Transcriptome analysis associated with polysaccharide synthesis and their antioxidant activity in Cyclocarya paliurus leaves of different developmental stages

Abstract

Background Cyclocarya paliurus (Batal.) Iljinskaja is a common endemic tree species and used as a Chinese medicine. The main active components in the leaves of this plant are polysaccharides. However, the temporal patterns of gene expression underlying the synthesis of polysaccharides in C. paliurus at different leaf developmental stages and its relationship with the polysaccharide content and antioxidant activities has not been reported to date. Methods RNA-seq was used to investigate the biosynthesis pathway of polysaccharides at the four developmental stages of C. paliurus leaves. The content and the antioxidant activities of polysaccharides were measured with typical biochemical methods and the identified correlations were statistically evaluated. Results Sixty-nine differentially expressed genes were found in the leaves during different developmental stages of C. paliurus. These are associated with glycosyltransferases and belong to 18 families. During different developmental stages of C. paliurus, the polysaccharide content first increased and then decreased, and the UDP-glucose 4-epimerase gene was found to be significantly positively correlated with the polysaccharide content. The clearance rates of DPPH radicals, superoxide anion radicals, hydroxyl radicals, and the reducing power of polysaccharides in the leaves of C. paliurus at different developmental stages showed a dose-dependent relationship with the concentration of polysaccharides. Conclusions The smallest fully expanded leaves are suitable for high-quality tea, and leaves with sizes below the largest fully expanded leaves are suitable for industrial production of polysaccharides.

Integrated Metabolomic and Transcriptomic Analysis of the Flavonoid Accumulation in the Leaves of Cyclocarya paliurus at Different Altitudes

“…It is characterized by four distinct seasons, abundant rainfall, no severe cold in winter, no intense heat in summer, early spring and long summer, warm and humid. On May 1, 2018, mature leaves with the largest leaf area at F4 stage ( Lin et al, 2020 , 2021 ; Sheng et al, 2021 ) were collected from C. paliurus plants growing at the two locations. The leaves collected from high altitude were significantly larger and longer than those collected from low altitude ( Supplementary Figure 1 and Supplementary Table 2 ).…”

“…In the Spring of 2015, 1-year-old seedlings of C. paliurus were purchased from Yongfeng Town, Shuangfeng County, Hunan Province, China. Subsequently, the seedlings were transplanted on a field basement of Longquan at low altitude (E119 • 1 10 , N28 (Lin et al, 2020(Lin et al, , 2021Sheng et al, 2021) were collected from C. paliurus plants growing at the two locations. The leaves collected from high altitude were significantly larger and longer than those collected from low altitude (Supplementary Figure 1 and Supplementary Table 2).…”

“…The metabolites in the leaves of C. paliurus vary with altitude and plant location. Wu (2019) found that the contents of polysaccharides, flavonoids, and terpenoids in C. paliurus leaves from Anhui Province were highest at altitudes of 600–800 m. Wang et al (2020) compared the flavonoids and polyphenol contents in C. paliurus leaves grown at 400 m and 1,300 m in Suicang County, Zhejiang Province, and found that those at 1,300 m were significantly higher than at 400 m. Mi et al (2009) found that the flavonoids content in C. paliurus leaves in Xiushui County, Jiangxi Province, showed sawtooth form with the increase in altitude, and the highest flavonoid content was found in leaves collected at 915 m. In our previous studies, we combined metabolomic and transcriptomic data to explore the biosynthetic pathway of phenolic acid ( Lin et al, 2020 ), polysaccharides ( Lin et al, 2021 ), and flavonoids ( Sheng et al, 2021 ) in the leaves of C. paliurus . However, little is still known about the effect of altitude on the metabolite content of C. paliurus leaves.…”

Potential Role of Natural Plant Medicine Cyclocarya paliurus in the Treatment of Type 2 Diabetes Mellitus

“…Multiple studies have confirmed that the main polysaccharide compounds in C. paliurus have antioxidant activities. After using RNA-seq technology to study the polysaccharide synthesis pathway at different stages of leaf development and to detect the polysaccharide content and antioxidant activity, Liu et al found that the hydroxyl scavenging activity was the highest and the antioxidant capacity was the strongest in the first stage [ 55 ]. The health beverage composed of C. paliurus polysaccharides and Momordica saponin has been proven in the worm model to ameliorate oxidative damage by reducing the levels of ROS, MDA, and nonesterified fatty acids [ 56 ].…”

Identification of key gene networks controlling polysaccharide accumulation in different tissues of Polygonatum cyrtonema Hua by integrating metabolic phenotypes and gene expression profiles

“…Previous studies also indicated that polysaccharides can act as compatible solutes and enhance abiotic stress tolerance, such as drought and salt stress in plants ( Yu et al, 2017 , 2021 ). In recent years, intermediate metabolites and genes related to polysaccharide biosynthesis have been explored in various plants, including Arabidopsis , wheat, rice, Cyclocarya paliurus , Cynomorium songaricum , Dendrobium officinale , and Polygonatum odoratum ( Northcote and Pickett-Heaps, 1966 ; Meng et al, 2009 ; Oh et al, 2013 ; Zhang et al, 2016 ; He et al, 2017 ; Zhang et al, 2020 ; Lin et al, 2021 ; Wang et al, 2021a ). Studies have discovered that polysaccharides are biosynthesized via continuous enzymatic reactions from sucrose, requiring invertase (INV), hexokinase (HK), fructokinase (scrK), mannose-6-phosphate isomerase (MPI), phosphomannomutase (PMM), mannose-1-phosphate guanylyltransferase (GMPP), GDP-mannose 4,6-dehydratase (GMDS), GDP-L-fucose synthase (TSTA3), UDP-glucose 4-epimerase (GALE), UDP-glucose 6-dehydrogenase (UGDH), UDP-apiose/xylose synthase (AXS), UDP-arabinose 4-epimerase (UXE), UDP-glucose 4,6-dehydratase (RHM), 3,5-epimerase/4-reductase (UER1), and glycosyltransferase (GT) ( Figure 2 ; Zhang et al, 2020 ).…”