EgKT2-1, an inwardly rectifying Shaker-type potassium channel in oil palm is involved in oil production

The oil extracted from the mesocarp of oil palm ( Elaeis guineensis , Jacq.) drupes is the world's leading source of vegetable fat. Oil palm cultivation requires large quantities of mineral nutrients supplied through fertilization, which represents a major production cost. Among essential nutrients, potassium (K⁺) plays a critical role in plant growth and fruit development. However, the mechanisms of K⁺ transport and its specific contribution to yield remain poorly understood. This study focuses on the identification and characterization of a Shaker-like potassium channel, EgKT2-1, which belongs to the AKT2-like subfamily. Gene expression analyses, using quantitative PCR, revealed that EgKT2-1 is strongly expressed in leaves, meristem, and young fruits correlated with increased K ⁺ accumulation during the early stages of fruit development. In situ hybridization further localized EgKT2-1 transcripts in the cortex and phloem of roots, the palisade parenchyma of leaves, and the mesocarp cells of young fruits. These results suggest that EgKT2-1 participates in K⁺ loading and transport between source tissues and sink organs. Interestingly, even though EgKT2-1 belongs par homology to the weakly rectifying AKT2-like subfamily, electrophysiological characterization revealed an inwardly rectifying ion channel activity pointing to a role in massive K ⁺ uptake. Taking together, the original results showing that EgKT2-1 is an inward rectifier channel and that higher expression of EgKT2-1 was observed in a cross with higher oil yield might point to an increase in the availability of K ⁺ in mesocarp cells for oil biosynthesis and, consequently, a direct correlation between the K ⁺ channel activity and oil production.