Molecular Plant Pathology On-Line [http://www.bspp.org.uk/mppol/1998/1019sanchez]

The top component of citrus psorosis virus contains two ssRNAs, the smaller encodes the coat protein

Sánchez de la Torre, E 1 Riva, O.1, Zandomeni, R.2, Grau, O.1,2
and M. L. García1

1Instituto de Bioquímica y Biología Molecular (IBBM), Facultad de Ciencias Exactas, UNLP, - 2Centro de Investigación en Ciencias Agropecuarias, Instituto Nacional de Tecnología Agropecuaria.

Sánchez de la Torre, María Eugenia. E-mail: eugenia@biol.unlp.edu.ar
Zandomeni, Rubén. E-mail: zandomeni@inta.gov.ar
Grau, Oscar. E-mail: grau@biol.unlp.edu.ar

Corresponding author: García, María Laura. Instituto de Bioquímica y Biología Molecular (IBBM), Facultad de Ciencias Exactas, UNLP. Fax number: +54-21-259223 E-mail: garcia_m@biol.unlp.edu.ar

ABSTRACT


Citrus psorosis virus (CPsV) is associated with a widespread and damaging disease of citrus in many parts of the world. Here we show that one isolate of CPsV, called citrus ringspot virus (CtRSV-4), contains at least three genomic RNAs, two of them (RNA 2 and RNA 3) are found in the top component and the largest (RNA 1) in the bottom component. RNA 3, the smallest RNA, was cloned and a partial sequence of 1454 nucleotides was determined. One open reading frame (ORF) was found, which encodes a 439 amino acid protein with a MW of 48,654. This was identified as the coat protein by expressing part of the ORF in E. coli and detecting the product in western blots using an antiserum specific for the virions. Analyses by Northern blot show that both positive and negative strands of CPsV RNA 3 are encapsidated, the negative strand much more abundantly, thus defining the negative strand as the viral (v) RNA. No subgenomic RNAs were found.