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ASSESSMENT OF GENETIC DIVERSITY AND SEED TRANSMISSION OF MANDARIVIRUS INFECTING CITRUS

KrishiKosh

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Title ASSESSMENT OF GENETIC DIVERSITY AND SEED TRANSMISSION OF MANDARIVIRUS INFECTING CITRUS
Ph D
 
Creator PRABHA K.
 
Subject fruits, biological phenomena, genomes, rna, sowing, planting, genetic structures, viruses, proteins, diseases
 
Description T-8386
Indian citrus ringspot disease is a common disease in Kinnow mandarin in
Indian citriculture. The major symptom of the disease is appearance of conspicuous
yellow rings on mature leaves in its natural host citrus. The disease is caused by a
flexuous virus, Indian citrus ringspot virus (ICRSV) of the genus Mandarivirus. A
detailed study involving biological, serological and molecular assay of ten samples of
citrus collected from different regions of India was done. In the bioassay, variability was
observed in the symptoms produced on grafted plants. The Jaffa orange cultivar from
Ganganagar showed vein flecking on younger leaves and the maturing leaves produced
light greenish water soaked like round spots on leaves of grafted plants while other
isolates produced typical ringspot symptoms. Virus isolates from all citrus cultivars were
not transmissible to French bean (Phasiolus vulgaris var singtamy) mechanically as also
confirmed by ELISA. Of the seven isolates sap inoculated, only four isolates produced
the symptoms and three of them were positive for ICRSV in ELISA. Electron
microscopic studies of graft inoculated leaves revealed flexuous particles of size 600-
650nm in the leaf samples of the six cultivars. Leaf samples of different symptomatic
citrus cultivars showing characteristic yellow rings showed variable results in ELISA for
ICRSV. All the cultivars which showed positive reaction in ELISA were also positive in
RT-PCR using ICRSV specific primers. Variable results were obtained in the RT-PCR
amplification of genomic region using two sets of virus specific primers from ORF5 and
ORF6 of ICRSV. ICRSV distribution study in citrus plant showed leaves and buds as
major pool of the virus indicating that the source of horizontal transmission of the virus to
other citrus plants is budwood. Distinct symptomatology, transmission, ELISA and RTPCR
assay results indicated these isolates can be either different strains of ICRSV or
different species of genus Mandarivirus.
 
Date 2016-11-01T09:08:46Z
2016-11-01T09:08:46Z
2011
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/83059
 
Format application/pdf
 
Publisher IARI,DIVISION OF PLANT PATHOLOGY