A wide range of microorganisms found in the rhizhosphere are able to regulate plant growth and development, but little is known about the mechanism by which epiphytic microbes inhibit plant growth. Here, an epiphytic bacteria Stenotrophomonas maltophilia, named as LZMBW216, were isolated and identified from the potato (Solanum tuberosum L. cv. Da Xi Yang) leaf surface. They could decrease primary root elongation and lateral root numbers in Arabidopsis seedlings. The inhibitory effects of LZMBW216 on plant growth were not due to a reduced indole-3-acetic acid (IAA) content, as exogenously applied IAA did not recover the inhibition. Furthermore, LZMBW216 did not affect the expression of DR5::GUS and CycB1;1::GUS. However, we found that LZMBW216 exhibited little effect on the primary root elongation in the pin2 mutant and on the lateral root numbers in the aux1-7 mutant. Moreover, LZMBW216 decreased expressions of AUX1 and PIN2 proteins. Together, these results suggest that root system architecture alterations caused by LZMBW216 may involve polar auxin transport.

This study aimed to investigate seed germination, seedling growth, and antioxidative responses in two wheat cultivars, Ningchun and Xihan, exposed to different H₂O₂ concentrations. Ningchun exhibited higher germination rate but lower root and shoot growth than Xihan when exposed to H₂O₂ treatment. Assays using fluorescent dye H₂DCFDA and propidium iodide showed a significantly enhanced H₂O₂ content and a cell elongation inhibition in H₂O₂-treated roots. The malondialdehyde content was elevated with increasing exogenous H₂O₂ concentration. Moreover, treatments of seedlings with H₂O₂ scavenger, catalase (CAT), and antioxidant, butylated hydroxytoluene, partly abolished H₂O₂-induced negative effect on root growth. In both untreated and H₂O₂-treated leaves, SOD activity in Ningchun was higher than that in Xihan, but POD and APX activities in Ningchun were lower than those in Xihan, leading to elevated H₂O₂ level in Ningchun leaves but decreased H₂O₂ content in Xihan ones under H₂O₂ treatment.

Nitrogen is an essential nutrient for plants. Different nitrate (NO₃^-)/ammonium (NH₄⁺) ratios have different effects on plant growth. However, the underlying mechanism in Toona sinensis remains unclear. Thus, we determined the effects of five different NO₃^-/NH₄⁺ ratios (16/0, 12/4, 8/8, 4/12, and 0/16, denoted T1, T2, T3, T4, and T5, respectively) in nutrient media on T. sinensis seedling growth. When the nitrogen source was NH₄⁺ alone (T5) or NO₃^- alone (T1), the soluble protein content in the leaves was the lowest. Additionally, the activities of key nitrogen assimilation-related enzymes, such as nitrate reductase (NR), glutamate synthase (GOGAT), and glutamine synthetase (GS), were altered by the NO₃^-/NH₄⁺ ratio. Principal component analysis (PCA) revealed that the T2 treatment was optimal for T. sinensis seedling growth. The NO₃^-/NH₄⁺ ratio regulates nitrogen assimilation at the transcription level, as under high NO₃^- conditions, the expressions of NR, GS, and NADH-GOGAT were high, and nitrate transporter (NRT) family members NRT1, NRT1.1, and NRT1.7 played leading roles in nitrogen transport. However, under low NO₃^- conditions, the level of NRT2.7 increased to ensure nutrient absorption. Our results provide a theoretical basis for understanding how different NO₃^-/NH₄⁺ ratios affect T. sinensis growth.

By decreasing root 1-aminocyclopropane-1-carboxylate (ACC) content and plant ethylene production, the microbial enzyme ACC deaminase is a widespread beneficial trait of plant growth-promoting rhizobacteria (PGPR), ameliorating ethylene-mediated root growth inhibition. However, relatively little is known about whether bacterial ACC deaminase modulates root architecture and root hair traits. Thus the dwarf tomato (Solanum lycopersicum) cultivar Micro-Tom was inoculated in vitro with Pseudomonas brassicacearum Am3, its ACC deaminase deficient mutant T8-1, a known PGPR strain Variovorax paradoxus 5C-2 or chemically treated with agents that promoted or inhibited ethylene production or sensitivity (Ag⁺, Co²⁺, and ACC). ACC treatment reduced both root elongation and the number of lateral roots, while ethylene inhibitors (Ag⁺, Co²⁺) and V. paradoxus 5C-2 promoted primary root elongation, but differentially affected lateral root length and number. Ag⁺ stimulated lateral root development, while Co²⁺ and V. paradoxus 5C-2 did not. Inoculation with P. brassicacearum Am3 and T8-1 inhibited elongation of the primary and lateral roots at a high inoculum concentration (10⁶ cells cm³). All bacterial strains significantly increased the length and number of root hairs, with these effects more pronounced in P. brassicacearum Am3 than in the mutant T8-1. Treatment with Ag⁺ inhibited root hair formation and elongation, while Co²⁺ had the opposite effects. ACC treatment had no effect on root hair elongation but increased root hair density. While root growth inhibition caused by P. brassicacearum Am3 was independent of ACC deaminase, the promotion of root hair elongation and density by this strain was augmented by ACC deaminase activity. Thus ACC deaminase can modulate the morphological impacts of bacteria on root hair response by affecting plant ethylene content.

