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The Arabidopsis Downy Mildew Resistance Gene, RPP13-Nd, Functions Independently of NDR1 and EDS1 and Does Not Require the Accumulation of Salicylic Acid

March 2001 , Volume 14 , Number  3
Pages  416 - 421

Peter D. Bittner-Eddy and Jim L. Beynon

Horticulture Research International, Wellesbourne, Warwick CV35 9EF, U.K.

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Accepted 25 October 2000.

RPP13-Nd-mediated resistance prevents parasitism by five isolates of Peronospora parasitica (At) in a transgenic Arabidopsis. Columbia background. We tested the effect of a number of known disease resistance mutations on the RPP13-Nd function and found that resistance remained unaltered in plants carrying mutations in either EDS1 or NDR1 and in double ndr1-1/eds1-2 mutant lines. Furthermore, we found that pbs2, pad4-1, npr1-1, and rps5-1, which compromise resistance to a number of P. parasitica (At) isolates, had no affect on RPP13-Nd function. In addition, RPP13-Nd-mediated resistance remained unchanged in a background of salicylic acid depletion (nahG). We conclude that RPP13-Nd is the first Arabidopsis R gene product reported to act via a novel signaling pathway that is independent of salicylic acid-mediated responses and is completely independent of NDR1 and EDS1.

© 2001 The American Phytopathological Society