IRON-REGULATED TRANSPORTER LIKE 2 is a major iron uptake transporter in Actinidia chinensis

Iron (Fe) is an essential micronutrient for plant growth and development, and functions as a cofactor in photosynthesis, respiration, and redox homeostasis. Although Fe is abundant in soil, its bioavailability is limited under high-pH or calcareous conditions, frequently leading to Fe deficiency in Actinidia chinensis . Here, we identified seven IRT1-LIKE ( IRTL ) proteins from the A. chinensis , of which AcIRTL2 clustered phylogenetically with Arabidopsis AtIRT1, a known high-affinity Fe transporter. Heterologous complementation assays in Saccharomyces cerevisiae Δfet3fet4 mutants and Arabidopsis irt1-3 mutants demonstrated that AcIRTL2 efficiently restores Fe uptake under Fe deficiency conditions. Expression analysis revealed that AcIRTL2 was strongly induced in roots during Fe deficiency, and subcellular localization confirmed that AcIRTL2 was localized at the plasma membrane. CRISPR/Cas9-mediated knockout of AcIRTL2 in A. chinensis resulted in severe chlorosis and reduced Fe accumulation, confirming its essential role in Fe uptake. Furthermore, overexpression of AcIRTL2 in Arabidopsis increased sensitivity to excess Zn, Mn, and Cd, indicating that AcIRTL2 may participate in the homeostasis of multiple divalent metal ions. Collectively, our results support that AcIRTL2 functions as a key component to Fe uptake in A. chinensis .