Natural occurrence of trichothecene-producing Fusaria isolated from India with particular reference to sorghum.

In this study a total of 167 isolates collected
from different food materials (68.8% from sorghum and the
remaining from various other food materials) were assayed
by PCR for amplification of the tri 5 gene present in
trichothecene-producing Fusaria. Amplification of the tri 5
fragment was observed in 45 isolates (39 isolates from
sorghum and 6 isolates from vegetables). Isolates found
positive for presence of the tri 5 gene were classified into
different morphological groups based on their cultural and
conidial characters; 11 of the tri 5 positive isolates from
moldy grains of sorghum, one from each morphology
group were selected for further analyses. Five deoxynivalenol
producers and three deoxynivalenol and Fusarenon-
X producers were detected by analysing culture
filtrates of the 11 isolates using GC-MS. One isolate each
were identified as producers of NIV alone, or NIV along
with DON or DAS toxins. Identification of these isolates to
the species level was carried out using spore morphology
and sequence comparison of the translation elongation
factor 1-alpha (EF-1a) gene against the database as well as
using phylogenetic analyses. The isolates were identified as
Fusarium proliferatum (6), F. nelsonii (2), F. equiseti (1),
F. thapsinum (1) and F. sacchari (1). Amplified Fragment
Length Polymorphism (AFLP) based grouping clustered
the isolates of same species together. This is the first
detailed study of trichothecene production by Fusarium
spp. associated with sorghum grain mold in India and the
identification of F. nelsonii and F. thapsinum as producers
of trichothecenes.