Colletotrichum pandanicola Tibpromma & K.D. Hyde, in Tibpromma et al., MycoKeys 33: 47 (2018).
Index Fungorum number: IF 823841; MycoBank number: MB 823841; Facesoffungi number: FoF 05832; Figs. 1, 2
Saprobic on Mangifera indica and pathogenic on Alstonia scholaris. Sexual morph: Not observed. Asexual morph: On PDA vegetative hyphae greyish white, dense, cottony. Conidiomata acervuli, black, circular to oval, submerged, solitary or aggregated. Sporulation abundant. Setae scattered, straight or±bent, dark brown up to the tip, opaque, 2- to 4-septate, 50–80 µm long, smooth-walled, base cylindrical, 2–5 µm diam., tip acute. Conidiophores hyaline to light brown, cylindrical to clavate, smooth-walled, simple, occurring in densely arranged clusters. Conidiogenous cells enteroblastic, hyaline, smooth-walled, cylindrical to slightly inflated, periclinal thickening not visible. Conidia 7–12 × 2–6 μm ( x̄ = 7 × 4 μm, n = 40), hyaline, smoothwalled, aseptate, ovoid, cylindrical or clavate with rounded apices, guttulate. Appressoria 9–16×5–6 μm (x̄ =13×5 μm, n=10), solitary to aggregated, in small groups or short chains, medium to dark brown, smooth-walled, irregular, rarely lobed.
Culture characteristics – Colonies grown from single conidia on PDA 50–70 mm diam. in 7 days, at first white becoming dark grey, reverse pale yellow.
Material Examined – Thailand, Chiang Rai Province, on leaf of Mangifera indica L. (Anaca rdiaceae), 19 May 2018, Ruvishika S. Jayawardena (MFLU 18-1852), living culture MFLUCC 18-1182. India, Karnataka, Mysuru on infected leaves of Alstonia scholaris (Apocyanaceae) as pathogen, May 2019, S. Mahadevakumar (UOM-IOE 19/15), living cultures (AsCs1, AsCs4).
GenBank numbers – MFLUCC 18-1182-MK629453 (ITS), MK639363 (gapdh), MK639357 (chs-1), MK639359 (act) and MK639361 (tub2) AsCs1–OM912803 (ITS), OM934812 (gapdh), OM934814 (tub2) AsCs4–OM912804 (ITS), OM934813(gapdh), OM934815 (tub2)
Notes – The species of the C. gloeosporioides species complex are mainly known as plant pathogens (Weir et al. 2012; Jayawardena et al. 2016, 2018, 2021a, b; Bhunjun et al. 2021), some species are also as endophytes or as saprobes (Jayawardena et al. 2021a, b). Strain MFLUCC 18-1182 belongs to the Colletotrichum gloeosporioides species complex and clusters with the ex-type of C. pandanicola (Fig. 3). However, strain MFLUCC 18–1182 differs from C. pandanicola by forming setae and appressoria, which were not observed in the ex-type strain of C. pandanicola (Tibpromma et al. 2018). This represents the first report of C. pandanicola on Mango from Thailand. Colletotrichum pandanicola was isolated from leaves of Alstonia scholaris, is an evergreen tropical tree and an important medicinal plant distributed throughout the Indian peninsula including Western Ghats regions of Karnataka. Colletotrichum gleosporioides has been reported as a pathogen on A. scholaris (Chandra 1974; Mathur 1979; Sarbhoy and Agarwal 1990; Sarbhoy et al. 1971). Pathogenicity tests were performed on healthy A. scholaris plants. After 10–12 days of pot inoculation, the initial necrotic spots developed on leaves were smaller and later coalesced to form larger necrotized lesions. The lesions developed on inoculated plants were fusiform and grayish brown. Phylogeny supports (Fig. 3) our strain to be C. pandanicola. This is a new report of C. pandanicola on Alstonia scholaris from India.
Figure 1 – Colletotrichum pandanicola (MFLU 18–1852, new host record) a Dead leaf of Mangifera indica. b Germinating spore. c Reverse view of the 7d old culture on PDA. d Upper view of the 7d old culture on PDA. e Setae. f Vegetative hyphae. g Conidiogenous cell. h Conidia. i–j Appressoria. Scale bars: e=50 μm, b=10 μm; scale bar of b applies to f–j
Figure 2 – a–b Leaf blight/early symptoms of anthracnose disease on Alstonia scholaris. c Complete death of infected branch due to anthracnose disease. d–e anthracnose symptoms appearing at the tip of the leaves caused necrosis. f a close view of anthracnose symptoms. g pure cultures of 10 days old Colletotrichum siamense on PDA. i–k Conidiogenous cells and conidia of C. siamense observed under a compound microscope (Scale bar: 10 µm)
Figure 3 – One of two most parsimonious trees obtained with PAUP v. 4.0b10 (Swofford 2003) from a heuristic search of the combined sequence alignment of ITS, gapdh, chs-1, act and tub2 of the Colletotrichum gleosporioides species complex, rooted with C. truncatum (CBS 151.35). Bootstrap support values of MP and ML≥70% and BYPP values≥0.90 are shown at the nodes. Ex-type and reference strains are in bold. New sequence data are in red