ERA1 is essential for meristem growth in Arabidopsis thaliana.

Penconazole is one of the most widely used triazole fungicides worldwide, and its widespread distribution raises serious concerns about its toxic effects on non-target organisms. The potential toxic effects of penconazole on Artemia salina (brine shrimp) and Allium cepa (onion), which are commonly used as bioindicators, have not yet been determined. In our study, we determined that the LC50 values of penconazole for Artemia salina were 1.363, 0.637, and 0.424 µg/mL after 24, 48, and 72 h, respectively, while the EC50 value for Allium cepa root growth after 72 h was 2.96 µg/mL. Anti-mitotic results revealed that penconazole exhibited a mitotic index (MI) ranging from 11.46% to 22.32% at concentrations of EC50x2, EC50, and EC50/2 (µg/mL) compared to the negative control (44.29%). Exposure to penconazole caused dose-dependent morphological changes in Artemia nauplii and disrupted the cell cycle in Allium cepa root meristem cells. These findings indicate that exposure to penconazole poses potential risks not only to target organisms but also to other species in ecosystems. Our findings highlight the ecological risks of penconazole exposure and emphasize the need for caution in its use. Furthermore, more comprehensive studies are needed to elucidate its toxic mechanisms using various toxicity tests.

Isopentenyltransferase (IPT) is the rate-limiting enzyme in cytokinin biosynthesis and plays a critical role in plant acclimation to abiotic stress. To explore soybean IPT genes, we performed genome-wide identification, bioinformatics analysis, and molecular experimental validation to systematically characterize the features and functions of the soybean IPT (GmIPT) gene family. We identified 15 GmIPT genes in the soybean genome, which are unevenly distributed across 12 chromosomes; their evolutionary expansion is primarily driven by whole-genome duplication events. Phylogenetic analysis of soybean IPT proteins with those from Arabidopsis, rice and maize clustered them into four groups, exhibiting lineage-specific functional specialization. GmIPT genes exhibit significant variations in conserved motifs, gene structure, and cis-acting elements; their promoter regions are enriched in light-responsive, abiotic stress-responsive, and hormone-responsive elements, indicating their involvement in complex transcriptional regulatory networks. Tissue expression profiling revealed that GmIPT7 and GmIPT10 are highly expressed in various tissues, whereas GmIPT14 shows specific expression in flowers and the shoot apical meristem. Transcriptomic analysis and qRT-PCR validation demonstrated that GmIPT7, GmIPT10 and GmIPT15 respond differentially to drought, salt and low-temperature stress, with GmIPT15 exhibiting a transient upregulation at 3 h (p < 0.01) followed by a gradual decline to levels close to the pre-treatment control at 6-12 h under low-temperature stress. We further performed haplotype analysis of GmIPT15 and identified a putative elite haplotype (hap1) associated with cold tolerance based on low-temperature germination index assessment. This study provides useful insights for the future functional characterization of plant IPT genes and offers potential genetic resources and molecular markers that may support molecular-assisted breeding for soybean abiotic stress tolerance.

At the Tip: Novel Regulators of Shoot Apical Meristem Development in Canola.

Phosphorus (P) deficiency severely limits crop yield. Plastid glucose-6-phosphate dehydrogenase 3 (G6PD3) is extensively involved in plant adaptation to abiotic stresses. However, little is known regarding the G6PD3 roles in plant adaptation to low P environments. Among G6PD family gene mutants, g6pd3 seedlings have the shortest primary root length under low P stress. G6PD3 transcription was markedly induced by low P stress, especially in the meristematic and elongation zones of primary roots and lateral root primordia. G6PD3 mutation increased the lateral root number but decreased the primary root length and the root/shoot ratio compared with WT, G6PD3 overexpression lines, disturbing root system architecture (RSA) reshaping induced by low P conditions. g6pd3 plants also exhibited other low P-sensitive phenotypes, such as high hydrogen peroxide (H2O2) levels and NADP+/NADPH ratio, reduced biomass, and delayed seed germination. qRT-PCR results further showed that the transcriptions of P-starvation responsive (PSR) genes (PHR1, Pht1;4/PT2 and Pht1;1/PT1) were markedly down-regulated in g6pd3 roots. Meanwhile, G6PD3 mutation down-regulated the expressions of genes related to auxin (IAA) synthesis, polar transport and signaling pathway, but up-regulated the expressions of cytokinin (CTK) synthetic genes under low P stress. This ultimately resulted in low IAA levels and high CTK levels in g6pd3 roots. Exogenous application of reduced glutathione (GSH) effectively alleviated the inhibition of primary root growth in g6pd3 seedlings under low P stress. Taken together, G6PD3 mutation disturbes RSA reshaping through affecting plant hormone (IAA and CTK) signals and H2O2 homeostasis, ultimately increasing the sensitivity of Arabidopsis to low P environments.

