Despite the extensive studies on latex, some fundamental questions on their chemical specialization and the factors influencing this specialization have yet to be investigated. To address this issue, latexes and their bearing tissues from diverse species were profiled by 1HNMR and GC-MS. Additionally, the antiherbivory activity of these materials was tested against thrips (Frankliniella occidentalis Pergande, 1895). The multivariate data analysis showed a clear separation between latexes and leaves from the same species. Conversely, the chemical profiles of latexes from different species were highly similar, that is, they displayed much less metabolic species-specificity. These shared chemical profiles of latexes were reflected in their overall higher mortality index (80.4% ± 7.5) against thrips compared with their bearing tissues (55.5% ± 14.9). The metabolites correlated to the antiherbivory activity of latexes were triterpenoids and steroids. However, the activity could not be attributed to any single terpenoid. This discrepancy and the reduction of the latex activity after fractionation suggested a complementary effect of the compounds when in a mixture as represented by the latex. Additionally, aqueous fractions of several latexes were found to possess simple spectra, even with only 1 metabolite. These metabolites were determined to be organic acids that might be involved in the modulation of the rate of latex coagulation, potentially increasing the sealing and trapping effects of the latex.

中文翻译：

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植物胶乳的化学分化及其对蓟马 Frankliniella occidentalis 的抗食草活性

尽管对乳胶进行了广泛的研究，但关于其化学专业化的一些基本问题以及影响这种专业化的因素还有待研究。为了解决这个问题，来自不同物种的乳胶及其承载组织通过 1HNMR 和 GC-MS 进行了分析。此外，还针对蓟马测试了这些材料的抗食草活性（Frankliniella occidentalis Pergande，1895）。多变量数据分析表明，来自同一物种的乳胶和叶子之间存在明显的分离。相反，来自不同物种的乳胶的化学特征非常相似，也就是说，它们表现出的代谢物种特异性要低得多。乳胶的这些共享化学特征反映在它们对蓟马的总体死亡率（80.4% ± 7.5）高于其承载组织（55.5% ± 14.9）。与乳胶抗食草活性相关的代谢物是三萜类化合物和类固醇。然而，该活性不能归因于任何单一萜类化合物。这种差异和分馏后胶乳活性的降低表明化合物在以胶乳为代表的混合物中时具有互补作用。此外，发现几种乳胶的水性部分具有简单的光谱，即使只有一种代谢物。这些代谢物被确定为有机酸，可能参与调节胶乳凝固速率，潜在地增加胶乳的密封和捕获作用。这种差异和分级后胶乳活性的降低表明化合物在以胶乳为代表的混合物中时具有互补作用。此外，发现几种乳胶的水性部分具有简单的光谱，即使只有一种代谢物。这些代谢物被确定为有机酸，可能参与调节胶乳凝固速率，潜在地增加胶乳的密封和捕获作用。这种差异和分级后胶乳活性的降低表明化合物在以胶乳为代表的混合物中时具有互补作用。此外，发现几种乳胶的水性部分具有简单的光谱，即使只有一种代谢物。这些代谢物被确定为有机酸，可能参与调节胶乳凝固速率，潜在地增加胶乳的密封和捕获作用。