Designing plant flavonoids: harnessing transcriptional regulation and enzyme variation to enhance yield and diversity

Decoding comparative taste and nutrition regulation in Chinese cabbage via integrated metabolome and transcriptome analysis

Chinese cabbage (Brassica rapa L. ssp. pekinensis) is a widely consumed leafy vegetable known for its various health-beneficial nutrients. Caixin (ET and JY) represent distinct cultivars of Chinese cabbage that exhibit differential consumer preference attributed to variations in taste and nutritional content, with ET being characterized as sweeter and more nutritionally superior compared to JY. However, limited research has been conducted to explore regulation of flavor and nutrition-related quality traits in Chinese cabbage. In this pioneer study, comprehensive trans-meta-analysis was used to compare the metabolic and molecular underpinnings behind unique taste and nutritional profiles of ET and JY. 8-Methylsulfonyloctyl glucosinolates and Uridine 5'-diphospho-D-glucose exhibited the highest correlation coefficient in Pearson meta-meta-association, which modulate flavor and nutrition processes. While DAMs primarily featured L-Homomethionine, saccharic acid, 1,6-Di-O-caffeoyl-β-D-glucose, and Rutin, with notable variations in expression between ET and JY. Conspicuously, DEGs encoding structural enzymes i.e. Glucosinolates (MAM, CYP, UGT), flavonoids (CHS, CHI, F3H) and sucrose (SPS, SPP, SUS) synthases were identified as key players in nutrient and flavor production. Multi-omics conjoint analysis revealed that saccharides, amino acids, ascorbates, flavonoids, organic acids and vitamins were positively correlated with taste and nutrition, and were found to be overexpressed in ET. While aliphatic glucosinolates were abundant in JY compared to ET, they might play a critical role in regulating quality traits. Besides, HPLC and RT-qPCR corroborated multi-omics data reliability. These findings offer novel insights into the mechanisms governing the regulation of taste and nutritional levels in Chinese cabbage.

Engineering Plant Metabolism for Synthesizing Amino Acid Derivatives of Animal Origin Using a Synthetic Modular Approach

The biosynthesis of amino acid derivatives of animal origin in plants represents a promising frontier in synthetic biology, offering a sustainable and eco-friendly approach to enhancing the nutritional value of plant-based diets. This study leverages the versatile capabilities of Nicotiana benthamiana as a transient expression system to test a synthetic modular framework for the production of creatine, carnosine, and taurine-compounds typically absent in plants but essential for human health. By designing and stacking specialized synthetic modules, we successfully redirected the plant metabolic flux toward the synthesis of these amino acid derivatives of animal origin. Our results revealed the expression of a standalone creatine module resulted in the production of 2.3 μg/g fresh weight of creatine in N. benthamiana leaves. Integrating two modules significantly carnosine yield increased by 3.8-fold and minimized the impact on plant amino acid metabolism compared to individual module application. Unexpectedly, introducing the taurine module caused a feedback-like inhibition of plant cysteine biosynthesis, revealing complex metabolic adjustments that can occur when introducing foreign pathways. Our findings underline the potential for employing plants as biofactories for the sustainable production of essential nutrients of animal origin.

Recent advances in exploring transcriptional regulatory landscape of crops

Crop breeding entails developing and selecting plant varieties with improved agronomic traits. Modern molecular techniques, such as genome editing, enable more efficient manipulation of plant phenotype by altering the expression of particular regulatory or functional genes. Hence, it is essential to thoroughly comprehend the transcriptional regulatory mechanisms that underpin these traits. In the multi-omics era, a large amount of omics data has been generated for diverse crop species, including genomics, epigenomics, transcriptomics, proteomics, and single-cell omics. The abundant data resources and the emergence of advanced computational tools offer unprecedented opportunities for obtaining a holistic view and profound understanding of the regulatory processes linked to desirable traits. This review focuses on integrated network approaches that utilize multi-omics data to investigate gene expression regulation. Various types of regulatory networks and their inference methods are discussed, focusing on recent advancements in crop plants. The integration of multi-omics data has been proven to be crucial for the construction of high-confidence regulatory networks. With the refinement of these methodologies, they will significantly enhance crop breeding efforts and contribute to global food security.

Mutation in BrFLS encoding flavonol synthase induced anthocyanin accumulation in Chinese cabbage

KEY MESSAGE

BrFLS mutation promoted anthocyanin accumulation in Chinese cabbage, which was verified in four allelic mutants. Chinese cabbage is a major vegetable crop in Eastern Asia. Anthocyanin-rich vibrantly colored varieties are increasingly favored by consumers for their higher nutritional and aesthetic value compared to the typical green varieties of Chinese cabbage. Herein, we identified an anthocyanin accumulation mutant aam1 from a mutant library of EMS-mutagenized Chinese cabbage DH line 'FT', which appeared partial purple on leaves, bolting stems and floral buds. This anthocyanin accumulation trait was genetically controlled by a recessive nuclear gene, and through MutMap mapping and KASP genotyping, BraA10g030950.3C was identified as the candidate causal gene with a G202 to A202 non-synonymous SNP variation in exon 1. Three additional mutants allelic to aam1 were obtained via screening of similar-phenotype mutants from the mutant library, namely aam2/3/4, where the causal SNPs reside in the same gene as aam1, corroborating that the mutation of BraA10g030950.3C caused anthocyanin accumulation. BraA10g030950.3C encodes a flavonol synthase that catalyzes dihydroflavonols substrate into flavonols and is homologous to Arabidopsis FLS1 (AT5G08640), named BrFLS. Compared to wildtype, the expression level of BrFLS was significantly reduced in the mutants, while BrDFR, which is involved in the anthocyanin biosynthesis and competes with FLS for the common substrate dihydroflavonols, was increased. The flavonol synthase activity decreased, and dihydroflavonol 4-reductase activity was elevated. Differentially accumulated flavonoid metabolites were detected between wildtype and aam1, which were enriched primarily in flavonol and anthocyanin pathways. Our results revealed that mutations in the BrFLS gene could contribute to anthocyanin accumulation and provide a new target for Chinese cabbage color modification.