Characterization of nonhost resistance of Arabidopsis to the Asian soybean rust.
Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, is a devastating disease of soybean. We report the use of the nonhost plant Arabidopsis thaliana to identify the genetic basis of resistance to P. pachyrhizi. Upon attack by P. pachyrhizi, epidermal cells of wild-type Arabidopsis accumulated H2O2, which likely orchestrates the frequently observed epidermal cell death. However, even when epidermal cell death occurred, fungal hyphae grew on and infection was terminated at the mesophyll boundary. These events were associated with expression of PDF1.2, suggesting that P. pachyrhizi, an ostensible biotroph, mimics aspects of a necrotroph. Extensive colonization of the mesophyll occurred in Arabidopsis pen mutants with defective penetration resistance. Although haustoria were found occasionally in mesophyll cells, the successful establishment of biotrophy failed, as evidenced by the cessation of fungal growth. Double mutants affected in either jasmonic acid or salicylic acid signaling in the pen3-1 background revealed the involvement of both pathways in nonhost resistance (NHR) of Arabidopsis to P. pachyrhizi. Interestingly, expression of AtNHL10, a gene that is expressed in tissue undergoing the hypersensitive response, was only triggered in infected pen3-1 mutants. Thus, a suppression of P. pachyrhizi-derived effectors by PEN3 can be inferred. Our results demonstrate that Arabidopsis can be used to study mechanisms of NHR to ASR.
Department of Plant Physiology, RWTH Aachen University, D-52056 Aachen, Germany.
Marco
M
Loehrer
Caspar
C
Langenbach
Katharina
K
Goellner
Uwe
U
Conrath
Ulrich
U
Schaffrath
D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics*; D001487:Basidiomycota / Q000502:physiology*; D023082:Defensins / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D006861:Hydrogen Peroxide / Q000378:metabolism; D007113:Immunity, Innate / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000382:microbiology
D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; D023082:Defensins; D006861:Hydrogen Peroxide; C487542:At5g44420 protein, Arabidopsis; C510424:PDR8 protein, Arabidopsis