Grouping and comparison of Indian citrus tristeza virus isolates based on coat protein gene sequences and restriction analysis patterns.
Citrus tristeza virus (CTV) is an aphid-transmitted closterovirus, which causes one of the most important citrus diseases worldwide. Isolates of CTV differ widely in their biological properties. CTV-infected samples were collected from four locations in India: Bangalore (CTV-B), Delhi (CTV-D), Nagpur (CTV-N), and Pune (CTV-P), and were maintained by grafting into Kagzi lime ( Citrus aurantifolia (Christm. Swing.). All isolates produced typical vein clearing and flecking symptoms 6-8 weeks after grafting. In addition, CTV-B and CTV-P isolates produced stem-pitting symptoms after 8-10 months. The CTV coat protein gene (CPG) was amplified by RT-PCR using CPG specific primers, yielding an amplicon of 672 bp for all the isolates. Sequence analysis of the CPG amplicon of all the four Indian isolates showed 93-94% nucleotide sequence homology to the Californian CTV severe stem pitting isolate SY568 and 92-93% homology to the Japanese seedling yellows isolate NUagA and Israeli VT p346 isolates. In phylogenetic tree analysis, Indian CTV isolates appeared far different from other isolates as they formed a separate branch. Comparison among the Indian isolates was carried out by restriction analysis and restriction fragment length polymorphism (RFLP). Specific primers to various genome segments of well-characterized CTV isolates were used to further classify the Indian CTV isolates.
Roy
A
A
Advanced Center for Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, India.
Ramachandran
P
P
Brlansky
R H
RH
D000595:Amino Acid Sequence; D001483:Base Sequence; D036022:Capsid Proteins / Q000235:genetics*; D032082:Citrus aurantiifolia / Q000821:virology*; D017790:Closterovirus / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity; D017931:DNA Primers; D005814:Genes, Viral; D007194:India; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000821:virology; D012150:Polymorphism, Restriction Fragment Length; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D014774:Virulence
D036022:Capsid Proteins; D017931:DNA Primers