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Functional characterization of the three Oryza sativa SPX-MFS proteins in maintaining phosphate homeostasis
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  • Runze Guo,
  • Qi Zhang,
  • Yinghui Ying,
  • Wenying Liao,
  • Yu Liu,
  • James Whelan,
  • Mao Chuanzao,
  • Huixia Shou
Runze Guo
Zhejiang University State Key Laboratory of Plant Physiology and Biochemistry

Corresponding Author:grz@zju.edu.cn

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Qi Zhang
Zhejiang University State Key Laboratory of Plant Physiology and Biochemistry
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Yinghui Ying
Zhejiang University State Key Laboratory of Plant Physiology and Biochemistry
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Wenying Liao
Zhejiang University State Key Laboratory of Plant Physiology and Biochemistry
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Yu Liu
Zhejiang University State Key Laboratory of Plant Physiology and Biochemistry
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James Whelan
Zhejiang University State Key Laboratory of Plant Physiology and Biochemistry
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Mao Chuanzao
Zhejiang University State Key Laboratory of Plant Physiology and Biochemistry
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Huixia Shou
Zhejiang University State Key Laboratory of Plant Physiology and Biochemistry
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Abstract

Plant vacuoles serve as the primary intracellular compartments for phosphorus (P) storage and play a central role to maintain P homeostasis. The Oryza sativa (rice) genome contains three genes that encode SPX (SYG1/PHO81/XPR1)-MFS (Major Facility Superfamily) proteins (OsSPX-MFS1, 2, 3). OsSPX-MFS1 and OsSPX-MFS3 were shown previously to have vacuolar phosphate (Pi) transporter activities, but the physiological role of the three transporters under varying P conditions and under field grown conditions for a crop plant is not known. To address this knowledge gap, we generated single, double, and triple mutants (7 mutants with at least two lines of each) for the three rice Os SPX-MFS genes. All the mutants except osspx-mfs2 display lower vacuolar Pi concentrations and all Os SPX-MFSs overexpression plant lines display higher Pi accumulation, demonstrating that all three OsSPX-MFSs are vacuolar Pi influx transporters. OsSPX-MFS3 plays the dominant role based on the phenotypes of three single mutants in terms of growth, vacuolar and tissue Pi concentrations. OsSPX-MFS2 is the weakest and only functions as vacuole Pi sequestration under osspx-mfs1/3 background. The vacuolar Pi sequestration was severely impaired in osspx-mfs1/ 3 and osspx-mfs1/2/ 3, which led to Pi toxicity and subsequently increased Pi allocation to aerial organs. High Pi in the panicle result in necrotic symptoms on husks and impaired panicle and grain development in osspx-mfs1/ 3 and osspx-mfs1/2/ 3 mutant lines. The mutation in the weak vacuolar Pi transporter OsSPX-MFS2 resulted more stable yield compared to the wildtype under low P field conditions. The results suggest that alteration of vacuolar Pi sequestration may be a novel effective strategy to improve rice (crop) tolerance to low phosphorus field conditions and maintain yield.
19 Apr 2022Submitted to Plant, Cell & Environment
20 Apr 2022Submission Checks Completed
20 Apr 2022Assigned to Editor
26 Apr 2022Reviewer(s) Assigned
10 Jun 2022Review(s) Completed, Editorial Evaluation Pending
14 Jun 2022Editorial Decision: Revise Minor
16 Jun 20221st Revision Received
16 Jun 2022Submission Checks Completed
16 Jun 2022Assigned to Editor
21 Jun 2022Reviewer(s) Assigned
25 Jun 2022Review(s) Completed, Editorial Evaluation Pending
26 Jun 2022Editorial Decision: Accept
31 Jul 2022Published in Plant, Cell & Environment. 10.1111/pce.14414