Morphological and Molecular Characterization of Colletotrichum gloeosporioides Causing Anthracnose on Passion FruitMorphological and Molecular Characterization of Colletotrichum gloeosporioides Causing Anthracnose on Passion Fruit

Abstract

Anthracnose symptoms characterized by dark sunken lesions, fruit rot, stem dieback, and premature fruit drop were observed in passion fruit (Passiflora edulis) plantations, leading to severe yield and quality losses under humid tropical conditions. Diseased fruit and stem samples collected from affected orchards were used for pathogen isolation and characterization through morphological, pathogenicity, and molecular approaches. Fungal isolates consistently produced fast-growing white to gray colonies that later developed orange to salmon-pink conidial masses typical of Colletotrichum species. Microscopic examination revealed cylindrical, hyaline, aseptate conidia consistent with the diagnostic features of Colletotrichum gloeosporioides. Considerable variation in colony morphology, sporulation intensity, and lesion development was observed among isolates obtained from different passion fruit-growing regions. Pathogenicity assays conducted on healthy fruits reproduced typical anthracnose symptoms, including sunken necrotic lesions and rapid fruit decay, whereas control fruits remained symptom-free. Re-isolation of the fungus from inoculated tissues fulfilled Koch’s postulates, confirming its pathogenic role. Molecular characterization was performed using amplification and sequencing of the internal transcribed spacer (ITS) region along with additional conserved loci such as β-tubulin and actin genes. Sequence analysis revealed high similarity with authenticated C. gloeosporioides isolates available in global databases. Phylogenetic analysis grouped field isolates within the C. gloeosporioides clade with strong bootstrap support, confirming species identity and revealing limited genetic variability among regional populations. Disease development was favored by high humidity, warm temperatures, and frequent rainfall, which enhanced spore germination and infection efficiency. Severe infections resulted in significant fruit losses and reduced marketability. The integration of morphological and molecular tools provided accurate identification and improved understanding of pathogen variability and epidemiology.