In natural environments, the growth and development of plants are frequently impeded by a variety of stresses. These can be categorized into biotic stresses, such as those caused by fungi and bacteria, and abiotic stresses, including factors like low temperature, drought, and salinity (Zhu, 2016). These stresses impact plant photosynthesis, osmotic adjustment, and nutrient uptake, thereby inhibiting plant growth and ultimately resulting in a reduced crop yield and quality. To adapt to the dynamic changes in the environment, plants have evolved a series of complex defense mechanisms that are precisely regulated at the molecular, cellular, biochemical, and physiological levels to respond to various stresses. Among them, transcription factors (TFs) are key regulators that control the majority of stress response genes and signal transduction pathways. They are activated by different pathways of signal transduction and can directly or indirectly combine with cis-acting elements to modulate the transcription efficiency of target genes, which play a crucial role in the regulation of plant response to biotic and abiotic stresses.

The role of auxins on root system architecture was studied by applying indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), and 1-naphthaleneacetic acid (NAA) to maize roots and analysing the main processes involved in root development: primary root (PR) elongation, lateral root (LR) formation, and LR root elongation. We found that these effects were not dependent only on concentration, but also on the type of auxin applied. We also studied temporal changes in auxin inhibition of PR elongation. These temporal changes were analysed calculating the elongation ratio between two consecutive one day periods after auxin application. It was observed that a reduction in root elongation was also dependent on the type of auxin applied and its concentration. The inhibitory effect of IBA and IAA decreased on the second day, and the ratio also increased with the concentration. In contrast, NAA increased root elongation inhibition with time. Indeed, the ratio decreased as the NAA concentration increased. Regarding LR formation, we observed that external auxin increased only LR formation in certain zones of the PR. Finally, comparison of inhibition elongation associated with auxin in the LR and PR clearly demonstrates that PR elongation was more sensitive to auxin than LR elongation.

Plant translation elongation factor 1 alpha (EF1A) is both a protein synthesis factor and an important component of plant signal transduction, immune responses, protein trafficking, and apoptosis. However, its role in plant growth and development remains unclear. Herein, a full-length EF1A gene was isolated from banana (Musa acuminata L.) fruit and termed MaEF1A. We found that MaEF1A shared a high sequence identify with respective genes in other plants and the deduced amino acid sequence contained conserved regions of GTP-EFTU, GTP-EFTU-02, and GTP-EFTU-03, as well as two tRNA binding domains and six GTP-binding sites which represent functional domains for protein biosynthesis. MaEF1A protein is mainly localized to the nucleus. MaEF1A was constitutively expressed in different banana organs including developing fruits, and the highest expression was detected in ovary 4 stage. Arabidopsis thaliana L. (ecotype Columbia) was transformed with MaEF1A and four transgenic lines were obtained. Three transgenic lines were selected for further phenotypic analyses. Our findings indicate that overexpressed MaEF1A could greatly enhance plant height, root length, and both rhachis and silique length by promoting cell expansion and elongation. These experiments suggest an important role for MaEF1A in plant growth and development.

The coastal areas of western Taiwan feature acidic and saline soils with low fertility. Sodium bicarbonate (NaHCO₃), produced readily by carbon capture and storage technologies, could be suitable for the neutralization of acidic soils, but its effects on plant growth and the ability of Bacillus subtilis var. natto to confer salinity tolerance remain unclear. In this study, we examined the potential of sodium bicarbonate and B. subtilis var. natto (NTU18) to improve the growth of tobacco (Nicotiana tabacum L.) under salt stress conditions. We found that salt stress was the main factor affecting tobacco growth, resulting in shorter roots and shoots, a reduced leaf area and leaf number, and clustered dark green leaves. The addition of sodium bicarbonate exacerbated the symptoms of salinity stress. Inoculating the soil with B. subtilis did not enhance salinity tolerance, but intriguingly it increased shoot and root growth under normal conditions and in the presence of sodium bicarbonate. The mechanism of growth promotion mediated by the bacteria is unknown and should be investigated in more detail.

