Distribution and characterization of Colletotrichum species associated with Citrus anthracnose in eastern Mediterranean region of Turkey

Citrus are economically important fruit crops produced worldwide. Anthracnose, post bloom fruit drop, and stem-end rot of fruit caused by Colletotrichum species are diseases that seriously threatens citrus production in Turkey. Surveys conducted in 2016–2017 allowed the detection of typical symptoms of anthracnose of the visited fields (126 among 203) in the citrus production area of the Eastern Mediterranean region of Turkey. A total of 194 Colletotrichum strains were obtained from different citrus cultivars, including lemon (85), mandarin (73), orange (30), sour orange (1) and grapefruit (5) and different plant tissues (twigs (90), leaves (84) and fruits (20)). A multi-locus phylogeny was established based on four genomic loci (ITS, GAPDH, ACT, CHS­1), and the morphological characters of the isolates were determined. Based on morphological characters and phylogenetic analysis, isolates were identified as belonging to C. gloeosporioides and C. karsti. Pathogenicity trials showed that, both species were able to colonise leaves, twigs, and fruits of the susceptible cultivar Interdonato of Citrus limon. Symptoms that developed on inoculated tissues were similar to those observed in the field on naturally infected citrus plants. Pathogenicity trials showed that C. gloeosporioides was more virulent on twigs and leaves, and C. karsti on fruits. To the best of our knowledge, this is the most comprehensive study on identification and characterization of C. gloeosporioides and C. karsti associated with citrus anthracnose in Turkey.