Protection against herbivores

The ecological function of polyprenylated benzoyl- and acylphloroglucinol derivatives was studied in 77. calycinum flowers 26). The constituents accumulate in those parts of petals that are exposed to the outside in the unopened bud. They are, besides flavonoids, a new class of products that serve as floral UV pigments. The constituents also accumulate in anthers and ovarian walls and provide protection against herbivores. Thus, phloroglucinol derivatives hilfill both attractive and defensive functions in 77 calycinum flowers. 

Terpenes are generally lipophilic compoimds based on a simple five-carbon building block (isoprene unit). Monoterpenes are composed of two isoprene units (CIO), sesquiterpenes possess three isoprene units (Cl5), whereas diterpenes have four (C20), etc. Some terpenes, mainly isoprenes, mono- and sesquiterpenes are volatile and are referred to as volatile organic compounds (VOC). The terpene family includes hormones, carotenoid pigments, latex and most essential oils [HOP 03]. Terpenes play different roles such as attracting pollinators and protecting against herbivores, toxic insecticides and insect repellents [HOP 03]. 

Wink, M. 1988. Plant breeding importance of plant secondary metabolites for protection against pathogens and herbivores. Theor. Appl. Gen. 75, 225-... 

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