Critical metabolic pathways and SAD/FADs, WRI1s, and DGATs cooperate for high-oleic acid oil production in developing oil tea (Camellia oleifera) seeds.

Oil tea trees produce high-quality edible oils with desirably high oleic acid (18:1) and low linoleic (18:2) and linolenic (18:3) fatty acid (FA) levels, but limited understanding of tea oil biosynthesis and regulation has become a significant obstacle for the breeding of high-yield and -quality oil tea varieties. By integrating metabolite and transcriptome analyses of developing oil tea seeds, we dissected the critical metabolic pathways, including glycolysis, fatty acid, and triacylglycerol (TAG) biosynthesis, as well as genes essential for tea seed oil production. Two plastidic stearoyl-acyl carrier protein desaturases (CoSAD1 and 2) and two endoplasmic reticulum-localized FA desaturases (CoFAD2 and 3) were functionally characterized as responsible for high 18:1 and low 18:2 and 18:3 proportions in tea oils. Two diacylglycerol O-acyltransferases (CoDGAT1 and 2) that may prefer to synthesize 18:1-TAG were functionally characterized and might be also important for high 18:1-TAG production. The highly expressed CoWRI1a and b were identified and characterized as activators of glycolysis and regulators of directing source carbon flux into FA biosynthesis in developing oil tea seeds. The upregulated CoSADs with downregulated CoFAD2 and CoFAD3 at the late seed developmental stages mainly accounted for high 18:1 levels. Two CoDGATs might be responsible for assembling TAGs with oleoyl acyl chains, whilst two CoWRI1s regulated carbons from parental sources, partitioning into oil production in oil tea embryo sinks. This study provides a deep understanding of the biosynthesis of tea seed oils and information on genes that may be used as molecular markers to breed oil tea varieties with higher oil yield and quality.

Antibody-dependent cellular cytotoxicity response to SARS-CoV-2 in COVID-19 patients.

Antibody-dependent cellular cytotoxicity (ADCC) responses to viral infection are a form of antibody regulated immune responses mediated through the Fc fragment. Whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) triggered ADCC responses contributes to COVID-19 disease development is currently not well understood. To understand the potential correlation between ADCC responses and COVID-19 disease development, we analyzed the ADCC activity and neutralizing antibody response in 255 individuals ranging from asymptomatic to fatal infections over 1 year post disease. ADCC was elicited by 10 days post-infection, peaked by 11-20 days, and remained detectable until 400 days post-infection. In general, patients with severe disease had higher ADCC activities. Notably, patients who had severe disease and recovered had higher ADCC activities than patients who had severe disease and deceased. Importantly, ADCC activities were mediated by a diversity of epitopes in SARS-COV-2-infected mice and induced to comparable levels against SARS-CoV-2 variants of concern (VOCs) (B.1.1.7, B.1.351, and P.1) as that against the D614G mutant in human patients and vaccinated mice. Our study indicates anti-SARS-CoV-2 ADCC as a major trait of COVID-19 patients with various conditions, which can be applied to estimate the extra-neutralization level against COVID-19, especially lethal COVID-19.

Comparative Transcriptomic Analysis Reveals Regulatory Mechanisms of Theanine Synthesis in Tea (Camellia sinensis) and Oil Tea (Camellia oleifera) Plants.

Tea provides a rich taste and has healthy properties due to its variety of bioactive compounds, such as theanine, catechins, and caffeine. Theanine is the most abundant free amino acid (40%-70%) in tea leaves. Key genes related to theanine biosynthesis have been studied, but relatively little is known about the regulatory mechanisms of theanine accumulation in tea leaves. Herein, we analyzed theanine content in tea (Camellia sinensis) and oil tea (Camellia oleifera) and found it to be higher in the roots than in other tissues in both species. The theanine content was significantly higher in tea than oil tea. To explore the regulatory mechanisms of theanine accumulation, we identified genes involved in theanine biosynthesis by RNA-Seq analysis and compared theanine-related modules. Moreover, we cloned theanine synthase (TS) promoters from tea and oil tea plants and found that a difference in TS expression and cis-acting elements may explain the difference in theanine accumulation between the two species. These data provide an important resource for regulatory mechanisms of theanine accumulation in tea plants.

Transcriptome and metabolite analyses reveal the complex metabolic genes involved in volatile terpenoid biosynthesis in garden sage (Salvia officinalis).

A large number of terpenoid compounds have been extracted from different tissues of S. officinalis. However, the molecular genetic basis of terpene biosynthesis pathways is virtually unknown. In this study, approximately 6.6 Gb of raw data were generated from the transcriptome of S. officinalis leaves using Illumina HiSeq 2000 sequencing. After filtering and removing the adapter sequences from the raw data, the number of reads reached 21 million, comprising 98 million of high-quality nucleotide bases. 48,671 unigenes were assembled de novo and annotated for establishing a valid database for studying terpenoid biosynthesis. We identified 135 unigenes that are putatively involved in terpenoid metabolism, including 70 mevalonate and methyl-erythritol phosphate pathways, terpenoid backbone biosynthesis genes, and 65 terpene synthase genes. Moreover, five terpene synthase genes were studied for their functions in terpenoid biosynthesis by using transgenic tobacco; most transgenic tobacco plants expressing these terpene synthetic genes produced increased amounts of terpenoids compared with wild-type control. The combined data analyses from the transcriptome and metabolome provide new insights into our understanding of the complex metabolic genes in terpenoid-rich sage, and our study paves the way for the future metabolic engineering of the biosynthesis of useful terpene compounds in S. officinalis.

Transport and transcriptional regulation of oil production in plants.

Triacylglycerol (TAG) serves as an energy reservoir and phospholipids as build blocks of biomembrane to support plant life. They also provide human with foods and nutrients. Multi-compartmentalized biosynthesis, trafficking or cross-membrane transport of lipid intermediates or precursors and their regulatory mechanisms are not fully understood. Recent progress has aided our understanding of how fatty acids (FAs) and phospholipids are transported between the chloroplast, the cytoplasm, and the endoplasmic reticulum (ER), and how the ins and outs of lipids take place in the peroxisome and other organelles for lipid metabolism and function. In addition, information regarding the transcriptional regulation network associated with FA and TAG biosynthesis has been further enriched. Recent breakthroughs made in lipid transport and transcriptional regulation has provided significant insights into our comprehensive understanding of plant lipid biology. This review attempts to highlight the recent progress made on lipid synthesis, transport, degradation, and their regulatory mechanisms. Metabolic engineering, based on these knowledge-powered technologies for production of edible oils or biofuels, is reviewed. The biotechnological application of metabolic enzymes, transcription factors and transporters, for oil production and composition improvement, are discussed in a broad context in order to provide a fresh scenario for researchers and to guide future research and applications.