OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 149/3/1435    most recent pp.108.132985v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Chandran, D. Articles by Wildermuth, M. C. Search for Related Content PubMed PubMed Citation Articles by Chandran, D. Articles by Wildermuth, M. C. Agricola Articles by Chandran, D. Articles by Wildermuth, M. C.

PLANTS INTERACTING WITH OTHER ORGANISMS

Temporal Global Expression Data Reveal Known and Novel Salicylate-Impacted Processes and Regulators Mediating Powdery Mildew Growth and Reproduction on Arabidopsis^1,[W],[OA]

Department of Plant and Microbial Biology (D.C., G.H., D.G.B., M.C.W.), Division of Biostatistics (Y.C.T.), and Department of Statistics (G.H., T.P.S.), University of California, Berkeley, California 94720; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114 (J.D., C.D., F.M.A.); and Department of Genetics, Harvard Medical School, Boston, Massachusetts 02114 (J.D., C.D., F.M.A.)

Salicylic acid (SA) is a critical mediator of plant innate immunity. It plays an important role in limiting the growth and reproduction of the virulent powdery mildew (PM) Golovinomyces orontii on Arabidopsis (Arabidopsis thaliana). To investigate this later phase of the PM interaction and the role played by SA, we performed replicated global expression profiling for wild-type and SA biosynthetic mutant isochorismate synthase1 (ics1) Arabidopsis from 0 to 7 d after infection. We found that ICS1-impacted genes constitute 3.8% of profiled genes, with known molecular markers of Arabidopsis defense ranked very highly by the multivariate empirical Bayes statistic (T² statistic). Functional analyses of T²-selected genes identified statistically significant PM-impacted processes, including photosynthesis, cell wall modification, and alkaloid metabolism, that are ICS1 independent. ICS1-impacted processes include redox, vacuolar transport/secretion, and signaling. Our data also support a role for ICS1 (SA) in iron and calcium homeostasis and identify components of SA cross talk with other phytohormones. Through our analysis, 39 novel PM-impacted transcriptional regulators were identified. Insertion mutants in one of these regulators, PUX2 (for plant ubiquitin regulatory X domain-containing protein 2), results in significantly reduced reproduction of the PM in a cell death-independent manner. Although little is known about PUX2, PUX1 acts as a negative regulator of Arabidopsis CDC48, an essential AAA-ATPase chaperone that mediates diverse cellular activities, including homotypic fusion of endoplasmic reticulum and Golgi membranes, endoplasmic reticulum-associated protein degradation, cell cycle progression, and apoptosis. Future work will elucidate the functional role of the novel regulator PUX2 in PM resistance.

² Present address: Institute for Human Genetics, University of California, San Francisco, CA 94143.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Mary C. Wildermuth (wildermuth{at}nature.berkeley.edu).

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.108.132985

^* Corresponding author; e-mail wildermuth{at}nature.berkeley.edu.

Received November 25, 2008; accepted January 23, 2009; published January 28, 2009.