Poster Presentation International Plant Molecular Biology Conference 2024

Root-specific overexpression of a phosphate transporter improves phosphate absorption, transport, and utilization efficiency in Arabidopsis (#12)

Yuichi Tada 1 , Noike Yuki 1 , Shimizu Aoi 1
  1. Tokyo University of Technology, Hachioji, TOKYO, Japan

Phosphorus (P) is a major essential mineral nutrient and biological component in plants. Previously, we reported that overexpression of the phosphate transporter TaPT2 driven by the Arabidopsis Shaker family inward rectifying potassium channel 1 (AKT1) promoter, predominantly expressed in root epidermal cells, led to enhanced growth in Arabidopsis under both Pi-rich and Pi-deficient conditions. However, the Pi and total P contents did not show a significant increase. In the present study, we employed promoters for the high-affinity potassium transporter (HKT1;1) and the Shaker family potassium ion channel (SKOR), which are predominantly expressed in vascular bundle tissue, for overexpression of TaPT2. Transgenic plants overexpressing HKT1;1-TaPT2 and SKOR-TaPT2 exhibited increased shoot growth under Pi-rich and Pi-deficient conditions, along with elevated root Pi content and xylem sap Pi concentration specifically under Pi-deficient conditions. These findings suggest that TaPT2 plays a role not only in Pi acquisition but also in Pi transport, and expression of TaPT2 in vascular bundle tissue can enhance Pi utilization efficiency. To further investigate these effects, we examined the transcriptional levels of several genes involved in phosphate absorption and homeostasis in the transgenic Arabidopsis. VPT1 and VPT3, responsible for transporting excess Pi into the vacuole to prevent Pi toxicity in the cytoplasm, were up-regulated in leaves or roots of SKOR-TaPT2 transformants under Pi-rich conditions. In contrast, PHO1, which is involved in root-to-shoot Pi translocation, was down-regulated in leaves under Pi-deficient conditions. These results indicate that tissue-specific overexpression of TaPT2 enhances plant growth while simultaneously influencing endogenous Pi homeostasis mechanisms.