for all samples made with MEGAN-LCA analyses. ...
Metagenomics can be used to identify potential biocontrol agents for invasive species and was used here to identify candidate species for biocontrol of an invasive club moss in New Zealand. Profiles were obtained for Selaginella kraussiana collected from nine geographically disjunct locations in Northern New Zealand. These profiles were distinct from those obtained for the exotic club moss Selaginella moellendorffii and the native club mosses Lycopodium deuterodensum and Lycopodium volubile also collected in Northern New Zealand. Fungi and bacteria implicated elsewhere in causing plant disease were identified on plants of Selaginella that exhibited signs of necrosis. Most notably, high densities of sequence reads from Xanthomonas translucens and Pseudomonas syringae were associated with some populations of Selaginella but not Lycopodium. Since these bacteria are already in use as biocontrol agents elsewhere, further investigation into their potential as biocontrol of Selaginella in New Zealand is suggested.
