Search Results (47)

Ascorbic acid (ASC) is a furan-based lactone derived from 2-ketogluconic acid that functions as a major antioxidant and redox buffer in mature plant tissues, although its content is lower in meristematic cells. ASC is commonly considered a reactive oxygen species (ROS) scavenger; however, its role in the regulation of plant development remains unclear. Additionally, the chemical behavior of ascorbate warrants special attention during ASC supplementation in in vitro plant culture. In this study, I investigated in detail the behavior of ascorbate in plant tissue culture medium and its uptake by plants. As a secondary objective, the role of ascorbate in root growth regulation was evaluated. The effects of low ASC levels on root architecture and its interaction with auxin signaling were studied using the vtc1 and vtc2 mutants of Arabidopsis thaliana, as well as through external ascorbate supplementation. Several marker lines for auxin response/distribution were used, along with direct ascorbate measurement via HPLC. Reducing ascorbate content through mutations had no significant effect on root development or auxin signaling, whereas high-concentration ASC supplementation inhibited both auxin signaling and root development, as demonstrated using auxin response and transport markers. At the organ level, ASC supplementation significantly downregulated auxin response-mediated cell cycle activation during lateral root induction. Based on the data presented, exogenous ascorbate may regulate root development through its interaction with auxin signaling pathways. Full article

The application of non-thermal (cold) plasmas is considered an environmentally friendly method that could affect plant metabolism and cellular development or can be used for the commercial production of natural products that cannot be chemically synthesized. In the present study, the non-embryogenic callus of iris (Iris reichenbachii Heuff.) was treated with a Radio Frequency (RF) plasma needle device using He as a working gas. We investigated short-term (up to seven days) and long-term (up to one year) changes on morphological, physiological and biochemical levels. An increased production of O₂⁻ and H₂O₂ was observed in the callus tissue after plasma treatment. The enzymes SOD and CAT represented the frontline in the antioxidant defense against reactive oxygen species (ROS) produced during the first hour of treatment, while POX was the leading antioxidant enzyme seven days after plasma treatment. Significant long-term morphological changes were observed in the calli due to the increased mitotic activity of the plant cells. In addition, three flavonoids (naringenin, apigenin and acacetin) and two isoflavonoids (irisolidone and irilone) were detected only in the plasma-treated tissue even one year after plasma treatment. The present study emphasizes the application of the plasma technique to promote meristematic activity and stimulate the production of specialized metabolites in iris calli. Full article

The growth of young roots is crucial for the development and yield of rice. However, the molecular mechanisms underlying young rice root development remain unclear. Our research indicates that the rice B-type cytokinin response regulator factor ORR3 negatively regulates the development of young rice roots. ORR3 is highly expressed in the root meristematic zone of young rice roots. In transgenic lines overexpressing ORR3, the lengths of primary roots and adventitious roots, as well as the corresponding root meristematic zone lengths, are significantly reduced. This is due to a decrease in both the number and size of longitudinal cells in the root meristematic zone. On the one hand, ORR3 can inhibit root apical cell division and reduce the number of longitudinal cells in the root meristematic zone by affecting the auxin synthesis and transport pathways. On the other hand, ORR3 may directly activate the transcription of cell wall metabolism-related genes, thereby restricting the size of cells in the root meristematic zone. In summary, ORR3 negatively regulates rice young root growth by responding to cytokinin signals to influence auxin signal transduction and cell wall metabolism pathways, thereby negatively regulating the number and size of cells in the root meristematic zone. Full article

Haloxylon ammodendron plays a pivotal role in combating aeolian desertification and restoring degraded arid ecosystems. Strategic afforestation protocols for this xerophytic species offer dual benefits in ecological stabilization and socioeconomic development, particularly in ecotonal zones between desert and oasis ecosystems, as exemplified by the Jilantai Salt Lake region. This investigation employs allometric scaling analysis to elucidate biomass allocation strategies in H. ammodendron plantations under three distinct silvicultural approaches: soil moisture retention afforestation, water flushing afforestation, and mechanical hole afforestation. Key findings demonstrate that water flushing afforestation treatment induced significant biomass enhancement (total biomass: 1718.69 ± 214.28 g), with phylloclade (photosynthetic branch) and vegetative organ biomass increasing by 29.03% and 60.34%, respectively, compared to conventional methods. Conversely, soil moisture retention afforestation preferentially promoted lignification processes, maximizing biomass allocation to structural components (stems: 15.2% increase) and reproductive structures (inflorescences: 22.7% elevation). Standardized major axis regression revealed differential scaling exponents among organ pairs under varying treatments (stem-phylloclade: 1.798; inflorescence-phylloclade: 1.752; vegetative-reproductive: 1.672; p < 0.001), indicating treatment-specific allometric allocation patterns. Notably, soil moisture retention afforestation induced lateral crown expansion through enhanced meristematic activity in secondary branches (p < 0.01), contrasting with the apical dominance observed in water flushing afforestation and mechanical hole afforestation specimens. These morphological divergences suggest resource allocation trade-offs between vertical exploration and horizontal exploitation strategies. The differential growth trajectories were strongly correlated with edaphic moisture redistribution patterns (R² = 0.83, p < 0.001), as quantified using soil water potential measurements. This study provides mechanistic insights into phenotypic plasticity responses to silvicultural interventions. These findings advance our understanding of allometric growth regulation in a psammophyte and establish an empirical basis for optimizing desert afforestation strategies in arid transitional ecotones. Full article

