Characterization and Pathogenicity of Colletotrichum gloeosporioides and C. karstii Causing Preharvest Disease on Citrus sinensis in Italy

Abstract

During the period from 2010 to 2013 preharvest symptoms were detected on different cultivars of sweet orange in six orchards in Catania, Siracusa and Enna provinces, Southern Italy. A total of 56 monosporic fungal isolates were obtained, and among these, 44 were identified as Colletotrichum gloeosporioides and 12 as C. karstii through morphological and molecular analysis. PCR with primers ITS1 and ITS4, primers TubGF1 and TubGR specific for β‐tubulin gene, primers GDF‐GDR, specific for Glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) gene, were used to confirm the identification of Colletotrichum isolates from citrus. The ITS1‐5.8S‐ITS2 region, a portion of approximately 500 bp of β‐tubulin gene and a fragment of 220 bp of GAPDH gene of the isolates were sequenced and analysed with the BLASTn program. Koch's postulates were fulfilled by pathogenicity tests carried out on fruit of ‘Tarocco Scirè’ and ‘Tarocco Nucellare’ with representative isolates of C. gloeosporioides and C. karstii. Field surveys and pathogenicity tests revealed significant differences in fruit susceptibility between ‘Tarocco Scirè’ and ‘Tarocco Nucellare’ and in virulence between the fungal species. To our knowledge, this is the first report on the emergence of Colletotrichum spp. causing anthracnose in preharvest conditions.

Characterisation and pathogenicity of fungal species associated with branch cankers and stem-end rot of avocado in Italy

“…In the field, severe symptoms of canker were observed on branches, shoots and fruit of 'Hass' avocado. Based on our results, the diversity of fungal species associated with symptoms is similar to that reported from other avocado-growing areas worldwide (Hartill and Everett 2002;McDonald and Eskalen 2011;Menge and Ploetz 2003) and also has congruence with reports of pathogens isolated from similar diseases of other tropical plants in Italy (Ismail et al 2013;Aiello et al 2015). The most frequently isolated species from both branch cankers and fruit stem-end rot was N. parvum.…”

“…as being more virulent than other Colletotrichum spp. (Aiello et al 2015). Colletotrichum fructicola, recently described by Prihastuti et al (2009), is reported worldwide, but centered in Asia, where it is associated with diseases on coffee and pear Velho et al 2015).…”

“…and Colletotrichum spp. are reported as pathogens on some plant species in southern Italy (Lombard et al 2014;Aiello et al 2015), but characterization of the causal species on avocado has not been ascertained in southern Italy. Furthermore, the taxonomic status of species within the Botryosphaeriaceae, Diaporthaceae and the genus Colletotrichum was recently revised using molecular methods (Crous et al 2006;Cannon et al 2012;Udayanga et al 2012).…”

Genetic diversity ofColletotrichum gloeosporioidesspecies complex associated withCitruswither‐tip of twigs in Tunisia using microsatellite markers

“…In addition, other Colleotrichum spp., such as C. acutatum , C. karstii, C. novae‐zelandiae, C. catinaense, C. helleniense, C. hystricis, C. limonicola, C. kahawae subp. ciggaro and C. citri‐maximae , and including several new species, have been recovered in Citrus in Italy, Portugal, Greece, Spain and Malta (Aiello et al, ; Douanla‐Meli & Unger, ; Guarnaccia et al, ; Perrone et al, ). Colletotrichum karstii has especially been involved with Citrus anthracnose symptoms on fruits (Aiello et al, ; Guarnaccia et al, ).…”

“…The disease has also been reported in Japan, Uruguay, Argentina, Brazil, South Africa, California, China, India, Australia and New Zealand (Achbani, Benbouazza, & Douira, ; Mayorquin et al, ). Anthracnose symptoms included spots on orange fruits and mandarin leaves in Italy (Aiello et al, ; Perrone, Magistà, & Ismail, ) and wither‐tip of twigs on orange trees in Tunisia (Rhaiem & Taylor, ).…”