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bioRxiv · 10.64898/2026.10.07.757215

Root-to-shoot ABA transport by NPF2.4 and NPF2.5 links stomatal regulation to photosynthetic performance

Yamori, W.·Qu, Y.·Rossille, A.·Dubos, C.·Kanno, Y.·Takebayashi, Y.·Hirari, M. Y.·Watanabe, S.·Seo, M.
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Abstract

Fluctuating light strongly limits photosynthetic efficiency in plants, yet the mechanisms coordinating stomatal dynamics with rapid photosynthetic induction remain incompletely understood. Here, through a forward physiological screen in Arabidopsis, we identify the abscisic acid (ABA) transporters NPF2.4 and NPF2.5 as regulators of photosynthetic responses to fluctuating light. Loss-of-function npf2.4 and npf2.5 mutants exhibited accelerated stomatal opening and photosynthetic induction during light transitions, resulting in enhanced biomass accumulation and seed yield without compromising long-term drought tolerance. NPF2.4 and NPF2.5 mediated ABA uptake in yeast and were predominantly expressed in the root pericycle and cortex/epidermal tissues, respectively. Reciprocal grafting, xylem sap ABA measurements, and ABA treatment to the roots demonstrated that both transporters regulate root-to-shoot ABA transport. Our findings reveal that root-derived ABA modulates stomatal dynamics and photosynthetic efficiency under fluctuating light, establishing long-distance hormone transport as a key regulator of plant carbon gain in dynamic environments.

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Yamori, W., Qu, Y., Rossille, A., Dubos, C., Kanno, Y., Takebayashi, Y., Hirari, M. Y., Watanabe, S., Seo, M.. 2026-10-07. Root-to-shoot ABA transport by NPF2.4 and NPF2.5 links stomatal regulation to photosynthetic performance. https://doi.org/10.64898/2026.10.07.757215

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