Type 2C Protein Phosphatase Is a Key Regulator of Antiviral Extreme Resistance Limiting Virus Spread

Abstract

Effector-triggered immunity (ETI) is an active immune response triggered by interactions between host resistance proteins and their cognate effectors. Although ETI is often associated with the hypersensitive response (HR), various R genes mediate an HR-independent process known as extreme resistance (ER). In the soybean-Soybean mosaic virus (SMV) pathosystem, the strain-specific CI protein of SMV functions as an effector of Rsv3-mediated ER. In this study, we used the soybean (Rsv3)-SMV (CI) pathosystem to gain insight into the molecular signaling pathway involved in ER. We used genome-wide transcriptome analysis to identify a subset of the type 2C protein phophatase (PP2C) genes that are specifically up-regulated in Rsv3-mediated ER. Gain-of-function analysis of the most significantly expressed soybean PP2C gene, GmPP2C3a, showed that ABA-induced GmPP2C3a functions as a key regulator of Rsv3-mediated ER. Our results further suggest that the primary mechanism of ER against viruses is the inhibition of viral cell-to-cell movement by callose deposition in an ABA signaling-dependent manner.

Soybean mosaic virus: a successful potyvirus with a wide distribution but restricted natural host range

“…Rsv3 ‐mediated resistance to SMV is not accompanied by obvious symptoms, and it has been referred to as ER (Fig. B) (Seo et al ., ). However, using a GUS‐tagged SMV strain, Zhang et al .…”

The Current Status of the Soybean-Soybean Mosaic Virus (SMV) Pathosystem

“…Recently, it has been shown that silencing GmHSP40.1 , a soybean nuclear-localized type-III DnaJ domain-containing HSP40, results in increased infectivity of SMV, indicating a positive role of GmHSP40.1 in basal resistance (Liu and Whitham, 2013). A subset of type 2C protein phophatase (PP2C) gene family, which participate ABA signaling pathway, is specifically up-regulated during Rsv3 -mediated resistance (Seo et al, 2014). Synchronized overexpression of GmPP2C3a using SMV-G7H vector inhibits virus cell-to-cell movement mediated by callose deposition in an ABA signaling-dependent manner, indicating that GmPP2C3a functions as a key regulator of Rsv3 -mediated resistance (Seo et al, 2014).…”

“…A subset of type 2C protein phophatase (PP2C) gene family, which participate ABA signaling pathway, is specifically up-regulated during Rsv3 -mediated resistance (Seo et al, 2014). Synchronized overexpression of GmPP2C3a using SMV-G7H vector inhibits virus cell-to-cell movement mediated by callose deposition in an ABA signaling-dependent manner, indicating that GmPP2C3a functions as a key regulator of Rsv3 -mediated resistance (Seo et al, 2014). An ortholog of Arabidopsis K + weak channel encoding gene AKT2, was significantly induced by SMV inoculation in the SMV highly resistant genotype, but not in the susceptible genotype (Zhou et al, 2014).…”

Review Article: Molecular Mechanisms of Resistance to Potato virus X and Y in Potato

“…Using transcriptomics to study soybean-Soybean mosaic virus (SMV) pathosystem Seo et al (2014) identified a 2C protein phosphatase type gene (PP2C) as a key regulator of ER, confirming transcriptomics as a valuable approach. Baebler et al (2009) detected differences in expression of hundreds of genes as soon as half an hour after inoculation of potato leaves with PVY NTN .…”

“…Three mechanisms whereby the NIa could act were proposed: [1] the structure of the NIa might have elicitor activity, [2] the elicitor might be produced by degradation of a host-encoded protein by NIa, [3] the NIa might degrade a negative regulator of the resistance (Mestre et al, 2000). The role of callose deposition in inhibition of viral cell-to-cell movement by R-mediated ER has also been reported in soybean-SMV pathosystem (Seo et al, 2014).…”