Colletotrichum fructicola
Colletotrichum fructicola Prihast., L. Cai & K.D. Hyde, in Prihastuti, Cai, Chen, McKenzie & Hyde, Fungal Diversity 39: 96 (2009)
Index Fungorum number: IF515409 Facesoffungi number:06767
Associated with leaf spots, blight, and blotches. Leaf spots circular or irregular, pale brown to brown, surrounded with a dark brown margin. Leaf blight brown, surrounded with a dark brown margin. Leaf blotches reddish brown to dark brown. Sexual morph on substrate: Ascomata 75–150 × 80–150 µm (x̄ = 95 × 98 µm, n = 5), solitary, semi-immersed, globose to subglobose, brown, ostiolate. Setae not observed. Sexual morph on PDA: Ascomata 100–200 × 100–190 µm (x̄ = 131 × 123 µm, n = 5), solitary or aggregated, semi-immersed or superficial, globose to subglobose, black. Setae not observed. Peridium 8–38 µm thick (x̄ = 19.1 µm, n = 10), composed of 3–4 layers of thick-walled pseudoparenchymatous cells of textura angularis. Asci 55–70 × 8–11 µm (x̄ = 63 × 9.5 µm, n = 10), operculate, unitunicate, cylindrical to clavate or cymbiform, 6–8-spored. Ascospores 13–23.5 × 4–6.5 µm (x̄ = 17.9 × 5.1 µm, n = 25; L/W ratio = 3.5), uniseriate or biseriate, hyaline, subellipsoidal or oblong, reniform to falcate, somewhat fusiform, slightly curved, smooth-walled, guttulate, aseptate, mostly with obtuse or acute ends. Asexual morph on substrate: Conidiomata 80–150 × 60–140 µm (x̄ = 100 × 90 µm, n = 5), solitary, semi-immersed, globose to subglobose, brown, producing creamy to orange conidial mass. Setae not observed. Asexual morph on PDA: Conidiomata 200–800 µm diam. (x̄ = 350 µm, n = 10), semi-immersed, scattered or aggregated, globose to subglobose, exuding creamy to orange conidial mass. Setae not observed. Conidiophores formed directly from mycelium, hyaline, cylindrical, branched, or unbranched. Conidiogenous cells 6.5–22 × 2–4 µm (x̄ = 12.1 × 3 µm, n = 10), hyaline, cylindrical, or ampulliform, straight or flexuous, tapering towards the apex. Conidia 12–18 × 4.5–5.5 µm (x̄ = 15.4 × 5 µm, n = 25; L/W ratio = 3.1), hyaline, cylindrical to ovoid, smooth-walled, guttulate, aseptate, with rounded ends. Chlamydospores 6–7 × 6.5–8 µm (x̄ = 6.3 × 7.2 µm, n = 5), globose to subglobose, pale brown. Appressoria Not observed.
Culture characteristics: Colonies on PDA reaching approximately 80 mm diam. after 7 d of incubation at 25 °C; mycelium initially white, becoming dark grey at the center when aged, elevation flat or raised, aerial and dense, with an entire margin.
Material examined: Thailand, Chiang Mai Province, Omkoi District, Yiang Piang Subdistrict, associated with leaf spots of Castanea sp. (Fagaceae), 16 Oct 2019, D. Gomdola DG367-L2 (MFLU 25-0012), living culture MFLUCC 25-0013; DG367(L2)-A (MFLU 25-0013), living culture MFLUCC 25-0014; DG367(L2)-B (MFLU 25-0014), living culture MFLUCC 25-0015; Thailand, Chiang Mai Province, Doi Lo District, associated with leaf blight of Hedychium sp. (Zingiberaceae), 15 Oct 2019, D. Gomdola DG327 (MFLU 25-0015), living culture MFLUCC 25-0016; Thailand, Chiang Rai Province, around the vicinity of Central Plaza, associated with leaf blotches of Rhododendron sp. (Ericaceae), 11 Jul 2019, D. Gomdola DG03.1 (MFLU 25-0016), living culture MFLUCC 25-0017.
