Ferulate 5-hydroxylase (F5H) is a cytochrome P450-dependent monooxygenase that plays a key role in the biosynthesis of syringyl (S) lignin. In this study, mining of flax (Linum usitatissimum) genomic data enabled the identification of nine LuF5H genes. Bioinformatics analysis revealed the physicochemical properties, gene structures, conserved motifs, phylogenetic evolutionary features and promoter cis-acting elements related to these genes and their encoded proteins. Based on the gene structural and phylogenetic features, the nine LuF5Hs were assigned to two subclasses. The expression levels of the nine LuF5Hs was analyzed by the RNA-seq technique, and the RNA-seq data were verified by qRT-PCR. The results of the RNA-seq analysis showed that LuF5H genes belonging to the same subclass exhibited similar expression patterns. Notably, the transcripts of the LuF5H3 and LuF5H7 subclass 1 genes accumulated at high levels in stem tissues, thus indicating that LuF5H3 and LuF5H7 are the main LuF5H genes involved in flax lignin biosynthesis. Furthermore, the expression levels of LuF5H1, LuF5H3, LuF5H4 and LuF5H7 were upregulated 1.2–1.9-fold under drought, NaCl stress and brassinosteroid treatment conditions. This first comprehensive study of the flax F5H gene family provides valuable data for use in gene function analysis toward improving flax fiber quality and reducing flax manufacturing costs and associated environmental pollution.

Hyperhydricity is a frequently occurring physiological disorder in plant tissue culture that impairs the regeneration and survival of vitrified plant materials, leading to significant losses and complicating research applications. Although numerous studies have focused on strategies to mitigate hyperhydricity, its molecular mechanisms remain poorly characterized. In this study, transcriptome sequencing and endogenous hormone content analysis were conducted on hyperhydric and normal callus of flax (Linum usitatissimum L.). Transcriptomic analysis revealed 2698 differentially expressed genes (DEGs) between these two tissue types. Pathway analysis through KEGG demonstrated that these DEGs predominantly linked to metabolic processes including phenylpropanoid formation, MAPK signaling cascades, and plant hormone signal transduction. Moreover, quantification of endogenous hormone levels indicated a significant reduction in all hormones except cytokinins (ZRs) in hyperhydric tissues. The observed disruption in endogenous hormone levels suggests its potential role in the development of plant vitrification. These findings provide valuable insights into the molecular processes underlying hyperhydricity, contributing to a more comprehensive understanding of this phenomenon.

Flax (Linum usitatissimum L.) seed is rich in α-linolenic acid, lignans, and fiber, which have potential health benefits. However, the potential toxicity of its cyanogenic glycosides limits its widespread use. The cytochrome P450 gene family is one of the largest gene families in plants and is involved in synthesizing phytohormones, secondary metabolites, and various defense compounds. Two P450 genes have been found to be important enzymes for the biosynthesis of cyanogenic glycosides in common sorghum (Sorghum bicolor (L.) Moench). However, the P450 gene family and its involvement in cyanogenic glycoside synthesis have been less studied in flax. In previous studies, we assembled a high-quality flax genome. In this study, a total of 412 P450 genes were identified in the flax genome, with molecular weights in the range of 7.42 kDa to 154.5 kDa and encoding amino acid lengths between 67 and 1378. These genes belonged to 48 families under eight clans and were distributed across 15 chromosomes. The number of introns varied from 0 to 14. Thirty-nine cis-acting elements were identified within 1500 bp upstream of the promoter, mainly related to the light response. There were 147 segmental duplications and 53 tandem duplication events among these P450 genes. Eleven genes potentially related to cyanogenic glycoside synthesis were identified by transcriptome analysis, and the RT-qPCR results verified the reliability of the transcriptome analysis. This study lays the foundation for the classification and functional study of the flax P450 gene family. The results will be useful for breeding new low-cyanogenic-glycoside flax varieties by genetic engineering.

