title: Convergent responses to stress. Solar ultraviolet-B radiation and Manduca sexta herbivory elicit overlapping transcriptional responses in field-grown plants of Nicotiana longiflora.
abstract: The effects of solar ultraviolet (UV)-B (280-315 nm) on plants have been studied intensively over the last 2 decades in connection with research on the biological impacts of stratospheric ozone depletion. However, the molecular mechanisms that mediate plant responses to solar (ambient) UV-B and their interactions with response mechanisms activated by other stressors remain for the most part unclear. Using a microarray enriched in wound- and insect-responsive sequences, we examined expression responses of 241 genes to ambient UV-B in field-grown plants of Nicotiana longiflora Cav. Approximately 20% of the sequences represented on the array showed differential expression in response to solar UV-B. The expression responses to UV-B had parallels with those elicited by simulated Manduca sexta herbivory. The most obvious similarities were: (a) down-regulation of several photosynthesis-related genes, and (b) up-regulation of genes involved in fatty acid metabolism and oxylipin biosynthesis such as HPL (hydroperoxide lyase), alpha-DIOX (alpha-dioxygenase), LOX (13-lipoxygenase), and AOS (allene oxide synthase). Genes encoding a WRKY transcription factor, a ferredoxin-dependent glutamate-synthase, and several other insect-responsive genes of unknown function were also similarly regulated by UV-B and insect herbivory treatments. Our results suggest that UV-B and caterpillar herbivory activate common regulatory elements and provide a platform for understanding the mechanisms of UV-B impacts on insect herbivory that have been documented in recent field studies.
authors.affiliation: Ifeva, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
authors.forename: Miriam M
authors.initials: MM
authors.lastname: Izaguirre
authors.forename: Ana L
authors.initials: AL
authors.lastname: Scopel
authors.forename: Ian T
authors.initials: IT
authors.lastname: Baldwin
authors.forename: Carlos L
authors.initials: CL
authors.lastname: Ballaré
mesh_terms: D000818:Animals; D015536:Down-Regulation / Q000528:radiation effects; D005247:Feeding Behavior; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D017343:Genes, Plant / Q000235:genetics; D018402:Manduca / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D015203:Reproducibility of Results; D014026:Nicotiana / Q000235:genetics* / Q000469:parasitology / Q000528:radiation effects*; D014158:Transcription, Genetic / Q000528:radiation effects*; D014466:Ultraviolet Rays; D015854:Up-Regulation / Q000528:radiation effects