Overexpression of a purple acid phosphatase GmPAP2.1 confers soybean mosaic virus resistant in a susceptible soybean cultivar.

A purple acid phosphatase (PAP) from soybean cultivar L29, GmPAP2.1, may function as a resistance factor against specific strains of soybean mosaic virus (SMV). Overexpression of GmPAP2.1 from the SMV-resistant cultivar L29 conferred viral resistance to a susceptible cultivar Lee 74. GmPAP2.1 interacts with the SMV protein P1 in the chloroplast, resulting in the upregulation of the ICS1 gene, which in turn promotes the pathogen-induced salicylic acid (SA) pathway. SA accumulation was elevated in response to the co-expression of GmPAP2.1 and SMV, while transient knock-down of endogenous SA-related genes resulted in systemic infection by SMV-G5H, suggesting that GmPAP2.1-derived resistance depends on the SA-pathway for the activation of a defense response. Our findings suggest that the PAP of soybean cultivar L29 functions as an SA-pathway-dependent resistance factor against SMV.