Interdependent Iron and Phosphorus Availability Controls Photosynthesis Through Retrograde Signaling

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 phot...

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Published inbioRxiv
Main Authors Nam, Hye-In, Shahzad, Zaigham, Dorone, Yanniv, Clowez, Sophie, Zhao, Kangmei, Bouain, Nadia, Cho, Huikyong, Rhee, Seung Y, Rouached, Hatem
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 12.02.2021
Subjects
Ascorbic acid
Association analysis
Chlorophyll
Chloroplasts
Chlorosis
Genomes
Iron
Nutrient availability
Nutrient deficiency
Nutrients
Phenotypes
Phosphorus
Photosynthesis
Retrograde transport
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Summary: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. Competing Interest Statement The authors have declared no competing interest.
DOI:10.1101/2021.02.11.430802