The Allium test is a cytological method used to monitor the impact of heavy metals. It can be used to evaluate meristematic tissues and highlight abnormalities occurring during mitotic division, with the advantage of being both rapid and economical. Copper and lead are among the most widespread metals in everyday life, mainly due to the worldwide expansion of industrialization, and are present in soil, water, and air. Using Allium sativum as a bioindicator for this study, statistical analysis confirmed significant differences in genotoxicity between the two metals, reflected by the inhibition of mitotic activity (MI) or increased indices of cellular abnormalities (AI). Toxicity was dose- and time-dependent for both metals, with copper exhibiting greater genotoxic effects than lead. Copper caused a significant reduction in MI, even at relatively low concentrations, with the IC₅₀ observed at 0.50 mM after 72 h of exposure. In contrast, for lead, the IC₅₀ was recorded from 0.75 mM after 72 h exposure. The advantages of the Allium test were demonstrated by its simplicity and high sensitivity in detecting abnormalities. In our experiment, chromosome abnormalities such as chromosome bridges, as well as isolated, delayed, or sticky chromosomes, were observed. In addition, at a concentration of 0.25 mM for copper (72 h exposure) and 0.50 mM for lead (72 h exposure), cellular abnormalities, including giant cells and binucleated cells, were identified. Full article

The periderm plays a crucial role in trees, acting as a barrier protecting internal tissues against biotic and abiotic stresses, thus having an impact on tree physiology, ecology, and general performance. It consists of the meristematic phellogen, whose activity gives rise to suberized phellem (cork) cells outwardly and the parenchymatous phelloderm inwardly. Despite the periderm importance, intra-annual and seasonal changes in phellogen activity and phellem and phelloderm differentiation are poorly recognized. Therefore, we aimed to compare periderm development and functioning in successive years in horse chestnut, utilizing standard histological methods. We distinguished six stages of periderm development, including phellogen initiation and the differentiation of its derivatives. In the following years, the phellogen was active for a similar period, but produced fewer derivative cells. Importantly, some phellogen cells lost their meristematic characteristics before the end of the season and differentiated into phellem. To maintain periderm integrity, the remaining phelloderm cells underwent divisions, leading to phellogen re-initiation. Alternatively, when all periderm cells differentiated into the phellem, the new (subsidiary) phellogen originated from the underneath collenchyma. We postulate that phellogen re-initiation could be a mechanism ensuring the functional integrity of the periderm and discuss the role of phelloderm or collenchyma cells in this process. Full article

We aimed to synthesize silver nanoparticles (AgNPs) using Elettaria cardamomum (cardamom) extracts and assess the cytotoxicity and genotoxicity of the cardamom extract, cardamom–AgNPs, and the insecticide ATCBRA—commonly used for pest control—on the root system of Vicia faba (broad bean). The chemical composition of the aqueous cardamom extract was identified and quantified using GC-MS, revealing a variety of bioactive compounds also present in cardamom essential oil. These included α-terpinyl acetate (21.3–44.3%), 1,8-cineole (10.7–28.4%), and linalool (6.4–8.6%). The successful green synthesis of AgNPs was confirmed through various micro-spectroscopic techniques, including UV-Vis spectroscopy, transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). UV-Vis analysis showed a strong peak between 420 and 430 nm, indicating the presence of AgNPs. TEM imaging revealed that the synthesized cardamom–AgNPs were monodispersed, primarily spherical, and semi-uniform in shape, with minimal aggregation. EDS analysis further confirmed the composition of the nanoparticles, with cardamom–AgNPs comprising around 60.5% by weight. Cytotoxicity was evaluated by measuring the mitotic index (MI), and genotoxicity was assessed by observing chromosomal aberrations (CAs). The roots of Vicia faba were treated for 24 and 48 h with varying concentrations of ATCBRA pesticide (0.1%, 0.3%, 0.5%, and 0.7%), aqueous cardamom extract (3%, 4%, 5%, and 6%), and green-synthesized cardamom–AgNPs (12, 25, and 60 mg). The cytogenetic analysis of MI and CA in the meristematic root tips indicated an improvement in the evaluated parameters with the cardamom extract. However, a marked reduction in mitotic activity was observed with both ATCBRA and cardamom–AgNP treatments across both time points, highlighting potential cytotoxic and genotoxic effects. Full article

