The coat protein of Alternanthera mosaic virus is the elicitor of a temperature-sensitive systemic necrosis in Nicotiana benthamiana, and interacts with a host boron transporter protein

Abstract

Different isolates of Alternanthera mosaic virus (AltMV; Potexvirus), including four infectious clones derived from AltMV-SP, induce distinct systemic symptoms in Nicotiana benthamiana. Virus accumulation was enhanced at 15 °C compared to 25 °C; severe clone AltMV 3-7 induced systemic necrosis (SN) and plant death at 15 °C. No interaction with potexvirus resistance gene Rx was detected, although SN was ablated by silencing of SGT1, as for other cases of potexvirus-induced necrosis. Substitution of AltMV 3-7 coat protein (CPSP) with that from AltMV-Po (CP(Po)) eliminated SN at 15 °C, and ameliorated symptoms in Alternanthera dentata and soybean. Substitution of only two residues from CP(Po) [either MN(13,14)ID or LA(76,77)IS] efficiently ablated SN in N. benthamiana. CPSP but not CP(Po) interacted with Arabidopsis boron transporter protein AtBOR1 by yeast two-hybrid assay; N. benthamiana homolog NbBOR1 interacted more strongly with CPSP than CP(Po) in bimolecular fluorescence complementation, and may affect recognition of CP as an elicitor of SN.

With or Without You: Altered Plant Response to Boron-Deficiency in Hydroponically Grown Grapevines Infected by Grapevine Pinot Gris Virus Suggests a Relation Between Grapevine Leaf Mottling and Deformation Symptom Occurrence and Boron Plant Availability

“…A correlation between viral-disease symptom expression and plant B homeostasis has already been described in other pathosystems, underlining how B supply leads to viral symptom remission or alleviation (Cooper et al, 1976;Shimomura, 1982;Bengsch et al, 1989). Moreover, Lim et al (2014) demonstrated how the coat protein of Alternanthera mosaic virus interacts with the host B transporter protein NbBOR1 in N. benthamiana, enabling speculation about a direct interaction between viruses and B transporters.…”

Alternanthera mosaic virus - an alternative ‘model’ potexvirus of broad relevance

“…A number of primer sets for AltMV detection and identification have been developed for either RT-PCR, including PP1/PP4 (Hammond et al, 2006a), PP23/BNSNC (for cDNA primed with NSNC-odT; Hammond et al, 2006b) and PP12/PP15 (Lim et al, 2014); or for real-time quantitative RT-PCR, including Coat-F/Coat-R and RdRp-F/RdRp-R (Lim et al, 2010a).…”

“…1). At least some of these differences are related to the ability of AltMV isolates to induce systemic necrosis at low temperature, as substitution of either MN(13,14)ID or LA(76,77)IS in an infectious clone was found to eliminate induction of systemic necrosis in Nicotiana benthamiana at 15℃ (Lim et al, 2014).…”

“…The CP has also been shown to affect symptom expression; an isolate from Portulaca (AltMV-Po) was found to induce chlorotic rather than necrotic local lesions, and mild mosaic in N. benthamiana (Hammond et al, 2006b), without necrosis at 15℃. Substitution of the CP of AltMV-Po into severe infectious clone 3-7 (which otherwise induces severe systemic necrosis at 25℃ and plant death at 15℃) resulted in mild mosaic in N. benthamiana without necrosis, even at 15℃ and 30 dpi, conditions under which clone 4-7 routinely kills plants (Lim et al, 2014). AltMV 3-7 Po-CP was also compared to parental AltMV 3-7 in Alternanthera dentata and soybean (Glycine max).…”

Comparison of helper component-protease RNA silencing suppression activity, subcellular localization, and aggregation of three Korean isolates of Turnip mosaic virus

“…Agrobacterium transformed with pGDR:Talin (actin marker), pGD:p19 [VSR of Tomato bushy stunt virus (TBSV)], and pGD:smGFP (solublemodified green fluorescent protein) were also utilized [24,28]. Equal volumes of pGDG:HC-Pro constructs and pGDR:Talin were mixed, usually with 0.1 volume of pGD:p19; agroinfiltrated leaves [28] of N. benthamiana were examined at 2-3 days post-agroinfiltration (dpa) using a Zeiss 710 confocal microscope [29,30], with DAPI staining as described [31]. Imaging revealed HC-Pro of all isolates distributed throughout the cytoplasm and at the cell periphery, together with perinuclear and microfilament-like association; R007 and R041 also induced many small punctate aggregates in the cytoplasm, presumed to result from self-interaction (Fig.…”