Yan Zhao

Lamiaceae plants produce essential oils (EOs) with diverse chemical compositions and biological activities. This study investigated the volatile composition and multiple biological activities of EOs from 13 Lamiaceae species. EOs were obtained by hydrodistillation and characterized by gas chromatography–mass spectrometry (GC-MS), followed by hierarchical clustering and principal component analysis. Antioxidant, antibacterial, cytotoxic, and anti-inflammatory activities were evaluated using in vitro and murine models. GC-MS analysis revealed substantial interspecific variation in volatile composition, with Origanum vulgare characterized by carvacrol and limonene, Thymus spp. by thymol, Rosmarinus officinalis by eucalyptol and α-pinene, Mentha canadensis by L-menthol, and Perilla frutescens by perillaldehyde. Scutellaria baicalensis, Elsholtzia ciliata, Phlomis mongolica, and Schizonepeta tenuifolia showed distinctive profiles associated with limonene and isopulegone, nepetalactone, pulegone, and anethole and anisaldehyde, respectively. Multivariate analysis further separated the 13 oils into three chemotype groups: a carvacrol-rich Origanum group, a Scutellaria and Thymus group enriched in sesquiterpenes or thymol, and a group comprising the remaining six genera dominated by shared monoterpene hydrocarbons. Most EOs exhibited substantial 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, with Rosmarinus officinalis and Perilla frutescens showing the strongest activity, with IC₅₀ values of 2.14 and 2.08 μg/mL, respectively. Origanum vulgare, Thymus citriodorus, Thymus vulgaris, and Thymus mongolicus displayed strong antibacterial activity against five pathogens, with minimum inhibitory concentration (MIC) values ranging from 2 to 8 μg/mL. Cytotoxicity assays showed potent activity against HepG2 and LNCaP cells, with IC₅₀ values ranging from 0.31 to 0.95 μg/mL. Elsholtzia ciliata and Perilla frutescens exhibited particularly strong potency, with IC₅₀ values ranging from 0.31 to 0.40 μg/mL. In a murine skin inflammation model, selected EOs significantly reduced inflammation-related markers, including COX-2, TNF-α, NF-κB, IKK, Akt, and PKC. Correlation analysis identified significant associations of carvacrol, thymol, and β-linalool with antibacterial activity, whereas no significant associations were observed between individual major constituents and antioxidant or cytotoxic activity after false discovery rate (FDR) correction. Overall, the 13 Lamiaceae EOs displayed distinct chemical profiles and activity patterns, providing a basis for further investigation of their bioactive constituents and potential applications.

Auxin plays a positive role in plant responses to low-phosphorus stress. However, the molecular mechanisms underlying indole-3-acetic acid (IAA)-mediated responses to phosphorus deficiency in alfalfa remain poorly understood. Alfalfa (Medicago sativa L.) cultivar ‘Zhongmu No. 3’ was subjected to two treatments: normal phosphorus (NP, 1000 μM KH₂PO₄) and low phosphorus supplemented with 1 μM IAA (LP + IAA, 10 μM KH₂PO₄). Morphological traits, physiological parameters, transcriptomic profiles, and metabolite accumulation were analyzed at 48 h and 10 days following treatment. Compared with the NP group, plants in the LP + IAA group showed marked changes in growth-related traits. At 48 h, plant height increased by 34%, total root length was 1.24-fold that of the NP group, and lateral root number increased by 23.48%. After 10 days, root fresh weight increased by 28%, total root length was 1.25-fold that of the NP group, lateral root number increased by 36.58%, and root volume increased by 22.2%, whereas plant height, stem diameter, and shoot fresh weight remained comparable to those of the NP group. Root acid phosphatase activity was 114.8% higher than that of the NP group at 48 h. Transcriptome analysis identified 1274 and 2277 differentially expressed genes (DEGs) between the NP and LP + IAA groups at 48 h and 10 days, respectively. At 48 h, the up-regulated genes were amino phospholipid ATPase 9 and amino alcohol phosphotransferase 1, whereas phosphate transporter 1 and purple acid phosphatase 12 were up-regulated at 10 days. Metabolomic analysis identified 308 and 1296 differentially accumulated metabolites (DAMs) at 48 h and 10 days, respectively. Early responses were enriched in purine metabolism and involved (5′-phosphoribosyl)-5-formamido-4-imidazolecarboxamide (FAICAR), whereas prolonged treatment involved L-aspartic acid, adenine, and cAMP. Integrated analyses identified tryptophan metabolism, cysteine and methionine metabolism, glycerophospholipid metabolism, and plant hormone signal transduction as major regulatory pathways. CDP-choline accumulation and changes in lipid-remodeling genes further indicated enhanced membrane phospholipid remodeling. Overall, these results provide insight into the morphological, physiological, transcriptional, and metabolic responses of alfalfa to low phosphorus in the presence of exogenous IAA.

