Overexpression of a plasma membrane protein generated broad-spectrum immunity in soybean

Plants fight-off pathogens and pests by manifesting an array of defence responses using their innate immunity mechanisms. Here we report the identification of a novel soybean gene encoding a plasma membrane protein, transcription of which is suppressed following infection with the fungal pathogen,Furatium virguliforme. Overexpression of the protein led to enhanced resistance against not only againstF. virguliforme, but also against spider mites (Tetranychus urticae,Koch), soybean aphids (Aphis glycines,Matsumura) and soybean cyst nematode (Heterodera glycines). We, therefore, name this protein asGlycine max disease resistance 1(GmDR1; Glyma.10g094800). The homologues ofGmDR1have been detected only in legumes, cocoa, jute and cotton. The deduced GmDR1 protein contains 73 amino acids. GmDR1 is predicted to contain an ecto- and two transmembrane domains. Transient expression of the green fluorescent protein fused GmDR1 protein in soybean leaves showed that it is a plasma membrane protein. We investigated if chitin, a pathogen-associated molecular pattern (PAMP), common to all pathogen and pests considered in this study, can significantly enhance defence pathways among theGmDR1-overexpressed transgenic soybean lines. Chitin induces marker genes of the salicylic- and jasmonic acid-mediated defence pathways, but suppresses the defence pathway regulated by ethylene. Chitin induced SA- and JA-regulated defence pathways may be one of the mechanisms involved in generating broad-spectrum resistance among theGmDR1-overexpressed transgenic soybean lines against two serious pathogens and two pests including spider mites, against which no known resistance genes have been identified in soybean and among the most other crop species.

Automated summary

Plants have innate immunity mechanisms to defend against pathogens and pests. The novel soybean gene GmDR1 identified in this study enhances resistance against various pathogens and pests, possibly through inducing salicylic- and jasmonic acid-mediated defence pathways. GmDR1 encodes a plasma membrane protein with 73 amino acids.