Identification of the Grapefruit (<i>Citrus paradisi</i>) Isocitrate Dehydrogenase Gene and Functional Analysis of <i>CpNADP-IDH1</i> in Citric Acid Metabolism

Citric acid serves as the principal organic acid in citrus fruits, with its concentration critically determining fruit flavor and market acceptability. Isocitrate dehydrogenase (IDH), a key enzyme in citric acid metabolism, mediates the conversion of citrate to α-ketoglutarate. This study cloned six...

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Bibliographic Details
Main Authors: Longfei Jin, Yang Yue, Feng Liu, Mingxia Wen, Bei Huang, Peng Wang
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Horticulturae
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Online Access:https://www.mdpi.com/2311-7524/11/6/598
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Summary:Citric acid serves as the principal organic acid in citrus fruits, with its concentration critically determining fruit flavor and market acceptability. Isocitrate dehydrogenase (IDH), a key enzyme in citric acid metabolism, mediates the conversion of citrate to α-ketoglutarate. This study cloned six candidate genes encoding IDH from grapefruit (<i>Citrus paradisi</i>). Bioinformatics analysis showed that all six genes contained the typical characteristic structure of IDH. Gene expression analysis found that <i>CpNADP-IDH1</i> is highly expressed in mature and low-acid varieties. Overexpression of <i>CpNADP-IDH1</i> significantly increased IDH enzyme activity and decreased citric acid content in transgenic grapefruit callus. These results showed that at least six genes encoding IDH exist in grapefruit, among which <i>CpNADP-IDH1</i> catalyzes the decomposition of citric acid and regulates the organic acid content in fruits at maturity. <i>CpNADP-IDH1</i> can be used as a candidate gene for molecular breeding of low-acid citrus varieties and as an essential target gene for developing citrus cultivation technology for reducing acid content.
ISSN:2311-7524