extracted from 4-week-old plants and used for RNA gel-blot analysis. Ethidium bromide staining of rRNA was used as loading control. (D) Endogenous SA levels in the leaves of 4-week-old plants. Values are presented as mean of three replicates and the error bars represent SD. Statistical significance was determined using Student’s t-test. Asterisks indicate data statistically significant between ssi2 fad7 and ssi2 eds1 fad7 or ssi2 fad7 fad8 and ssi2 eds1 fad7 fad8 (P,0.05, n = 5). (E) Endogenous SAG levels in the leaves of 4-week-old plants. Values are presented as mean of three replicates and the error bars represent SD. Asterisks indicate data statistically significant between ssi2 fad7 and ssi2 eds1 fad7 or ssi2 fad7 fad8 and ssi2 eds1 fad7 fad8 (P,0.05, n = 5). (F) RT-PCR analysis of R genes in indicated genotypes. The level of b-tubulin was used as an internal control to normalize the amount of cDNA template. The SSI2 EDS1 FAD7 and SSI2 EDS1 FAD7 FAD8 F2 plants showed wt-like morphology and basal levels expression of PR-1 and R genes (data not shown). Found at: doi:10.1371/journal.pgen.1000545.s003 (0.96 MB TIF) Figure S4 Morphology, cell death, PR-1, and R gene expression and SA/SAG levels in ssi2 sag101-1, ssi2 sag101-1 eds1-2 and ssi2 sag101-1 sid2-1 plants. (A) Comparison of the morphological phenotypes displayed by 4-week-old soil-grown wt (SSI2; Col-0 ecotype), sag101, ssi2, ssi2 sag101, ssi2 sid2, ssi2 sag101 sid2, ssi2 eds1 and ssi2 sag101 eds1 plants (scale, 0.5 cm). (B) Microscopy of trypan blue-stained leaves from indicated genotypes (scale bars, 270 mi- crons). (C) Expression of PR-1 in indicated genotypes. Total RNA was extracted from 3-week-old plants and used for RNA gel-blot analysis. Ethidium bromide staining of rRNA was used as the loading control. (D) RT-PCR analysis of R genes in indicated genotypes. The level of b-tubulin was used as an internal control to normalize the amount of cDNA template. (E) Endogenous SA levels in the leaves of 4-week-old soil-grown plants. Values are presented as averages of four replicates and the error bars represent SD. (F) Endogenous SAG levels in the leaves of 4-week- old soil-grown plants. Error bars represent SD. The SSI2 SAG101, SSI2 EDS1 SAG101 and SSI2 SAG101 SID2 F2 plants showed wt- like morphology, accumulated wt-like levels of SA and showed wt- like expression of PR-1 and R genes (data not shown). Statistical significance in (E) and (F) were determined using Student’s t-test. Asterisks indicate data statistically significant compared to results from SSI2 (Col-0) plants (P,0.05, n = 4). Found at: doi:10.1371/journal.pgen.1000545.s004 (1.17 MB TIF) Figure S5 Morphology, cell death, PR-1, SA/SAG levels, and R gene expression in ssi2 pad4-1 sid2-1 and ssi2 eds5-1 sid2-1 plants. (A) Comparison of the morphological phenotypes displayed by 4- week-old soil-grown wt (SSI2; Col-0 ecotype), ssi2, ssi2 sid2, ssi2 pad4, ssi2eds5, ssi2 pad4 sid2 and ssi2 eds5 sid2 plants (scale, 0.5 cm). (B) Microscopy of trypan blue-stained leaves shown in (A) (scale bars, 270 microns). (C) Expression of PR-1 gene in indicated genotypes. Total RNA was extracted from 4-week-old plants and used for RNA gel-blot analysis. Ethidium bromide staining of rRNA was used as the loading control. (D) RT-PCR analysis of R genes in indicated genotypes. The level of b-tubulin was used as an internal control to normalize the amount of cDNA template. The SSI2 PAD4 SID2 and SSI2 EDS5 SID2 F2 plants showed wt-like morphology and showed wt-like expression of PR-1 and R genes (data not shown). (E) Endogenous SA levels in the leaves of 4- References Redundancy in Plant Defense week-old soil-grown plants. Values are presented as averages of four replicates and the error bars represent SD. (F) Endogenous SAG levels in the leaves of 4-week-old soil-grown plants. Error bars represent SD. The SSI2 PAD4 and SSI2 EDS5 plants showed wt-like morphology, accumulated wt-like levels of SA and showed wt-like expression of PR-1 and R genes (data not shown). Statistical significances in E and F were determined using Student’s t-test. Asterisks indicate data statistically significant compared to results from SSI2 (Col-0) plants (P,0.05, n = 4). Found at: doi:10.1371/journal.pgen.1000545.s005 (1.09 MB TIF) Table S1 A list of genetic crosses analyzed in this study. Found at: doi:10.1371/journal.pgen.1000545.s006 (0.08 DOC) MB Table S2 Fold change in transcript levels of R and PR genes in ssi2 sid2 and ssi2 eds1 sid2 plants compared to results from Col-0 (wt) plants. R genes showing 2–2.5, 2.5–3, and .3-fold activation are marked yellow, orange, or red, respectively. Transcriptional profiling was performed using Affymetrix arrays. Found at: doi:10.1371/journal.pgen.1000545.s007 (0.09 MB DOC) Table S3 FA composition from leaf tissues of SSI2 (Col-0), eds1, sid2, ssi2, ssi2 eds1, ssi2 sid2, and ssi2 eds1 sid2 plants. All measurements were made on 4-week-old plants grown at 22uC and data are described as mol%6SD calculated for a sample size of six. Found at: doi:10.1371/journal.pgen.1000545.s008 (0.06 MB DOC) Table S4 FA composition from leaf tissues of SSI2 (Col-0), ssi2, ssi2 eds1, fad7, ssi2 fad7, ssi2 eds1 fad7, fad7 fad8, ssi2 fad7 fad8 and ssi2 eds1 fad7 fad8 plants. All measurements were made on plants grown at 22uC and data are described as mol%6SD calculated for a sample size of six. nd, not detected. Found at: doi:10.1371/journal.pgen.1000545.s009 (0.07 MB DOC) Table S5 Primer sequences used to amplify various genes. Found at: doi:10.1371/journal.pgen.1000545.s010 (0.04 DOC) MB Acknowledgments We thank David Smith for critical comments; John Johnson for help with gas chromatography; Ludmila Lapchyk, Thomas Muse, and Lev Orlov for help with fatty acid extractions and genotyping; and Amy Crume for maintaining the growth facility. We thank Jeff Dangl for rps2-101c, RPM1- MYC, and RPS2-HA seeds; Keiko Yoshioka for Ler NahG; and Jane Parker for sag101 seeds. We thank Walter Grassmann for the Pseudomonas syringae strain containing AvrRPS4 and Barbara Kunkle for the AvrRPT2 strain. We thank Jack Morris for providing anti-TCV CP antisera. Author Contributions Conceived and designed the experiments: SCV RDJ MKM SZ ACCS AK PK. Performed the experiments: SCV RDJ MKM SZ ACCS YX DN AK PK. Analyzed the data: SCV RDJ MKM SZ ACCS YX MH AJS DN AK PK. Contributed reagents/materials/analysis tools: SCV RDJ MKM SZ ACCS YX MH AJS DN AK PK. Wrote the paper: AK PK. 1. 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