Elsinoe leucospermi L. Swart & Crous, in Swart, Crous, Kang, Mchau, Pascoe & Palm, Mycologia 93(2): 370 (2001)
Index Fungorum number: IF 627343; MycoBank number: MB 571788; Facesoffungi number: FoF 15302; Figs. 1, 2
Pathogenic on Leucadendron sp., causing scab on stems and leaves. Scab lesions on leaves are brown to gray, mostly abaxial, circular, raised, 10–15 mm in diameter, sometimes surrounded by a reddish halo. Sexual morph: No spores or spore bearing structures found on plant material. Asexual morph:
No spores or spore bearing structures found on plant material or in culture.
Culture characteristics – Very slow growth on PDA at 21 °C under black light, with colonies reaching 10 mm in diameter after 30 days of growth. Colonies well raised above agar surface, folded, with smooth, lobate margins and short white aerial hyphae in tufts. Surface black, light-brown to coral, reverse scarlet or coral. Hyphae densely septate, hyaline to pigmented, branched, smooth-walled.
Material examined – NEW ZEALAND, Wanganui, from scab on Leucadendron sp. leaves, June 2023, L. Braithwaite, PHEL T23_02700. Culture stored at the International Collection of Microorganisms from Plants (ICMP 25035) and dried specimen voucher at the New Zealand Fungarium (PDD 120167).
Hosts and distribution – AUSTRALIA, on Leucadendron chamelaea-pubibracteolatum, Leucad. laureolum and Leucad. thymifoloum, Leucad. sp., Leucospermum cordifolium, Leucos. sp., and Serruria florida; CANARY ISLANDS, on Leucos. cordifolium; NEW ZEALAND, Leucad. sp.; USA, on Leucad. chamelaea-pubibracteo latum, Leucad. laureolum, Leucad. pubibracteolatum, Leucad. thymifoloum, Leucad. sp., Leucos. cordifolium, Leucos. sp.; SPAIN, on Leucos. sp.; SOUTH AFRICA, on Leucad. pubibracteolatum, Leucad. sp., Leucos. cordifolium, Leucos. cordifolium, Leucos. sp., and Serruria florida; ZIMBABWE, on Leucos. sp., Leucos. glabrum, Leucos. reflexum Leucad. sp., and Leucos. sp. (Swart et al. 2001; Fan et al. 2017; Farr et al. 2021; this study).
GenBank – ICMP 25035: OR807180 (ITS), OR814104 (rpb2).
Notes – The identification of Elsinoe is often difficult due to their slow-growing nature, and the lack of fertile structure production in nature. This can make the detection of Elsinoe fruiting structures and spores challenging, as was observed in this instance. Both sectioning of symptomatic leaf and stem material and examining the pure culture did not result in finding spores or spore bearing structures. However, the symptoms clearly indicated that the disease could be caused by an infection with Elsinoe and DNA sequence analysis confirmed the identity of the obtained culture as E. leucospermi. Multi-gene phylogenetic analysis using the combined ITS and rpb2 regions demonstrated that isolate ICMP 25035 groups in a well-supported clade with other isolates of E. leucospermi, including the type strain CBS 11207 (Fig. 8). The sequences of the ITS and rpb2 regions were 100% identical to the sequences of CBS 11207. This is the first record of E. leucospermi from New Zealand.
Figure 1 – Elsinoe leucospermi (PDD 120167; ICMP 25035, living culture). a Scab symptom on Leucadendron sp. stem and leaves. b Scab symptoms on adaxial leaf surface. c Scab symptoms on abaxial leaf surface. d, e Appearance of characteristic raised and cracked cork-like structures on infected leaves. f Growth on PDA media after 60 days. g Closer view of the raised folded colony forming on PDA.
Figure 2 – Maximum Likelihood (GTR + G + I) tree illustrating the phylogenetic placement of the Elsinoe leucospermi isolate ICMP 25035 from New Zealand (in bold). The phylogram is based on the analysis of concatenated ITS and rpb2 sequences. Branches are labelled with bootstrap probabilities = 70% across 10,000 bootstrapping replicates, and type specimens are denoted by a superscript “T”. Myrangium hispanicum CBS 247.33 was used as an outgroup.