Present address: Department of Plant Pathology, Physiology and Weed Science, Fralin Biotechnology Center, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0346, USA.
Downy mildew (Peronospora parasitica) resistance genes in Arabidopsis vary in functional requirements for NDR1, EDS1, NPR1 and salicylic acid accumulation
Article first published online: 25 DEC 2001
The Plant Journal
Volume 22, Issue 6, pages 523–529, June 2000
How to Cite
McDowell, J. M., Cuzick, A., Can, C., Beynon, J., Dangl, J. L. and Holub, E. B. (2000), Downy mildew (Peronospora parasitica) resistance genes in Arabidopsis vary in functional requirements for NDR1, EDS1, NPR1 and salicylic acid accumulation. The Plant Journal, 22: 523–529. doi: 10.1046/j.1365-313x.2000.00771.x
- Issue published online: 25 DEC 2001
- Article first published online: 25 DEC 2001
- Received 3 February 2000; revised 28 March 2000; accepted 28 March 2000.
To better understand the genetic requirements for R gene-dependent defense activation in Arabidopsis, we tested the effect of several defense response mutants on resistance specified by eight RPP genes (for resistance to Peronospora parasitica) expressed in the Col-0 background. In most cases, resistance was not suppressed by a mutation in the SAR regulatory gene NPR1 or by expression of the NahG transgene. Thus, salicylic acid accumulation and NPR1 function are not necessary for resistance mediated by these RPP genes. In addition, resistance conferred by two of these genes, RPP7 and RPP8, was not significantly suppressed by mutations in either EDS1 or NDR1. RPP7 resistance was also not compromised by mutations in EIN2, JAR1 or COI1 which affect ethylene or jasmonic acid signaling. Double mutants were therefore tested. RPP7 and RPP8 were weakly suppressed in an eds1-2/ndr1-1 background, suggesting that these RPP genes operate additively through EDS1, NDR1 and as-yet-undefined signaling components. RPP7 was not compromised in coi1/npr1 or coi1/NahG backgrounds. These observations suggest that RPP7 initiates resistance through a novel signaling pathway that functions independently of salicylic acid accumulation or jasmonic acid response components.