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DOWNY MILDEW RESISTANT 6 and DMR 6‐ LIKE OXYGENASE 1 are partially redundant but distinct suppressors of immunity in Arabidopsis
Author(s) -
Zeilmaker Tieme,
Ludwig Nora R.,
Elberse Joyce,
Seidl Michael F.,
Berke Lidija,
Van Doorn Arjen,
Schuurink Robert C.,
Snel Berend,
Van den Ackerveken Guido
Publication year - 2015
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.12719
Subject(s) - downy mildew , arabidopsis , biology , pseudomonas syringae , mutant , oomycete , phytophthora capsici , salicylic acid , microbiology and biotechnology , botany , genetics , gene , pathogen , phytophthora
Summary Arabidopsis downy mildew resistant 6 (dmr6) mutants have lost their susceptibility to the downy mildew Hyaloperonospora arabidopsidis . Here we show that dmr6 is also resistant to the bacterium Pseudomonas syringae and the oomycete Phytophthora capsici . Resistance is accompanied by enhanced defense gene expression and elevated salicylic acid levels. The suppressive effect of the DMR 6 oxygenase was confirmed in transgenic Arabidopsis lines overexpressing DMR 6 that show enhanced susceptibility to H .  arabidopsidis , P .  capsici , and P .  syringae . Phylogenetic analysis of the superfamily of 2‐oxoglutarate Fe( II )‐dependent oxygenases revealed a subgroup of DMR 6‐ LIKE OXYGENASE s ( DLO s). Within Arabidopsis, DMR 6 is most closely related to DLO 1 and DLO 2. Overexpression of DLO 1 and DLO 2 in the dmr6 mutant restored the susceptibility to downy mildew indicating that DLO s negatively affect defense, similar to DMR 6. DLO 1 , but not DLO 2 , is co‐expressed with DMR 6 , showing strong activation during pathogen attack and following salicylic acid treatment. DMR 6 and DLO 1 differ in their spatial expression pattern in downy mildew‐infected Arabidopsis leaves; DMR 6 is mostly expressed in cells that are in contact with hyphae and haustoria of H .  arabidopsidis , while DLO 1 is expressed mainly in the vascular tissues near infection sites. Strikingly, the dmr6‐3_dlo1 double mutant, that is completely resistant to H .  arabidopsidis , showed a strong growth reduction that was associated with high levels of salicylic acid. We conclude that DMR 6 and DLO 1 redundantly suppress plant immunity, but also have distinct activities based on their differential localization of expression.

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