Genetic Analysis of the Monopartite Tomato Yellow Leaf Curl Geminivirus: Roles of V1, V2, and C2 ORFs in Viral Pathogenesis

Abstract

Tomato yellow leaf curl virus (TYLCV) is a whitefly-transmitted geminivirus with a monopartite genome. We have investigated the functions of the V1, V2, and C2 ORFs by mutational analysis. We analyzed the ability of TYLCV mutants containing disrupted ORFs V1, V2, or C2 to replicate, spread, and cause symptoms in Nicotiana benthamiana and tomato plants. All the mutants retained the capability of autonomous replication in protoplast-derived cells of tomato and leaf discs of N. benthamiana, although both V1 and V2 gene products appeared to play a role in the accumulation of viral single-stranded DNA. In contrast, none of the mutants was able to systemically infect tomato plants, demonstrating that the V1, V2, and C2 gene products are all required for a successful infection process in this host. The effect of the mutation in ORF C2 appeared to be host-specific, since N. benthamiana plants were systemically infected, although symptom development was attenuated.

Geminiviruses Subvert Ubiquitination by Altering CSN-Mediated Derubylation of SCF E3 Ligase Complexes and Inhibit Jasmonate Signaling inArabidopsis thaliana

“…Among them, C2 from several begomoviruses has been shown to be needed for viral propagation (Etessami et al, 1988;Wartig et al, 1997). To confirm if this is also applicable to Tomato yellow leaf curl Sardinia virus Spain isolate (TYLCSV; accession number L27708), one of the begomoviruses responsible for the Tomato yellow leaf curl disease (TYLCD) in Spain, we constructed a null mutant virus for the C2 gene with a T-C transition in the start codon, hereafter called TYLCSV C2 T2C .…”

Mutational Analysis of Effectors Encoded by Monopartite Begomoviruses and Their Satellites

“…However, gene function has been studied extensively in other types of geminiviruses which share organization and nucleotide sequence similarities with TYLCV. Mutational analysis of few monopartite begomoviruses like TYLCV define similarities and differences between this single component geminivirus and bipartite geminiviruses in functions essential for systemic spread and infectivity [103]. The CP appeared to be required for systemic movement of TYLCV in N. benthamiana and tomato, consistent with those of mutation analyses obtained with other monopartite geminiviruses such as MSV, BCTV, and TLCV [5,12,69,61] have shown that Tomato yellow leaf curl virus-Sardinia (TYLCV-Sar) C2 can form stable complexes with ssDNA (and less preferably with dsDNA) and that the binding is sequence nonspecific.…”

“…In fact, the PQ mutants, which are unable to assemble virions, accumulate CP in leaf discs, showing that its expression and stability were not altered. Another TYLCV protein, V2, for which a role in virus assembly has recently been, suggested [103].…”

Rapid evolution of the population of begomoviruses associated with the tomato yellow leaf curl disease after invasion of a new ecological niche: a review

“…Encoded proteins are the CP (V1 ORF), the capsid protein; the replication-associated protein (Rep, C1 ORF), a protein essential for replication; the transcriptional activator protein (TrAP, C2 ORF), involved in the activation of the transcription of virus sense genes; the replication enhancer protein (REn, C3 ORF), which interacts with C1 protein enhancing viral DNA accumulation; and protein products encoded by the V2 «precoat» and C4 ORFs, that have been involved in symptom expression and virus movement. The noncoding IR region contains key elements for the replication and transcription of the viral genome including the origin of replication, within a stem-loop structure conserved in the geminiviruses (Jupin et al, 1994;Wartig et al, 1997;Noris et al, 1998).…”