Glutamate-1-semialdehyde aminotransferase is redox regulated by a TRX f/m-NTRC module coordinating chlorophyll biosynthesis and photosynthesis in pea.

In pea (Pisum sativum), PsGSA encodes a chloroplast GSAAT whose redox control via Cys169–Cys191 and a TRX f/m-NTRC module strongly tunes ALA synthesis and photosynthesis.

• Why it matters: Chlorophyll production in tetrapyrrole biosynthesis depends on ALA, but how GSAAT is regulated in pea—especially by chloroplast redox signaling—was unclear.
• What they did: The study identified a single PsGSA gene, tested leaf expression and light responsiveness, silenced PsGSA and redox genes, and used in vitro assays showing NADPH-dependent TRX f, TRX m, and NTRC synergistically reduce and reactivate oxidized GSAAT.
• The result: PsGSA silencing severely reduced GSAAT activity, ALA-synthesizing capacity, chlorophyll biosynthesis, and photosynthesis, and caused feedback down-regulation of other TBS genes; combined silencing of NTRC plus TRX f and TRX m produced pronounced GSAAT oxidation and chlorophyll deficiency, while single or double silencing caused milder effects.

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