title: Disruption of Rpp1-mediated soybean rust immunity by virus-induced gene silencing.
abstract: Phakopsora pachyrhizi, a fungus that causes rust disease on soybean, has potential to impart significant yield loss and disrupt food security and animal feed production. Rpp1 is a soybean gene that confers immunity to soybean rust, and it is important to understand how it regulates the soybean defense system and to use this knowledge to protect commercial crops. It was previously discovered that some soybean proteins resembling transcription factors accumulate in the nucleus of Rpp1 soybeans. To determine if they contribute to immunity, Bean pod mottle virus was used to attenuate or silence the expression of their genes. Rpp1 plants subjected to virus-induced gene silencing exhibited reduced amounts of RNA for 5 of the tested genes, and the plants developed rust-like symptoms after subsequent inoculation with fungal spores. Symptoms were associated with the accumulation of rust fungal RNA and protein. Silenced plants also had reduced amounts of RNA for the soybean Myb84 transcription factor and soybean isoflavone O-methyltransferase, both of which are important to phenylpropanoid biosynthesis and lignin formation, crucial components of rust resistance. These results help resolve some of the genes that contribute to Rpp1-mediated immunity and improve upon the knowledge of the soybean defense system. It is possible that these genes could be manipulated to enhance rust resistance in otherwise susceptible soybean cultivars.
authors.affiliation: Soybean Genomics and Improvement Laboratory; USDA-ARS; Beltsville, MD USA.
authors.forename: Bret
authors.initials: B
authors.lastname: Cooper
authors.affiliation: Soybean Genomics and Improvement Laboratory; USDA-ARS; Beltsville, MD USA.
authors.forename: Kimberly B
authors.initials: KB
authors.lastname: Campbell
authors.affiliation: Foreign Disease-Weed Science; USDA-ARS; Ft. Detrick, MD USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: McMahon
authors.affiliation: Foreign Disease-Weed Science; USDA-ARS; Ft. Detrick, MD USA.
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Luster
mesh_terms: D001487:Basidiomycota / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D017343:Genes, Plant; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D057865:Plant Immunity; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D010942:Plant Viruses / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013025:Glycine max / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger
keywords: Rpp1; disease resistance; gene silencing; soybean rust; transcription factor