The Unusual Acid-Accumulating Behavior during Ripening of Cherimoya (Annona cherimola Mill.) is Linked to Changes in Transcription and Enzyme Activity Related to Citric and Malic Acid Metabolism

Abstract

Cherimoya (Annona cherimola Mill.) is a subtropical fruit characterized by a significant increase in organic acid levels during ripening, making it an interesting model for studying the relationship between acidity and fruit flavor. In this work, we focused on understanding the balance between the concentration of organic acids and the gene expression and activity of enzymes involved in the synthesis and degradation of these metabolites during the development and ripening of cherimoya cv. "Concha Lisa". Our results showed an early accumulation of citric acid and other changes associated with the accumulation of transcripts encoding citrate catabolism enzymes. During ripening, a 2-fold increase in malic acid and a 6-fold increase in citric acid were detected. By comparing the contents of these compounds with gene expression and enzymatic activity levels, we determined that cytoplasmic NAD-dependent malate dehydrogenase (cyNAD-MDH) and mitochondrial citrate synthase (mCS) play important regulatory roles in the malic and citric acid biosynthetic pathways.

Changes in secondary metabolites, organic acids and soluble sugars during the development of plum fruit cv. ‘Furongli’ (Prunus salicina Lindl)

“…Our finding that the malate content increased with decreasing NAD‐ME activity and gene expression level during ‘Furongli’ development is consistent with the result for Cherimoya ( Annona cherimola Mill.) (Figs B and C) . Citrate showed a sigmoidal pattern during ‘Furongli’ development (Fig.…”

Effects of water stress on the sugar accumulation and organic acid changes in Cabernet Sauvignon grape berries

“…Inside the cell, malic acid is formed from phosphoenolpyruvate (PEP) through the activities of phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenase (MDH) (Sweetman et al 2009), and cytosolic malate is transported and sequestered in the vacuole (Schulze et al 2002). Malate can be degraded by the reversible reaction of MDH and nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) (González-Agüero et al 2016). In grapes (V. vinifera L.), the malic acid content always decreases as the light intensity increases and as the water supply decreases (Zheng et al 2018).…”

Ripening of bananas using Bowdichia virgilioides Kunth leaves

“…However, the biosynthesis of AsA is an antioxidant response by the D-glucosone, D-galacturonate, myo-inositol and D-mannose/L-galactose 30–32 . The AsA accumulation in these fruits may also be associated with the low oxidation of this pH-dependent molecule, with maximum at pH 5 and 11.5, being faster in alkaline media 33 pathways but not necessarily related to its accumulation 34 .…”