Tong Lian

Legionella pneumophila is a Gram-negative opportunistic pathogen responsible for Legionnaires’ disease, a severe form of atypical pneumonia associated with high morbidity and mortality, particularly in immunocompromised individuals. Despite its growing global burden and the persistence of environmental reservoirs, no licensed vaccine is currently available. In this study, an integrative immunoinformatics and reverse vaccinology approach was employed to design a multi-epitope vaccine candidate targeting L. pneumophila. The complete proteome was systematically analyzed to identify essential, virulent, and surface-accessible proteins. Subsequent antigenicity assessment and non-homology screening against the human proteome led to the selection of key immunogenic targets, including KDO transferase and TolR. B-cell and T-cell epitopes were predicted and rigorously filtered based on antigenicity, non-allergenicity, and non-toxicity. Selected epitopes were assembled into a multi-epitope vaccine construct using appropriate linkers and adjuvants to enhance immunogenicity and structural stability. The designed construct exhibited favorable physicochemical properties, high antigenicity, and good solubility. Structural modeling and refinement confirmed the reliability of the predicted three-dimensional structure. Molecular docking analysis demonstrated strong binding interactions with immune receptors TLR-2 and TLR-9, which were further validated by molecular dynamics simulations indicating stable complex formation under physiological conditions. In addition, immune simulation predicted robust humoral and cellular immune responses, including memory cell generation. Overall, this study presents a promising computationally designed multi-epitope vaccine candidate against L. pneumophila. However, further in vitro and in vivo studies are required to validate its immunogenicity, safety, and protective efficacy.

Identifying genes involved in folate accumulation is critical for elucidating the regulatory mechanisms of folate metabolism and breeding folate‐rich crops. Here, a natural A‐to‐G variation at the 682nd bp is identified in the coding sequence of an identified plant gene glutamate formiminotransferase ( GFT ) in maize, leading to a glycine‐to‐asparagine substitution at the 228th in the protein sequence and contributing to the variation of folate accumulation in mature seeds of a maize inbred line population. This gene encodes a protein highly similar to the f ormimino t ransferase domain of mammalian f ormimino t ransferase c yclo d eaminase . In vitro biochemical analysis of this protein reveals an activity of triggering 5‐methyl‐tetrahydrofolate (5‐M‐THF)‐to‐MeFox conversion, other than exerting an activity of formiminotransferase in mammals. Loss of ZmGFT function triples 5‐M‐THF levels, and overexpression of G‐allele‐carrying ZmGFT boosts the metabolic flow toward MeFox. Functional conservation of GFT is validated in rice and Arabidopsis . The asparagine‐to‐glycine substitution enhances 5‐M‐THF‐to‐MeFox conversion, as demonstrated by in vitro assays and in silico analyses. The functional characterization of the GFT gene has uncovered a new metabolic fate of 5‐M‐THF, apart from a C1 donor for methionine synthesis, in plants, and a distinct activity from its mammalian ortholog. The natural variation identified is useful for breeding folate‐fortified maize varieties.

Rising atmospheric CO₂ levels, a significant consequence of anthropogenic activities, profoundly impact global agriculture and food security by altering plant physiological processes. Despite extensive research, a comprehensive understanding of the specific effects of elevated CO₂ on maize (Zea mays L.)’s primary and secondary metabolism remains elusive. This study investigated the responses of maize seedlings cultivated in open-top chambers (OTCs) under three CO₂ concentrations: ambient (380 ppm), elevated (600 ppm), and high (1800 ppm). Key growth parameters, including plant height, leaf area, and aboveground biomass (leaf and stem), were assessed alongside metabolic profiles encompassing nonstructural and structural carbohydrates, syringyl (S) and guaiacyl lignin, the syringyl-to-guaiacyl (S/G)-lignin ratio, photosynthetic pigments, total soluble protein, and malondialdehyde (MDA) levels. The results demonstrated that exposure to 600 ppm CO₂ significantly enhanced plant height, leaf area, and aboveground biomass compared to ambient conditions. Concurrently, there were notable increases in the concentrations of primary metabolites. In contrast, exposure to 1800 ppm CO₂ severely inhibited these growth parameters and induced reductions in secondary metabolites, such as chlorophyll and soluble proteins, throughout the growth stages. The findings underscore the intricate responses of maize metabolism to varying CO₂ levels, highlighting adaptive strategies in primary and secondary metabolism under changing atmospheric conditions. This research contributes to a nuanced understanding of maize’s physiological adaptations to future climate scenarios characterized by elevated CO₂, with implications for sustainable agriculture and food security.

