The basic helix–loop–helix transcription factors MYC1 and MYC2 have a dual role in the regulation of constitutive and stress‐inducible specialized metabolism in tomato

• DOI: 10.1111/nph.18379
• Publication Date: 2022-07-15T10:15:41Z
• Authors: Gwen Swinnen; Margaux De Meyer; Jacob Pollier; Francisco Javier ...; Evi Ceulemans; Jhon Venegas‐Molina; Liesbeth De Milde; Patricia Fernánde...; Mily Ron; Laurens Pauwels; Alain Goossens
• Keywords: Jasmonate; Secondary metabolism; Transcription

Summary Plants produce specialized metabolites to protect themselves from biotic enemies. Members of the Solanaceae family accumulate phenylpropanoid–polyamine conjugates (PPCs) in response attackers while also maintaining a chemical barrier steroidal glycoalkaloids (SGAs). Across plant kingdom, biosynthesis such defense compounds is promoted by jasmonate signaling which clade IIIe basic helix–loop–helix (bHLH) transcription factors play central role. By characterizing hairy root mutants obtained through Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)‐CRISPR associated protein 9 (CRISPR‐Cas9) genome editing, we show that tomato bHLH factors, MYC1 and MYC2, redundantly control jasmonate‐inducible PPC SGA production, are essential for constitutive biosynthesis. Double myc1 myc2 loss‐of‐function roots displayed suppressed expression genes, severely reduced levels main SGAs α‐tomatine dehydrotomatine. In contrast, basal genes involved was not affected. CRISPR‐Cas9(VQR) editing specific cis ‐regulatory element, targeted MYC1/2, promoter precursor gene led decreased this gene, but did affect its inducibility. Our results demonstrate transcriptional regulators have evolved under distinct regulatory cues specifically steer stress‐inducible metabolism.