Pathogenicity, Morphology, and ITS-Based Identification of Mucor and Rhizopus Species Causing Post-Harvest Rot of Strawberry

Abstract

Pathogenicity, morphology, and ITS-based identification of Mucor and Rhizopus species causing post-harvest rot of strawberry were investigated to determine the causal agents, their diversity, and infection potential. Rotten strawberry fruits exhibiting soft rot, watery decay, surface mycelial growth, and rapid tissue disintegration were collected from storage and market environments. Fungal isolates were obtained and characterized based on cultural and morphological features including colony growth pattern, sporangiophore structure, sporangia formation, and spore morphology. Pathogenicity tests were performed on healthy strawberry fruits under controlled conditions to confirm Koch’s postulates and assess virulence differences among isolates. Results revealed that both Mucor and Rhizopus species were consistently associated with post-harvest fruit rot, with Rhizopus spp. generally exhibiting higher aggressiveness and faster colonization. Molecular identification using internal transcribed spacer (ITS) region sequencing confirmed species-level identity and revealed genetic variability among isolates. Phylogenetic analysis grouped isolates into distinct clades corresponding to known Mucorales taxa, supporting morphological identification while resolving cryptic variation. Pathogenicity assays demonstrated significant differences in lesion size, decay rate, and sporulation intensity among isolates, indicating variable virulence within and between species. The study highlights the importance of integrated morphological and molecular approaches for accurate identification of post-harvest fungal pathogens. These findings emphasize the need for improved post-harvest handling, cold storage management, and sanitation practices to reduce losses caused by Mucor and Rhizopus species in strawberry supply chains.