Abstract: Potassium (K⁺), an essential macronutrient, strongly influences myriad fundamental processes, while its deficiency inhibits plant growth. Jasmonic acid (JA) regulates plant growth; however, its role in plant growth inhibition under K⁺ deficiency remains nebulous. Herein, we determined that JA significantly inhibits low K⁺ tolerance and K⁺ uptake in tomato. Methyl jasmonate treatment induced the expression of SlMYC3-like under low K⁺ stress, which bound the promoters of the genes that encode KT/KUP/HAK-type transporter (SlHAK5) and voltage-gated K⁺ channel (SlLKT1) and inhibited their expression. Knockdown of SlMYC3-like enhanced low K⁺ stress tolerance and decreased JA responses, while its overexpression led to low K⁺ stress sensitivity and promoted jasmonate responses in tomato. In addition, jasmonate ZIM-domain transcriptional repressor 2/3 (SlJAZ2/3) interacted with SlMYC3-like; this interaction decreased DNA-binding activity of SlMYC3-like. SlMYC3-like promoted SlJAZ2/3 expression, forming a negative feedback circuit in JA signaling. Silencing SlJAZ2/3 increased plant susceptibility to low K⁺ stress. Our findings demonstrate the involvement of the JA–SlJAZ2/3–SlMYC3-like module in K⁺ uptake and plant growth in tomato under low K⁺ stress, providing novel insights into the regulation of plant growth and K⁺ uptake.

Key words: jasmonic acid, potassium deficiency, root growth, SlJAZ2/3, SlMYC3‐like