EgKT2-1, an inwardly rectifying Shaker-type potassium channel in oil palm that correlates with oil yield

The oil extracted from the mesocarp of oil palm (Elaeis guineensis, Jacq.) drupes is the world's leading source of vegetable oil. Oil palm cultivation requires large amounts of mineral nutrients supplied through fertilization, representing a major production cost. Among essential nutrients, potassium (K⁺) plays a critical role in plant growth and fruit development. However, the mechanisms underlying K⁺ transport and its relationship with yield remain poorly understood. Here, we identified and characterized EgKT2-1, a Shaker-like potassium channel belonging to the AKT2-like subfamily. Quantitative PCR analyses showed that EgKT2-1 is expressed in leaves, meristem, and during early fruit development, with higher transcript abundance during early fruit development coinciding with increased K⁺ accumulation. In situ hybridization localized EgKT2-1 transcripts to the root cortex and phloem tissues, leaf palisade parenchyma, and mesocarp cells during early fruit development. These expression patterns are consistent with a potential contribution of EgKT2-1 to K⁺ transport and allocation between source and sink tissues. Although sequence similarity places EgKT2-1 within the weakly rectifying AKT2-like subfamily, electrophysiological characterization in Xenopus laevis oocytes revealed inwardly rectifying channel activity, suggesting a potential role in K⁺ uptake. EgKT2-1 expression was higher in an oil palm progeny C3 which exhibited greater K⁺ allocation to aerial organs and greater oil yield. Together, these findings identify EgKT2-1 as an inwardly rectifying K⁺ channel potentially involved in K⁺ transport and redistribution during oil palm development and suggest a correlation between EgKT2-1 expression, K⁺ allocation, and oil yield variation.