IDENTIFICATION OF GENES INVOLVED IN REPLICATION AND MOVEMENT OF PEANUT CLUMP VIRUS

The genome of peanut clump pecluvirus (PCV) consists of two messenger RNA components which contain, respectively, three and five open readin g frames (ORFs). Inoculation of transcripts from full-length cDNA clon es derived from the PCV RNAs showed that RNA-I is able to replicate in the absence of RNA-2 in protoplasts, but: both RNAs are necessary for plant infection. To investigate the role of different gene products i n viral RNA replication and movement, transcripts from mutant cDNA clo nes were inoculated to protoplasts and to Chenopodium quinoa or Nicoti ana benthamiana plants, and progeny RNA was detected by Northern blot analysis. The protein P15, encoded by the third ORF of RNA-I, is essen tial for efficient replication of the viral genome. The three proteins , P51, P14, and P17, of the triple gene block contained in RNA-2 are i nvolved in localized movement of the viral genome, whereas the coat pr otein (P23] is also required for Vascular movement. Insertion of the P -glucuronidase reporter gene (GUS) in place of the P23 or P39 genes (t he first and the second genes of RNA-2] allows visualization of the vi rus infection in inoculated leaves. Although the presence of the GUS g ene resulted in a lower accumulation of progeny RNA and, despite insta bility of the construct in planta, histochemical detection of PCV mult iplication was more sensitive than Northern blot detection. (C) 1998 A cademic Press.