Isolation and characterization of a new fungal species, Fusarium equiseti (Corda) Sacc., from Brassica juncea in Bharatpur

Abstract

A field survey of emerging collar root disease incidence at farmer’s fields of Indian mustard (Brassica juncea L.) was
conducted in Bharatpur district of Rajasthan to confirm the casual organism of the disease. The pathogen from collected
diseased samples was isolated, purified and supply to Agarkar Research Institute, Pune, India for identification. Analysis
of the sequences of different fragments of the ribosomal genes demonstrated that isolated pathogen species belongs to
the Nectriaceae family and is genetically different from other morphologically similar species of Fusarium. This new
species is unique in having colonies on PDA at 25oC+ 2oC, fast growing, rosy pink to vanacous, reverse pell leuteus to
light ochraceous. As per the micromorphology, hyphae was hyaline, smooth, pigmented and 2.75-4.77μm wide. Singlespore
pure culture produced chlamydospores were intercalary, fusoid, hyaline and smooth walled. Although, macroconidia
were abundantly produced, fusoid, smooth walled, hyaline, foot cell present and sickle shaped, 2-septate with 14.59-
45.48 x 2.88-4.10μm in size. Though, microconidia were fusoid, 1-septate and 2.5-2.67 x 2.67-13.7 μm in size. As per our
studies, the fungus was morphologically identified as Fusarium equiseti (Corda) Sacc. (NFCCI 4564).