D. spectabile is an orchid species endemic to Papua, which has the characteristic of sepals, petals, and a curly labellum, which is very attractive, so it needs to be preserved. Propagation of this plant with in vitro culture techniques promises plant propagation in large quantities and uniformly in a short time. In plants, the HOMEOBOX gene is recognized as a key regulator of gene transcription, playing a crucial role in plant organogenesis, particularly in the shoot apical meristem. This study aims to identify the optimal in vitro culture media for D. spectabile and to conduct molecular analysis of the HOMEOBOX gene. The methods used are: subculture, amplification, motif location analysis, physicochemical characterization, phylogenetic construction, and 2D protein sequence modeling. The results of the study showed that the subculture of D. spectabile on KC+IAA 20 µM media (20.67±1.76) significantly increased shoot growth. PCR with POH1 primer successfully amplified a 700 bp HOMEOBOX fragment containing 2 motifs: ELK, involved in protein-to-protein interactions, and Homeobox-KN, a transcriptional regulator. Phylogenetic analysis showed a close evolutionary relationship between D. spectabile and D. catenatum. Further studies are needed to obtain the complete sequence for functional validation in D. spectabile.

Genetic and molecular regulation of flowering time in Brassica napus L.

Comparative morphology of the labial gland in Formicidae.

The oxytocin receptor (OR) is a G-protein-coupled receptor recently identified in human spermatozoa, whose origin and role in sperm physiology remain unknown. In this study, using the pig as a model, we examine the presence of the OR in ejaculated spermatozoa through immunofluorescence and immunoblotting, and investigate the receptor's origin in the male gamete via immunohistochemistry in testicular and epididymal tissues. Additionally, we assess the involvement of the OR in in vitro capacitation and the acrosome reaction by utilizing physiological concentrations of agonists (oxytocin and carbetocin) and an antagonist (L-371,257). The results indicate that, in addition to the expected presence in ejaculated spermatozoa, the OR is expressed during spermatogenesis. Besides, this receptor is found in Leydig and Sertoli cells, as well as in the principal, basal, and apical cells of the epididymis. Furthermore, our data suggest that, during epididymal maturation, the OR could be incorporated in spermatozoa via extracellular vesicles within the apical blebs. The OR is involved in sperm capacitation, as the combination of the antagonist (L-371,257) and the agonist (carbetocin) increases intracellular calcium levels and membrane lipid disorders, which are known as capacitation markers. The presence of the OR in mammalian spermatozoa could originate from both spermatogenesis and epididymal maturation. Moreover, in the male gamete, this receptor regulates sperm capacitation by interacting with its ligand in the female reproductive tract.

Mechanical conditions preventing live cell extrusion during primary neurulation in amniotes.

The formation of boundaries separating developmental fields with distinct gene expression and cell fate trajectories is a universal feature of noncolonial multicellular organisms. Developmental boundaries arise reiteratively during ontogeny and are characterized by stiff, slowly dividing cells that demarcate adjacent and divergent morphogenetic domains; the genetic mechanisms of cell fate acquisition within these boundaries are incompletely understood. Grass leaves are initiated at a developmental boundary in the periphery of the shoot apical meristem, an organogenic pool of plant stem cells that generates all lateral organs in the plant shoot. During later primordial growth, maize leaves form a de novo developmental boundary that ultimately separates the distal, photosynthetic leaf blade from the proximal, clasping leaf sheath. Morphogenesis at this blade/sheath boundary in maize leaves generates an epidermal outgrowth called the ligule and two tissue-wedges forming the auricle, a hinge-like structure with major effects on leaf angle, light capture, and yield. Here, we use cell lineage mapping, morphometric measures of cell division and expansion, cell-specific multidimensional transcriptomic analyses, and topological landscape modeling to investigate the mechanisms of cell fate acquisition at the ligule/auricle morphogenetic boundary in the maize leaf. The data suggest a model where auricle initial cells are recruited from blade founder cells at this boundary, via repression of blade identity during early stages in auricle ontogeny. Thereafter, auricle primordial cells assume a developmental genetic trajectory that is distinct from the blade, sheath, and ligule, thereby acquiring a unique auricle cell fate in the maize leaf.

Ecotoxicological impact of removing pharmaceutical residues from aqueous solutions using recycled ultrafiltration membranes.

