The miR1118– TaCaM5‐3A Module Regulates K ⁺ Uptake and Enhances K ⁺ Deficiency Tolerance in Wheat (

ABSTRACT

Potassium (K ⁺ ) deficiency significantly decreases the productivity of crops (e.g., wheat). MicroRNAs (miRNAs) are master regulators of plant responses to stress, including K ⁺ deficiency. In our previous study, miR1118 was identified as a Triticeae ‐specific miRNA that is highly expressed at multiple time points after exposure to K ⁺ deficiency; however, the regulatory roles of miR1118 and its target gene TaCaM5‐3A (calmodulin‐encoding gene) in K ⁺ uptake and tolerance to K ⁺ deficiency remained unclear. In this study, miR1118 enhances the tolerance of wheat to K ⁺ deficiency by improving K ⁺ uptake capacity under K ⁺ deficiency conditions, and simultaneously increases grain yield. TaCaM5‐3A , as a target of miR1118, negatively regulates K ⁺ uptake and decreased wheat tolerance to K ⁺ deficiency. Additional analyses revealed that TaCaM5‐3A physically interacts with TaHAK1‐2A at the key residue I172 via a calcium (Ca ²⁺ )‐independent pathway, which not only downregulates TaHAK1‐2A protein levels but also decreases its apparent affinity for K ⁺ ‐binding. Collectively, the miR1118– TaCaM5‐3A functional module modulates plant K ⁺ uptake capacity by influencing the protein level and the K ⁺ uptake activity of TaHAK1‐2A, thereby playing a critical role in determining wheat tolerance to K ⁺ deficiency and providing valuable information for breeding wheat varieties with high potassium efficiency.