Engineering high coenzyme Q10 tomato

SlERF.G3-Like mediates a hierarchical transcriptional cascade to regulate ripening and metabolic changes in tomato fruit

The tomato ripening process contains complex changes, including ethylene signalling, cell wall softening and numerous metabolic changes. So far, much is still unknown about how tomato plants precisely coordinate fruit maturation and metabolic regulation. In this paper, the ERF family transcription factor SlERF.G3-Like in tomato was found to be involved in the regulation of ethylene synthesis, cell wall degradation and the flavonoid pathway. We show that the master ripening regulator SlRIN was found to directly bind to the promoter region of SlERF.G3-Like to activate its expression. In addition, we managed to increase the production of resveratrol derivatives from ~1.44 mg/g DW in E8:VvStSy line to ~2.43 mg/g DW by crossing p35S: SlERF.G3-Like with the E8:VvStSy line. Our data provide direct evidence that SlERF.G3-Like, a hierarchical transcriptional factor, can directly manipulate pathways in which tomatoes can coordinate fruit maturation and metabolic changes. We also attest that SlERF.G3-Like can be used as an effective tool for phenylpropanoid metabolic engineering.

Single-cell RNA sequencing reveals a hierarchical transcriptional regulatory network of terpenoid biosynthesis in cotton secretory glandular cells

Plants can synthesize a wide range of terpenoids in response to various environmental cues. However, the specific regulatory mechanisms governing terpenoid biosynthesis at the cellular level remain largely elusive. In this study, we employed single-cell RNA sequencing to comprehensively characterize the transcriptome profile of cotton leaves and established a hierarchical transcriptional network regulating cell-specific terpenoid production. We observed substantial expression levels of genes associated with the biosynthesis of both volatile terpenes (such as β-caryophyllene and β-myrcene) and non-volatile gossypol-type terpenoids in secretory glandular cells. Moreover, two novel transcription factors, namely GoHSFA4a and GoNAC42, are identified to function downstream of the Gossypium PIGMENT GLAND FORMATION genes. Both transcription factors could directly regulate the expression of terpenoid biosynthetic genes in secretory glandular cells in response to developmental and environmental stimuli. For convenient retrieval of the single-cell RNA sequencing data generated in this study, we developed a user-friendly web server . Our findings not only offer valuable insights into the precise regulation of terpenoid biosynthesis genes in cotton leaves but also provide potential targets for cotton breeding endeavors.

A Trifolium repens flavodoxin-like quinone reductase 1 (TrFQR1) improves plant adaptability to high temperature associated with oxidative homeostasis and lipids remodeling

Maintenance of stable mitochondrial respiratory chains could enhance adaptability to high temperature, but the potential mechanism was not elucidated clearly in plants. In this study, we identified and isolated a TrFQR1 gene encoding the flavodoxin-like quinone reductase 1 (TrFQR1) located in mitochondria of leguminous white clover (Trifolium repens). Phylogenetic analysis indicated that amino acid sequences of FQR1 in various plant species showed a high degree of similarities. Ectopic expression of TrFQR1 protected yeast (Saccharomyces cerevisiae) from heat damage and toxic levels of benzoquinone, phenanthraquinone and hydroquinone. Transgenic Arabidopsis thaliana and white clover overexpressing TrFQR1 exhibited significantly lower oxidative damage and better photosynthetic capacity and growth than wild-type in response to high-temperature stress, whereas AtFQR1-RNAi A. thaliana showed more severe oxidative damage and growth retardation under heat stress. TrFQR1-transgenic white clover also maintained better respiratory electron transport chain than wild-type plants, as manifested by significantly higher mitochondrial complex II and III activities, alternative oxidase activity, NAD(P)H content, and coenzyme Q10 content in response to heat stress. In addition, overexpression of TrFQR1 enhanced the accumulation of lipids including phosphatidylglycerol, monogalactosyl diacylglycerol, sulfoquinovosyl diacylglycerol and cardiolipin as important compositions of bilayers involved in dynamic membrane assembly in mitochondria or chloroplasts positively associated with heat tolerance. TrFQR1-transgenic white clover also exhibited higher lipids saturation level and phosphatidylcholine:phosphatidylethanolamine ratio, which could be beneficial to membrane stability and integrity during a prolonged period of heat stress. The current study proves that TrFQR1 is essential for heat tolerance associated with mitochondrial respiratory chain, cellular reactive oxygen species homeostasis, and lipids remodeling in plants. TrFQR1 could be selected as a key candidate marker gene to screen heat-tolerant genotypes or develop heat-tolerant crops via molecular-based breeding.

How plants synthesize coenzyme Q

Coenzyme Q (CoQ) is a conserved redox-active lipid that has a wide distribution across the domains of life. CoQ plays a key role in the oxidative electron transfer chain and serves as a crucial antioxidant in cellular membranes. Our understanding of CoQ biosynthesis in eukaryotes has come mostly from studies of yeast. Recently, significant advances have been made in understanding CoQ biosynthesis in plants. Unique mitochondrial flavin-dependent monooxygenase and benzenoid ring precursor biosynthetic pathways have been discovered, providing new insights into the diversity of CoQ biosynthetic pathways and the evolution of phototrophic eukaryotes. We summarize research progress on CoQ biosynthesis and regulation in plants and recent efforts to increase the CoQ content in plant foods.

Engineering the expression of plant secondary metabolites-genistein and scutellarin through an efficient transient production platform in Nicotiana benthamiana L

Plant natural products (PNPs) are active substances indispensable to human health with a wide range of medical and commercial applications. However, excessive population growth, overexploitation of natural resources, and expensive total chemical synthesis have led to recurrent supply shortages. Despite the fact that the microbial production platform solved these challenges, the platform still has drawbacks such as environmental pollution, high costs, and non-green production. In this study, an efficient platform for the production of PNPs based on the transient expression system of Nicotiana benthamiana L. combined with synthetic biology strategies was developed. Subsequently, the feasibility of the platform was verified by a simple "test unit." This platform was used to synthesize two high-value PNPs: genistein (5.51 nmol g^-1 FW) and scutellarin (11.35 nmol g^-1 FW). Importantly, this is the first report on the synthesis of scutellarin in heterologous plants. The platform presented here will possibly be adopted for the heterologous production of genistein and scutellarin in tobacco plants as a novel and sustainable production strategy.