title: UVR8 mediates UV-B-induced Arabidopsis defense responses against Botrytis cinerea by controlling sinapate accumulation.
abstract: Light is emerging as a central regulator of plant immune responses against herbivores and pathogens. Solar UV-B radiation plays an important role as a positive modulator of plant defense. However, since UV-B photons can interact with a wide spectrum of molecular targets in plant tissues, the mechanisms that mediate their effects on plant defense have remained elusive. Here, we show that ecologically meaningful doses of UV-B radiation increase Arabidopsis resistance to the necrotrophic fungus Botrytis cinerea and that this effect is mediated by the photoreceptor UVR8. The UV-B effect on plant resistance was conserved in mutants impaired in jasmonate (JA) signaling (jar1-1 and P35S:JAZ10.4) or metabolism of tryptophan-derived defense compounds (pen2-1, pad3-1, pen2 pad3), suggesting that neither regulation of the JA pathway nor changes in levels of indolic glucosinolates (iGS) or camalexin are involved in this response. UV-B radiation, acting through UVR8, increased the levels of flavonoids and sinapates in leaf tissue. The UV-B effect on pathogen resistance was still detectable in tt4-1, a mutant deficient in chalcone synthase and therefore impaired in the synthesis of flavonoids, but was absent in fah1-7, a mutant deficient in ferulic acid 5-hydroxylase, which is essential for sinapate biosynthesis. Collectively, these results indicate that UVR8 plays an important role in mediating the effects of UV-B radiation on pathogen resistance by controlling the expression of the sinapate biosynthetic pathway.
authors.affiliation: IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad de Buenos Aires, Ave. San Martín 4453, C1417DSE, Buenos Aires, Argentina.
authors.forename: Patricia V
authors.initials: PV
authors.lastname: Demkura
authors.forename: Carlos L
authors.initials: CL
authors.lastname: Ballaré
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000378:metabolism*; D020171:Botrytis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D003373:Coumaric Acids / Q000737:chemistry / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology; D060467:Disease Resistance / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D005961:Glucosinolates / Q000378:metabolism; D007211:Indoles / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D054883:Oxylipins / Q000494:pharmacology; D010636:Phenols / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D013844:Thiazoles / Q000378:metabolism; D014466:Ultraviolet Rays; D000094162:Phytoalexins
chemical_list: D029681:Arabidopsis Proteins; D002868:Chromosomal Proteins, Non-Histone; D003373:Coumaric Acids; D003517:Cyclopentanes; D005961:Glucosinolates; D007211:Indoles; D054883:Oxylipins; D010636:Phenols; D013844:Thiazoles; C525052:Uvr8 protein, Arabidopsis; C102405:camalexin; D000094162:Phytoalexins; C073734:sinapinic acid; C011006:jasmonic acid