Postharvest fruit rot of Bell pepper (Capsicum annuum L.): Pathogenicity and Host range of Alternaria alternata

Abstract

Bell pepper is a fleshy vegetable cultivated in many countries. A severe fruit rot symptom was observed on green bell pepper in the local vegetable market in New Delhi, India. Fruit rot-associated fungal pathogen isolated on culture medium showed greyish-to-olive green mycelium with prolific conidial production. The pathogenicity test on green bell pepper indicated that inoculated fungus remained quiescent for ten days, triggering typical fruit rot upon the physiological maturation of bell pepper. Based on microscopic features and sequencing of genomic loci such as ITS, Alt a1, and RPB2, the pathogen identity was established as Alternaria alternata. Annotated nucleotides sequence of three genes were deposited and assigned NCBI GenBank accession numbers. Phylogenetic analysis using the taxonomic species of Alternaria strains revealed that the isolate A. alternata Cap_Aa clustered with reference strains of Alternaria alternata. A host range study of A. alternata Cap_Aa confirmed its pathogenicity on tomatoes and eggplant. Results presented in the present work provide knowledge on pathogen identity, host range, and genetic-relationship for developing suitable fruit rot management strategies and postharvest handling in the future.