During the entire period of internode growth of Merremia emarginata contents of gibberellic acid (GA₃), phenyl-acetic acid (PAA), indole-3-acetic acid (IAA, free and conjugated) and abscisic acid (ABA, free and conjugated) were estimated by ELISA using polyclonal antibodies raised against each hormones. At the time of internode elongation free auxin content was low and increased with the decrease in the rate of elongation. In contrast, conjugated IAA showed declining trend where free IAA content was remarkably high, suggesting thereby that conjugated IAA might have mobilized during the later phase of internode development. The endogenous GA₃ contents were high as compared to other hormones; however, no significant role of GA₃ was discernible in elongation growth. Conjugated ABA contents remained very low during the elongation growth and increased thereafter.

Background: Tomato plants exposed to salinity stress may experience dynamic changes in root growth and cell wall (CW) composition and structure. Aims: Here, we determined the CW composition and cation-exchange capacity (CEC) of two tomato cultivars (Daniela, salt-tolerant and Naomi, salt-sensitive) as well as their growth and root characteristics. Methods: Seedlings of the tomato cultivars were exposed to six NaCl plus CaCl₂ concentrations hydroponically, root growth and CW chemical composition were measured. Results: The root growth of Naomi was adversely (P ≤ 0.05) reduced at the elongation zone, but there was little change in the chemical composition of the CW under salinity. A marked reduction occurred in the CW-constituting polysaccharides of Naomi relative to Daniela, whether at the 8.00 dS m^-1 NaCl treatment or its combination with CaCl₂. For both root zones, CW viscosity was better enhanced under NaCl and CaCl₂ combinations, but the contents of uronic acid across the CW constituents increased under sole treatment with CaCl₂ at the mature root zone of Naomi. The root CW CEC increased (P ≤ 0.05) with increases in the ionic concentration of the external solution. Salt concentrations at 8.0 dS m^-1 NaCl or 8.0 dS m^-1 NaCl + CaCl₂ increased (P ≤ 0.05) the CEC of the CW, especially for Daniela. Conclusions: The overall results showed that CaCl₂ could enhance some tolerance in CW polysaccharides of tomato under salinity stress. The salt-tolerant Daniela with higher CW and ionic contents had superior stability in cell structure under salt stress.

Seed germination and following seedling growth are largely affected by environmental conditions. However, the genes involved in adaptations to these conditions are largely unknown. In this study, we cloned and characterized an Arabidopsis uridine diphosphate glycosyltransferase gene UGT76E12 and investigated its function in seed germination and plant growth under adverse environments. We found that UGT76E12 gene expression was induced by NaCl, mannitol, and abscisic acid (ABA) treatments. Under these treatments, the UGT76E12 overexpression lines exhibited a delayed seed germination and cotyledon growth compared with a wild type, and this delayed growth could be restored by treatment with sodium tungstate, an ABA synthesis inhibitor. Further, real-time quantitative PCR analysis reveals that the stress-induced expressions of genes involved in ABA biosynthesis were greatly enhanced in the UGT76E12 overexpression lines. Therefore, our data suggest that the UGT76E12 gene plays an important role in regulation of seed germination and growth under adverse environmental conditions by affecting ABA biosynthesis.

Preventing extinction is one of the greatest challenges facing the global community. Nursery stock breeding is an effective means to restore endangered species, such as Horsfieldia hainanensis Merr., with difficulty in natural regeneration period. In this study, we investigated the optimum combination of irradiance and nitrogen for the cultivation of H. hainanensis seedlings by comparing twenty treatments with different combinations of irradiances (100, 67.5, 45.7, 15.6 % of full natural irradiance) and five levels of N supply (0, 1.8, 3.6, 5.4, 7.2 g plant^-1). We found that the growth and photosynthetic efficiency of seedlings under full irradiance were significantly inhibited compared with shaded seedlings. Under full irradiance, a lack of N resulted in reduced chlorophyll (Chl) synthesis, causing lower photosynthetic efficiency and an imbalance in metabolism. Proper shading (67.5 and 45.7 % of natural irradiance) and N addition (1.8 - 5.4 g plant^-1) promoted root development, increase Chl content and photosynthesis, and ultimately the accumulation of larger amount of biomass. The biomass of the shaded seedlings was mainly distributed to aboveground tissues, while seedlings exposed to stronger radiation accumulated greater root biomass. Therefore, the best seedling management for this species is a combination of 67.5 % of natural irradiance and moderate N supply (4.6 g plant^-1).

