Characterization of Antifungal Activity and Molecular Diversity of Trichoderma Isolates
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Date
2011
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UAS, Dharwad
Abstract
Eighty six Trichoderma isolates belonging to five species were used for
antagonism test using dual culture assay against three fungal plant pathogens viz.,
Sclerotium rolfsii, Rhizoctonia solani and Cercospora capsici. Per cent inhibition of
mycelial growth and time taken by Trichoderma isolates to overgrow the pathogen
were recorded. Trichoderma isolates showed variation in their antagonistic property
against S. rolfsii, R. solani and C. capsici. Further, these 86 isolates were grouped into
five classes viz., most efficient, efficient, moderately efficient, poor and very poor.
Three isolates IABT1242, IABT1243 and IABT1252 were grouped in most efficient
class and took less time (8 days) to overgrow on S. rolfsii, R. solani and C. capsici.
Isolate IABT1243 (T. harzianum) was most efficient against all three pathogens and
showed the highest (91.83 pmol/μg/min) chitinolytic activity at 48 hours after
induction on colloidal chitin containing medium and was significantly different from
other isolates.
Molecular diversity of twenty nine Trichoderma isolates belonging to five
different species was assessed by twenty seven RAPD primers. Genetic similarities
ranged from 49 to 83 per cent indicating substantial diversity present in the
Trichoderma isolates. Twenty nine isolates were grouped into nine clusters, among
which cluster IX was solitary. Isolates from the same region showed some similarities
in RAPD clustering in UPGMA analysis. The diversity shown by the isolates did not
correlate with the levels of antagonism shown against the pathogen. However, in few
cases the correlation was observed between the cluster formed based on RAPD and
the antagonistic property of Trichoderma isolates.
The ITS region of eleven potent Trichoderma isolates were sequenced and
confirmed that the isolates belonged to species T. harzianum, T. asperellum, T. viride
and T. atroviride. The similar clustering of Trichoderma isolates was observed
between dendrograms constructed using RAPD data and ITS sequences.
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Keywords
Plant Biotechnology