Methionine is an essential amino acid that initiates protein synthesis and serves as a substrate for various chemical reactions. Methionine metabolism plays an important role in Arabidopsis seed germination, but how methionine works in seed germination of maize has not been elucidated. We compared the changes in germination rate, the contents of methionine and folates, and transcriptional levels using transcriptome analysis under water or exogenous methionine treatment. The results indicate that the application of methionine increases seed germination rate (95% versus 70%), leading to significant differences in the content of methionine at 36 h, which brought the rapid increase forward by 12 h in the embryo and endosperm. Transcriptome analysis shows that methionine mainly affects the proliferation and differentiation of cells in the embryo, and the degradation of storage substances and signal transduction in the endosperm. In particular, multiple phenylpropanoid biosynthetic genes were triggered upon methionine treatment during germination. These results provide a theoretical foundation for promoting maize seed germination and serve as a valuable theoretical resource for seed priming strategies.

Vitamin B and its derivatives possess diverse physiological functions and are essential micronutrients for humans. Their variation in crops is important for the identification of genetic resources used to develop new varieties with enhanced vitamin B. In this research, remarkable variations were observed in kernels of 156 maize inbred lines, ranging from 107.61 to 2654.54 μg per 100 g for vitamin B1, 1.19–37.37 μg per 100 g for B2, 19.60–213.75 μg per 100 g for B3, 43.47–590.86 μg per 100 g for B5, and 138.59–1065.11 μg per 100 g for B6. Growing inbreeds in Hainan and Hebei provinces of China revealed environmental and genotype interactions among these vitamins and the correlations between them in maize grain. Several inbred lines were identified as good sources of vitamin B and promising germplasms for maize breeding, namely By855 and Si273 are overall rich in all the studied vitamins, and GY386B and CML118 are specially enriched with derivatives of vitamin B6. The present study can assist maize breeders with germplasm resources of vitamin B for biofortification to offer people nutritious foods.

Previously, the complexity of folate accumulation in the early stages of maize kernel development has been reported, but the mechanisms of folate accumulation are unclear. Two maize inbred lines, DAN3130 and JI63, with different patterns of folate accumulation and different total folate contents in mature kernels were used to investigate the transcriptional regulation of folate metabolism during late stages of kernel formation by comparative transcriptome analysis. The folate accumulation during DAP 24 to mature kernels could be controlled by circumjacent pathways of folate biosynthesis, such as pyruvate metabolism, glutamate metabolism, and serine/glycine metabolism. In addition, the folate variation between these two inbred lines was related to those genes among folate metabolism, such as genes in the pteridine branch, para-aminobenzoate branch, serine/tetrahydrofolate (THF)/5-methyltetrahydrofolate cycle, and the conversion of THF monoglutamate to THF polyglutamate. The findings provided insight into folate accumulation mechanisms during maize kernel formation to promote folate biofortification.

As essential B vitamin for humans, folates accumulation in edible parts of crops, such as maize kernels, is of great importance for human health. But its breeding is always limited by the prohibitive cost of folate profiling. The molecular breeding is a more executable and efficient way for folate fortification, but is limited by the molecular knowledge of folate regulation. Here we report the genetic mapping of folate quantitative trait loci (QTLs) using a segregated population crossed by two maize lines, one high in folate (GEMS31) and the other low in folate (DAN3130). Two folate QTLs on chromosome 5 were obtained by the combination of F₂ whole‐exome sequencing and F₃ kernel‐folate profiling. These two QTLs had been confirmed by bulk segregant analysis using F₆ pooled DNA and F₇ kernel‐folate profiling, and were overlapped with QTLs identified by another segregated population. These two QTLs contributed 41.6% of phenotypic variation of 5‐formyltetrahydrofolate, the most abundant storage form among folate derivatives in dry maize grains, in the GEMS31×DAN3130 population. Their fine mapping and functional analysis will reveal details of folate metabolism, and provide a basis for marker‐assisted breeding aimed at the enrichment of folates in maize kernels.

Summary Vitamin deficiencies are major forms of micronutrient deficiencies, and are associated with huge economic losses as well as severe physical and intellectual damages to humans. Much evidence has demonstrated that biofortification plays an important role in combating vitamin deficiencies due to its economical and effective delivery of nutrients to populations in need. Biofortification enables food plants to be enriched with vitamins through conventional breeding and/or biotechnology. Here, we focus on the progress in the manipulation of the vitamin metabolism, an essential part of biofortification, by the genetic modification or by the marker-assisted selection to understand mechanisms underlying metabolic improvement in food plants. We also propose to integrate new breeding technologies with metabolic pathway modification to facilitate biofortification in food plants and, thereby, to benefit human health.

Folate regulates DNA methylation to affect Arabidopsis flowering time.