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Endogenous silencing of P uccinia triticina pathogenicity genes through in planta ‐expressed sequences leads to the suppression of rust diseases on wheat
Author(s) -
Panwar Vinay,
McCallum Brent,
Bakkeren Guus
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12047
Subject(s) - biology , gene silencing , gene , agroinfiltration , wheat leaf rust , genetics , rna silencing , pathogenicity island , puccinia , oomycete , virulence , rna interference , microbiology and biotechnology , botany , rna , mildew
Summary Rust fungi are destructive plant pathogens. The draft genomes of several wheat‐infecting species have been released and potential pathogenicity genes identified through comparative analyses to fungal pathogens that are amenable to genetic manipulation. Functional gene analysis tools are needed to understand the infection process of these obligate parasites and to confirm whether predicted pathogenicity genes could become targets for disease control. We have modified an Agrobacterium tumefaciens ‐mediated in planta ‐induced transient gene silencing ( PITGS ) assay for use in Triticum spp. (wheat), and used this assay to target predicted wheat leaf rust fungus, Puccinia triticina ( Pt ) pathogenicity genes, a MAP kinase ( Pt MAPK 1 ), a cyclophilin ( Pt CYC 1 ) and calcineurin B ( Pt CNB ), to analyze their roles in disease. Agroinfiltration effectively delivered hairpin silencing constructs in wheat, leading to the generation of fungal gene‐specific si RNA molecules in infiltrated leaves, and resulting in up to 70% reduction in transcription of the endogenous target genes in superinfected Pt . In vivo silencing caused severe disease suppression, compromising fungal growth and sporulation, as viewed by confocal microscopy and measured by reductions in fungal biomass and emergence of uredinia. Interestingly, using the same gene constructs, suppression of infection by Puccinia graminis and Puccinia striiformis was also achieved. Our results show that A. tumefaciens ‐mediated PITGS can be used as a reverse‐genetics tool to discover gene function in rust fungi. This proof‐of‐concept study indicates that the targeted fungal transcripts might be important in pathogenesis, and could potentially be used as promising targets for developing RNA interference‐based resistance against rust fungi.