Directed deterrence by capsaicin in chillies

Abstract

The primary function of ripe, fleshy fruit is to facilitate seed dispersal by attracting consumers, yet many fruits contain unpleasant-tasting chemicals that deter consumption by vertebrates. Here we investigate this paradox in the chili (Capsicum) and find that capsaicin, the chemical responsible for the fruit's peppery heat, selectively discourages vertebrate predators without deterring more effective seed dispersers.

Unfolding the codes of short-term feed appetence in farm and companion animals. A comparative oronasal nutrient sensing biology review

“…Responses to oral pungency or spiciness are mediated through the trigeminal nerve. Both hot temperature and capsaicin stimulate the TRPV1 receptor in animals triggering a pain-related alarm response (Tominaga and Julius 2000). A sigmoid type response of the TRPV1 receptor to capsaicin has been reported for both mammals and chickens although the responsive concentration range to capsaicin in lab rodents is in the nM (To´th et al 2004), while in chickens is in the M and does not result in a full neuronal response such as in lab rodents (Kirifides et al 2004).…”

“…Differences among animals have been reported regarding the sensitivity of the somatosensing system. While most mammals seem to be pain-mediated highly responsive to several spices, birds are more tolerant (Tewksbury and Nabhan 2001;Jordt and Julius 2002). For example even moderate levels of cinnamaldehyde, carvacrol, capsicum oleoresin or formic acid in feed resulted in decreased feed intake in pigs (Bikker et al 2003;Eisemann and van Heugten 2007) but not in chickens (Roura, unpublished data).…”

“…The somatic sensing in the oronasal cavity is linked to the cranial nerve V (the trigeminal) and covers all the oronasal epithelium (Miller and Teates 1984;Jones and Roper 1997;Witt et al 2003). Sensory neurons of the trigeminal nerve are part of the pain pathway and are involved in the detection of noxious stimuli such as thermal (low or high temperatures) and pungent (e.g., acids, spices) (Miller and Teates 1984;Hyde and Witherly 1993;Tominaga and Julius 2000). Both high and low temperatures and pungency are perceived through the stimulation of transmembrane ion channel members of the transient receptor potential (TRP) family (Julius and Basbaum 2001;Dhaka et al 2006).…”

“…Thus, moderate seasoning will stimulate digestive secretions [salivary, gastric, bile, pancreatic and intestinal mucosa secretions Srinivasam 2001, 2004)], while heavily spiced food, such as with capsaicin, might be perceived as noxious stimuli and trigger a pain-mediated alarm response (Tominaga and Julius 2000). Oral painmediated responses cause food rejection (Tewksbury and Nabhan 2001) followed by an integrated mucous y Pseudogenes include genes with missing transmembrane domains or part of the ORF sequence.…”

A Root-Expressed l-Phenylalanine:4-Hydroxyphenylpyruvate Aminotransferase Is Required for Tropane Alkaloid Biosynthesis in Atropa belladonna

“…Plants synthesize a variety of chemically diverse specialized metabolites, many of which have defined roles in defense against abiotic or biotic stresses and herbivory or are involved in chemical attraction to facilitate predation, pollination, or seed dispersal (Tewksbury and Nabhan, 2001;Klee, 2010;Klahre et al, 2011;Weinhold and Baldwin, 2011;De Luca et al, 2012;Mithöfer and Boland, 2012;Dudareva et al, 2013). The bioactive properties of plant specialized metabolites have led to their exploitation by humans as flavors, fragrances, pigments, and medicines.…”