Hordeum brevisubulatum ‘Mengnong No. 2’ is a new forage variety developed using traditional group selection breeding techniques. It features notable advantages in plant height, tillering capacity, and overall biomass yield. However, key molecular breeding techniques such as molecular marker identification and genetic manipulation have yet to be established for this variety, limiting improvements in important traits. Consequently, we assessed the biomass of ‘Mengnong No. 2’ against ‘Mengnong No. 1’, the most widely cultivated variety in the central and western regions of Inner Mongolia, China. We report that fresh forage, dry forage, and seed yields of ‘Mengnong No. 2’ increased by 20.6%, 31.78%, and 34.35%, respectively, compared with the control variety, indicating broad prospects for its application and promotion. To enable rapid identification of ‘Mengnong No. 2’ during its promotion and to prevent production losses caused by variety admixture, we used three screened SSR primer pairs (GST25, GST37, GST127) to construct a DNA fingerprint for five H. brevisubulatum varieties, including ‘Mengnong No. 2’. With the percentage of polymorphic bands exceeding 95%, these profiles enabled precise identification of the ‘Mengnong No. 2’ variety. Furthermore, callus regeneration in H. brevisubulatum represents a bottleneck for directed molecular breeding techniques such as genetic transformation and gene editing. Accordingly, we selected the inflorescences of ‘Mengnong No. 2’ as explants and investigated the callus induction and regeneration capacity of inflorescences at different developmental stages. We found that explants at the spikelet primordia differentiation stage exhibited the highest callus induction and regeneration efficiencies, reaching 62.7% and 72.8%, respectively. The resulting embryogenic callus lines can serve as recipients for Agrobacterium-mediated transformation or gene gun bombardment, facilitating the development of subsequent high-efficiency genetic transformation and gene-editing systems. The SSR-based variety identification system and the highly efficient regeneration technology using inflorescence-derived callus established in this study lay a solid foundation for the development of a molecular breeding system for ‘Mengnong No. 2’.

RNA interference (RNAi) provides a sequence-specific strategy for pest management, but efficient and stable double-stranded RNA (dsRNA) delivery remains a key challenge. Here, we established a plant-probiotic-based gene silencing system using the endophytic fungus Fusarium commune G3-29 as a dsRNA delivery vector against western flower thrips (WFTs, Frankliniella occidentalis). Recombinant G3-29 strains expressing dsRNA targeting the essential WFT genes ACT and SNF were constructed and confirmed to colonize kidney bean leaves without pathogenicity. Bioassays showed that feeding on leaves colonized by dsRNA-expressing G3-29 significantly decreased survival and downregulated target gene expression in both WFT larvae and adults. Within 4 days, survival of both larvae and adults fell below 10%. In larvae, target gene expression decreased by 63% (ACT) and 33% (SNF), while in adults, reductions of 74% (ACT) and 65% (SNF) were observed. In contrast, in vitro-synthesized dsRNA failed to induce significant gene silencing or mortality in larvae, and its control efficacy against adults was also inferior to that of endophytic fungus-mediated dsRNA delivery. Our findings establish endophytic fungus F. commune G3-29 as an effective and sustainable dsRNA delivery vehicle for RNAi-based pest control, offering distinct advantages over existing strategies such as HIGS and SIGS. This approach provides a promising new direction for managing WFTs and other insect pests.