WRKY transcription factors play key roles in plant immune responses, including resistance to fungal pathogens. In the present study, we identified a flax resistance-related gene Lus10021999, named LuWRKY39. Here, to identify the role of WRKY transcription factor in resistance of flax against Septoria linicola, we cloned and analyzed the gene LuWRKY39 via homologous cloning using bioinformatics methods and localized the encoded protein. Quantitative real-time PCR (qRT-PCR) was used to explore the response of this gene to S. linicola. The results showed that the gene that is 948 bp long exhibited the closest genetic relationship to WRKY in castor (Ricinus communis), as revealed by phylogenetic analysis, and the encoded protein was localized in the nucleus. The LuWRKY39 gene showed higher expression levels in resistant flax materials than in susceptible ones, and higher in roots and stems than in leaves. Furthermore, gene expression showed an upward trend following treatment with salicylic acid (SA) and methyl jasmonate (MeJA), indicating that LuWRKY39 is involved in the regulation of SA and JA signals. By silencing LuWRKY39 in flax using virus-induced gene silencing (VIGS), the processed plants were more sensitive to S. linicola than untreated plants. Gene expression analysis and disease index statistics confirmed that the silenced plants were more susceptible, highlighting the crucial role of LuWRKY39 in flax disease resistance. This study provides a foundation for functional investigations of WRKY genes in flax and the identification of disease resistance genes.

Flowering regulation in hemp is critical for determining fiber yield, seed production, and the accumulation of medicinal components. This paper, based on bibliometric analysis, highlights the current gap in basic research on cannabis floral organs. The latest advancements in flowering regulation are then systematically reviewed. The morphological and physiological foundations of flowering are examined, including the flowering phenotype, timing, and flower differentiation. Furthermore, the direct regulatory mechanisms of key environmental and cultivation factors—such as photoperiod (type, light quality, duration) and plant nutrition (fertilization, hormones)—on flowering are discussed. Potential pathways through which biotic and abiotic stresses indirectly affect flowering by disrupting metabolic processes are also explored. In addition, the genetic basis of flowering regulation, including key gene loci such as Autoflower1, Early1, and CsPRR37, as well as molecular networks like the FT-mediated photoperiod pathway and the miR156-SPL age pathway, is examined in detail. Finally, the industrial significance of flowering regulation is summarized, and future research directions are proposed to provide a theoretical foundation for the precise breeding and cultivation management of high-quality hemp varieties.

This study aims to elucidate the molecular mechanisms underlying cyanogenic glycoside accumulation in flax. As an important oil and fiber crop, the nutritional value of flax is compromised by the toxicity of cyanogenic glycoside. To clarify the key genetic regulators and temporal patterns of cyanogenic glycoside biosynthesis, transcriptomic sequencing was performed on seeds from high- and low-cyanogenic glycoside flax varieties (‘MONTANA16’ and ‘Xilibai’) at three developmental stages: bud stage, full flowering stage, and capsule-setting stage. A total of 127.25 Gb of high-quality data was obtained, with an alignment rate exceeding 87.80%. We identified 31,623 differentially expressed genes (DEGs), which exhibited distinct variety- and stage-specific expression patterns. Principal component analysis (PCA) and hierarchical clustering demonstrated strong reproducibility among biological replicates and revealed the seed pod formation stage as the period with the most significant varietal differences, suggesting it may represent a critical regulatory window for cyanogenic glycoside synthesis. GO and KEGG enrichment analyses indicated that DEGs were primarily involved in metabolic processes (including secondary metabolism and carbohydrate metabolism), oxidoreductase activity, and transmembrane transport functions. Of these, the cytochrome P450 pathway was most significantly enriched at the full bloom stage (H2 vs. L2). A total of 15 LuCYP450 and 13 LuUGT85 family genes were identified, and their expression patterns were closely associated with cyanogenic glycoside accumulation: In high-cyanogenic varieties, LuCYP450-8 was continuously upregulated, and LuUGT85-12 was significantly activated during later stages. Conversely, in low-cyanogenic varieties, high expression of LuCYP450-2/14 may inhibit synthesis. These findings systematically reveal the genetic basis and temporal dynamics of cyanogenic glycoside biosynthesis in flax and highlight the seed pod formation stage as a decisive regulatory window for cyanogenic glycoside synthesis. This study provides new insights into the coordinated regulation of cyanogenic pathways and establishes a molecular foundation for breeding flax varieties with low CNG content without compromising agronomic traits.