MOLECULAR CHARACTERIZATION OF TOBACCO STREAK VIRUS CAUSING SUNFLOWER NECROSIS DISEASE AND ITS INTEGRATED MANAGEMENT
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Date
2017-09-18
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Sunflower necrosis disease (SND) caused by tobacco streak virus (TSV) and
transmitted by thrips is a major constraint for sunflower cultivation in India. Survey
conducted to assess the SND incidence in major sunflower growing districts of Karnataka
during 2015-17 revealed that, SND incidence and mean thrips population ranged from 0
to 28.57 per cent and 0 to 5.4 thrips per plant, respectively. The DAC-ELISA deployed to
detect TSV in weed hosts (21 species) and thrips species (Thrips palmi, Frankliniella
schultzei, Scirtothrips dorsalis). Eight weed species (Parthenium hysterophorus,
Euphorbia geniculata, Abutilon indicum, Malvastrum coromandelianum,
Acanthospermum hispidum, Phyllanthus niruri, Stachytarpheta indicum and Galinsoga
parviflora) and T. palmi tested positive for the presence of TSV. The virus causing SND
was identified by RT-PCR using newly designed RNA1, RNA2 and RNA3 specific
primers which yielded 890, 765 and 717 bp amplicons, respectively. The sequences of
GKVK isolate viz., RNA1 gene with TSV-Kad and TSV-Okra, RNA2 gene with TSVPumpkin
and TSV-FL1307, and RNA3 gene with TSV-Gulbarga and TSV-CPKAR
shared 99 per cent nucleotide similarity. Based on nucleotide sequence similarity and
phylogenetic relatedness, the GKVK-isolate identified as a strain of TSV prevalent in
India. The stability and integration of coat protein and nptII genes in T5 generation
transgenic plants of sunflower genotypes RHA 95-C-1 and NSFH-1 was confirmed by
PCR analysis. Expression of coat protein gene was confirmed by RT-PCR and ELISA.
For the management of SND, an integrated approach comprising of maize border crop
around field (15 days prior to sowing of sunflower) and seed treatment with imidacloprid
600 F.S. @ 5 mL/kg of seeds and spray of defense inducing molecule (oligocarranegen)
@ 4 mL/L along with foliar application of fipronil 5% S.C @ 1.5 mL/L at 15, 30 and 45
DAS was found effective.
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