Long Sequences in the 5′ Noncoding Region of Plum Pox Virus Are Not Necessary for Viral Infectivity but Contribute to Viral Competitiveness and Pathogenesis

Abstract

The 5'-terminal 31 nucleotides of the 146-nucleotides-long 5' noncoding region of plum pox potyvirus (PPV) are highly conserved in all the members of the Potyvirus genus. To map the sequences of the 5' noncoding region that are necessary in vivo for infectivity, we have constructed a nested set of substitution and deletion mutants. While we were not able to infect Nicotiana clevelandii plants with full-length PPV transcripts bearing mutations in the 5'-terminal 35 nucleotides of the viral genome, the deletion of long sequences located between nucleotides 39 and 145 did not alter either the rate of infection or viral accumulation. Nevertheless, these mutants were not able to compete with the wild-type strain in coinoculation experiments. Plants infected with a PPV mutant that lacked nucleotides 127 to 145 showed a very mild symptomathology; the wild-type symptom severity was recovered after spontaneous second-site mutations.

Zucchini yellow mosaic virus (ZYMV, Potyvirus): Vertical transmission, seed infection and cryptic infections

“…For example, plum pox virus mutants with a sequence deletion of nt 127-145 in the 5’UTR exhibited mild symptoms (Simon-Buela et al, 1997). Similarly, a seven nt insertion in the 5’UTR region in bean common mosaic virus resulted in more severe symptoms in asparagus bean (Zheng et al, 2002).…”

Comparisons of complete RNA-2 sequences, pathological and serological features among three Japanese isolates of Arabis mosaic virus

“…These include the CP gene of Alfalfa mosaic virus (AMV) [19], Cucumber mosaic virus (CMV) [20,21], Tobacco mosaic virus (TMV) [22], Turnip crinkle virus (TCV) [23], and Potato virus Y [24], the MP gene of Brome mosaic virus (BMV) [25]. Meanwhile, the involvement of 5 0 UTR for virulence, but dispensable for infection or replication, of AMV [26], Plum pox virus [27], and Tomato aspermy virus [28] has also been described. In addition, Fernandez et al [29] have reported that the 5 0 UTR of RNA-2 of Grapevine chrome mosaic virus, a member of Nepovirus, is triggered to induce severe necrotic symptoms on three Nicotiana species.…”

Untitled

“…In the ihprolC-PP197 construct, the region of homology to PPV RNA genome spans the AUG initiation codon of the PPV polyprotein. It includes 13 nucleotides of the 5'UTR before the AUG initiation codon and the first 181 bp of the PPV polyprotein coding region, including sequences that are necessary for efficient translation [37] and part of the 18 nucleotide long sequence from base 127 to 145 reported to be required for efficient PPV-host interaction [38]. IhprolC-PP197 transgenic plants contain siRNAs of 23 and 25 bases homologous to the 197 bases of the PPV genome used in the hairpin construct.…”