The Role of TCA Cycle Enzymes in Plants

Abstract

As one of the iconic pathways in plant metabolism, the tricarboxylic acid (TCA) cycle is commonly thought to not only be responsible for the oxidization of respiratory substrate to drive ATP synthesis but also provide carbon skeletons to anabolic processes and contribute to carbon–nitrogen interaction and biotic stress responses. The functions of the TCA cycle enzymes are characterized by a saturation transgenesis approach, whereby the constituent expression of proteins is knocked out or reduced in order to investigate their function in vivo. The alteration of TCA cycle enzyme expression results in changed plant growth and photosynthesis under controlled conditions. Moreover, improvements in plant performance and postharvest properties are reported by overexpression of either endogenous forms or heterologous genes of a number of the enzymes. Given the importance of the TCA cycle in plant metabolism regulation, here, the function of each enzyme and its roles in different tissues are discussed. This article additionally highlights the recent finding that the plant TCA cycle, like that of mammals and microbes, dynamically assembles functional substrate channels or metabolons and discusses the implications of this finding to the current understanding of the metabolic regulation of the plant TCA cycle.

Comparison of the transcriptome and metabolome of wheat (Triticum aestivum L.) proteins content during grain formation provides insight

“…The citrate cycle is a catabolic pathway that provides precursor molecules for the biosynthesis of several substances ( Zhang and Fernie, 2018 ). For example, sugar and glycerol are metabolized in the body to produce α-ketoglutaric acid, oxaloacetic acid and other intermediate products of the tricarboxylic acid cycle; oxaloacetic acid is a precursor for the synthesis of aspartic acid; and α-ketoglutaric acid is a precursor for the synthesis of glutamic acid ( Zhang and Fernie, 2023 ). Some amino acids can also produce sugars through different pathways through gluconeogenesis ( Zhang and Fernie, 2023 ).…”

“…For example, sugar and glycerol are metabolized in the body to produce α-ketoglutaric acid, oxaloacetic acid and other intermediate products of the tricarboxylic acid cycle; oxaloacetic acid is a precursor for the synthesis of aspartic acid; and α-ketoglutaric acid is a precursor for the synthesis of glutamic acid ( Zhang and Fernie, 2023 ). Some amino acids can also produce sugars through different pathways through gluconeogenesis ( Zhang and Fernie, 2023 ). These findings suggested that changes in the sugar and gluten contents of wheat grains may have been transformed by this process.…”

“…Metabolomics refers to the inheritance and development of genomics, transcriptomics and proteomics and can directly reflect the biochemical pathways and potential molecular mechanisms in organisms by elucidating the metabolites downstream of the genome as a whole and subsequently revealing the relevant metabolic pathways and metabolic networks ( Li et al., 2022 ; Prakash et al., 2023 ). In recent years, transcriptomic and metabolomic-based techniques have provided powerful tools and methods for revealing molecular characteristics and identifying candidate genes related to plant growth and development and fruit quality ( Jiang et al., 2022 ; Wan et al., 2022 ; Zhang and Fernie, 2023 ). Coexpression network analysis is a systems biology method in which gene coexpression networks are constructed by analysing the correlation of gene expression to discover functionally relevant gene modules ( Ma et al., 2021 ).…”

A transcriptome atlas of zygotic and somatic embryogenesis in Norway spruce

“…As such, there were clear contrasts in the regulation of DEGs during desiccation between the two developmental processes. Genes specifically DE in desiccated Zem and not during SE included ribosomal elements known to be associated with the storage and regulation of mRNA translation during seed dormancy (Bai et al 2020), genes associated with mitochondrial activity related to the TCA cycle important during germination (Zhang and Fernie, 2023) and expression of genes related to the onset of germination as a morphogenic event involving cellular processes that require utilization of lipids, carbohydrates and starch. Previous analysis of quantitative data on water content, carbohydrates and total protein collected from the later stages of Zem development and Sem development in Pinus pinaster also indicated that the most advanced mature stage that the somatic embryos could reach in culture corresponded to the fresh, non-desiccated stage of Zem development, suggesting that the Sem maturation does not get fully completed (Morel et al 2014).…”