title: Low red/far-red ratios reduce Arabidopsis resistance to Botrytis cinerea and jasmonate responses via a COI1-JAZ10-dependent, salicylic acid-independent mechanism.
abstract: Light is an important modulator of plant immune responses. Here, we show that inactivation of the photoreceptor phytochrome B (phyB) by a low red/far-red ratio (R:FR), which is a signal of competition in plant canopies, down-regulates the expression of defense markers induced by the necrotrophic fungus Botrytis cinerea, including the genes that encode the transcription factor ETHYLENE RESPONSE FACTOR1 (ERF1) and the plant defensin PLANT DEFENSIN1.2 (PDF1.2). This effect of low R:FR correlated with a reduced sensitivity to jasmonate (JA), thus resembling the antagonistic effects of salicylic acid (SA) on JA responses. Low R:FR failed to depress PDF1.2 mRNA levels in a transgenic line in which PDF1.2 transcription was up-regulated by constitutive expression of ERF1 in a coronatine insensitive1 (coi1) mutant background (35S::ERF1/coi1). These results suggest that the low R:FR effect, in contrast to the SA effect, requires a functional SCFCOI1-JASMONATE ZIM-DOMAIN (JAZ) JA receptor module. Furthermore, the effect of low R:FR depressing the JA response was conserved in mutants impaired in SA signaling (sid2-1 and npr1-1). Plant exposure to low R:FR ratios and the phyB mutation markedly increased plant susceptibility to B. cinerea; the effect of low R:FR was (1) independent of the activation of the shade-avoidance syndrome, (2) conserved in the sid2-1 and npr1-1 mutants, and (3) absent in two RNA interference lines disrupted for the expression of the JAZ10 gene. Collectively, our results suggest that low R:FR ratios depress Arabidopsis (Arabidopsis thaliana) immune responses against necrotrophic microorganisms via a SA-independent mechanism that requires the JAZ10 transcriptional repressor and that this effect may increase plant susceptibility to fungal infection in dense canopies.
authors.affiliation: Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, C1417DSE Buenos Aires, Argentina.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Cerrudo
authors.forename: Mercedes M
authors.initials: MM
authors.lastname: Keller
authors.forename: Miriam D
authors.initials: MD
authors.lastname: Cargnel
authors.forename: Patricia V
authors.initials: PV
authors.lastname: Demkura
authors.forename: Mieke
authors.initials: M
authors.lastname: de Wit
authors.forename: Micaela S
authors.initials: MS
authors.lastname: Patitucci
authors.forename: Ronald
authors.initials: R
authors.lastname: Pierik
authors.forename: Corné M J
authors.initials: CM
authors.lastname: Pieterse
authors.forename: Carlos L
authors.initials: CL
authors.lastname: Ballaré
mesh_terms: D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020171:Botrytis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D003517:Cyclopentanes / Q000494:pharmacology; D060467:Disease Resistance / Q000187:drug effects / Q000528:radiation effects*; D015536:Down-Regulation / Q000187:drug effects / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D017343:Genes, Plant / Q000235:genetics; D008027:Light; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D054883:Oxylipins / Q000494:pharmacology; D010636:Phenols / Q000378:metabolism; D010641:Phenotype; D051939:Phytochrome B / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D020156:Salicylic Acid / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; C112279:COI1 protein, Arabidopsis; D003517:Cyclopentanes; C525049:JAS1 protein, Arabidopsis; D009687:Nuclear Proteins; D054883:Oxylipins; C497952:PHYB protein, Arabidopsis; D010636:Phenols; D051939:Phytochrome B; C011006:jasmonic acid; D020156:Salicylic Acid