The miR1118– <i>TaCaM5‐3A</i> Module Regulates K ⁺ Uptake and Enhances K ⁺ Deficiency Tolerance in Wheat ( <i>Triticum aestivum</i> L.)

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.