Soluble Acid Invertases Act as Key Factors Influencing the Sucrose/Hexose Ratio and Sugar Receding in Longan (Dimocarpus longan Lour.) Pulp

Abstract

Soluble acid invertases (SAIs) cleave sucrose into hexose in vacuoles and play important roles in influencing fruit quality. However, their potential roles in regulating sugar composition and the "sugar receding" process of longan fruits lacked systematic investigations. Our results showed that sucrose/hexose ratios and sugar receding rates of longan pulp varied among cultivars. Analysis of enzymes for sucrose synthesis and cleavage indicated that DlSAI showed the highest negative correlation with sucrose/hexose ratio at both of activity and expression level. Moreover, high SAI activity and DlSAI expression resulted in extremely low sucrose/hexose ratio in 'Luosanmu' longan from development to mature stages and a remarkable loss of sugar in 'Shixia' longan fruits during on-tree preservation. In conclusion, DlSAIs act as key factors influencing sucrose/hexose ratio and sugar receding through transcriptional and enzymatic regulations. These results might help improve the quality of on-tree preserved longan.

Postharvest melatonin treatment inhibited longan (Dimocarpuslongan Lour.) pericarp browning by increasing ROS scavenging ability and protecting cytomembrane integrity

“…Longan ( Dimocarpus longan Lour. ), one of the typical tropical and subtropical fruits with high commercial value, is a kind of globally consumed fruit but is extremely unresistant to long‐term postharvest storage and transportation (Han et al., 2020 ; Luo, Niu, et al., 2019 ; Luo et al., 2021 ; Luo, Shuai, et al., 2019 ). Longan fruits are usually harvested in summer with high temperatures and humidity.…”

Regulation of Maize Kernel Carbohydrate Metabolism by Abscisic Acid Applied at the Grain-Filling Stage at Low Soil Water Potential

“…Carbohydrates originating from Suc constitute nearly 90% of the plant biomass [7]. Suc is metabolized into hexose (Hex) by invertase through phloem unloading, resulting in a swelling pressure difference by osmosis [8]. The mass flow of water is driven by this difference in turgor, which brings assimilates from source to sink, tissues to power, and supports the growth of the latter [9].…”

Effect of 2,4-D pre-treatment on quality during ripening of on-tree longan fruit

“…The assay method of sugar component was reported by Luo et al [8] with a small modification. 1 g pericarp samples were in a microwave oven for 30 s to deactivate the enzymes, and homogenized in a mortar with 2 mL ultrapure water, the homogenate was transferred into a centrifuge tube.…”

“…Sucrose is the major end product in photosynthesis and often hydrolyzed into glucose and fructose [35] . The decrease of sucrose caused the sugar receding in longan fruit which seriously affected the fruit quality [8] . Obviously choosing optimal harvest time is vitally important.…”

“…Sugar of longan fruit mainly consists of sucrose, fructose and glucose with different ratios at different stages [7] . Previous studies have shown that longan fruit sugar receding may occur at unreasonable harvest time, resulting in a change of sugar composition [8] , contents of total soluble solids and titratable acidity increase during fruit development, and this is related to the content of sugar [9][10][11] , thus control sugar receding is an important subject to preserve the quality of longan fruit.…”