Among major cereals domesticated as staple food, only sorghum has a high proportion of cultivars with condensed tannins in grain, which can trigger bitter taste perception in animals by binding to type 2 taste receptors (TAS2Rs). Here, we report the completion of uncovering of a pair of duplicate recessive genes (Tannin1 and Tannin2) underlying tannin presence. Three loss-of-function alleles from each gene were identified in non-tannin sorghum desired as palatable food. Condensed tannins effectively prevented sparrows from consuming sorghum grain. Parallel geographic distributions between tannin sorghum and Quelea quelea supported the role of tannins in fighting against this major herbivore threat. Association between geographic distributions of human TAS2R variants and tannin sorghum across Africa suggested that different causes had probably driven this bidirectional selection according to varied local herbivore threats and human taste sensitivity. Our investigation uncovered coevolution among humans, plants and environments linked by allelochemicals.

中文翻译：

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旨在平衡非洲农业生态系统中竞争选择的化感化学物质。

在作为主食驯化的主要谷物中，只有高粱具有较高比例的谷物中单宁浓缩的品种，可通过与2型味觉受体（TAS2Rs）结合而引发动物对苦味的感知。在这里，我们报告完成了揭示单宁存在的一对重复的隐性基因（Tannin1 和 Tannin2）。在需要作为可口食物的非单宁高粱中鉴定出来自每个基因的三个功能丧失等位基因。浓缩的单宁有效地阻止了麻雀食用高粱。单宁高粱和 Quelea quelea 之间的平行地理分布支持单宁在对抗这一主要食草动物威胁中的作用。人类 TAS2R 变体的地理分布与非洲单宁高粱之间的关联表明，根据不同的当地食草动物威胁和人类味觉敏感性，不同的原因可能推动了这种双向选择。我们的调查揭示了人类、植物和环境之间由化感物质相关联的共同进化。