Evolutionary origin and functional role of CsAlaDC in theanine biosynthesis in C. sinensis. (IMAGE)

Nanjing Agricultural University The Academy of Science

Evolutionary origin and functional role of CsAlaDC in theanine biosynthesis in C. sinensis.

Caption

Evolutionary origin and functional role of CsAlaDC in theanine biosynthesis in C. sinensis. (A) Proposed evolutionary trajectory of CsAlaDC via gene duplication and subsequent neofunctionalization from the ancestral CsSDC. Gene structures of CsSDC, CsASDC1, CsASDC2, and CsAlaDC are depicted, with exon lengths indicated in base pairs (bp). Key residues for enzymatic function are highlighted. During evolution, codon substitutions TAC(Tyr) → TTT(Phe) and TGT(Cys) → GGT(Gly) gave rise to Phe106 and Gly168 in CsAlaDC, both located near the catalytic center and essential for alanine decarboxylase activity. Notably, the combined length of the first two exons of CsAlaDC approximates that of the first exon of CsSDC, suggesting an exon-splitting event post-duplication. (B) Model illustrating the contribution of CsAlaDC to theanine biosynthesis. The emergence of CsAlaDC enables efficient ethylamine production, promoting theanine synthesis and accumulation in C. sinensis. Theanine content in C. sinensis, C. oleifera, and the outgroup A. thaliana is shown for comparison.

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Horticulture Research

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