The FTSH4 protease is a major component of the Arabidopsis mitochondrial protein quality control system. It has both a proteolytic and a chaperone-like activity and forms complexes anchored in the inner mitochondrial membrane. Here, we show that FTSH4 assembles into two distinct forms: a dominant high-molecular-weight megacomplex with stomatin-like protein 1 (SLP1), and smaller SLP1-free assemblies. In the slp1-1 mutant, the FTSH4-SLP1 megacomplex is absent, while the abundance of SLP1-free FTSH4 assemblies is nearly doubled. Despite this, slp1-1 maintains wild-type levels of FTSH4 substrates, TIM17-2 and NAD9, indicating that the SLP1-free assemblies retain proteolytic activity. Furthermore, slp1-1 mitochondria accumulate fewer detergent-resistant HSP23.6 aggregates under elevated temperature than ftsh4-1 and even wild-type. Consequently, the mitochondrial unfolded protein response reported in ftsh4-1 is not induced in slp1-1. Although slp1-1 plants display morphological changes previously associated with ftsh4-1, such as shorter inflorescence stems due to premature arrest of the shoot apical meristem, these are less pronounced. Taken together, the increased abundance of SLP1-free FTSH4 assemblies is sufficient to support general mitochondrial proteostasis, providing effective protection against heat-induced aggregation of mitochondrial proteins. In contrast, the FTSH4-SLP1 megacomplex more effectively fulfils the meristem-specific functions of FTSH4.

Abstract Salicylic acid is a phenolic plant hormone widely studied for its role in enhancing tolerance to biotic and abiotic stresses, yet its concurrent cytological, antibacterial, and genetic impacts across different biological systems remain insufficiently characterized. In this study, we adopt a dual bioassay strategy (plant + bacteria) to provide an integrated assessment of salicylic acid’s bioactivity and potential toxicity, thereby linking its role in stress physiology to both plant cell division and bacterial growth inhibition within a single experimental framework. The study’s purpose is to evaluate the cytological, antibacterial, and genetic effects of salicylic acid on Staphylococcus epidermidis and Allium cepa root tip meristematic cells. By combining plant cytology with bacterial inhibition assays and molecular profiling (protein electrophoresis and IRAP markers) in the same study, we aim to connect visible cytological alterations with underlying genetic and proteomic variation, and to explore whether the doses that affect plant meristematic cells are also relevant for antibacterial activity. A. cepa root tip cells were treated with different concentrations of salicylic acid (1, 5, and 10 mM) to determine the mitotic index (MI), chromosomal aberrations, antibacterial activity, protein electrophoresis, and the inter-retrotransposon-amplified polymorphism (IRAP) markers. In A. cepa root tip cells, salicylic acid dramatically decreased MI; this decrease was more pronounced at higher doses and for longer exposure times. The highest percentage of chromosomal aberrations, 81.25% at 10 mM after 24 h, was seen in sticky chromosomes, lagging chromosomes, star anaphase, and bridges. According to antibacterial testing, salicylic acid inhibited S. epidermidis; the biggest inhibitory zone (2.367 cm) was produced at 2% concentration. Genetic fingerprinting with IRAP markers yielded 126 amplicons with 59.5% polymorphism, whereas protein analysis identified 20 peptide bands. By lowering the mitotic index and causing chromosomal aberrations in A. cepa root tip cells, salicylic acid has an impact on cell division. By using protein and IRAP marker analysis, it shows the considerable genetic diversity in onion root samples and exhibits antibacterial activity against S. epidermidis. Future studies should investigate the molecular mechanisms involved and assess the long-term effects of salicylic acid exposure to guide its use in stress management and sustainable crop production.

Plant bioactive compounds, particularly carotenoids, anthocyanins and flavonoids, plays a pivotal role in the pigmentation of plant tissues. In the current study, two distinct cambial meristematic cell (CMC) lines named REG-CMC-1 and REG-CMC-2 were derived from R. glutinosa roots through tissue culture, with significant differences in carotenoid content. REG-CMC-1 showed a significantly higher carotenoid content compared to REG-CMC-2 cell lines. A total of 1.78 mg/g DW (dry weight) of carotenoids were detected from REG-CMC-1 cells, compared to only 0.1 mg/g DW from REG-CMC-2 cells. Comprehensive transcriptomics and proteomics analysis were conducted further to investigate the difference in carotenoid content between two cell lines. Transcriptomics analysis of REG-CMC-1 and REG-CMC-2 cell lines identified 14,773 differentially expressed genes (DEGs) including genes encoding xanthoxin dehydrogenase, zeta-carotene desaturase, zeaxanthin epoxidase and 9-cis-epoxycarotenoid dioxygenase, which may be involved in carotenoid production. Significantly enriched genes were involved in secondary metabolite biosynthesis, plant hormone signaling and stress responses. Proteomics study identified 5,361 unique proteins, of which 1,710 were differentially expressed, with critical categories related to proteolysis, carbohydrate metabolism and phosphorylation highlighting various enzymes critical to carotenoid biosynthesis pathway, including lycopene beta-cyclase and phytoene desaturase. These findings indicate the presence of carotenoid biosynthesis-related components in R. glutinosa root cambial meristematic cells and suggest potential relevance for biotechnological studies of carotenoid production.

