Unveiling the molecular symphony: MicroRNA160a-Auxin Response Factor 18 module orchestrates low potassium tolerance in banana (Musa acuminata L.)

Potassium (K) is an essential nutrient for the growth and development of most plants. In banana (Musa acuminata L.), microRNA160a (miR160a) is suggested to potentially contribute to the response to low K⁺ stress by modulating the auxin signaling pathway. However, further investigation is required to elucidate its specific regulatory mechanism. This study presents evidence highlighting the critical role of the miR160a-Auxin Response Factor 18 (ARF18) module in conferring low K⁺ tolerance in banana. Both miR160a and its predicted target gene ARF18 displayed elevated expression levels in banana roots, with their expression profiles significantly altered under low K⁺ stress. The inhibitory effect of mac-miR160a on the expression of MaARF18-like-2 was confirmed through tobacco transient transformation and dual-Luciferase reporter assay. Surprisingly, Arabidopsis lines overexpressing mac-miR160a (mac-miR160a OE) exhibited enhanced tolerance to low K⁺ stress. Conversely, Arabidopsis lines overexpressing MaARF18-like-2 (MaARF18-like-2 OE) displayed increased sensitivity to K⁺ deficiency. Additionally, RNA sequencing (RNA-seq) analysis revealed that MaARF18-like-2 mediates the response of Arabidopsis to low K⁺ stress by influencing the expression of genes associated with Ca²⁺, ion transport, and reactive oxygen species (ROS) signaling. In conclusion, our study provides novel insights into the molecular mechanism of the miR160a-ARF18-like-2 module in the plant response to low K⁺ stress.