Accurate counting of spikes in crested wheatgrass, an important forage resource, is essential for breeding and yield evaluation. However, traditional manual counting is inefficient, and instance-level supervised methods face challenges such as high annotation costs and counting errors caused by overlapping targets in complex field scenes. To address these issues, this study proposes the Multi-Granularity Gating Image-Level Supervision Count Network (MGG-ISCNet), a lightweight image-level supervised counting network. The network integrates multi-granularity features adaptively and employs a lightweight regression head with two 1D convolution layers and global average pooling for efficient feature compression, greatly reducing parameter complexity. Requiring only image-level count labels without positional annotations, the proposed approach substantially lowers labeling costs. On a self-constructed crested wheatgrass dataset, the MGG-ISCNet achieved an MAE of 2.73, RMSE of 3.86, and R² of 0.81. Furthermore, transfer experiments on the wheat spike dataset GWHD2020 demonstrated strong generalization. The proposed method achieved the best accuracy among both instance-level and image-level supervised approaches, with MAE = 3.63, RMSE = 4.73, and R² = 0.95, while featuring significantly fewer parameters (61.08 M) compared to the existing image-level method. Overall, this work provides an efficient and lightweight solution for spike counting in crested wheatgrass and other cereal crops, offering valuable support for breeding and forage production.

Agropyron mongolicum is a xerophytic perennial grass with good palatability and nutritional value, predominantly distributed in sandy, arid regions and desert steppes of northwest China. However, its low biomass and limited seed yield pose significant challenges for large-scale cultivation and forage production. To date, there have been limited genomic or transcriptomic studies on A. mongolicum, particularly regarding the molecular genetic mechanisms underlying yield-related traits. In this study, we employed an integrated transcriptomic approach combining long-read sequencing (PacBio Iso-Seq) and short-read sequencing (Illumina RNA-seq) to generate a comprehensive full-length transcriptome from four tissues—leaves, stems, young spikes, and mature spikes. Transcriptomic comparisons between multi-spike and few-spike germplasms were performed to identify candidate genes involved in the regulation of spike number. A total of 762,116 full-length transcripts were generated, among which 214,500 were successfully annotated. We identified 185,424 unique genes, including 91,514 differentially expressed genes (DEGs). Functional enrichment analysis revealed 43 DEGs associated with the protein processing pathway in the endoplasmic reticulum. Notably, 8 DEGs were specifically expressed in young spikes and mature spikes of the contrasting spike-number germplasms, suggesting their potential role in spike number regulation. This study provides a high-quality transcriptomic resource and identifies candidate genes that may facilitate molecular breeding for enhanced seed yield in A. mongolicum.

Background: Most of the grasslands in China are experiencing varying degrees of degradation, desertification, and salinization (collectively referred to as the “three degradations”), posing a serious threat to the country’s ecological security. Agropyron desertorum, known for its wide distribution, strong adaptability, and resistance, is an excellent grass species for the ecological restoration of grasslands affected by the “three degradations”. This study focused on two currently popular varieties of A. desertorum, exploring their salt tolerance mechanisms and identifying candidate genes for salt and alkali tolerance. Methods: Transcriptome sequencing was performed on two varieties of A. desertorum during the seed germination and seedling stages under varying degrees of saline–alkali stress. At the seed stage, we measured the germination rate, relative germination rate, germination index, and salt injury rate under different NaCl concentrations. During the seedling stage, physiological indicators, including superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), proline (PRO), soluble protein (SP), and catalase (CAT), were analyzed after exposure to 30, 60, 120, and 180 mM NaCl for 12 days. Analysis of differentially expressed genes (DEGs) at 6 and 24 h post-treatment with 120 mM NaCl revealed significant differences in the salt stress responses between the two cultivars. Results: Our study indicates that during the seed stage, A. desertorum (Schult.) exhibits a higher relative germination potential, relative germination rate, and relative germination index, along with a lower relative salt injury rate compared to A. desertorum cv. Nordan. Compared with A. desertorum cv. Nordan, A. desertorum (Schult.) has higher salt tolerance, which is related to its stronger antioxidant activity and different antioxidant-related pathways. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to identify the key biological processes and pathways involved in salt tolerance, including plant hormone signal transduction, antioxidant defense, and cell membrane stability. Conclusions: A. desertorum (Schult.) exhibits stronger salt tolerance than A. desertorum cv. Nordan. Salt stress at a concentration of 30–60 mM promotes the germination of the seeds of both Agropyron cultivars. The two Agropyron plants mainly overcome the damage caused by salt stress through the AsA-GSH pathway. This study provides valuable insights into the molecular mechanisms of salt tolerance in Agropyron species and lays the groundwork for future breeding programs aimed at improving salt tolerance in desert grasses.

