Photosynthesis-derived carbohydrate supply sustains CuCl2-induced phytoalexin production in rice leaves

Darkness suppresses CuCl2-induced phytoalexin production in rice leaf disks, and restoring photosynthesis-derived sugars—especially sucrose—rescues diterpenoid and flavonoid accumulation.

• Why it matters: Light-triggered phytoalexin biosynthesis is known to require elicitor signaling, but the physiological supply conditions that keep metabolite production going were unclear.
• What they did: Rice (Oryza sativa L.) leaf disks were treated with CuCl2 under light or darkness; endogenous sugars were measured, biosynthetic gene induction was tracked, and sucrose, glucose, mannitol, 2-deoxy-D-glucose, and DCMU were applied.
• The result: In darkness, phytoalexins and biosynthetic genes fell while sucrose restored accumulation dose-dependently (mannitol did not), glucose partially restored diterpenoids and restored sakuranetin, and DCMU depleted sugars and suppressed phytoalexins with sucrose reversal.

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