Analysis of Phenotypic Characteristics and Sucrose Metabolism in the Roots of Raphanus sativus L

TgMYBS1-TgSUS1 regulatory module mediates sucrose metabolism in Torreya grandis kernels

Sucrose synthase (SUS) is a key enzyme in sucrose metabolism, catalyzing the reversible synthesis and degradation of sucrose. It plays a crucial role in plant growth and development. Previous studies have shown that SUS-mediated sucrose metabolism is essential during various developmental stages in plants like Arabidopsis. However, its specific functions in Torreya grandis, an important economic tree species, have not yet been fully elucidated. Here, we identified five SUS genes in T. grandis and found that TgSUS1, a highly expressed gene in kernels, was significantly increased during kernels development. TgSUS1 protein was localized to the nucleus and cell membrane. Transient overexpressed TgSUS1 in kernels and heterologous overexpression of TgSUS1 in Oryza sativa significantly enhanced SUS activity in the sucrose cleavage (SS-c) direction and reduced sucrose content. Conversely, silencing TgSUS1 markedly reduced SS-c activity and increased sucrose content in kernels. Additionally, we found that the transcription factor TgMYBS1 directly bound to the promoter of TgSUS1 by Y1H and EMSA experiments. TgMYBS1 significantly reduced SS-c activity and increased sucrose content in kernels by inhibiting TgSUS1 expression. In summary, our findings indicate that TgMYBS1 directly inhibits the expression of TgSUS1 to suppress SS-c activity, thereby modulating the sucrose metabolism in T. grandis kernels.

Changes in Quality and Metabolites of Pickled Purple Radish During Storage

This study investigated the changes in the physicochemical properties and metabolites of pickled purple radish during storage. Pickles of purple radish ('Boraking') prepared by the addition of acetic acid and sugar were stored in the dark at 4 °C for 60 days. The color of the pickled purple radish changed from purple to pink, while the pickling solution changed from pink to purple. During storage, sucrose content gradually decreased, while glucose and fructose levels increased. LC-ESI-QToF-MS metabolomic analysis indicated that metabolites, including organic acids, amino acids, sulfur-containing compounds, lysophosphatidylcholine, lysophosphatidylethanolamine, and anthocyanins, were identified. The antioxidant capacity and color meter of pickled purple radish may undergo changes due to the altered levels of non-volatile compounds (cyanidins, adenosine, and amino acids) during storage. Anthocyanins had negative correlations with the color of pickled purple radish. The radical scavenging activity and ferric-reducing antioxidant power of pickled purple radish declined during storage. These findings emphasized the need for further research to develop processing and storage methods that enhance the bioactivity and stability of pickled purple radish.

RsWOX13 promotes taproot development by activating cell division and expansion and sucrose metabolism in radish

Radish is an important annual root vegetable crop, whose yield is largely dependent on taproot thickening and development. However, the regulatory network of WOXs-mediated taproot development remains poorly understood in radish. Herein, the RsWOX13 was classified in an ancient clade of the WOX gene family that harbors a conserved homeodomain. RT-qPCR analysis revealed that the RsWOX13 gene was highly expressed in radish roots, leaves and flowers. Interestingly, both the promoter activity and expression of the RsWOX13 gene were significantly induced by cytokinin treatment, particularly at 3h. RsWOX13 possessed a transcriptional activation property, that was localized in the nucleus in tobacco leaves. Moreover, overexpression of RsWOX13 resulted in increased plant weight and root width in Arabidopsis, while virus-induced silencing of RsWOX13 inhibited cell expansion and cambium cell activities in radish. Several genes involved in cell wall biogenesis, hormone signaling and sucrose metabolic pathways were differentially expressed in the pTY and RsWOX13-silenced radish plants. Further investigations demonstrated that RsWOX13 directly activated the transcription of RsARR9, RsSUS1a, RsEXPA9 and RsEXPA1 genes by binding to their promoters, indicating that it promoted taproot development by integrating cell division and expansion and sucrose metabolism pathways. These results would provide novel insight into the molecular mechanisms underlying taproot development and facilitate enhancing root yields through genetic engineering approaches in radish.

Green Radish Polysaccharides Ameliorate Hyperlipidemia in High-Fat-Diet-Induced Mice via Short-Chain Fatty Acids Production and Gut Microbiota Regulation

The objective of this study was to examine the hypolipidemic effect and potential mechanism of action of green radish polysaccharide (GRP) in hyperlipidemic mice. We found that in mice fed a high-fat diet, supplementing with GRP reduced body weight and liver index, significantly improved serum lipid levels and markers of liver damage, and mitigated oxidative stress and inflammation. Mechanistically, in these hyperlipidemic mice, the size of fat cells was reduced by GRP, and the abnormal accumulation of lipid droplets was reduced. We also found that GRP regulates the composition of the intestinal microbiota, including the ratio of Firmicutes to Mycobacteria F/B and the levels of Blautia spp., which have been shown to alleviate liver damage and treat hyperlipidemia. Metabolite pathway analysis using the Kyoto Encyclopedia of Genes and Genomes identified the glycolysis/glycolytic metabolism and propionate metabolism pathways as potential targets for GRP in the amelioration of hyperlipidemia.

