Virulence
and genetic diversity of Sclerotium rolfsii Sacc., infecting groundnut
using nuclear (RAPD & ISSR) markers
M.
Daniel Jebaraj*, K. Eraivan Arutkani Aiyanathan and S. Nakkeeran
Department of
Plant Pathology, Centre for Plant Protection Studies, Tamil Nadu Agricultural
University, Coimbatore-641 003, India
*Corresponding
Author E-mail: daniel.jebaraj2011@gmail.com
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Key
words
Genetic diversity,
Groundnut, ISSR,
RAPD, Sclerotium rolfsii,
Virulence
Publication Data
Paper received : 24.02.2016
Revised received : 14.06.2016
Re-revised received : 10.10.2016
Accepted : 24.10.2016
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Abstract
Aim : Assess the
virulence and genetic diversity of Sclerotium rolfsii isolates causing
stem rot disease in groundnut collected from different geographical regions
of Tamil Nadu using nuclear markers viz., RAPD and ISSR.
Methodology
:
Survey was conducted in major groundnut growing areas of Tamil Nadu and
twenty two cultures of S.rolfsii (18 from groundnut and 4 from other
crops) were collected and isolated. Subsequently the virulence of S.rolfsii
was tested. Genomic DNA was extracted from S.rolfsii isolates and
assessed their genetic diversity using nuclear markers viz., RAPD and
ISSR.
Results
:
Among the 22 isolates of S. rolfsii, the isolate from Udumalpet
(SrUDM) showed higher per cent disease incidence (80.95%) followed by K.G.
Savadi (SrKGS) and Tindivanam (SrTVM) isolates (61.90%), whereas the isolate
from Madurai recorded lower per cent disease incidence (33.33%). ITS region
of rDNA amplification with specific ITS-1 and ITS-4 universal primers
produced the amplicon of approximately 650 to 700 bp and confirmed that all
the 22 isolates belongs to the genus Sclerotium. Ten different oligonucleotide
primers of RAPD and ISSR were used to assess the genetic diversity among 22
isolates of S. rolfsii. The dendrogram results indicated that all the S.
rolfsii isolates from Tamil Nadu formed two distinct clusters. A total of
121 and 123 reproducible and scorable polymorphic bands recorded and ranging
from 100 to 2500 bp and 250 to 2000 bp were generated with ten numbers of
RAPD and ISSR primers, respectively. The ISSR marker recorded an average PIC
of 0.87 as against 0.86 of RAPD and the effective multiplication ratio was
also superior in ISSR (12.21) compared to RAPD (12.00).
Interpretation : The result of the
present study indicated that ISSR markers were suited well for genetic
diversity studies of S. rolfsii than RAPD and no correlation was
observed between the virulence and genetic diversity of various S. rolfsii
isolates using? nuclear markers.
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