Biological and molecular characterization of Okra yellow vein mosaic virus (OYVMV) infecting okra in South Gujarat
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Date
2016
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Plant Pathology Dept., NMCA, Nau, Navsari
Abstract
Incidence of Yellow vein mosaic disease (YMD) of the Okra ranging from 1050 per cent in the different field of NAU as well as the adjoining area was observed during the survey in 2015 in late winter to summer. Total seven different fields of Okra in the villages around the Navsari Agricultural University, viz., Allu, Vankaner, Sejvad, Hathuka, Bhatlav, shiker and Delvada were surveyed. The crop grown in the Vegetable Research Farm of NAU, Navsari in open fields was also surveyed. The disease appeared with the appearance of true leaves and was seen at all the stages of the growth. YMD in okra appeared with the appearance of true leaves and was seen at all the stages of the growth. The initial symptoms on young leaves were diffuse and mottled in appearance. Clearing of the small veins starts near the leaf margins, at various points however, were more pronounced towards the petiole end as compared towards the expanded margins of the leaf. Gradually the yellowing increases covering the interveinal area and entire leaf appeared yellow. In few cases the leaf necrosis has also been reported. Fruit, stem and above ground parts of the infected plants also turned yellow in color. Early infected plant remains dwarf. Market acceptability of the yellow colored fruits reduced
severely causing enormous economic loss. In some of the plants no green colour symptoms were seen, however, had another type of symptoms principally characterized by the vein thickening. Plant if seen from the top or side, appeared rough, rugose, dark green and dwarfed. In case of severe infection the entire leaf crumpled, curled inside, petiole bend and even cannot hold leaf up. Swelling of the vein and enation can also be seen on the backside of the leaf. In graft transmission the similar symptoms were also observed, however, the vein thickenings were not observed. In PCR A ~1200 bp band of DNA-A molecule was obtained by the Begomovirus specific primers. On sequencing the virus had maximum 98 per cent sequence homology with the Okra yellow vein mosaic virus isolate Aurangabad (GU181356.1), therefore, it was considered as a strain of this virus only. Accordingly the sequenced isolate has been considered as tentative strain of Okra yellow vein mosaic virus [Aurangabad] and named as Okra yellow vein mosaic virus [Aurangabad] [India:Nvs:Okra:2016] and was abbreviated as OYVMV [Aurangabad] [India:Nvs:Okra:2016]. Study of the Phylogenetic tree of the viruses from the different crops and geographical area revealed that the virus isolated and sequenced during the present investigation is closely related to the viruses of okra and cotton from the different parts of the world.
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