关键词: 宁夏枸杞, 糖代谢, 酶活性, 表达量

Abstract:

Objective: This study aims to explore the effect of elevated CO₂ concentration on carbohydrate accumulation during the development of Lycium barbarum fruits,so as to provide a reference for adaptive management of L. barbarum to cope with climate change. Method: L. barbarum ‘Ningqi 1’ was used as the experimental material. An open-top chamber simulation control system was applied to elevate the CO₂ concentration (800±20 μmol·mol^?1), with the ambient CO₂ concentration (400±20 μmol·mol^?1) served as the control. After 60 days of treatment, the root, stem, leaf, and fruit samples were collected respectively at the young fruit stage, green fruit stage, coloring fruit stage, and red fruit stage, and the content of their sugar components, sugar metabolism-related enzyme activity, and relevant gene expression were determined. Result: 1) The elevated CO₂ concentration promoted the accumulation of lactose, sucrose, and total sugars during the fruit development, and at the red fruit stage, the content of lactose, fructose, sucrose, and total sugars significantly increased by 35.71%, 23.18%, 19.57%, and 12.23%, respectively, compared to the control group (P<0.05). 2) Furthermore, elevated CO₂ concentrations significantly (P<0.05) increased the activity of malic acid synthase (LbMS), neutral conversion enzyme (LbAI), sucrose phosphate synthase (LbSPS), and sucrose synthase (LbSS) in the root, stem, leaf, and fruit tissues of ‘Ningqi 1’ during its development. The activity of α-galactosidase (LbGALA) increased from leaf to fruit. Under the elevated CO₂ concentration treatment, the activity of the α-galactosidase in the fruits at four different stages was significantly increased by 19.54%, 36.68%, 21.00%, and 24.93%, respectively, compared to the control group (P<0.05). The activity of sucrose synthase and sucrose phosphate synthase in leaves was significantly higher than that in the other tissues (P<0.05). The gene expressions of LbGALA and LbNI were significantly up-regulated at the mature fruit stage (P<0.05). 3) The elevated CO₂ concentrations significantly up-regulated the gene expressions of LbGAE, LbNI, and LbSPS in stems, LbGALA in fruits, and LbMS and LbAI in roots. The expression levels of LbSPS and LbSS were significantly up-regulated in leaves (P<0.05). Conclusion: The elevated CO₂ concentration promotes the expression of sugar metabolism-related genes in different tissues of L. barbarum, and it also increases enzyme activity, and thereby promoting the accumulation of lactose, sucrose, and total sugars in the fruit.

Key words: Lycium barbarum, sugar metabolism, enzyme activity, expression quantity