GenBank accession numbers: MFLUCC 25-0013; ITS = PV263300; GAPDH = PV290906; CHS1 = PV274257; ACT = PV297883; and TUB2 = PV295625; MFLUCC 25-0014; ITS = PV263301; GAPDH = PV290907; CHS1 = PV274258; ACT = PV297884; and H3 = PV549703; MFLUCC 25-0015; ITS = PV263302; GAPDH = PV290908; CHS1 = PV274259; ACT = PV297885; and H3 = PV400146; MFLUCC 25-0016; ITS = PV263303; GAPDH = PV290909; CHS1 = PV274260; and H3 = PV400147; and CAM = PV299290; and MFLUCC 25-0017; ITS = PV263304; GAPDH = PV290910; CHS1 = PV274261; ACT = PV297886; TUB2 = PV295626; H3 = PV400148; and CAM = PV299291.
Notes: Our isolates (MFLUCC 25-0013, MFLUCC 25-0014, MFLUCC 25-0015, MFLUCC 25-0016, and MFLUCC 25-0017) grouped with other strains of Colletotrichum fructicola with 99% ML and 1.00 PP support. Colletotrichum fructicola is located in the C. gloeosporioides species complex (Figs 1, 2), consistent with findings of Prihastuti et al. (2009), Ma et al. (2018), Norphanphoun and Hyde (2023), and Zhang et al. (2023b). No intraspecies nucleotide differences were observed between our isolates and the ex-type of C. fructicola (ICMP 18581) across the ITS, GAPDH, CHS1, ACT, and TUB2 regions. However, a sequence divergence of 0.7% (5/731 bp) was observed in CAM between our isolate (MFLUCC 25-0017) and C. fructicola (ICMP 18581). Our isolates morphologically resemble the ex-type of C. fructicola (ICMP 18581), having hyaline, smooth-walled, guttulate, and aseptate conidia and ascospores, with the conidia being cylindrical to ovoid with rounded ends and ascospores being oblong, reniform to falcate with obtuse or acute ends (Prihastuti et al. 2009). Notably, the ascospore and conidial lengths of our isolates vary slightly with other strains of C. fructicola. However, the L/W ratios of our isolates are similar to those of other C. fructicola strains. The ascospore L/W ratio of our isolates is 3.5, while those from other studies are ICMP 18581 = 3.6 (Prihastuti et al. 2009), MFLUCC 14-0087 = 3.4 (Ma et al. 2018), MFLUCC 17-1752 = 3.2 (Norphanphoun and Hyde 2023), and ZHKUCC 23-0829 = 3.7 (Zhang et al. 2023b). The conidial L/W ratio of our isolates is 3.1, while those from other studies are ICMP 18581 = 3.2 (Prihastuti et al. 2009), MFLUCC 14-0087 = 2.9 (Ma et al. 2018), and MFLUCC 17-1752 = 2.6 (Norphanphoun and Hyde 2023). Based on phylogenetic and morphological species concepts, we identify our isolates as Colletotrichum fructicola. This study represents three new host records for C. fructicola associated with leaf spots of Castanea sp., leaf blight of Hedychium sp., and leaf blotches of Rhododendron sp. in Thailand.
Figure 1. Maximum likelihood analysis (IQ-tree) based on a combined dataset of ITS, GAPDH, CHS1, ACT, TUB2, H3, and CAM sequences from dataset 2, which includes all species in the C. gloeosporioides species complex. Bootstrap support values (ML ≥ 80%) and Bayesian posterior probabilities (PP ≥ 0.95) are given above the branches or near the nodes as ML/PP. Hyphens (--) indicate bootstrap support values below 80% for ML and posterior probabilities below 0.95. The tree is rooted with C. beeveri (CBS 128527) and C. boninense (CBS 123755), belonging to the C. boninense species complex. Type, ex-type, and reference species are denoted with T. Our isolates are in bold red font. Different color blocks represent distinct species complexes.
Figure 2. Colletotrichum fructicola. a. Leaf spots (Castanea sp.); b. Leaf blight (Hedychium sp.); c. Leaf blotches (Rhododendron sp.); d. Ascomata on substrate (Rhododendron sp.); e. Conidiomata sporulating on substrate (Hedychium sp.); f. Top and reverse of colony on PDA after 21 d; g. Clusters of ascomata formed on culture; h. Section through ascomata; i. Peridium; j, k. Asci; l–q. Ascospores; r. Chlamydospore; s. Conidiogenesis and developing conidia; t–v. Conidia. Scale bars: 500 μm (d, e, g); 100 μm (h); 10 μm (i–v).
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