Tomato Bushy Stunt Virus Spread Is Regulated by Two Nested Genes That Function in Cell-to-Cell Movement and Host-Dependent Systemic Invasion

• Published in: Virology (New York, N.Y.) Vol. 213; no. 2; pp. 425 - 438
• Main Authors: SCHOLTHOF, HERMAN B., SCHOLTHOF, KAREN-BETH G., KIKKERT, MARJOLEIN, JACKSON, A.O.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10-11-1995
• Subjects: Base Sequence; CAPSICUM ANNUUM; GENE; GENES; Genes, Plant; HOTE; HUESPEDES; INFECCION; INFECTION; Molecular Sequence Data; MOUVEMENT; MOVIMIENTO; Mutation; NICOTIANA; Nicotiana - virology; Phenotype; Plants - virology; Plants, Toxic; PODER PATOGENO; POUVOIR PATHOGENE; PROTEINAS; PROTEINE; Solubility; SPINACIA; SPINACIA OLERACEA; TOMBUSVIRUS; Tombusvirus - genetics; Tombusvirus - physiology; Transcription, Genetic; Viral Proteins - genetics; Viral Proteins - physiology; VIRUS DE LAS PLANTAS; VIRUS DES VEGETAUX; Virus Replication
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1006/viro.1995.0015

We have investigated the importance of two small nested genes (p19 and p22) located near the 3′ end of the genome of tomato bushy stunt virus (TBSV) for infectivity in several hosts. Our results show that both genes are dispensable for replication and transcription and that the p19 gene encodes a soluble protein, whereas the p22 gene specifies a membrane-associated protein. Assays using TBSV derivatives that have the β-glucuronidase gene substituted for the capsid protein gene demonstrate that p22 is required for cell-to-cell movement in all plants tested. Mutations inactivating p19 ameliorate the severe necrotic systemic symptoms elicited by wild-type TBSV inNicotiana benthamianaandNicotiana clevelandii,but p19 does not obviously affect movement in these hosts. However, in some local lesion hosts p19 influences the lesion diameter, which suggests that it has an auxiliary host-dependent role in movement. This notion is supported by the observation that p19 is required for long-distance spread of TBSV in spinach and for systemic infection of pepper plants. Thus, movement of TBSV is regulated by two nested genes; p22 governs cell-to-cell movement and p19 has a host-specific role in systemic invasion.