Potassium Application Boosts Photosynthesis and Sorbitol Biosynthesis and Accelerates Cold Acclimation of Common Plantain (Plantago major L.)

Abstract

Potassium (K) is essential for the processes critical for plant performance, including photosynthesis, carbon assimilation, and response to stress. K also influences translocation of sugars in the phloem and regulates sucrose metabolism. Several plant species synthesize polyols and transport these sugar alcohols from source to sink tissues. Limited knowledge exists about the involvement of K in the above processes in polyol-translocating plants. We, therefore, studied K effects in Plantago major, a species that accumulates the polyol sorbitol to high concentrations. We grew P. major plants on soil substrate adjusted to low-, medium-, or high-potassium conditions. We found that biomass, seed yield, and leaf tissue K contents increased in a soil K-dependent manner. K gradually increased the photosynthetic efficiency and decreased the non-photochemical quenching. Concomitantly, sorbitol levels and sorbitol to sucrose ratio in leaves and phloem sap increased in a K-dependent manner. K supply also fostered plant cold acclimation. High soil K levels mitigated loss of water from leaves in the cold and supported cold-dependent sugar and sorbitol accumulation. We hypothesize that with increased K nutrition, P. major preferentially channels photosynthesis-derived electrons into sorbitol biosynthesis and that this increased sorbitol is supportive for sink development and as a protective solute, during abiotic stress.

Cold-Triggered Induction of ROS- and Raffinose Metabolism in Freezing-Sensitive Taproot Tissue of Sugar Beet

“…We found that concentrations of the monosaccharides glucose and fructose increased in the leaf tissue at 0°C (Supplementary Figure S5), in a manner similar to other plant species in which these sugars accumulate during cold treatment (Usadel et al, 2008;Klemens et al, 2014;Ho et al, 2020). The concentrations of glucose and fructose were highest in the leaves, whereas concentrations of sucrose were highest in the heterotrophic storage parenchyma (Supplementary Figure S5).…”

“…Sugar alcohols, organic acids, raffinose, and galactinol were quantified via ion-chromatography as described by Ho et al, 2020. Briefly, a 761 Compact IC system (Metrohm, Herisau, Switzerland) was used.…”

Cold-triggered induction of ROS- and raffinose-related metabolism in freezing-sensitive taproot tissue of sugar beet

“…Sugar concentrations, especially those of monosaccharides, increased at 0°C in the leaf tissue ( Supplemental Figure S3 ) in a similar manner as in other plant species, where metabolites accumulate during prolonged cold treatment (Ho et al, 2020; Klemens et al, 2014; Usadel et al, 2008). Overall, concentrations of sucrose were highest in the heterotrophic tissues, whereas concentrations of the monosaccharides glucose and fructose were highest in the leaves ( Supplemental Figure S3 ).…”

The vacuolar sugar transporterEarly Response to Dehydration 6-Like4regulates fructose signaling and plant growth

“…Upon exposure to low temperatures, plants increase their overall sugar content in leaves drastically within a comparably short time, usually within one to three days, in a process known as cold acclimation (Klemens et al ., 2013; Rodrigues et al ., 2020; Ho et al ., 2020). In Arabidopsis, cold acclimation-dependent sugar accumulation occurs mainly in vacuoles and depends on TST proteins (Klemens et al, 2013, Vu et al, 2020).…”

“…In addition, sugars affect early plant germination, development of the vasculature or govern onset of flowering. It is well known that sugars are key components controlling yield of fruits and storage organs and influence positively plant tolerance to abiotic stresses like drought or cold temperatures (Ruan, 2014;Le Hir et al, 2015;Julius et al, 2017;Pommerrenig et al, 2020;Keller et al, 2021).…”