Boeremia linicola
Boeremia linicola (Naumov & Vassiljevsky) Jayaward., Jayasiri & K.D. Hyde
Boeremia linicola (Naumov & Vassiljevsky) Jayaward., Jayasiri & K.D .Hyde, in Jayawardena et al., Fungal Diversity 94 :51 (2019)
Index Fungorum number: IF 555807; Facesofungi number: FoF 13880
Saprobic on dead woody twigs of Castanopsis mekongensis. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 110–130 μm high × 140–160 μm diam., (x̅ = 120 × 150 μm, n = 5), scattered, immersed, coriaceous, globose to subglobose, brown to dark-brown. Conidiomatal wall 10–18 μm wide, 2–3-layered, composed of brown outer layers and hyaline inner layers comprising thin-walled cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 2.7–5 × 2.9–4.1 μm (x̅ = 4.2 × 3.6 μm, n = 10), enteroblastic, phialidic, determinate, discrete, ampulliform, hyaline, smooth-walled, arising from stratum. Conidia 5.3–7 × 2.4–3.4 μm (x̅ = 6.3 × 2.9 μm, n = 30), straight, hyaline, oval, one-celled, aseptate, rounded ends, thick-walled, guttulate.
Culture Characters: Conidia germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the ends of conidia. Colonies on PDA, reaching 50 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, surface rough with sparse mycelium, cultures atrovirens with white; reverse, atrovirens.
Material examined: China, Yunnan Province, Lancang, Lahu Autonomous Prefecture, Hani, on dead woody twigs of Castanopsis mekongensis (Fagaceae), 23 March 2020, G.C. Ren, LGY07 (HKAS 122772), living culture KUMCC 21-0667.
GenBank numbers: LSU: OQ170848, ITS: OQ158928, SSU: OQ168204, rpb2: OR578558, tub2: OR578551.
Notes: The type strain of Boeremia linicola (CBS 116.76) was identified from living stems of Linum usitatissimum from Russia and introduced without morphological descriptions. Qian et al. (2023) described Boeremia linicola as hyphomycetous oatmeal agar (OA) medium. The asexual morphs of B. linicola are characterized by hyaline, ampulliform to doliiform conidiogenous cells and ellipsoidal to cylindrical, piriform, columnar, drop-shaped, dumbbell-shaped or oval, hyaline, thin-walled, smooth, aseptate conidia with guttules (Guan et al. 2021, Qian et al. 2023). Our isolate shares similar characteristics to B. linicola in having ampulliform, hyaline conidiogenous cells and hyaline, oval, one-celled, aseptate conidia with guttules. Furthermore, the morphology of our collection is compared to the generic description and our isolate shares similar characteristics to Boeremia (Aveskamp et al. 2010). In the phylogenetic analysis, our new isolate clustered with Boeremia linicola strains (CBS 116.76, CBS 114.28 and CBS 248.38 with 85% ML bootstrap support and 1.00 BYPP value. Based on morphological characteristics and phylogenetic results, our isolates were identified as B. linicola. Boeremia linicola was reported as a pathogen from many important plant species (Irinyi et al. 2009, Aveskamp et al. 2010, Chen et al. 2015, Guan et al. 2021, Lee et al. 2022); however, in our study, it was isolated from Castanopsis mekongensis as a saprobe. This is the first report of Boeremia linicola from Castanopsis mekongensis. Based on its distribution, Boeremia linicola shows a very broad host range.
Figure 1. Phylogram generated from ML analysis based on LSU, ITS, rpb2 and tub2 sequence data representing Boeremia. Related sequences are obtained following Jayawardena et al. (2019) and Dayarathne et al. (2020). Forty-two strains are included in the combined analyses, which comprise 2746 characters for LSU, ITS, rpb2, and tub2 alignment. Phoma herbarum (CBS 615.75) was used as the outgroup taxon. The best-scoring RAxML tree with a final likelihood value of -5948.314119 is presented. The matrix had 234 distinct alignment patterns with 15.71% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.242542, C = 0.237458, G = 0.272062, T = 0.247938; substitution rates AC = 1.303992, AG = 3.475548, AT = 1.174892, CG = 0.799946, CT = 10.609598, GT = 1.0000. The tree topology of the ML analysis is similar to the Bayesian analysis. Bootstrap values for ML equal to or greater than 70% and BYPP values greater than 0.95 (the rounding of values to 2 decimal proportions) are labelled on the nodes. Strains of the newly described species are in blue, while type strains are in bold.
Figure 2. Boeremia linicola (HKAS 122726). a Material examined. b Conidiomata on the natural wood surface. c Sections through conidioma. d Conidioma wall. e, f Conidiogenous cells and developing conidia. g–l Conidia. m Germinated conidium. n, o Culture characters on PDA (n = from above, o = from below). Scale bars: c = 50 μm, d–f, m = 20 μm, g–l = 5 μm, n, o = 20 mm.
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