title: Transcriptome analysis of resistant and susceptible genotypes of Glycine tomentella during Phakopsora pachyrhizi infection reveals novel rust resistance genes.
abstract: Soybean rust, caused by Phakopsora pachyrhizi, is a destructive foliar disease in nearly all soybean-producing countries. To identify genes controlling resistance to soybean rust, transcriptome profiling was conducted in resistant and susceptible Glycine tomentella genotypes triggered by P. pachyrhizi infection. Among 38,400 genes monitored using a soybean microarray, at 5% false discovery rate, 1,342 genes were identified exhibiting significant differential expression between uninfected and P. pachyrhizi-infected leaves at 12, 24, 48, and 72 h post-inoculation (hpi) in both rust-susceptible and rust-resistant genotypes. Differentially expressed genes were grouped into 12 functional categories, and among those, large numbers relate to basic plant metabolism. Transcripts for genes involved in the phenylpropanoid pathway were up-regulated early during rust infection. Similarly, genes coding for proteins related to stress and defense responses such as glutathione-S-transferases, peroxidases, heat shock proteins, and lipoxygenases were consistently up-regulated following infection at all four time points. Whereas, subsets of genes involved in cellular transport, cellular communication, cell cycle, and DNA processing were down-regulated. Quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) on randomly selected genes from the different categories confirmed these findings. Of differentially expressed genes, those associated with the flavonoid biosynthesis pathway as well as those coding for peroxidases and lipoxygenases were likely to be involved in rust resistance in soybean, and would serve as good candidates for functional studies. These findings provided insights into mechanisms underlying resistance and general activation of plant defense pathways in response to rust infection.
authors.affiliation: Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, IL, 61821, USA.
authors.forename: Ruth Elena
authors.initials: RE
authors.lastname: Soria-Guerra
authors.forename: Sergio
authors.initials: S
authors.lastname: Rosales-Mendoza
authors.forename: Sungyul
authors.initials: S
authors.lastname: Chang
authors.forename: James S
authors.initials: JS
authors.lastname: Haudenshield
authors.forename: Annamalai
authors.initials: A
authors.lastname: Padmanaban
authors.forename: Sandra
authors.initials: S
authors.lastname: Rodriguez-Zas
authors.forename: Glen L
authors.initials: GL
authors.lastname: Hartman
authors.forename: Said A
authors.initials: SA
authors.lastname: Ghabrial
authors.forename: Schuyler S
authors.initials: SS
authors.lastname: Korban
mesh_terms: D001487:Basidiomycota / Q000502:physiology*; D004198:Disease Susceptibility; D015536:Down-Regulation / Q000235:genetics; D020869:Gene Expression Profiling / Q000379:methods*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D005838:Genotype; D007113:Immunity, Innate / Q000235:genetics*; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013025:Glycine max / Q000166:cytology / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D015854:Up-Regulation / Q000235:genetics