Partial Characterization of a Badnavirus Associated with Citrus Yellow Mosaic Disease in India

Abstract

A previously undescribed badnavirus was found to be associated with a yellow mosaic disease occurring commonly in citrus orchard trees and nursery plants in India. The virus was graft and dodder transmitted to 14 of 15 citrus species or cultivars, and was also transmitted mechanically from citrus to citrus. A protocol for the purification of citrus yellow mosaic virus was developed. By electron microscopy, the virus particles were found to have the bacilliform structure typical of badnaviruses. In ultrathin sections, the virions were observed in the cytoplasm of diseased tissue but not in the nucleus. Electrophoresis of enzyme-digested viral nucleic acid preparation revealed it to be DNA. The virus was also shown to have a dsDNA genome by PCR amplification using degenerate oligonucleotide primers based on conserved badnavirus genome sequences. The virus was named citrus yellow mosaic bacilliform virus (CYMBV). A homologous antiserum specifically reacted to CYMBV antigen in DAS-ELISA and IEM tests. In IEM tests, CYMBV was found to be related serologically to sugarcane bacilliform badnavirus and to eight other badnaviruses. Mixed infections of CYMBV, tristeza and Indian citrus ringspot were common in orchard trees.