Potassium transporter KUP9 participates in K+ distribution in roots and leaves under low K+ stress

Abstract

Potassium (K) is a major essential element in plant cells, and KUP/HAK/KT-type K+ transporters participate in the absorption of K+ into roots and in the long-distance transport to above-ground parts. In Arabidopsis thaliana, KUP9 is involved in the transport of K+ and Cs+ in roots. In this study, we investigated KUP9 function in relation to the K+ status of the plant. The expression of KUP9 was upregulated in older leaves on K+-depleted medium, compared to the expression of the other 12 KUP genes in the KUP/HAK/KT family in Arabidopsis. When grown on low K+ medium, the kup9 mutant had reduced chlorophyll content in seedlings and chlorosis in older rosette leaves. Tissue-specific expression of KUP9 determined by KUP9 promoter:GUS assay depended on the K+ status of the plants: In K+ sufficient medium, KUP9 was expressed in the leaf blade towards the leaf tip, whereas in K+ depleted medium expression was mainly found in the petioles. In accordance with this, K+ accumulated in the roots of kup9 plants. The short-term 43K+ tracer measurement showed that 43K was transferred at a lower rate in roots and shoots of kup9, compared to the wild type. These data show that KUP9 participates in the distribution of K+ in leaves and K+ absorption in roots under low K+ conditions.

Rice potassium transporter OsHAK18 mediates phloem K+loading and redistribution

“…AtKUP9, an ER-localized KUP/HAK/KT transporter, was reported to mediate K + and auxin efflux from ER to cytoplasm in root quiescent center (QC) cells to maintain meristem activity, which is essential to root growth under K + deficiency (Zhang et al, 2020). Recently, Yamanashi et al (2022) proposed that AtKUP9 participated in the K + distribution in leaves and K + uptake in roots under low K + conditions (Yamanashi et al, 2022). The atkup9 mutant accumulated more K + in roots and has similar K + level with WT in various above-ground parts (Yamanashi et al, 2022).…”

“…Recently, Yamanashi et al (2022) proposed that AtKUP9 participated in the K + distribution in leaves and K + uptake in roots under low K + conditions (Yamanashi et al, 2022). The atkup9 mutant accumulated more K + in roots and has similar K + level with WT in various above-ground parts (Yamanashi et al, 2022). Taken together these previous findings with our results here, we propose that OsHAK18 plays a different role form OsHAK12 and AtKUP9, although they have a close phylogenetic relationship.…”

Rice potassium transporter OsHAK18 mediates phloem K+ loading and redistribution

“…AtKUP9, an ERlocalized KUP/HAK/KT transporter, was reported to mediate K + and auxin efflux from ER to the cytoplasm in root QC cells to maintain meristem activity, which is essential to root growth under K + deficiency (Zhang et al, 2020). Recently, Yamanashi et al (2022) proposed that AtKUP9 participated in the K + distribution in leaves and K + uptake in roots under low K + conditions (Yamanashi et al, 2022). Taken together these previous findings with our results here, we propose that OsHAK18 plays a different role from OsHAK12 and AtKUP9, although they have a close phylogenetic relationship.…”

“…Recently, Yamanashi et al. (2022) proposed that AtKUP9 participated in the K + distribution in leaves and K + uptake in roots under low K + conditions (Yamanashi et al., 2022). Taken together these previous findings with our results here, we propose that OsHAK18 plays a different role from OsHAK12 and AtKUP9, although they have a close phylogenetic relationship.…”

Quantitative trait loci for mineral accumulation efficiency and biomass production in barley under different levels of zinc supply

“…For example, functional validation of HMA genes revealed their involvement in transporting of Zn and Cd into the roots and shoots(Mills et al 2012) and mobilisation of Cu and Zn within the plastids and aleurone cells in barley(Mikkelsen et al 2012). Lastly, potassium transporter genes have been previously identi ed to participate in the uptake and translocation of K + to leaves(Yamanashi et al 2022). In the present study, the potential candidate gene for regulating shoot biomass is owering promoting factor1 (FPF1;Guo et al 2020).…”