Fig. 1. Symptoms of Glomerella leaf spot (GLS) on apple. (A) Initial brown to ochre necrotic leaf lesions and (B) advanced, irregular and necrotic leaf lesions associated to chlorosis. (C) Fruit lesions surrounded by a red border. (D) Random distribution of leaf lesions in the tree. (E) Random distribution of symptoms in the orchards and severe defoliation in cv. Galaxy and (F) cv. Cripps pink. (G) Reproductive structures of Colletotrichum spp. over leaf lesion (black arrow). Structures present on leaves with typical symptoms of Glomerella leaf spot disease, collected from apple orchards. Detail of (H) acervuli and (I) perithecia. Micrsocopic detail of crushed (J) acervulus showing conidiphore and conida and (K) peritecium showing asci and ascospores.
Fig. 2. Colony morphology of Colletotrichum fructicola isolate F71 (right) with abundant black perithecia and of C. karstii isolate L51 (left) after three weeks growing on PDA.
Fig. 3. Maximum likelihood phylogenetic tree generated from conctenated actine, β-tubulin and glyceraldehyde-3-phosphate dehydrogenase sequences alignment of 46 Uruguayan isolates obtained from leaf (indicated with L) and fruit (indicated with F) of apple with GLS (Glomerella Leaf Spot) symptoms. Sequences of the representative species of Colletotrichum boninense and C. gloeosporiodes species complexes extracted from GenBank (ex-type are indicated as bold) were included. C. acutatum CBS 112996 was used as the outgroup. Bootstrap support values of maximum likelihood and maximum parsimony are shown at the nodes before and after the bar, respectively.
Fig. 4. Pathogenicity tests on twigs and leaves of apple cv. Galaxy and fruits cv. Cripps pink. (A) Twigs used as control ten days after inoculation with steril destiled wather. (B) Initial symptom on leaves three days after inoculation with the isolate L49 of Colletotrichum fructicola. (C) Detail of initial symptoms on leaves. (D) Necrotic lesions on leaves and presence abundant acervuli on leaf seven days after inoculation with the isolate F71 of C. fructicola. (E) Necrotic lesions on destached leaves seven days after inoculathion with the isolate L53 of C. fructicola (above) and leaves used as control (below). (F) Mild defoliation ten days after inoculation with the isolate L51 of C. karstii. (G) Severe defoliation ten days after inoculation with the isolate L49 of C. fructicola. (H) Lesions fruit (black arrows) 21 days after inoculation with the the isolate L53 of C. fructicola. (I) Detail of lesions fruit (J) Ascospore germinated of isolate L49 of C. fructicola after 12 hours of inoculation on apple leaf; (a) ascospore, (gt) germination tube and (ap) appressoria.
Table 1. Isolates of Colletotrichum, host and cultivar, isolation organ, origin and GenBank accession no. of isolates of apple generated in this study and obtained from GenBank
Table 2. Result of pathogenicity test of Colletotrichum fructicola and C. karstii isolates on apple leaves cv. Galaxy and apple fruits cv. Cripps pink
Table 1. Continued
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