A potassium (K)-transporter, OsHAK3, is required for K- homeostasis in
rice under low-K and high-salinity conditions
Abstract
Potassium (K+) is a macronutrient for plant growth and development.
Although a number of K-transporters are encoded in various plant
genomes, functional characterization of these transport genes have
lagged behind of genomic information in crop plants. In rice genome, a
large expansion of high-affinity K-transporters (HAKs/KUPs/KTs) has been
identified as compared to those in Arabidopsis genome suggesting a
functional diversity of these transporters in cereals. We report here
the functional characterization of a HAK member, OsHAK3, in rice using
CRISPR-assisted genetic analysis. Expression of OsHAK3 was mainly found
in roots and its protein was targeted to the plasma membrane. Loss of
function of OsHAK3 led to a reduction of K+ uptake rate and K+ content,
consistent with the finding that mutant plants became stunted under
low-K+ conditions. In addition, the growth of Oshak3 mutants was more
sensitive to salt stress due to altered K/Na ratio in the plants.
Together, our data demonstrate that OsHAK3 plays a crucial role in K+
homeostasis, especially under K+-limited conditions and when plants face
salinity stress.