Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a Agricultura, Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad de Buenos Aires, C1417DSE Buenos Aires, Argentina.
Plant Physiol. 2010 Feb;152(2):1084-95. doi: 10.1104/pp.109.148999. Epub 2009 Dec 9.
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.
紫外线 B（UV-B）辐射，是日光光谱中非常小的一部分，它会引起植物次生代谢的变化，从而对植物与昆虫的相互作用产生重大影响。介导这些太阳 UV-B 特定影响的信号转导途径尚不清楚。我们通过测量野生型和转基因茉莉酸缺陷拟南芥（其中一种脂氧合酶基因（NaLOX3）被沉默）对 UV-B 的反应，研究了茉莉酸信号转导的作用。在野生型植物中，UV-B 未能引起茉莉酸（JA）或生物活性 JA-异亮氨酸结合物的积累，但放大了茉莉酸诱导基因（如胰蛋白酶抑制剂（TPI））对创伤和茉莉酸甲酯的反应，并增加了几种苯丙烷衍生物的积累。在 as-lox 植物中，这些酚类反应中的一些（咖啡酰多胺结合物的积累）完全缺失，而其他一些（芦丁和绿原酸的积累）在两种基因型中相似。在开放田间条件下，as-lox 植物比野生型植物受到更多的昆虫伤害，这是意料之中的，但 UV-B 暴露引起的对草食性的抵抗力的显著增加（在野生型植物中非常显著）并没有在 as-lox 植物中发生。我们得出结论，太阳 UV-B（1）在酚类化合物的诱导中使用茉莉酸依赖和非依赖途径，（2）增加了对茉莉酸的敏感性，导致伤口反应基因（TPI）的表达增强。在 as-lox 植物中缺乏 UV-B 诱导的抗草食性保护表明，茉莉酸信号转导在太阳 UV-B 增加田间昆虫草食性抗性的机制中发挥着核心作用。
