J Integr Plant Biol. ›› 2023, Vol. 65 ›› Issue (5): 1099-1112.DOI: 10.1111/jipb.13443

• Abiotic Stress Responses •     Next Articles

Brassinosteroid signaling regulates phosphate starvation‐induced malate secretion in plants

Tongtong Liu1,2†, Suren Deng1,2†, Cheng Zhang1,2, Xu Yang1,2, Lei Shi1,2, Fangsen Xu1,2, Sheliang Wang1,2 and Chuang Wang1,2*   

  1. 1. Microelement Research Center, College of Resources & Environment, Huazhong Agricultural University, Wuhan 430070, China;
    2. Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China
    These authors contributed equally to this work.
    *Correspondence: Chuang Wang (chuang.wang@mail.hzau.edu.cn)
  • Received:2022-08-30 Accepted:2022-12-28 Online:2023-02-10 Published:2023-05-01

Abstract: Inorganic phosphate (Pi) is often limited in soils due to precipitation with iron (Fe) and aluminum (Al). To scavenge heterogeneously distributed phosphorus (P) resources, plants have evolved a local Pi signaling pathway that induces malate secretion to solubilize the occluded Fe‐P or Al‐P oxides. In this study, we show that Pi limitation impaired brassinosteroid signaling and downregulated BRASSINAZOLE‐RESISTANT 1 (BZR1) expression in Arabidopsis thaliana. Exogenous 2,4‐epibrassinolide treatment or constitutive activation of BZR1 (in the bzr1‐D mutant) significantly reduced primary root growth inhibition under Pi‐starvation conditions by downregulating ALUMINUM‐ACTIVATED MALATE TRANSPORTER 1 (ALMT1) expression and malate secretion. Furthermore, AtBZR1 competitively suppressed the activator effect of SENSITIVITY TO PROTON RHIZOTOXICITY 1 (STOP1) on ALMT1 expression and malate secretion in Nicotiana benthamiana leaves and Arabidopsis. The ratio of nuclear‐localized STOP1 and BZR1 determined ALMT1 expression and malate secretion in Arabidopsis. In addition, BZR1‐inhibited malate secretion is conserved in rice (Oryza sativa). Our findings provide insight into plant mechanisms for optimizing the secretion of malate, an important carbon resource, to adapt to Pi‐deficiency stress.

Key words: ALMT1, brassinosteroid signaling, bzr1, malate, phosphate deficiency, STOP1

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