Integration of attractive and defensive phytochemicals is unlikely to constrain chemical diversification in a perennial herb

Diversification of plant chemical phenotypes is typically associated with spatially and temporally variable plant-insect interactions. Floral scent is often assumed to be the target of pollinator-mediated selection, whereas foliar compounds are considered targets of antagonist-mediated selection. However, floral and vegetative phytochemicals can be biosynthetically linked and may thus evolve as integrated phenotypes. Utilizing a common garden of 28 populations of the perennial herb Arabis alpina (Brassicaceae), we investigated integration within and among floral scent compounds and foliar defense compounds (both volatile compounds and tissue-bound glucosinolates). Within floral scent volatiles, foliar volatile compounds, and glucosinolates, phytochemicals were often positively correlated, and correlations were stronger within these groups than between them. Thus, we found no evidence of integration between compound groups indicating that these are free to evolve independently. Relative to self-compatible populations, self-incompatible populations experienced stronger correlations between floral scent compounds and a trend towards lower integration between floral scent and foliar volatiles. Our study serves as a rare test of the integration of multiple, physiologically related plant traits that each are potential targets of insect-mediated selection. Our results suggest that independent evolutionary forces are likely to diversify different axes of plant chemistry without major constraints.

Methods
This data was collected in 2020 and 2021 at Lund university, Sweden and ETH Zürich, Switzerland. 

The data has been processed and cleaned for publication according to standard practices in the field of phytochemistry. Details on data handling can be found in the associated manuscript and supporting information.

植物化学表型的多样化通常与时空动态变化的植物-昆虫互作紧密相关。学界普遍认为，花香是传粉者介导选择的作用靶标，而叶部化合物则被视为拮抗生物介导选择的作用靶标。然而，花部与营养体的植物次生代谢物存在生物合成层面的关联，因此可能作为整合型表型共同演化。
本研究以多年生草本植物高山南芥（Arabis alpina，十字花科Brassicaceae）的28个种群的同质种植园（common garden）为研究材料，探究了花香化合物、叶部防御化合物（包括挥发性化合物与组织结合型硫代葡萄糖苷（glucosinolates））内部及二者之间的代谢整合关系。研究发现，在花香挥发物、叶部挥发物以及硫代葡萄糖苷这三类组分内部，植物化学物质往往呈现正相关关系，且组内相关性显著强于组间相关性。因此，本研究未发现不同化合物类群间存在整合性的证据，表明这些类群可独立演化。
相较于自交亲和种群，自交不亲和种群的花香化合物间相关性更强，且花香与叶部挥发物间的整合程度呈现下降趋势。本研究是罕见的针对多类生理相关植物性状整合演化的检验，这些性状均为昆虫介导选择的潜在靶标。研究结果表明，独立的演化压力可能驱动植物化学不同维度的多样化，且未受到显著的演化约束。

研究方法
本数据集于2020年与2021年分别在瑞典隆德大学（Lund University）与瑞士苏黎世联邦理工学院（ETH Zürich）采集完成。
本数据已按照植物化学领域的标准操作流程完成处理与清洗，以用于发表。数据处理的详细细节可参阅相关研究论文及其配套支持信息材料。