Wound-induced rgs-CaM gets ready for counterresponse to an early stage of viral infection

Plants and animals can recognize the invasion of pathogens through their perception of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). Plant PRRs identified have been exclusively receptor-like kinases/proteins (RLK/Ps), and no RLK/P that can detect viruses has been identified to date. RNA silencing (RNA interference, RNAi) is regarded as an antiviral basal immunity because the majority of plant viruses has RNA as their genomes and encode RNA silencing suppressor (RSS) proteins to counterattack antiviral RNAi. Many RSSs were reported to bind to double-stranded RNAs (dsRNAs), which are regarded as viral PAMPs. We have recently identified a tobacco calmodulin (CaM)-like protein, rgs-CaM, as a PRR that binds to diverse viral RSSs through its affinity for the dsRNA-binding domains. Because rgs-CaM seems to target RSSs for autophagic degradation with self-sacrifice, the expression level of rgs-CaM is important for antiviral activity. Here, we found that the rgs-CaM expression was induced immediately (within 1 h) after wounding at a wound site on tobacco leaves. Since the invasion of plant viruses is usually associated with wounding, and several hours are required for viruses to replicate to a detectable level in invaded cells, the wound-induced expression of rgs-CaM seems to be linked to its antiviral function, which should be ready before the virus establishes infection. CaMs and CaM-like proteins usually transduce calcium signals through their binding to endogenous targets. Therefore, rgs-CaM is a unique CaM-like protein in terms of binding to exogenous targets and functioning as an antiviral PRR

A support tool incorporating a district disaster mitigation performance evaluation method for the examination of improvement plans in built-up areas

Approximately 20, 000 ha of densely built-up areas still remain in Japan. However, the advance of improvements in these areas has been very slow. Thus, making draft improvement plans through citizen–administration partnerships is indispensable to promote improvements. The planning support tool proposed in this study supports a consensus-building process during the creation of draft improvement plans. We develop a disaster mitigation performance evaluation method (DMPEM) for built-up areas at the district level and incorporate this method into a disaster mitigation support Web-GIS. However, DMPEM requires lengthy calculation time because it uses the probabilistic Monte Carlo computation method. Using this tool in real-time planning is therefore difficult. In this study, we first develop a system that reduces the calculation time required by DMPEM. Second, the support tool is used to make draft plans through citizen–administration partnerships in districts where residents are conducting various disaster mitigation activities. Finally, we investigate the usefulness of the tool for consensus building through the promotion of lively discussions among residents and clarify the issues associated with practical use of the tool

A support tool incorporating a district disaster mitigation performance evaluation method for the examination of improvement plans in built-up areas

Approximately 20,000 ha of densely built-up areas still remain in Japan. However, the advance of improvements in these areas has been very slow. Thus, making draft improvement plans through citizen–administration partnerships is indispensable to promote improvements. The planning support tool proposed in this study supports a consensus-building process during the creation of draft improvement plans. We develop a disaster mitigation performance evaluation method (DMPEM) for built-up areas at the district level and incorporate this method into a disaster mitigation support Web-GIS. However, DMPEM requires lengthy calculation time because it uses the probabilistic Monte Carlo computation method. Using this tool in real-time planning is therefore difficult. In this study, we first develop a system that reduces the calculation time required by DMPEM. Second, the support tool is used to make draft plans through citizen–administration partnerships in districts where residents are conducting various disaster mitigation activities. Finally, we investigate the usefulness of the tool for consensus building through the promotion of lively discussions among residents and clarify the issues associated with practical use of the tool

rgs-CaM Detects and Counteracts Viral RNA Silencing Suppressors in Plant Immune Priming

Primary infection of a plant with a pathogen that causes high accumulation of salicylic acid in the plant typically via a hypersensitive response confers enhanced resistance against secondary infection with a broad spectrum of pathogens, including viruses. This phenomenon is called systemic acquired resistance (SAR), which is a plant priming for adaption to repeated biotic stress. However, the molecular mechanisms of SAR-mediated enhanced inhibition, especially of virus infection, remain unclear. Here, we show that SAR against cucumber mosaic virus (CMV) in tobacco plants (Nicotiana tabacum) involves a calmodulin-like protein, rgs-CaM. We previously reported the antiviral function of rgs-CaM, which binds to and directs degradation of viral RNA silencing suppressors (RSSs), including CMV 2b, via autophagy. We found that rgs-CaM-mediated immunity is ineffective against CMV infection in normally growing tobacco plants but is activated as a result of SAR induction via salicylic acid signaling. We then analyzed the effect of overexpression of rgs-CaM on salicylic acid signaling. Overexpressed and ectopically expressed rgs-CaM induced defense reactions, including cell death, generation of reactive oxygen species, and salicylic acid signaling. Further analysis using a combination of the salicylic acid analogue benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and the Ca2+ ionophore A23187 revealed that rgs-CaM functions as an immune receptor that induces salicylic acid signaling by simultaneously perceiving both viral RSS and Ca2+ influx as infection cues, implying its autoactivation. Thus, secondary infection of SAR-induced tobacco plants with CMV seems to be effectively inhibited through 2b recognition and degradation by rgs-CaM, leading to reinforcement of antiviral RNA silencing and other salicylic acid-mediated antiviral responses. IMPORTANCE Even without an acquired immune system like that in vertebrates, plants show enhanced whole-plant resistance against secondary infection with pathogens; this so-called systemic acquired resistance (SAR) has been known for more than half a century and continues to be extensively studied. SAR-induced plants strongly and rapidly express a number of antibiotics and pathogenesis-related proteins targeted against secondary infection, which can account for enhanced resistance against bacterial and fungal pathogens but are not thought to control viral infection. This study showed that enhanced resistance against cucumber mosaic virus is caused by a tobacco calmodulin-like protein, rgs-CaM, which detects and counteracts the major viral virulence factor (RNA silencing suppressor) after SAR induction. rgs-CaM-mediated SAR illustrates the growth versus defense trade-off in plants, as it targets the major virulence factor only under specific biotic stress conditions, thus avoiding the cost of constitutive activation while reducing the damage from virus infection