Metabolic leaf responses to potassium availability in oil palm (Elaeis guineensis Jacq.) trees grown in the field

Oil palm growth and production is highly dependent on potassium (K) fertilization. Presently, monitoring K fertilization is difficult since it depends on soil properties, crosses and other nutrients. To adjust K fertilization precisely during cultivation, leaf biomarkers that can indicate changes in tree K status before the appearance of symptoms on fruit production and yield, are required. However, the metabolic response of oil palm leaves to K availability is poorly documented. Here, we investigated the response of oil palm leaf metabolome and proteome to K availability in two crosses (Deli x La Mé, and Deli x Yangambi) grown in the field. Our result show that one to two years only after the onset of K fertilization treatments, there were changes in N metabolism, photosynthesis and mitochondrial metabolism, with a differential effect in the two crosses. In particular, there were changes in sugars, amino and organic acids pointing to modifications in photosynthetic and catabolic (Krebs cycle) capacity and this agreed with the effect seen on enzyme content. Therefore, K availability led to rapid changes in leaf primary metabolism, opening avenues for the utilization of leaf metabolic signature as a marker of K nutrition in oil palm.