IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
artículos
Título:
Jasmonate dependent and independent pathways mediate specific effects of solar ultraviolet-B radiation on leaf phenolics and anti-herbivore defense
Autor/es:
DEMKURA PV; ABDALA G; BALDWIN IT; BALLARÉ CL
Revista:
PLANT PHYSIOLOGY.
Editorial:
AMER SOC PLANT BIOLOGISTS
Referencias:
Año: 2010 vol. 152 p. 1084 - 1095
ISSN:
0032-0889
Resumen:
Ultraviolet-B (UV-B) radiation, a very small fraction of the daylight spectrum, elicits changes in plant secondary metabolism that have large effects on plant-insect interactions. The signal transduction pathways that mediate these specific effects of solar UV-B are not known. We examined the role of jasmonate signaling by measuring responses to UV-B in wild type (WT) and transgenic jasmonate-deficient Nicotiana attenuata plants in which a lipoxygenase gene (NaLOX3) was silenced (as-lox). In WT plants, UV-B failed to elicit the accumulation of jasmonic acid (JA) or the bioactive JA-Ile conjugate, but amplified the response of jasmonate-inducible genes, such as trypsin proteinase inhibitor (TPI) to wounding and methyl-JA, and increased the accumulation of several phenylpropanoid derivatives. Some of these phenolic responses (accumulation of caffeoyl-polyamine conjugates), were completely lacking in as-lox plants, whereas others (accumulation of rutin and chlorogenic acid) were similar in both genotypes. In open field conditions, as-lox plants received more insect damage than WT plants, as expected, but the dramatic increase in resistance to herbivory elicited by UV-B exposure, which was highly significant in WT plants, did not occur in as-lox plants. We conclude that solar UV-B (1) uses jasmonate-dependent and independent pathways in the elicitation of phenolic compounds; and (2), increases sensitivity to jasmonates, leading to enhanced expression of wound-response genes (TPI). The lack of UV-B-induced anti-herbivore protection in as-lox plants suggests that jasmonate signaling plays a central role in the mechanisms by which solar UV-B increases resistance to insect herbivores in the field.