Sugar beet is an important sugar-yielding crop with some tolerance to salt, but the mechanistic basis of this tolerance is not known. In the present study, we have used whole-transcriptome RNA-seq and degradome sequencing in response to salt stress to uncover differentially expressed (DE) mRNAs, microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) in both leaves and roots. A competitive endogenous RNA (ceRNA) network was constructed with the predicted DE pairs, which revealed regulatory roles under salt stress. A functional analysis suggests that ceRNAs are implicated in copper redistribution, plasma membrane permeability, glycometabolism and energy metabolism, NAC transcription factor and the phosphoinositol signaling system. Overall, we conducted for the first time a full transcriptomic analysis of sugar beet under salt stress that involves a potential ceRNA network, thus providing a basis to study the potential functions of lncRNAs/circRNAs.

The traditional method of gas chromatography-mass spectrometry for monosaccharide component analysis with pretreatment of acetylation is described with slight modifications and verified in detail in this paper. It was then successfully applied to the quantitative analysis of component monosaccharides in polysaccharides extracted from the pine cones. The results demonstrated that the three pine cone polysaccharides all consisted of ribose, rhamnose, arabinose, xylose, mannose, glucose and galactose in different molar ratios. According to the recovery experiment, the described method was proved accurate and practical for the analysis of pine cone polysaccharides, meeting the need in the field of chemical analysis of Pinus plants. Furthermore; the chemical characteristics, such as neutral sugar, uronic acids, amino acids, molecular weights, and antioxidant activities of the polysaccharides were investigated by chemical and instrumental methods. The results showed that the chemical compositions of the polysaccharides differed from each other, especially in the content of neutral sugar and uronic acid. In the antioxidant assays, the polysaccharide fractions exhibited effective scavenging activities on ABTS radical and hydroxyl radical, with their antioxidant capabilities decreasing in the order of PKP > PAP > PSP. Therefore, although the polysaccharide fractions had little effect on superoxide radical scavenging, they still have potential to be developed as natural antioxidant agents in functional foods or medicine.

The aim of this study was to investigate the synergistic antioxidant potential and protective effect of grape seed procyanidins (GSP) in combination with Auricularia auricular-judae polysaccharides (AAP IV) on radiation injury in splenocytes. Rat splenocyte irradiation resulted in significantly higher apoptosis rate, malondialdehyde (MDA) (p < 0.005), reactive oxygen species (ROS) (p < 0.01); cell viability, total superoxide dismutase (T-SOD) (p < 0.01), catalase (CAT) (p < 0.01), glutathione peroxidase (GSH-P_X) (p < 0.05), activity and glutathione (GSH) (p < 0.01) levels were significantly reduced, compared with the control group. “GSP + AAP IV” treatment of rat splenocytes at doses of “GSP (0.3 μg/mL) + AAP IV (50 μg/mL)” displayed higher radioprotective and antioxidative effects than the administration of either GSP or AAP IV, as evident by lower levels of MDA (p < 0.001) concentration, as well as higher cell viability and T-SOD (p < 0.05), CAT (p < 0.005), GSH-P_X (p < 0.01) and GSH content compared to the radiation group. In addition, in vivo studies have shown that “GSP + AAP IV” significantly ameliorated the decrease of spleen index (p < 0.005) and spleen GSH (p < 0.005) levels and significantly inhibited the increase of MDA (p < 0.005) levels of spleen with radiation-induced damage, compared with the non-treated group. The in vivo and in vitro results suggested that GSP and AAP IV have a synergistic protective effect against radiation-induced injury by improving the antioxidant and immunomodulation activities.

Salinity is one of the most serious threats to agriculture worldwide. Sugar beet is an important sugar-yielding crop and has a certain tolerance to salt; however, the genome-wide dynamic response to salt stress remains largely unknown in sugar beet. In the present study, physiological and transcriptome analyses of sugar beet leaves and roots were compared under salt stress at five time points. The results showed that different salt stresses influenced phenotypic characteristics, leaf relative water content and root activity in sugar beet. The contents of chlorophyll, malondialdehyde (MDA), the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) were also affected by different salt stresses. Compared with control plants, there were 7391 and 8729 differentially expressed genes (DEGs) in leaves and roots under salt stress, respectively. A total of 41 hub genes related to salt stress were identified by weighted gene co-expression network analysis (WGCNA) from DEGs, and a transcriptional regulatory network based on these genes was constructed. The expression pattern of hub genes under salt stress was confirmed by qRT-PCR. In addition, the metabolite of sugar beet was compared under salt stress for 24 h. A total of 157 and 157 differentially accumulated metabolites (DAMs) were identified in leaves and roots, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis further indicated that DEGs and DAMs act on the starch and sucrose metabolism, alpha-linolenic acid metabolism, phenylpropanoid biosynthesis and plant hormone signal transduction pathway. In this study, RNA-seq, WGCNA analysis and untargeted metabolomics were combined to investigate the transcriptional and metabolic changes of sugar beet during salt stress. The results provided new insights into the molecular mechanism of sugar beet response to salt stress, and also provided candidate genes for sugar beet improvement.