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Asteraceae Paradox: Chemical and Mechanical Protection of Taraxacum Pollen

“…The reduced pollen collection on Taraxacum diets may be indicative of feeding deterrence that could be due to low digestibility (i.e., physical defense), nutrient deficit, or presence of toxic compounds (i.e., chemical defense), which may be either directly toxic or interfere with nutrient assimilation [62,63]. Regarding the hypothesis of physical defense, Asteraceae pollen grains possess a thick multilayer wall that retains sporopollenin [44], as well as high amounts of pollenkit [16]. These structural properties of pollen grains could interfere with the nutrient assimilation process and render digestion difficult, requiring specific enzymes for extracting nutrients [17,21].…”

“…In addition to these variations of pollen primary and secondary metabolites, pollen also varies in its wall resistance properties, which may result in incomplete digestion. Transmission electron microscopy has revealed that Asteraceae pollen possesses a thick multilayer wall [44], which might inhibit the extraction of nutrients and act as a mechanical defense [17,21]. Despite these hypotheses, it is unclear why Asteraceae pollen is unsuitable for most bee species and the Asteraceae paradox remains unsolved.…”

Extraction of sporopollenin exine capsules from sunflower pollen grains

“…Importantly, the exine also provides environmental protection for successful pollination, motivating its extraction for use as natural microcapsules which are generally recognized as safe by the US Food and Drug Administration (FDA). 14,15 Sporopollenin exine capsules (SECs) produced from spores and pollen grains are resistant to extreme temperatures, pressures, and harsh chemical treatments as well as are devoid of allergenic materials. 1,14 In order to extract SECs, a simple chemical process is highly desirable to remove all interior and surface pollen constituents without altering the native microstructure of the exine capsule.…”

16. The problem of the Aryans and the Soma: The botanical evidence

“…However, as this is the only known case where flowers have been used in a burial from this period, no basis for comparison is available. Prehistoric, but much younger, remains of ephedras have also been reported from the temple-fortress complex of Togolok 21 in the Merv oasis (ancient Margiana -Parpóla 1988;Meier-Melikyan 1990) along with the remains of poppies (PapaverL., but it is unclear whether the species was P. somniferum, P. setigerum or some other poppy). In 1991,1 received some samples from the site, 3 which were subjected to pollen analysis at the Department of Botany, University of Helsinki.…”