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Pathogenicity properties of some fungal species from Colletotrichum acutatum species complex

Julija Vilcane: University of Latvia

<div>Molecular tools have been extensively used for identification of fungal species in <em>Colletotrichum acutatum</em> species complex, while the differences in their pathogenicity and virulence in crop plants are not sufficiently studied. The aim of the study was to compare morphological progress of infection by <em>C.godetia</em>, <em>C.nymphae</em> and <em>C.fiorianei</em> on artificially inoculated apple fruits, with the changes in levels of jasmonic (JA) and salicylic acid (SA) as measured by HPLC-MS. Apples cv. ‘Honeygold’ were wound-inoculated with the 0.5 mm<sup>2</sup> pieces of fungal mycelia and stored in sealed plastic boxes at 21 °C for three weeks, along with the non-wounded and wounded, but non-inoculated controls. Inoculations with <em>Penicillium expansum</em> and <em>Monilinia fructigena</em> were done. Similar size lesions developed on apple surface after inoculation with all the three <em>Colletotrichum</em> species. Differences in the sporulation were observed on lesion surface, and the levels of SA and JA were significantly higher in samples with <em>Colletotrichum</em> sporulation. HPLC-MS analysis revealed a relatively higher expression of JA in apples inoculated with <em>Colletotrichum</em> compared to samples inoculated with <em>M.fructigena</em> and <em>P.expansum</em>, as well as, in both controls. Significantly higher level of JA was detected in a sample inoculated with <em>C.fiorianei</em> (isolated from strawberry), while increase in JA was also observed in a sample inoculated with <em>C.fiorianei</em> (from raspberry and blueberry). Significantly higher levels of SA were measured in samples inoculated with <em>C.fiorianei</em> from strawberry, raspberry and blueberry. Overall, the results indicated significant link between levels of JA and SA in apple fruits, and the infection by <em>Colletotrichum</em> <em>fiorianei</em>.</div>