Incidence, Characterization and Pathogenicity of Seed-Borne Fungi of Lentil (Lens culinaris L.) in Pakistan

Abstract

Lentil (Lens culinaris Medik.) is an important protein-rich Rabi pulse crop after chickpea in Pakistan. Its area and production in the country is decreasing drastically due to its susceptibility to various biotic and abiotic stresses. Among biotic-stresses, seed-borne fungi are the most imperative issue and the accurate identification and characterization of target pathogen isolates/races is crucial for the management of plant diseases in lentils. Therefore, the current study was performed to identify the fungi associated with lentil seeds, to confirm their pathogenicity and to assess their incidence. For this purpose, isolation of fungal pathogens was made on potato dextrose agar medium (PDA) from 56 Lens culinaris L. genotypes. These pathogens were characterized using morphological and molecular techniques and their pathogenicity was performed following blotter paper and agar plate method. Seven fungi belonging to five genera were isolated from lentil seeds (Fusarium avenaceum, Alternaria alternata, Aspergillus flavus, Aspergillus niger, Aspergillus tubingensis, Penicillium citrinum and Bipolaris sorokiniana) of different genotypes. Of these seven fungal species, F. avenaceum, A. tubingensis and B. sorokiniana are new records for lentil seeds from Pakistan.  Aspergillus flavus was found to occur in high frequency followed by A. niger, F. avenaceum, P. citrinum, A. alternata, A. tubingensis and B. sorokiniana. Under pathogenicity test on blotter paper and on PDA F. avenaceum, A. flavus, A. niger, A. tubingensis were highly pathogenic, while A. alternata, P. citrinum and B. sorokiniana were found to be less pathogenic. The presence of well-known toxigenic fungal pathogens in lentil seeds suggests the possible risk of contamination of the seeds and enhances the possibility of pre- and post-infections of crop. Therefore, the present study will help to devise effective management strategies to reduce contamination in seeds and also to control the further spread of these pathogens to reduce crop losses.