J Integr Plant Biol. ›› 2023, Vol. 65 ›› Issue (9): 2157-2174.DOI: 10.1111/jipb.13537

• Molecular Physiology • Previous Articles     Next Articles

Plastid KEA-type cation/H+ antiporters are required for vacuolar protein trafficking in Arabidopsis

Xiao Zhang1,2,3,4, Lu Wang1,2,3,4, Ting Pan1, Xuexia Wu1, Jinbo Shen5, Liwen Jiang6, Hiromi Tajima7, Eduardo Blumwald7 and Quan‐Sheng Qiu1,2,3,4*   

  1. 1. MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 73000, China;
    2. Academy of Plateau Science and Sustainability, School of Life Sciences, Qinghai Normal University, Xining 810000, China;
    3. College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang 524088, China;
    4. State Key Laboratory of Herbage Improvement and Grassland Agro‐ecosystems, Lanzhou University, Lanzhou 730000, China;
    5. State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China;
    6. School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China;
    7. Department of Plant Sciences, University of California, Davis, CA 95616, USA
    *Correspondence: Quan‐Sheng Qiu (qiuqsh@lzu.edu.cn)
  • Received:2023-05-03 Accepted:2023-05-28 Online:2023-05-30 Published:2023-09-01

Abstract: Arabidopsis plastid antiporters KEA1 and KEA2 are critical for plastid development, photosynthetic efficiency, and plant development. Here, we show that KEA1 and KEA2 are involved in vacuolar protein trafficking. Genetic analyses found that the kea1 kea2 mutants had short siliques, small seeds, and short seedlings. Molecular and biochemical assays showed that seed storage proteins were missorted out of the cell and the precursor proteins were accumulated in kea1 kea2. Protein storage vacuoles (PSVs) were smaller in kea1 kea2. Further analyses showed that endosomal trafficking in kea1 kea2 was compromised. Vacuolar sorting receptor 1 (VSR1) subcellular localizations, VSR–cargo interactions, and p24 distribution on the endoplasmic reticulum (ER) and Golgi apparatus were affected in kea1 kea2. Moreover, plastid stromule growth was reduced and plastid association with the endomembrane compartments was disrupted in kea1 kea2. Stromule growth was regulated by the cellular pH and K+ homeostasis maintained by KEA1 and KEA2. The organellar pH along the trafficking pathway was altered in kea1 kea2. Overall, KEA1 and KEA2 regulate vacuolar trafficking by controlling the function of plastid stromules via adjusting pH and K+ homeostasis.

Key words: Arabidopsis, K+ homeostasis, plastid antiporters, plastid stromule, pH, protein trafficking

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