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

Abstract

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.