Grapevine is one of the most economically important fruit crops due to the high value of its fruit and its importance in winemaking. The current decrease in grape berry quality and production can be seen as the consequence of various abiotic constraints imposed by climate changes. Specifically, produced wines have become too sweet, with a stronger impression of alcohol and fewer aromatic qualities. Potassium is known to play a major role in grapevine growth, as well as grape composition and wine quality. Importantly, potassium ions (K⁺) are involved in the initiation and maintenance of the berry loading process during ripening. Moreover, K⁺ has also been implicated in various defense mechanisms against abiotic stress. The first part of this review discusses the main negative consequences of the current climate, how they disturb the quality of grape berries at harvest and thus ultimately compromise the potential to obtain a great wine. In the second part, the essential electrical and osmotic functions of K⁺, which are intimately dependent on K⁺ transport systems, membrane energization, and cell K⁺ homeostasis, are presented. This knowledge will help to select crops that are better adapted to adverse environmental conditions.

Grapevine (Vitis vinifera L.), one of the most important fruit crops, is a model plant for studying the physiology of fleshy fruits. Here, we report on the characterization of a new grapevine Shaker-type K⁺ channel, VvK5.1. Phylogenetic analysis revealed that VvK5.1 belongs to the SKOR-like subfamily. Our functional characterization of VvK5.1 in Xenopus oocytes confirms that it is an outwardly rectifying K⁺ channel that displays strict K⁺ selectivity. Gene expression level analyses by real-time quantitative PCR showed that VvK5.1 expression was detected in berries, roots, and flowers. In contrast to its Arabidopsis thaliana counterpart that is involved in K⁺ secretion in the root pericycle, allowing root to shoot K⁺ translocation, VvK5.1 expression territory is greatly enlarged. Using in situ hybridization we showed that VvK5.1 is expressed in the phloem and perivascular cells of berries and in flower pistil. In the root, in addition to being expressed in the root pericycle like AtSKOR, a strong expression of VvK5.1 is detected in small cells facing the xylem that are involved in lateral root formation. This fine and selective expression pattern of VvK5.1 at the early stage of lateral root primordia supports a role for outward channels to switch on cell division initiation.

Ganoderma boninense, a soil-borne pathogenic fungus causing basal stem rot (BSR) disease in oil palm, is the major threat to cultivation in Southeast Asia, with the potential to reduce oil production by up to 80% in severely affected plantations. With a view to marker-assisted selection (MAS) of resistant planting material, we combined genetics and transcriptomics approaches to investigate the defense mechanisms of oil palm against infection by G. boninense. We first performed quantitative trait locus (QTL) mapping of BSR resistance using a multi-locus Bayesian variable selection approach applied to more than 10 years of data collected during pre-nursery tests of Deli and La Mé breeding populations. We found 6 and 5 BSR resistance loci segregating in Deli and La Mé respectively, with no overlap between them. Then we performed an RNA-sequencing approach on libraries of roots and bole of oil palm seedlings inoculated or not with G. boninense, focusing on Deli × La Mé crosses with contrasted BSR resistance. A Bayesian variable selection on predictors obtained by tracing the resistance loci haplotypes in profiled individuals identified 195 differentially expressed genes (DEGs) for the G. boninense inoculation × QTL interaction, among the 551 DEGs found for inoculation effects. The DEGs were located both in cis and trans positions compared to the segregating QTL intervals, enabling the prioritization of candidate genes and resistance mechanisms associated. Focusing on a strong effect QTL region on chromosome 4 in the Deli genetic background, we identified three candidate genes in cis positions that exhibited differential expression both in response to G. boninense inoculation and between resistant and susceptible haplotypes. Our study is the first combining QTL and RNA-seq approaches in oil palm based on genetically connected experimental setup, providing valuable information on the underlying mechanisms and paving the way for MAS of BSR resistant planting material.

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.