Enantiomers of Carbohydrates and Their Role in Ecosystem Interactions: A Review

Abstract

D- and most L-enantiomers of carbohydrates and carbohydrate-containing compounds occur naturally in plants and other organisms. These enantiomers play many important roles in plants including building up biomass, defense against pathogens, herbivory, abiotic stress, and plant nutrition. Carbohydrate enantiomers are also precursors of many plant compounds that significantly contribute to plant aroma. Microorganisms, insects, and other animals utilize both types of carbohydrate enantiomers, but their biomass and excrements are dominated by D-enantiomers. The aim of this work was to review the current knowledge about carbohydrate enantiomers in ecosystems with respect to both their metabolism in plants and occurrence in soils, and to identify critical knowledge gaps and directions for future research. Knowledge about the significance of D- versus L-enantiomers of carbohydrates in soils is rare. Determining the mechanism of genetic regulation of D- and L-carbohydrate metabolism in plants with respect to pathogen and pest control and ecosystem interactions represent the knowledge gaps and a direction for future research.

Alleviation of Cadmium Adverse Effects by Improving Nutrients Uptake in Bitter Gourd through Cadmium Tolerant Rhizobacteria

“…Similar kinds of results were also documented by many scientists [25,26,30,31]. Glick et al [44] proposed that enzyme ACC deaminase break ethylene into α-ketobutyrate and ammonia [65,66]. Accumulated ethylene in roots moved towards rhizosphere; thus, ethylene becomes low in plant roots, and stress is alleviated.…”

“…Among different crop plants, bitter gourd is a rich source of vitamins, carbohydrates, and proteins [43,44]. As compared to cucumber and tomato, one cup of bitter gourd juice (94 g) has 93% reference daily intake (RDI) of vitamin C [45].…”

Drought Stress Alleviation by ACC Deaminase Producing Achromobacter xylosoxidans and Enterobacter cloacae, with and without Timber Waste Biochar in Maize

“…A significant improvement in plant height signified the imperative role of co-application of E. cloacae and A. xylosoxidans with TWBC over sole application of TWBC and control. Roots secrete organic acids, sugars, vitamins, phytosiderophores, nucleosides amino acids and mucilage, that attract PGPRs and resulted in better colonization of PGPRs, uptake of water and nutrients [85][86][87]. However, it is well documented that the colonization of PGPR is also improved when PGPR are inoculated with biochar [47].…”

Resolution and Quantification of Carbohydrates by Enantioselective Comprehensive Two-Dimensional Gas Chromatography

“…Due to their biological implications, the enantioselective analysis of sugars plays a significant role in various fields including i) pharmaceutics to determine purity and stereochemistry of new drugs [1]; ii) the food industry to ensure the quality and authenticity of food products as sugar enantiomers affect taste, texture, and stability [2]; iii) environmental studies to monitor the presence and distribution of sugars in environmental samples such as soil and water [3]; and iv) biotechnology, where sugar enantiomers play a role in cellular processes, including protein and DNA synthesis, cell signaling, and gene regulation [4]. Moreover, monosaccharides are increasingly considered as crucial target molecules in the search for the origin of life, because understanding the presence and distribution of sugar enantiomers in different environments can provide insights into the evolution of life and the conditions necessary for life to exist.…”