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Interdependent Iron and Phosphorus Availability Controls Photosynthesis Through Retrograde Signaling

Abstract : Iron deficiency hampers photosynthesis and is associated with chlorosis. We recently showed that iron deficiency-induced chlorosis depends on phosphorus availability. How plants integrate these cues to control chlorophyll accumulation is unknown. Here, we show that iron limitation downregulates photosynthesis genes in a phosphorus-dependent manner. Using transcriptomics and genome-wide association analysis, we identify two genes, a chloroplastic ascorbate transporter ( PHT4;4 ) and a nuclear transcription factor ( bZIP58 ), which prevent the downregulation of photosynthesis genes leading to the stay-green phenotype under iron-phosphorus deficiency. Joint limitation of these nutrients induces ascorbate accumulation by activating expression of an ascorbate biosynthesis gene, VTC4 , which requires bZIP58. Exogenous ascorbate prevents iron deficiency-induced chlorosis in vtc4 mutants, but not in bzip58 or pht4;4 . Our study demonstrates chloroplastic ascorbate transport is essential for preventing the downregulation of photosynthesis genes under iron-phosphorus combined deficiency. These findings uncover a molecular pathway coordinating chloroplast-nucleus communication to adapt photosynthesis to nutrient availability.
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Preprints, Working Papers, ...
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https://hal.inrae.fr/hal-03153603
Contributor : Chantal Baracco <>
Submitted on : Friday, February 26, 2021 - 3:13:07 PM
Last modification on : Saturday, March 20, 2021 - 3:31:39 AM

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Hatem Rouached, Hye-In Nam, Zaigham Shahzad, Yanniv Dorone, Sophie Clowez, et al.. Interdependent Iron and Phosphorus Availability Controls Photosynthesis Through Retrograde Signaling. 2021. ⟨hal-03153603⟩

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