Characterization of Organic Acid Metabolism and Expression of Related Genes During Fruit Development of Actinidia eriantha ‘Ganmi 6’

Abstract

Studies on organic acid metabolism have been mainly concentrated on the fruit, whereas, few have focused on the mechanism of high organic acids content in the fruit of Actinidia eriantha. Fruits of ‘Ganmi 6’ harvested at eleven developmental periods were used as materials. The components and content of organic acids were determined by high-performance liquid chromatography (HPLC) system, the activities of the related enzyme were detected, and gene expression levels were measured by quantitative real-time PCR (qRT-PCR). Components of ascorbic acid (AsA) and eight kinds of organic acids were detected. These results showed that quinic acid and citric acid were the main organic acids in the fruit of ‘Ganmi 6’. Correlation analysis showed that NADP-Quinate dehydrogenase (NADP-QDH), NADP-Shikimate dehydrogenase (NADP-SDH), and Cyt-Aconitase (Cyt-Aco) may be involved in regulating organic acids biosynthesis. Meanwhile, the SDH gene may play an important role in regulating the accumulation of citric acid. In this study, the activities of NADP-SDH, Mit-Aconitase (Mit-Aco), and NAD-Isocitrate dehydrogenase (NAD-IDH) were regulated by their corresponding genes at the transcriptional level. The activity of Citrate synthase (CS) may be affected by post-translational modification. Our results provided new insight into the characteristics of organic acid metabolism in the fruit of A. eriantha.

Changes in the Content of Organic Acids and Expression Analysis of Citric Acid Accumulation-Related Genes during Fruit Development of Yellow (Passiflora edulis f. flavicarpa) and Purple (Passiflora edulis f. edulis) Passion Fruits

“…Citric acid is an intermediate in the TCA cycle, and the synthesis and degradation of citric acid is closely related to the TCA cycle [35]. The changes of citric acid content are consistent with the activities of CS, PEPC and Cyt-Aco enzymes [36], indicating that these are the important enzymes which affect the citric acid metabolism [37]. In order to validate the regulation of citrate contents by organic acid metabolism-related enzymes, the activities of PEPC, CS, Cyt-ACO and Cyt-IDH were observed.…”

“…Phosphoenolpyruvate carboxylase (PEPC), citrate synthase (CS), cytosolic aconitase (Cyt-ACO) and cytosolic isocitrate dehydrogenase (Cyt-IDH) were extracted and measured using the Solarbio enzyme activity kits (Solarbio Life Sciences, Beijing, China) according to the manufacturer's instructions [36,45].…”

Modifying Carbohydrate Supply to Fruit during Development Changes the Composition and Flavour of Actinidia chinensis var. chinensis ‘Zesy002’ Kiwifruit

“…Oxalic acid was present in 'Zesy002' fruit at much lower concentrations than citric and quinic acids, but followed a similar development pattern to quinic acid. Accumulation of oxalic acid in fruit was similar to that reported in an A. eriantha genotype [58]. Concentrations of malic acid initially declined, increased to a second peak at the end of rapid fruit growth, and then declined rapidly at the beginning of the second period of slower fruit growth.…”

“…deliciosa , A. chinensis var. chinensis and A. eriantha genotypes [ 18 , 57 , 58 ]. Citric acid accumulated in ‘Zesy002’ fruit during the second phase of growth and fruit maturation.…”

A Special Summer Pruning Method Significantly Increases Fruit Weight, Ascorbic Acid, and Dry Matter of Kiwifruit (‘Jinyan’, Actinidia eriantha × A. chinensis)

“…Although both soluble solids concentration and soluble sugar were higher than in the control, only soluble solids concentration showed a significant difference. It is likely that the new summer pruning method has no significant effect on the components and contents of organic acids (Jiang et al, 2020). The difference in the ratio of total soluble solids:acids leads to the difference in taste.…”