Chromosome numbers and morphology are important characteristics of a species and its evolution. Root tips are the most commonly used tissue as a source of actively dividing cells for chromosome visualization in plants. Previously, rapidly growing root tips were collected from germinating kernels or from seedlings growing in pots or fields. However, the use of adventitious roots (ARs) derived from aerial tissue as meristems for chromosome visualization has always been overlooked. Here, we successfully induced ARs in 12 materials that were investigated, with the exception of Sorghum nitidum. Using ARs meristem we obtained high-quality chromosome spreads for Morus alba, Broussonetia papyrifera, Lolium multiflorum, Sorghum sudanense, S. propinquum, S. bicolor × S. sudanense, Zea mays, Z. mexicana, Glycine max, Medicago sativa, and Brassica napus. The results reported here demonstrate that layering is an alternative and effective method for producing meristematic cells for high-quality chromosome preparation in plant species producing ARs. For species that produce ARs by layering, this protocol is particularly valuable for the development of cost-effective and high-throughput non-invasive cytogenetic studies. Full article

Boron (B) deficiency has been shown to inhibit root cell growth and division. However, the precise mechanism underlying B deficiency-mediated root tip growth inhibition remains unclear. In this study, we investigated the role of BnaA3.NIP5;1, a gene encoding a boric acid channel, in Brassica napus (B. napus). BnaA3.NIP5;1 is expressed in the lateral root cap and contributes to B acquisition in the root tip. Downregulation of BnaA3.NIP5;1 enhances B sensitivity in B. napus, resulting in reduced shoot biomass and impaired root tip development. Transcriptome analysis was conducted on root tips from wild-type B. napus (QY10) and BnaA3.NIP5;1 RNAi lines to assess the significance of B dynamics in meristematic cells during seedling growth. Differentially expressed genes (DEGs) were significantly enriched in plant circadian rhythm and nitrogen (N) metabolism pathways. Notably, the circadian-rhythm-related gene HY5 exhibited a similar B regulation pattern in Arabidopsis to that observed in B. napus. Furthermore, Arabidopsis mutants with disrupted circadian rhythm (hy5/cor27/toc1) displayed heightened sensitivity to low B compared to the wild type (Col-0). Consistent with expectations, B deficiency significantly disrupted N metabolism in B. napus roots, affecting nitrogen concentration, nitrate reductase enzyme activity, and glutamine synthesis. Interestingly, this disruption was exacerbated in BnaA3NIP5;1 RNAi lines. Overall, our findings highlight the critical role of B dynamics in root tip cells, impacting circadian rhythm and N metabolism, ultimately leading to retarded growth. This study provides novel insights into B regulation in root tip development and overall root growth in B. napus. Full article

Panax ginseng, a traditional Chinese medicine with a history spanning thousands of years, faces overexploitation and challenges related to extended growth periods. Tissue-cultured adventitious roots and stem cells are alternatives to wild and field-cultivated ginseng. In this study, we assessed the in vitro xanthine oxidase and α-glucosidase inhibitory activities of saponin extracts among cultured cambial meristematic cells (CMC), adventitious ginseng roots (AGR), and field-cultivated ginseng roots (CGR). The xanthine oxidase (XO) and α-glucosidase inhibitory activities were determined by uric acid estimation and the p-NPG method, respectively. Spectrophotometry and the Folin–Ciocalteu, aluminum nitrate, and Bradford methods were employed to ascertain the total saponins and phenolic, flavonoid, and protein contents. The calculated IC₅₀ values for total saponin extracts against XO and α-glucosidase were 0.665, 0.844, and >1.6 mg/mL and 0.332, 0.745, and 0.042 mg/mL for AGR, CMC, CGR, respectively. Comparing the total saponin, crude protein, and total phenolic contents revealed that AGR > CMC > CGR. To the best of our knowledge, this study presents the first report on the in vitro comparison of xanthine oxidase and α-glucosidase inhibitory activities among AGR, CMC, and CGR. The findings offer valuable insights into the development of hypoglycemic and antihyperuricemic medicinal, nutraceutical, and functional products utilizing AGR and CMC. Full article

