Jasmonate - dependent and - independent pathways mediate specific effects of solar ultraviolet B radiation on leaf phenolics and antiherbivore defense

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 and transgenic jasmonate-deficient Nicotiana attenuata plants in which a lipoxygenase gene [NaLOX3] was silenced [as-lox]. In wild-type plants, UV-B failed to elicit the accumulation of jasmonic acid [JA] or the bioactive JA-isoleucine conjugate but amplified the response of jasmonate-inducible genes, such as trypsin proteinase inhibitor [TPI], to wounding and methyl jasmonate, 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 wild-type plants, as expected, but the dramatic increase in resistance to herbivory elicited by UV-B exposure, which was highly significant in wild-type 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 antiherbivore 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.

Bibliographic Details

Main Authors:	Demkura, Patricia Verónica, Abdala, Guillermina I., Baldwin, Ian T., Ballaré, Carlos Luis
Format:	Texto biblioteca
Language:	spa
Subjects:	ACETIC ACID DERIVATIVE, CYCLOPENTANE DERIVATIVE, JASMONIC ACID, JASMONIC ACID METHYL ESTER, OXYLIPIN, PHENOL DERIVATIVE, GENE SILENCING, GENETICS, METABOLISM, PLANT LEAF, RADIATION EXPOSURE, SIGNAL TRANSDUCTION, SUNLIGHT, TOBACCO, TRANSGENIC PLANT, ULTRAVIOLET RADIATION, ACETIC ACIDS, ANIMALS, CYCLOPENTANES, INSECTS, OXYLIPINS, PHENOLS, PLANT LEAVES, PLANTS, GENETICALLY MODIFIED, ULTRAVIOLET RAYS, HEXAPODA, NICOTIANA ATTENUATA,
Online Access:	http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=46617
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