Agropyron michnoi is a perennial grass with rhizomes in the genus Agropyron. It has a strong tolerance to drought and low temperature, and it is an established species in sandy flat and hilly slope lands, which constitute sandy grassland. So, it is an important forage species in dry grassland and desert steppes. Rhizomes not only enable asexual reproducibility but also confer strong resilience to stresses in A. michnoi. However, during production and utilization, it has been found that there are significant differences in the development of rhizomes among individuals of A. michnoi, yet the regulatory mechanism remains unclear. Therefore, in this study, the A. michnoi ‘Baiyinxile’ was used as the material, and the anatomical structures of the rhizomes, roots, and stems were analyzed using the paraffin sectioning technique. The results showed that the anatomical structure composition of the cross-section of the rhizome was similar to that of the root, while the arrangement of the vascular bundles in the stele was different from that of the root but similar to that of the stem. Subsequently, the Agropyron michnoi plants were classified into two types: plants with rhizomes and plants without rhizomes. Root, stem, and rhizome samples were collected from each type, and RNA sequencing was conducted. De novo transcriptomic analysis was performed to identify the candidate genes involved in rhizome development. From the RNA sequencing, a total of 103.73 Gb clean bases were obtained, from which 215,282 unigenes with an average length of 905.67 bp were assembled. Among these unigenes, 161,175 (74.87%) were functionally annotated based on seven common public databases. From pairwise comparisons of differentially expressed genes between the five samples, 129 candidate genes that are potentially specifically expressed in rhizomes were selected. Pathway enrichment analysis revealed that the rhizome-expressed genes are highly enriched in pathways of phenylpropanoid biosynthesis and starch and sucrose metabolism. The rhizome-specific expression pattern of 10 of the 129 candidate genes was further validated using qRT-PCR. Through the analysis of metabolites, 11 metabolites closely related to rhizome development, such as choline and betaine, were successfully identified. CYP family genes were selected for functional verification, and phylogenetic analysis revealed that CYP86B1 was grouped with CYP 86B1 of species such as Triticum aestivum and Lolium rigidum and was named AmrCYP86B1. The cloning results showed that its size was 1599 bp, and its subcellular localization was in the endoplasmic reticulum. Through stable genetic transformation, the study found that AmrCYP86B1 can promote the development of plant roots and stems and increase the dry matter content of the roots. Hormone detection showed that overexpression of AmrCYP 86B1 decreased the content of ABA hormone and increased the content of GA3 hormone in the plants. Combined with previous studies, it was determined that AmrCYP 86B1 promoted rhizome elongation by regulating ABA and GA3 hormones. The selected candidate genes involved in rhizome development, along with the preliminary functional verification, provide a preliminary mechanistic interpretation of rhizome development. This will contribute to in-depth research on the molecular mechanism of rhizome development in A. Michnoi.

Background: Using genomic DNA from 79 F1 plants resulted from a crossing between parents with strong and weak grazing tolerance inMedicago falcataL., we generated anEcoRIrestriction site-associated DNA (RAD) sequencing library. After sequencing and assembly, a high-density genetic map with high-quality SNP markers was constructed, with a total length of 1312.238 cM and an average density of 0.844 SNP/cM.Methods: The phenotypic traits of 79 F1 families were observed and the QTLS of 6 traits were analyzed by interval mapping.Results: Sixty three QTLs were identified for seven traits with LOD values from 3 to 6 and the contribution rates from 15% to 30%. Among the 63 QTLs, 17 were for natural shoot height, 12 for rhizome Length, 10 for Shoot canopy diameter, 9 for Basal plant diameter, 6 for stem number, 5 for absolute shoot height, and 4 for rhizome width. These QTLs were concentrated on LG2, LG4, LG5, LG7, and LG8. LG6 had only 6 QTLs. According to the results of QTL mapping, comparison of reference genomes, and functional annotation, 10 candidate genes that may be related to grazing tolerance were screened. qRT-PCR analysis showed that two candidate genes (LOC11412291 and LOC11440209) may be the key genes related to grazing tolerance ofM. falcata.Conclusion: The identified trait-associated QTLs and candidate genes in this study will provide a solid foundation for future molecular breeding for enhanced grazing-tolerance inM. falcata.