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Diversity and phylogeography of begomovirus-associated beta satellites of okra in India

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Title Diversity and phylogeography of begomovirus-associated beta satellites of okra in India
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Creator Venkataravanappa, V., Lakshminarayana Reddy, C.N., Swaranalatha, P., Salil Jalali, Rob W. Briddon and Krishna Reddy, M
 
Subject Geminivirus, Begomovirus, Betasatellites, Diversity, Okra, Recombination
 
Description Not Available
Background: Okra (Abelmoschus esculentus; family Malvaceae) is grown in temperate as well as subtropical regions
of the world, both for human consumption as a vegetable and for industrial uses. Okra yields are affected by the
diseases caused by phyopathogenic viruses. India is the largest producer of okra and in this region a major biotic
constraint to production are viruses of the genus Begomovirus. Begomoviruses affecting okra across the Old World
are associated with specific, symptom modulating satellites (beta satellites). We describe a comprehensive analysis
of the diversity of beta satellites associated with okra in India.
Results: The full-length sequences of 36 beta satellites, isolated from okra exhibiting typical begomovirus
symptoms (leaf curl and yellow vein), were determined. The sequences segregated in to four groups. Two
groups correspond to the beta satellites Okra leaf curl beta satellite (OLCuB) and Bhendi yellow vein beta
satellite (BYVB) that have previously been identified in okra from the sub-continent. One sequence was distinct
from all other, previously isolated beta satellites and represents a new species for which we propose the name
Bhendi yellow vein India beta satellite (BYVIB). This new beta satellite was nevertheless closely related to BYVB
and OLCuB. Most surprising was the identification of Croton yellow vein mosaic beta satellite (CroYVMB) in okra;
a beta satellite not previously identified in a malvaceous plant species. The okra beta satellites were shown to
have distinct geographic host ranges with BYVB occurring across India whereas OLCuB was only identified in
northwestern India. Okra infections with CroYVMB were only identified across the northern and eastern central
regions of India. A more detailed analysis of the sequences showed that OLCuB, BYVB and BYVIB share highest
identity with respect bC1 gene. bC1 is the only gene encoded by beta satellites, the product of which is the
major pathogenicity determinant of begomovirus-beta satellite complexes and is involved in overcoming host
defenses based on RNAi.
Conclusion: The diversity of beta satellites in okra across the sub-continent is higher than previously realized
and is higher than for any other malvaceous plant species so far analyzed. The beta satellites identified in okra
show geographic segregation, which has implications for the development and introduction of resistant okra
varieties. However, the finding that the bC1 gene of the major okra beta satellites (OLCuB, BYVB and BYVIB)
share high sequence identity and provides a possible avenue to achieve a broad spectrum resistance.
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Date 2019-03-29T07:45:26Z
2019-03-29T07:45:26Z
2011-08-01
 
Type Journal
 
Identifier 42
Not Available
http://krishi.icar.gov.in/jspui/handle/123456789/17775
 
Language English
 
Relation Not Available;
 
Publisher Not Available