Enhancing transcriptome analysis in medicinal plants: multiple unigene sets in Astragalus membranaceus

Astragalus membranaceus is a medicinal plant mainly used in East Asia and contains abundant secondary metabolites. Despite the importance of this plant, the available genomic and genetic information is still limited. De novo transcriptome construction is recognized as an essential method for transcriptome research when reference genome information is incomplete. In this study, we constructed three individual transcriptome sets (unigene sets) for detailed analysis of the phenylpropanoid biosynthesis pathway, a major metabolite of A. membranaceus. Set-1 was a circular consensus sequence (CCS) generated using PacBio sequencing (PacBio-seq). Set-2 consisted of hybridized assembled unigenes with Illumina sequencing (Illumina-seq) reads and PacBio CCS using rnaSPAdes. Set-3 unigenes were assembled from Illumina-seq reads using the Trinity software. Construction of multiple unigene sets provides several advantages for transcriptome analysis. First, it provides an appropriate expression filtering threshold for assembly-based unigenes: a threshold transcripts per million (TPM) ≥ 5 removed more than 88% of assembly-based unigenes, which were mostly short and low-expressing unigenes. Second, assembly-based unigenes compensated for the incomplete length of PacBio CCSs: the ends of the 5`/3` untranslated regions of phenylpropanoid-related unigenes derived from set-1 were incomplete, which suggests that PacBio CCSs are unlikely to be full-length transcripts. Third, more isoform unigenes could be obtained from multiple unigene sets; isoform unigenes missing in Set-1 were detected in set-2 and set-3. Finally, gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed that phenylpropanoid biosynthesis and carbohydrate metabolism were highly activated in A. membranaceus roots. Various sequencing technologies and assemblers have been developed for de novo transcriptome analysis. However, no technique is perfect for de novo transcriptome analysis, suggesting the need to construct multiple unigene sets. This method enables efficient transcript filtering and detection of longer and more diverse transcripts.

Trehalose metabolism coordinates transcriptional regulatory control and metabolic requirements to trigger the onset of cassava storage root initiation

Cassava storage roots (SR) are an important source of food energy and raw material for a wide range of applications. Understanding SR initiation and the associated regulation is critical to boosting tuber yield in cassava. Decades of transcriptome studies have identified key regulators relevant to SR formation, transcriptional regulation and sugar metabolism. However, there remain uncertainties over the roles of the regulators in modulating the onset of SR development owing to the limitation of the widely applied differential gene expression analysis. Here, we aimed to investigate the regulation underlying the transition from fibrous (FR) to SR based on Dynamic Network Biomarker (DNB) analysis. Gene expression analysis during cassava root initiation showed the transition period to SR happened in FR during 8 weeks after planting (FR8). Ninety-nine DNB genes associated with SR initiation and development were identified. Interestingly, the role of trehalose metabolism, especially trehalase1 (TRE1), in modulating metabolites abundance and coordinating regulatory signaling and carbon substrate availability via the connection of transcriptional regulation and sugar metabolism was highlighted. The results agree with the associated DNB characters of TRE1 reported in other transcriptome studies of cassava SR initiation and Attre1 loss of function in literature. The findings help fill the knowledge gap regarding the regulation underlying cassava SR initiation.

Profiling of Health-Promoting and Taste-Relevant Compounds in Sixteen Radish (Raphanus sativus L.) Genotypes Grown under Controlled Conditions

It is becoming increasingly challenging to maintain crop yields and quality as the global climate changes. The aim of this study was to determine whether and how the profile of health-promoting and taste-related compounds of radishes changes within a growing season. A total of 16 radish (Raphanus sativus L.) genotypes that are commercially available on the Czech market were assessed by means of chemical analysis. Radishes were cultivated in three independent growing cycles under controlled conditions, and the effects of the genotype and growing cycle, as well as their interactions, on the chemical traits were evaluated. Most of the variability in chemical composition was associated with the growing cycle, which accounted for 51.53% of total variance, followed by the genotype (26% of total variance). The interaction between the growing cycle and genotype explained 22.47% of total variance. The growing cycle had the strongest effect on amino acid profiles. More specifically, the amino acids that are known to contribute to overall taste (glycine, along with glutamic and aspartic acids) showed the highest degree of variation, while the amino acids related to glucosinolate biosynthesis (methionine, isoleucine, tryptophan, and phenylalanine) showed relatively low variability. On the other hand, indole glucosinolates were found to differ the most between genotypes.