Rice potassium transporter OsHAK18 mediates phloem K⁺loading and redistribution

Abstract

High-Affinity K+transporters/K+Uptake Permeases/K+Transporters (HAK/KUP/KT) are important pathways mediating K+transport across cell membrane, which function in maintaining K+homeostasis during plant growth and stress response. An increasing number of studies have shown that HAK/KUP/KT transporters play important roles in potassium uptake and root-to-shoot translocation. However, whether some HAK/KUP/KT transporters mediate K+redistribution in phloem remains unknown. In this study, we revealed that a phloem-localized HAK/KUP/KT transporter, OsHAK18 operated as a typical KUP/HAK/KT transporter mediating cell K+uptake when expressed in yeast,E. coliandArabidopsis. It was localized at plasma membrane. Disruption ofOsHAK18rendered rice seedlings insensitive to low-K+stress. Compared with WT, theoshak18mutants accumulated more K+in shoots but less K+in roots, leading to a higher shoot/root ratio of K+per plant. Although disruption ofOsHAK18doesn't affect root K+uptake and K+level in xylem sap, it significantly decreases phloem K+concentration and inhibits root-to-shoot-to-root K+translocation in split-root assay. These results reveal that OsHAK18 mediates phloem K+loading and redistribution, whose disruption is favor of shoot K+retention under low-K+stress. Our findings not only reveal a unique function of rice HAK/KUP/KT family member, but also provide a promising strategy to improve rice tolerance under K+deficiency.

Vernier-effect-based fiber microcoupler for highly sensitive liquid refractive index sensing

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Potassium transporter OsHAK9 regulates seed germination under salt stress by preventing gibberellin degradation through mediating OsGA2ox7 in rice

“…Potassium (K) is an essential macronutrient that plays crucial roles in biochemical and physiological processes underlying plant growth and development (Maathuis and Amtmann, 1999; Shabala and Cuin, 2008; Zörb et al, 2014; Shen et al, 2023). Potassium retention under saline conditions is instrumental in conferring salt tissue tolerance (Shabala and Pottosin, 2014; Wu et al, 2018; Zhao et al, 2020), and enhancing K absorption and maintaining a high K + /Na + ratio constitute a key strategy for plants to withstand salt stress (Véry and Sentenac, 2003; Zhu, 2003; Shabala and Cuin, 2008).…”

A B‐box transcription factor OsBBX17 regulates saline‐alkaline tolerance through the MAPK cascade pathway in rice

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