Low red/far - red ratios reduce arabidopsis resistance to Botrytis cinerea and jasmonate responses via a COI1 - JAZ10 - dependent, salicylic acid - independent mechanism

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 fun...

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Otros Autores: Cerrudo, Ignacio, Keller, Mercedes M., Cargnel, Miriam D., Demkura, Patricia Verónica, de Wit, Mieke, Patitucci, Micaela Soledad, Pierik, Ronald, Pieterse, Corne M. J., Ballaré, Carlos Luis
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Lenguaje:Español
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Acceso en línea:http://ri.agro.uba.ar/files/intranet/articulo/2012Cerrudo.pdf
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Sumario: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 SCF COI1-JASMONATE ZIMDOMAIN [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.
ISSN:0032-0889