The movement protein (NSm) of Tomato spotted wilt virus is the avirulence determinant in the tomato Sw‐5 gene‐based resistance

Abstract

The avirulence determinant triggering the resistance conferred by the tomato gene Sw-5 against Tomato spotted wilt virus (TSWV) is still unresolved. Sequence comparison showed two substitutions (C118Y and T120N) in the movement protein NSm present only in TSWV resistance-breaking (RB) isolates. In this work, transient expression of NSm of three TSWV isolates [RB1 (T120N), RB2 (C118Y) and non-resistance-breaking (NRB)] in Nicotiana benthamiana expressing Sw-5 showed a hypersensitive response (HR) only with NRB. Exchange of the movement protein of Alfalfa mosaic virus (AMV) with NSm supported cell-to-cell and systemic transport of the chimeric AMV RNAs into N. tabacum with or without Sw-5, except for the constructs with NBR when Sw-5 was expressed, although RB2 showed reduced cell-to-cell transport. Mutational analysis revealed that N120 was sufficient to avoid the HR, but the substitution V130I was required for systemic transport. Finally, co-inoculation of RB and NRB AMV chimeric constructs showed different prevalence of RB or NBR depending on the presence or absence of Sw-5. These results indicate that NSm is the avirulence determinant for Sw-5 resistance, and mutations C118Y and T120N are responsible for resistance breakdown and have a fitness penalty in the context of the heterologous AMV system.

Plasmodesmata targeting and intercellular trafficking of Tomato spotted wilt tospovirus movement protein NSm is independent of its function in HR induction

“…Lopez et al (2011) suggested that amino-acid substitution at position 118 (C118Y) or 120 (T120N) in the TSWV NSm might result in breaking of the Sw-5-mediated resistance in tomato. , Peiró et al (2014 demonstrated that the presence of a tyrosine at position 118 or an asparagine at position 120 in NSm abolished the Sw-5-mediated HR. To further analyse these two amino acids, a single amino-acid substitution (C118Y or T120N) was introduced into the PD-nontargeting NSm A54-56 mutant.…”

“…This Sw-5b resistance gene has been cloned and shown to contain a coiled-coil, a central nucleotide-binding site (NBS), C-terminal leucine-rich repeats (LRRs), and an extra N-terminal domain (Brommonschenkel et al, 2000;Spassova et al, 2001). The avirulence (Avr) factor of the tomato Sw-5b-resistance protein has been determined as the nonstructural movement protein NSm of TSWV (Hallwass et al, 2014;Lopez et al, 2011;Peiró et al, 2014). Transient expression of the NSm protein in leaves of Sw-5 tomato or Sw-5 transgenic Nicotiana benthamiana resulted in a hypersensitive response (HR) (Hallwass et al, 2014;Peiró et al, 2014).…”

“…The avirulence (Avr) factor of the tomato Sw-5b-resistance protein has been determined as the nonstructural movement protein NSm of TSWV (Hallwass et al, 2014;Lopez et al, 2011;Peiró et al, 2014). Transient expression of the NSm protein in leaves of Sw-5 tomato or Sw-5 transgenic Nicotiana benthamiana resulted in a hypersensitive response (HR) (Hallwass et al, 2014;Peiró et al, 2014).…”

Proposal of a Genome Editing System for Genetic Resistance to Tomato Spotted Wilt Virus

“…Sw-5 is responsible of triggering Hypersensitive Response (HR) in sites of infections impeding systemic infections in the host. Sw-5 targeted the pathogen avirulence protein (NSm) (Peiro et al, 2014). Although five paralogues are present in plant genomes, it was shown that only one is necessary and sufficient to induce resistance against TSWV (Spassova et al, 2001).…”

Estudo funcional da proteína de movimento (NSm) de distintos Tospovirus

“…The ORF located in the complementary viral M RNA encodes the precursor of the Gn and Gc glycoproteins that are localized in the viral particle envelope and that are important for tospovirus transmission mediated by thrips in a circulative and propagative mode Sin et al, 2005). The ORF in the viral RNA sense encodes a non-structural protein (NSm) involved in the short distance (cell-to-cell) and systemic movements ) and, more recently, proved to work as an avirulence determinant Peiro et al, 2014a).…”