Journal Article

Mutation of a bHLH transcription factor allowed almond domestication

Cigliano, R. Aiese, Sánchez-Pérez, R., Lotti, C., López-Marqués, R. L., Ricciardi, F., Moldovan, C., Møller, B. Lindberg, Dicenta, F., Mazzeo, R., Del Cueto, J., Ricciardi, L., Pavan, S.

2019

Overview

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.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: Amino Acid Substitution / Amygdalin - biosynthesis / Amygdalin - genetics / Amygdalin - metabolism / Basic Helix-Loop-Helix Transcription Factors - chemistry / Basic Helix-Loop-Helix Transcription Factors - genetics / Bitter taste / Cloning / Cytochrome P-450 Enzyme System - genetics / Cytochrome P450 / Cytochromes P450 / Dimerization / Domestication / Gene Expression Regulation, Plant / Genes / Genomes / Genotypes / Helix-loop-helix proteins (basic) / Kernels / Leucine - genetics / Monooxygenase / Multigene Family / Mutation / Phenylalanine - genetics / Plant Proteins - genetics / Point Mutation / Protein Conformation / Protein Multimerization - genetics / Prunus dulcis - genetics / Prunus dulcis - metabolism / Sweet taste / Taste / Transcription factors / Transcription, Genetic