Climate change-induced heat stress (HS) increasingly threatens potato (Solanum tuberosum L.) production by impacting tuberization and causing the premature sprouting of tubers grown during the hot season. However, the effects of post-harvest HS on tuber sprouting have yet to be explored. This study aims to investigate the effects of post-harvest HS on tuber sprouting and to explore the underlying transcriptomic changes in apical bud meristems. The results show that post-harvest HS facilitates potato tuber sprouting and negates apical dominance. A meticulous transcriptomic profiling of apical bud meristems unearthed a spectrum of differentially expressed genes (DEGs) activated in response to HS. During the heightened sprouting activity that occurred at 15–18 days of HS, the pathways associated with starch metabolism, photomorphogenesis, and circadian rhythm were predominantly suppressed, while those governing chromosome organization, steroid biosynthesis, and transcription factors were markedly enhanced. The critical DEGs encompassed the enzymes pivotal for starch metabolism, the genes central to gibberellin and brassinosteroid biosynthesis, and influential developmental transcription factors, such as SHORT VEGETATIVE PHASE, ASYMMETRIC LEAVES 1, SHOOT MERISTEMLESS, and MONOPTEROS. These findings suggest that HS orchestrates tuber sprouting through nuanced alterations in gene expression within the meristematic tissues, specifically influencing chromatin organization, hormonal biosynthesis pathways, and the transcription factors presiding over meristem fate determination. The present study provides novel insights into the intricate molecular mechanisms whereby post-harvest HS influences tuber sprouting. The findings have important implications for developing strategies to mitigate HS-induced tuber sprouting in the context of climate change. Full article

The Knotted1-like homeobox (KNOX) gene family plays a pivotal role in regulating meristem activity, organ differentiation, and cell meristematic identity. However, there has been a lack of large-scale, systematic, and comprehensive comparative analyses to explore their expression patterns and evolutionary mechanisms. In this study, a total of 1425 KNOX genes were identified across 118 plant species. The result showed that higher plants exhibited a significantly higher abundance of KNOX genes compared to lower plants. Phylogenetic analysis revealed that all KNOX genes can be divided into two classes (class I and II) and evolved independently after species differentiation. An analysis of gene duplication or loss showed that gene loss was more common than gene duplication in lower plants within the KNOX gene family. These findings suggest that gene loss in the KNOX gene family occurs after events such as whole-genome duplication (WGD) or whole-genome triplication (WGT). In addition, conserved motif analysis was also conducted to uncover the evolutionary trajectories of KNOX genes. We found that three motifs (M1, M2, and M4) were present in nearly all KNOX genes, while four novel motifs (M7–M10) were lost in lower plants but present in higher plants. Moreover, the loss of certain motifs in the KNOX genes was also observed in higher plants, indicating sequence divergence in KNOX genes throughout evolution. To understand the expression patterns of KNOX genes, a gene expression pattern analysis was performed in A. thaliana and O. sativa. The results showed that class I KNOX genes exhibit conserved high expression in stems, suggesting their potential similar biological roles across different plant species and the conservation of their functions during evolution. Additionally, we analyzed the KNOX genes in the Citrus genus and closely related species, and we found that the number of KNOX genes evolved at a slower rate in these species, indicating a relatively conservative nature. In conclusion, this study provides valuable resources for the investigation of KNOX gene family evolution and function in plants. Full article

Different components of the symbiotic interface play an important role in providing positional information during rhizobial infection and nodule development: successive changes in cell morphology correspond to subsequent changes in the molecular architecture of the apoplast and the associated surface structures. The localisation and distribution of pectins, xyloglucans, and cell wall proteins in symbiotic nodules of Pisum sativum and Medicago truncatula were studied using immunofluorescence and immunogold analysis in wild-type and ineffective mutant nodules. As a result, the ontogenetic changes in the symbiotic interface in the nodules of both species were described. Some differences in the patterns of distribution of cell wall polysaccharides and proteins between wild-type and mutant nodules can be explained by the activation of defence reaction or premature senescence in mutants. The absence of fucosylated xyloglucan in the cell walls in the P. sativum nodules, as well as its predominant accumulation in the cell walls of uninfected cells in the M. truncatula nodules, and the presence of the rhamnogalacturonan I (unbranched) backbone in meristematic cells in P. sativum can be attributed to the most striking species-specific features of the symbiotic interface. Full article

