Effect of Elevated CO(2) on Seed Yield, Essential Oil Metabolism, Nutritive Value, and Biological Activity of Pimpinella anisum L. Accessions at Different Seed Maturity Stages

SIMPLE SUMMARY: This study was conducted to investigate whether the positive impact of elevated CO(2) (eCO(2)) on the chemical composition of aniseed (Pimpinella anisum L.) seeds is dependent on seed developmental stages and origin. To this end, we investigated the biochemical changes in eCO(2)-treated aniseed accessions from Tunisia, Syria, Turkey, Morocco, Yemen, and Egypt during three developmental stages (immature, premature, and mature). The highest dry weight percentages and seed yields were recorded for the Egypt and Morocco accessions. eCO(2) has inducing properties on the nutritive and biological values of aniseeds, yet its effectiveness is related to seed maturity and provenances. For instance, seed maturation increased the nutrients and antioxidant metabolites in most eCO(2)-treated accessions. Conversely, essential oil metabolism was decreased by seed maturation but this effect was significantly reduced by the use of eCO(2). The enhanced accumulation of bioactive compounds in eCO(2)-treated seeds was accompanied by improved health benefits. In this regard, eCO(2) induces the antioxidant and hypocholesterolemic activities of aniseeds, particularly at mature stages. Thus, the present study confirms that there are significant interactions between eCO(2) exposure, aniseed maturity, and origin on the chemical composition and pharmaceutical properties of aniseed. ABSTRACT: Besides the lack of studies regarding applying elevated CO(2) (eCO(2)) as a strategy to improve the chemical composition of anise (Pimpinella anisum L.) seeds, studies on its interaction with seed developmental stages and origin are very limited. The seed yield, chemical composition, and biological activity of 6 aniseed accessions (Egypt, Tunisia, Syria, Turkey, Yemen, and Morocco) were investigated during three developmental stages (immature, premature, and mature) under control and elevated CO(2) conditions. Mature seeds from all aniseed accessions had significantly higher (p < 0.05) dry weight (DW) percentages than premature and immature seeds. The highest DW percentages were recorded in Egypt and Morocco accessions. Seed maturation increased nutrients and antioxidant metabolites in most eCO(2)-treated accessions. In contrast, essential oils were decreased by seed maturation, while eCO(2) reversed this effect. Essential oil-related precursors (e.g., phenylalanine) and enzyme activities (3-Deoxy-d-arabino-heptulosonate-7-phosphate synthase (DAHPS) and O–methyltransferase) decreased with seed maturity. However, high CO(2) reduced this impact and further induced the other essential oil-related precursors (shikimic and cinnamic acids). Consequently, eCO(2) provoked changes in the antioxidant and hypocholesterolemic activities of aniseeds, particularly at mature stages. Overall, eCO(2) application, as an efficient way to improve aniseed growth, essential oil metabolism, and chemical composition, was affected by seed maturation and origin. Future studies of eCO(2)-treated aniseeds as a nutraceutical and pharmaceutical product are suggested.