Impact of the potassium transporter TaHAK18 on wheat growth and potassium uptake under stressful K conditions.

Potassium (K), an indispensable nutrient for plant growth and development, plays a crucial role in plant stress resistance. Within the K regulatory network in plants, the HAK/KUP/KT gene family comprises a dominant group of K transport proteins responsible for K uptake and transport. This study functionally characterized the wheat gene TaHAK18, which encodes a putative K transporter. Plasma membrane-localized TaHAK18 was significantly upregulated under low-K conditions and showed tissue-specific expression, being most abundant in leaves. A functional analysis in yeast demonstrated that TaHAK18 complements K-uptake deficiencies, confirming its role in K transport. Arabidopsis plants overexpressing TaHAK18 experienced enhanced growth under both low- and normal-K conditions, with greater fresh weight, lateral root formation, and primary root length. Barley stripe mosaic virus-mediated gene silencing in wheat revealed that TaHAK18 is instrumental for K accumulation and plant growth under low-K stress. TaHAK18 has the capacity to enhance the growth and the accumulation of K in transgenic rice plants. These results indicated that TaHAK18 is a key regulator of K uptake and homeostasis in wheat, with potential implications for improving plant tolerance to low-K stress.