Soil salinity is a worldwide problem that adversely affects plant growth and development. Soil salinization in Xinjiang of China is very serious. Ping’ou hybrid hazelnut, as an important ecological and economic tree species, as well as a salt-tolerant plant, has been grown in Xinjiang for over 20 years. Understanding the salt-tolerance mechanism of Ping’ou hybrid hazelnut is of great significance for the breeding of salt-tolerant varieties and the rational utilization of salinized land. In this study, ‘Liaozhen 7’, a fine variety of Ping’ou hybrid hazelnut, was selected as test material, and seedlings were treated with 0 (control), 50, 100 and 200 mM NaCl. Subsequently, the pattern of NaCl-induced fluxes of Na⁺, K⁺ and H⁺ in the root meristematic zone and their response to ion transport inhibitors were studied using non-invasive micro-test technology (NMT). Different concentrations of NaCl stress significantly increased the Na⁺ concentration in roots, while K⁺ concentration decreased first and then increased with the increase of NaCl concentration. Meanwhile, NaCl stress induced a significant decline in K⁺/Na⁺ ratio. Control and 200 mM NaCl-induced Na⁺ and K⁺ fluxes in roots exhibited an outward efflux, whereas an inward flux was observed for H⁺. Under 200 mM NaCl stress, the average rates of net Na⁺ and K⁺ efflux, as well as H⁺ influx in roots were significantly increased, which were 11.6, 6.7 and 2.3 times higher than that of control, respectively. Furthermore, pharmacological experiments showed that 200 mM NaCl-induced Na⁺ efflux; H⁺ influx was significantly suppressed by amiloride, an inhibitor of plasma membrane (PM) Na⁺/H⁺ antiporter, and sodium vanadate, an inhibitor of PM H⁺-ATPase. Net Na⁺ efflux and H⁺ influx induced by NaCl decreased by 89.9% and 135.0%, respectively. The NaCl-induced Na⁺ efflux was mediated by a Na⁺/H⁺ antiporter using energy provided by PM H⁺-ATPase. The NaCl-induced K⁺ efflux was significantly restricted by tetraethylamine chloride, a K⁺ channel inhibitor, and promoted by sodium vanadate, which decreased by 111.2% and increased by 80.8%, respectively, indicating that K⁺ efflux was regulated by depolarization-activated outward-rectifying K⁺ channels and non-selective cation channels (NSCCs). In conclusion, NMT data revealed that NaCl stress up regulated the root Na⁺/H⁺ antiporter and H⁺ pump (an activity of PM Na⁺/H⁺ antiport system) of ‘Liaozhen 7’, which compelled the Na⁺/H⁺ exchange across the PM and restricted K⁺ loss via depolarization-activated K⁺ channels and NSCCs simultaneously, thereby maintaining the K⁺/Na⁺ homeostasis and higher salt tolerance. Full article

Plant architecture is a major motif of plant diversity, and shoot branching patterns primarily determine the aerial architecture of plants. In this study, we identified an inbred pepper line with fewer lateral branches, 20C1734, which was free of lateral branches at the middle and upper nodes of the main stem with smooth and flat leaf axils. Successive leaf axil sections confirmed that in normal pepper plants, for either node n, P_n (Primordium n) < 1 cm and P_n+1 < 1 cm were the critical periods between the identification of axillary meristems and the establishment of the region, whereas P_n+3 < 1 cm was fully developed and formed a completely new organ. In 20C1734, the normal axillary meristematic tissue region establishment and meristematic cell identity confirmation could not be performed on the axils without axillary buds. Comparative transcriptome analysis revealed that “auxin-activated signaling pathway”, “response to auxin”, “response to abscisic acid”, “auxin biosynthetic process”, and the biosynthesis of the terms/pathways, such as “secondary metabolites”, were differentially enriched in different types of leaf axils at critical periods of axillary meristem development. The accuracy of RNA-seq was verified using RT-PCR for some genes in the pathway. Several differentially expressed genes (DEGs) related to endogenous phytohormones were targeted, including several genes of the PINs family. The endogenous hormone assay showed extremely high levels of IAA and ABA in leaf axils without axillary buds. ABA content in particular was unusually high. At the same time, there is no regular change in IAA level in this type of leaf axils (normal leaf axils will be accompanied by AM formation and IAA content will be low). Based on this, we speculated that the contents of endogenous hormones IAA and ABA in 20C1734 plant increased sharply, which led to the abnormal expression of genes in related pathways, which affected the formation of Ams in leaf axils in the middle and late vegetative growth period, and finally, nodes without axillary buds and side branches appeared. Full article