Spicy foods elicit a pungent or hot and painful sensation that repels almost all mammals. Prof. LAI Ren’ group from Kunming Institute of Zoology, Chinese Academy of Sciences and researchers from Zhejiang University observed that tree shrews (Tupaia belangeri chinensis), which possess a close relationship with primates, can directly and actively consume chili peppers, despite the deep geographic isolation between the animal and the food.
Figure. P. boehmeriaefolium is the main environmental stress responsible for the positive selection of M579 in tree shrew TRPV1, which enables the unique feeding behavior of tree shrews with regards to pungent plants, such as chili peppers. (Image from LAI’s Group)
In this study, the genomic and functional analyses reveal that a single point mutation in the tree shrew’s transient receptor potential vanilloid type-1 (TRPV1, a polymodal nociceptor) ion channel (tsV1) lowers its sensitivity to capsaicinoids, which enables the unique feeding behavior of tree shrews with regards to pungent plants. The experimental evidence elucidates that strong selection for this residue in tsV1 might be driven by Piper boehmeriaefolium, a spicy plant that geographically overlaps with the tree shrew and produces Cap2, a capsaicin analog, in abundance.
Therefore, the researchers favor the idea that feeding adaptation to P. boehmeriaefolium is the most likely explanation to the fixation of this mutation by positive selection, which enabled an expansion of the tree shrew’s dietary repertoire. Consequently, this study broadens the evolutionary and molecular mechanism of pungency tolerance behavior.
HAN Yalan, LI Bowen, and YIN Tingting (Kunming Institute of Zoology, CAS) are the co-first authors of this paper. YANG Fan (Zhejiang University), Wang Guodong, YANG Shilong and LAI Ren (Kunming Institute of Zoology, CAS) are the corresponding authors. This work was supported by funding from the National Science Foundation (NSF) of China, Chinese Academy of Sciences (CAS) and Yunnan Province.