Table 1.
Locations where yam farms were surveyed, and symptomatic leaves collected.
Table 2.
Dioscorea alata and Dioscorea rotundata yam Accession/landraces and collection locations.
Fig 1.
Variation in appearance of anthracnose symptoms sampled on D. alata and D. rotundata in all the locations.
Infected leaves sampled from Obubra sampling area (a-d), Yakurr (e-l), Ogoja (k-q); Ikom (r-s), Akpabuyo (t-u), and Calabar South (v-x). Arrow indicates symptoms.
Fig 2.
Morphological variability of fungi isolates obtained from the different locations (top row, upper side of the colony; bottom row, reverse side of the colony).
Fig 3.
Photomicrographs showing growth pattern of fungi isolates from D. alata (a-e) and D. rotundata (f-h) at 10x.a(Ca5), one sided branching, non-branched tip, distance between branches ranges from 0.5–1.7cm, short bead-like hyphae with swollen tip. b (Lt1), alternate branching, non-branched tip, distance between branches ranges from 0.5–2.0cm, long cylindrical hyphae with tapering tip. c (Ca14), alternate branching, double branched tip, distance between branches ranging from 0.5–2.0cm, long branched thread-like hyphae with slightly swollen tip. d (Ca16), alternate branching with double branched tip, distance between branches ranges from 1.0–2.5cm, long branched thread-like hyphae with swollen tip. e (Ca22), alternate branching with non-branched tip, distance between branches ranging from 0.3–2.5cm, long branched cylindrical hyphae with tapering tip. f (Ca24), alternate branching, double branched at tip, distance between branches of about 0.5cm, short bead-like hyphae with slightly swollen tip. g (Ca32), alternating after two branches, triple branched at tip, distance ranging from 0.5–1.0, short bead-like branch with swollen tip. h (Ca34), alternating after two branches, multiple branched at tip, distance between branches ranging from 0.3–1.8cm, long bead-like hyphae with swollen tip. i, acervuli with dark spines (setae) at the edge of the structure and among the conidiophores. j, oblong and single-celled conidia.
Table 3.
Cultural characteristics of Colletotrichum alatae isolates.
Fig 4.
PCR amplification of ITS gene from 8 isolates causing yam anthracnose.
a) PCR analysis using the three sets of primers. b) PCR analysis using primer set 2. 5,11,14, 16, 22 are isolates from D. alata. 24, 32 and 34 isolates D. rotundata. M, 1 kb DNA ladder, mx, DNA master mix.
Fig 5.
Phylogenetic tree showing relationships of closely related accessions with our isolates using maximum likelihood method and based on the ITS gene sequences.
OM365422 (Ca5), OM365423 (Lt1), OM365424 (Ca14), OM365425 (Ca24), OM365426 (Ca32) and OM427500 (Ca34) are isolates obtained from this study.
Table 4.
Disease incidence, disease severity score and resistance status in Dioscorea alata and Dioscorea rotundata landraces screened for anthracnose resistance.