Mutation of a bHLH transcription factor allowed almond domestication

First author: R. Sánchez-Pérez; Affiliations: University of Copenhagen (哥本哈根大学): Frederiksberg, Denmark

Corresponding author: R. Sánchez-Pérez

Wild almond species accumulate the bitter and toxic cyanogenic diglucoside amygdalin. Almond domestication was enabled by the selection of genotypes harboring sweet kernels. We report the completion of the almond reference genome. Map-based cloning using an F1 population segregating for kernel taste led to the identification of a 46-kilobase gene cluster encoding five basic helix-loop-helix transcription factors, bHLH1 to bHLH5. Functional characterization demonstrated that bHLH2 controls transcription of the P450 monooxygenase–encoding genes PdCYP79D16 and PdCYP71AN24, which are involved in the amygdalin biosynthetic pathway. A nonsynonymous point mutation (Leu to Phe) in the dimerization domain of bHLH2 prevents transcription of the two cytochrome P450 genes, resulting in the sweet kernel trait.

野生的杏仁会积累苦且具有毒性的生氰二葡糖苷苦杏仁苷。杏仁的驯化主要是选择那些能够产生甜仁的基因型。作者在本文中报道了杏仁的参考基因组。利用F1杏仁甜味分离群体，基于图位克隆的方法，作者鉴定到了一个46Kb长的基因簇序列区域，该区域存在五个编码bHLH转录因子的基因。功能鉴定显示bHLH2能够控制P450单加氧酶编码基因PdCYP79D16和PdCYP71AN24的转录，而这两个基因参与了苦杏仁苷的生物合成通路。bHLH2蛋白上二聚化结构域中一个非同义替换（亮氨酸替换为苯丙氨酸）会导致这两个细胞色素P450基因的转录降低，从而得到甜味的杏仁。

通讯：R. Sánchez-Pérez (https://plen.ku.dk/english/employees/?pure=en/persons/326340)

研究方向：李属植物的重要农艺性状的研究。

doi: 10.1126/science.aav8197

Journal: Science

Published date: June 14, 2019