Formaldehyde assimilation through coordination of the glyoxylate pathway and the tricarboxylic acid cycle in broad bean roots

Autor: Wenjia Cao, Limei Chen, Zhihao Si, Yong Min, Dawood Khan, Yun Xiong
Rok vydání: 2019
Předmět:
Zdroj: Plant Physiology and Biochemistry. 138:65-79
ISSN: 0981-9428
DOI: 10.1016/j.plaphy.2019.02.019
Popis: Formaldehyde (HCHO) assimilation in broad bean (Vicia faba L. cv. YD) roots was investigated using 13C-labeled HCHO followed by 13C-NMR analysis. Results revealed that H13CHO was first oxidized to H13COOH in the roots treated with 2 mM H13CHO in a time-dependent manner. Subsequently, a massive signal peak of [2, 4–13C]citrate (Cit) and a signal peak of [2, 3–13C]succinate (Su) were observed in accompany with an enhancement in the signal intensity of [3–13C]Cit. The data suggested that the glyoxylate pathway and the tricarboxylic acid (TCA) cycle functioned simultaneously in the subsequent assimilation of H13COOH. The yield of [2, 4–13C]Cit accounted for more than 80% of the total metabolites. The activity of isocitrate lyase (ICL), a key enzyme in the glyoxylate pathway, was stimulated by HCHO in a dosage-dependent manner. As a result, [2, 4–13C]Cit production was increased significantly in YD roots treated with high concentrations (4 and 6 mM) of H13CHO. Moreover, induction of the ICL activity by methanol resulted in a simultaneous elevation in the production of [2, 4–13C]Cit and [3–13C]Cit in methanol-pretreated roots under 2 mM H13CHO stress. Pretreatment of roots with cyclosporin A, which hinders the transport of 13C-enriched compounds into mitochondria, caused a notable decline in the signal peak and yield of [2, 4–13C]Cit and consequently induced a notable accumulation of [2, 3–13C]Su and an increase in the HCO3− production (generated from H13COOH oxidation) in H13CHO-treated roots. These results suggested that the glyoxylate pathway and the TCA cycle function coordinately in HCHO assimilation in broad bean roots.
Databáze: OpenAIRE
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