Center for Chemical Ecology, Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA.
J Chem Ecol. 2010 Mar;36(3):319-25. doi: 10.1007/s10886-010-9764-8. Epub 2010 Feb 27.
Fatty acid amino acid conjugates (FACs) have been found in noctuid as well as sphingid caterpillar oral secretions; in particular, volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] and its biochemical precursor, N-linolenoyl-L-glutamine, are known elicitors of induced volatile emissions in corn plants. These induced volatiles, in turn, attract natural enemies of the caterpillars. In a previous study, we showed that N-linolenoyl-L-glutamine in larval Spodoptera litura plays an important role in nitrogen assimilation which might be an explanation for caterpillars synthesizing FACs despite an increased risk of attracting natural enemies. However, the presence of FACs in lepidopteran species outside these families of agricultural interest is not well known. We conducted FAC screening of 29 lepidopteran species, and found them in 19 of these species. Thus, FACs are commonly synthesized through a broad range of lepidopteran caterpillars. Since all FAC-containing species had N-linolenoyl-L-glutamine and/or N-linoleoyl-L-glutamine in common, and the evolutionarily earliest species among them had only these two FACs, these glutamine conjugates might be the evolutionarily older FACs. Furthermore, some species had glutamic acid conjugates, and some had hydroxylated FACs. Comparing the diversity of FACs with lepidopteran phylogeny indicates that glutamic acid conjugates can be synthesized by relatively primitive species, while hydroxylation of fatty acids is limited mostly to larger and more developed macrolepidopteran species.
脂肪酸-氨基酸缀合物（FACs）已在夜蛾和鳞翅目毛毛虫的口腔分泌物中被发现；特别是，[N-（17-羟基亚麻酰基）-L-谷氨酰胺]（volicitin）及其生化前体 N-亚麻酰基-L-谷氨酰胺，是玉米植株中诱导挥发性排放的已知激发子。这些诱导的挥发性物质反过来又吸引了毛毛虫的天敌。在之前的一项研究中，我们表明，幼虫斜纹夜蛾中的 N-亚麻酰基-L-谷氨酰胺在氮同化中起着重要作用，这可能解释了毛毛虫尽管面临吸引天敌的风险增加，但仍会合成 FACs。然而，这些农业关注的科以外的鳞翅目物种中存在 FACs 的情况并不为人所知。我们对 29 种鳞翅目物种进行了 FAC 筛选，发现其中 19 种含有 FACs。因此，FACs 是通过广泛的鳞翅目毛毛虫共同合成的。由于所有含有 FAC 的物种都含有 N-亚麻酰基-L-谷氨酰胺和/或 N-亚油酸-L-谷氨酰胺，而其中进化最早的物种只含有这两种 FAC，因此这些谷氨酰胺缀合物可能是进化上更古老的 FAC。此外，一些物种含有谷氨酸缀合物，一些物种含有羟化 FACs。将 FAC 的多样性与鳞翅目系统发育进行比较表明，谷氨酸缀合物可以由相对原始的物种合成，而脂肪酸的羟化主要局限于更大和更发达的大型鳞翅目物种。
