GENOME CHARACTERIZATION AND DEVELOPMENT OF DIAGNOSTICS OF CITRUS YELLOW VEIN CLEARING VIRUS (CYVCV) ASSOCIATED WITH CITRUS IN INDIA
Loading...
Date
2017
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Citrus yellow vein clearing virus (CYVCV) belongs to genus Mandarivirus,
produces conspicuous yellow vein clearing symptoms on Etrog citron and was first
reported in 1997 in India. Our study indicated that it is not confined to Etrog citron
and produces chlorotic irregular ring spots on other citrus species such as kinnow
mandarin and sweet orange and mimic the symptom of Indian citrus ringspot virus
(ICRSV). The virus was initially identified by the RT-PCR using degenerate primer
designed from RdRp gene of the alphaflexiviruses. The complete genome sequence of
four isolates of CYVCV (ECAI;_RMGI; PALI and KPMI) were determined
following overlapping primers strategy and sequences of 5’ & 3’ ends was obtained
by RACE. Genome of all the Indian isolates were of 7531 nucleotide long excluding
the 3’poly (A) tail and comprises of six open reading frames. The phylogenetic
analysis indicates that ICRSV is the most closely related virus and shares 72% overall
sequencing identity at nucleotides level, while the CP gene shared identity of 73.8 to
74.2% nucleotide level and 80.7 to 81.3% amino acid level with the ICRSV K1
isolate. Based on molecular and serological features both the viruses are distinct but
with regard of genome organization, virion particles and host range they shares
similarity. Genetic distance among the Mandarivirus was 0.025+ 0.009 in Indian
CYVCV isolates. The recombination analysis revealed stable nature of the genome
and found some traces of recombination events. To gain insight into biodiversity and
molecular variability of virus, surveys were conducted during 2012 to 2014 of citrus
orchards in various geography of India. Forty isolates were examined and diverse
symptoms, viz. irregular ring spots, yellowing of veins and vein lets, water soaking of
veins, leaf distortion and mottling, necrosis, conspicuous ringspots, chlorotic spots
and mixed infection governed mosaic like patterns on different citrus cultivars were
observed. Some of these symptoms may be governed by mixed infection of viruses.
Further, to determine molecular variability, coat protein was targeted in RT-PCR and
from fifteen isolates the CP sequences of CYVCV were retrieved and submitted to
NCBI database. The pair wise analysis of the coat protein sequences showed 96 to
99% homology with the CYVCV-ECAI isolate and 73% sequence identity with the
ICRSV isolates. In phylogenetic tree all isolates of the CYVCV clustered together on
Description
t 9652
Keywords
null