title: Identification of promising host-induced silencing targets among genes preferentially transcribed in haustoria of Puccinia.
abstract: BACKGROUND
  The cereal rust fungi are destructive pathogens that affect grain production worldwide. Although the genomic and transcript sequences for three Puccinia species that attack wheat have been released, the functions of large repertories of genes from Puccinia still need to be addressed to understand the infection process of these obligate parasites. Host-induced gene silencing (HIGS) has emerged a useful tool to examine the importance of rust fungus genes while growing within host plants. In this study, HIGS was used to test genes from Puccinia with transcripts enriched in haustoria for their ability to interfere with full development of the rust fungi.
  
  
  RESULTS
  Approximately 1200 haustoria enriched genes from Puccinia graminis f. sp. tritici (Pgt) were identified by comparative RNA sequencing. Virus-induced gene silencing (VIGS) constructs with fragments of 86 Puccinia genes, were tested for their ability to interfere with full development of these rust fungi. Most of the genes tested had no noticeable effects, but 10 reduced Pgt development after co-inoculation with the gene VIGS constructs and Pgt. These included a predicted glycolytic enzyme, two other proteins that are probably secreted and involved in carbohydrate or sugar metabolism, a protein involved in thiazol biosynthesis, a protein involved in auxin biosynthesis, an amino acid permease, two hypothetical proteins with no conserved domains, a predicted small secreted protein and another protein predicted to be secreted with similarity to bacterial proteins involved in membrane transport. Transient silencing of four of these genes reduced development of P. striiformis (Pst), and three of also caused reduction of P. triticina (Pt) development.
  
  
  CONCLUSIONS
  Partial suppression of transcripts involved in a large variety of biological processes in haustoria cells of Puccinia rusts can disrupt their development. Silencing of three genes resulted in suppression of all three rust diseases indicating that it may be possible to engineer durable resistance to multiple rust pathogens with a single gene in transgenic wheat plants for sustainable control of cereal rusts.
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA.
authors.forename: Chuntao
authors.initials: C
authors.lastname: Yin
authors.affiliation: Department of Crop and Soil Sciences, Washington State University, Pullman, WA, 99164-6430, USA.
authors.forename: Samantha I
authors.initials: SI
authors.lastname: Downey
authors.affiliation: Department of Biology, Carleton College, One North College St., Northfield, MN, 55057, USA.
authors.forename: Naeh L
authors.initials: NL
authors.lastname: Klages-Mundt
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA.
authors.forename: Sowmya
authors.initials: S
authors.lastname: Ramachandran
authors.affiliation: US Department of Agriculture, Agricultural Research Service, Wheat Genetics, Quality, Physiology and Disease Research Unit, Pullman, WA, 99164-6430, USA.
authors.forename: Xianming
authors.initials: X
authors.lastname: Chen
authors.affiliation: US Department of Agriculture, Agricultural Research Service, Cereal Disease Laboratory, St. Paul, MN, 55108, USA.
authors.forename: Les J
authors.initials: LJ
authors.lastname: Szabo
authors.affiliation: Department of Crop and Soil Sciences, Washington State University, Pullman, WA, 99164-6430, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Pumphrey
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA. scot_hulbert@wsu.edu.
authors.forename: Scot H
authors.initials: SH
authors.lastname: Hulbert
mesh_terms: D001487:Basidiomycota / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D059647:Gene-Environment Interaction; D005800:Genes, Fungal; D006019:Glycolysis / Q000235:genetics; D059014:High-Throughput Nucleotide Sequencing; D010935:Plant Diseases / Q000382:microbiology / Q000821:virology; D014158:Transcription, Genetic; D059467:Transcriptome; D014908:Triticum / Q000382:microbiology / Q000821:virology