STUDIES ON MOLECULAR DIVERSITY IN Fusarium spp. CAUSING POMEGRANATE WILT
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Date
2011
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MPKV, UNIVERSITY LIBRARY RAHURI
Abstract
Pomegranate (Punica granatum L.) a hardy evergreen to
deciduous shrub tending to be a tree is an ecologically adopted
species to dry climate. It belongs to family Punicaceae, which is
known as Anar in Hindi and Dalimb in Marathi. The ancient world
fruit originated in Persia, Iran, Afghanistan and Baluchistan (DeCandolle,
1967).
The present investigations were carried out on wilt of
pomegranate caused by Fusarium oxysporum in respect of
occurrence, symptomatology, isolation of pathogens, pathogenicity,
identification of pathogen, morphological studies and molecular
diversity in vitro.
Wilted pomegranate plants were collected from
Sangamner Tahsil of Ahmednagar District, Devala, Malegaon and
Satana Tahsils of Nashik District. Baramati tahsil of Pune District,
Jat tahsil of Sangli District and Pandarpur tahsil of Solapur
District. The sample were collected from the orchard grown under
drip irrigation method. The plants showing partial wilting, typical
yellowing and wilting symptoms were digged out and the root
samples were brought to laboratory for further studies.
The symptoms of the disease were characterized as
change in colour of young leaves from dark green to light green and
finally become yellow. In advance stage, leaves dry and finally
entire plant wilt and died.
The isolation of the fungus was carried out from the
infected root and bark of collar region of wilted plants. The
pathogenicity of the isolated fungus was proved by culture filtrate
method.
The morphological characters of the pathogens were
studied. The fungal pathogen i.e. Fusarium oxysporum produced
cottony white mycelium which was branched, septate and hyaline.
The macro-conidia were fusiform, curved or falcate and septate
while the micro-conidia were usually oval, hyaline and mostly a
septate. The mycelium was septate hyaline, profusely branched
measured 1.15-4.15 µm in width. Chlamydospores produced in all
the isolates were vary in their diameter which ranged from 4.56 to
9.82 µm. The length and breadth of macrocondia were in the range
of 8.92-28.26 µm and 0.92-3.72 µm respectively while length and
breadth of microconidia were in the range of 2.94-5.84 µm and
0.69-2.31 µm, respectively.
In the pathgoenicity test of the isolates of Fusarium
oxysporum was determined by culture filtrate method in-vitro.
Times taken for wilting of plants were different with different
isolates.
For determination of molecular variability in Fusarium
oxysporum total number of 16 fungal primers were used out of
these 16 primers were polymorphic primers. There were total 204
number of band generated out of which 114 bands were
polymorphic bands and 88 bands were unique bands showing
55.88 per cent polymorphism in general.
Out of 16 primers used primers Rfa-2, Rfa-5, Rfa-10,
Rfa-13, Rfa-14 and Rfa-16 were best for variability study as they
generated more polymorphic bands. Rfa-5, Rfa-10, Rfa-13, Rfa-14
and Rfa-11 showed 81.81, 69.23, 69.23, 72.72, 85.71 and 66.66
per cent polymorphism respectively. According to tree dendrogram
and 2-D scatter plot analysis the Sangmner and Baramati isolates
are closely related to each other than the isolate of Jat, while the
Malegaon, Deola and Satana isolates were closely related to each
other than Pandharpur isolate. Finally, according to all 2D-scatter
and tree dendrogram analysis it was clear that Sangamner,
Baramati and Jat isolates was distinct from remaining four isolates
viz., Pandharpur, Malegaon, Deola and Satana isolates.
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