A vacuolar phosphate transporter essential for phosphate homeostasis inArabidopsis

• Published in: Proceedings of the National Academy of Sciences - PNAS 2015-11, Vol.112 (47), p.E6571-E6578
• Main Authors: Liu, Jinlong, Yang, Lei, Luan, Mingda, Wang, Yuan, Zhang, Chi, Zhang, Bin, Shi, Jisen, Zhao, Fu-Geng, Lan, Wenzhi, Luan, Sheng
• Format: Article
• Language: English
• ISSN: 0027-8424; 1091-6490

Inorganic phosphate (Pi) is stored in the vacuole, allowing plants to adapt to variable Pi availability in the soil. The transporters that mediate Pi sequestration into vacuole remain unknown, however. Here we report the functional characterization of Vacuolar Phosphate Transporter 1 (VPT1), an SPX domain protein that transports Pi into the vacuole inArabidopsis.Thevpt1mutant plants were stunted and consistently retained less Pi than wild type plants, especially when grown in medium containing high levels of Pi. In seedlings,VPT1was expressed primarily in younger tissues under normal conditions, but was strongly induced by high-Pi conditions in older tissues, suggesting that VPT1 functions in Pi storage in young tissues and in detoxification of high Pi in older tissues. As a result, disruption ofVPT1rendered plants hypersensitive to both low-Pi and high-Pi conditions, reducing the adaptability of plants to changing Pi availability. Patch-clamp analysis of isolated vacuoles showed that the Pi influx current was severely reduced invpt1compared with wild type plants. When ectopically expressed inNicotiana benthamianamesophyll cells, VPT1 mediates vacuolar influx of anions, including Pi, SO₄2−, NO₃⁻, Cl⁻, and malate with Pi as that preferred anion. The VPT1-mediated Pi current amplitude was dependent on cytosolic phosphate concentration. Single-channel analysis showed that the open probability of VPT1 was increased with the increase in transtonoplast potential.We conclude that VPT1 is a transporter responsible for vacuolar Pi storage and is essential for Pi adaptation inArabidopsis.