Temporal Global Expression Data Reveal Known and Novel Salicylate-Impacted Processes and Regulators Mediating Powdery Mildew Growth and Reproduction on Arabidopsis

• Published in: Plant physiology (Bethesda) 2009-03, Vol.149 (3), p.1435-1451
• Main Authors: Chandran, Divya, Tai, Yu Chuan, Hather, Gregory, Dewdney, Julia, Denoux, Carine, Burgess, Diane G., Ausubel, Frederick M., Speed, Terence P., Wildermuth, Mary C.
• Format: Article
• Language: English
• Subjects: Arabidopsis - drug effects; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - microbiology; Arabidopsis Proteins - chemistry; Ascomycota - drug effects; Ascomycota - growth & development; Biological and medical sciences; Cell death; Datasets; DNA, Bacterial - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - drug effects; Genes; Genes, Plant; Host-Pathogen Interactions - drug effects; Host-Pathogen Interactions - genetics; Infections; Intramolecular Transferases - genetics; Leaves; Mildews; Multigene Family; Mutagenesis, Insertional; Mutation - genetics; Plant cells; Plant Diseases - genetics; Plant Diseases - microbiology; Plant physiology and development; Plants; Plants Interacting with Other Organisms; Protein Structure, Tertiary; Regulator genes; Regulatory Sequences, Nucleic Acid - genetics; Reproduction - drug effects; Salicylic Acid - pharmacology; Time Factors; Transcription factors; Transcription Factors - metabolism; Transcription, Genetic - drug effects
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.108.132985

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 wildtype and SA biosynthetic mutant isochorismate synthasel (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.