The medullosans are ancient spermatophytes (order Medullosales) with an unusual stem anatomy and have been studied extensively from the late Palaeozoic of North America and Europe. Among the extensive fossil material of Medullosa, a single apex has been discovered from the early Permian Chemnitz Fossil Forest. By setting it in an updated functional and developmental context, we aim to provide new knowledge and understanding on the evolution of the vascular development in ancient seed plants. We re-examine historical sections of a stem apex of Medullosa stellataCotta, 1832 emend.Luthardt et al., 2021 with state-of-the-art stereomicroscopic analysis techniques and digital drawings. The apex exhibits the following unusual combination of features in comparison to modern spermatophytes: (1) an uncommon type of shoot apical meristem with a zone of multiple cell initials only; (2) various coiled leaf primordia completely covering the apex; (3) a flat morphology of the apex indicating considerable primary stem thickening; (4) a primary vascular system of mainly tangentially and horizontally oriented vascular strands; (5) secondary tissues developing centripetally and centrifugally around the primary vascular tissues; and (6) numerous spherical mucilage cavities distributed throughout the sections. Medullosans exhibited a peculiar stem development not comparable to that of most extant seed plants. Only extant cycads show several specific functional analogies (e.g. a 'stem-girdling' vasculature) that might refer to arborescent growth by a pachycaulous stem. This configuration requires sophisticated hydraulic support at an early developmental stage, including vertical and horizontal transportation of water. Our study demonstrates that the stelar evolutionary path of the medullosans was complex and characterized by various adaptive modifications and transitional stages.

The shoot apical meristem (SAM) determines plant architecture, but the key components of its regulatory network remain elusive in rapeseed (Brassica napus L.). Here, we integrated transcriptomic profiling of 3 multilocular silique mutants (Bnaclv1, Bnaclv2, and Bnaclv3) across key SAM development stages (IM, stage6, and stage8) with large-scale CRISPR/Cas9 functional screening to identify regulators of SAM maintenance. Differential gene expression and GO enrichment highlighted genes significantly associated with meristem development processes. Weighted gene co-expression network analysis of stage-specific transcriptomes identified 42 candidate genes potentially related to SAM development. To enable systematic functional screening, we established a high-throughput multiplex CRISPR/Cas9 pipeline, simultaneously targeting 198 sites across 42 candidate genes through optimized sgRNA design and pooled transformation. We successfully obtained mutants for 25 genes with homozygous mutants for 9 genes. Phenotypic analysis demonstrated that mutants of BnaSCPL family genes (SCPL29, SCPL44, and SCPL45) exhibited a multi-stem phenotype and disrupted SAM organization. Mechanistic studies revealed that BnaSCPL mutations disrupt the canonical CLV3/WUS feedback loop, uncovering their roles in SAM homeostasis. Additionally, knockout of BnaLFY homologs caused permanent vegetative state and sterility, demonstrating their conserved role in floral meristem identity in Brassica napus. Collectively, our study not only elucidates the critical function of BnaSCPLs in SAM maintenance but also establishes a regulatory framework for understanding meristem phase transitions in B. napus, providing potential targets for crop architecture improvement.

In many plants, leaves are arranged around the stem in a pattern called Fibonacci spiral phyllotaxis. These patterns have been well studied in flowering plants and are thought to arise from a spacing mechanism based on the cell-to-cell transport of the plant hormone auxin. This causes new primordia to emerge as far as possible from previous ones in the available space on a multicellular meristem. However, it is not clear how a spacing mechanism can create spirals in plants with a unicellular meristem. Through time-lapse imaging, quantification, and computer modeling, we study the single tetrahedral apical stem cell of the moss Physcomitrium patens and the emergence of a spiral pattern of leaf-like structures. We find that the apical cell divides asymmetrically in a spiral pattern, giving rise to a leaf progenitor daughter cell and another apical cell; thus, phyllotaxis in P. patens is controlled by cell division orientation. Apical cell divisions are asymmetric both in fate and geometry, the latter being explained through displacement of the new wall from the centroid of the apical cell. Modeling shows that incorporation of displacement from the centroid with the default division plane selection by the minimal wall area ("shortest wall" rule) is sufficient to explain the spiraling division planes leading to phyllotaxis. Thus, the whole architecture of the shoot is defined by the orientation of cell division. Some cell types in flowering plants undergo a similar spiraling division plane pattern, suggesting that this may be a common mechanism across phyla.

Divergent routes to specialization: Guard cells, myrosin cells, and beyond.

Evolution and development: What makes a merry stem?