Ultraviolet-B (UV-B) radiation inhibits root system growth, however, the influence of UV-B radiation on the regulation of root development remains unclear. Here, we investigated the effects of UV-B radiation on root growth and metabolism in Arabidopsis using physiological, pharmacological, and transcriptome approaches. Our previous study has demonstrated that UV-B radiation depresses auxin accumulation in roots by reducing auxin biosynthesis, transport, and response. In this study, we found that UV-B radiation inhibited primary root (PR) growth by inducing root tip cell death and thereby disrupting cell division and elongation in root tips. The destructed root structure and distorted auxin flow caused by UV-B-induced root tip cell death also led to a reduced auxin accumulation in roots. Supplementation with an auxin α-naphthylacetic acid alleviated UV-B-repressed PR growth and further supported a notion that auxin is involved in UV‑B-repressed PR growth. The UV-B radiation downregulated the expression of genes encoding the enzymes or regulators of the biosyntheses and degradations of the structural constituents of cell wall and genes involved in wax, cutin, and suberin biosyntheses, thereby repressing root system growth and development. The UV-B radiation also markedly repressed photosynthesis-related gene expression in roots, a non-photosynthetic organ. Taken together, this study suggests that UV-B radiation affects root growth by inducing cell death in root tips and reprogramming metabolism in roots.

The capacity of extracellular self-DNA (esDNA) to inhibit growth is getting more research attention as this could be explored for several purposes, including the development of specific bioherbicides. While the inhibitory effect has been studied in several dicotyledon species, little is known about the effects and subsequent signaling processes in monocots. Here, we measured the growth, counted the number of lateral and crown roots, determined greenness index, quantified the production of O₂^.- and H₂O₂, and determined the expressions of genes encoding antioxidant enzymes (SODs and CATs) in rice (Oryza sativa L.), a model plant of monocots. After 7 d of germination, rice roots were exposed to 0, 75, and 150 µg cm^-3 of esDNA. Inhibitory effect was found to be negatively correlated to esDNA concentration, as indicated by the length of primary roots. Interestingly, this negative effect was only observed in the directly exposed organ (root) but not in the length of shoot or fresh mass of the whole seedling. The percentage of greenness index of leaves and number of crown and lateral roots were also similar across treatments. However, esDNA exposure to root increased production of O₂^.- and H₂O₂ in the root. At the molecular level, the response was characterized by the decreased expression of the antioxidant genes SOD3, CATB, and CATC. These findings suggest that esDNA inhibits rice growth locally in, e.g. in treated roots, and the responses involve increased production of ROS and suppression of antioxidants. This study could be the basis for determining the combination of concentration and period of exposure that might significantly inhibit total growth of monocot weeds with a minimum effect on the crop.

Auxin signal transduction in plants depends on regulation by short-lived nuclear plant proteins called auxin/indole-3-acetic acid (Aux/IAA) proteins. The OsIAA9, which is highly and rapidly induced by auxin, encodes the entire Aux/IAA domain characteristic of the Aux/IAA family in rice. The promoter region of OsIAA9 contains several cis-elements. Analysis of P_OsIAA9:GUS transgenic plants indicates a specific expression of OsIAA9 in roots and seedling shoots, especially lateral roots and root tips. Based on real-time PCR, the expression of OsIAA9 was induced by multiple hormones and abiotic stresses. Furthermore, ectopic overexpression of OsIAA9 in rice led to fewer crown and lateral roots and reduced the inhibition of root elongation by auxin. These observations indicate that OsIAA9 was a negative regulator of auxin-regulated root growth.

Root hairs play important roles in plant nutrient and water acquisition. To better understand the genetic mechanism controlling root hair development in rice (Oryza sativa L.), a rice mutant with root hair defects was isolated and characterized. Cryo-scanning electron microscope (SEM) showed that the density and length of root hairs in the mutant were significantly reduced compared to wild type (WT). Map-based cloning and complementation test revealed that the mutation occurred in a NADPH oxidase gene OsNOX3 (LOC_Os01g61880). The OsNOX3 displays high sequence similarity with the previously characterized NOX genes RTH5 in maize and RHD2 in Arabidopsis, which play critical roles in root hair development. Expression pattern analysis indicated that OsNOX3 is expressed in various tissues throughout the plant with high expression in roots and root hairs. Subcellular localization analysis confirmed that OsNOX3 is located on the plasma membrane. Staining assays showed that the content of superoxide and hydrogen peroxide are significantly reduced in root hair tips of Osnox3 when compared to WT. Our results showed critical roles of OsNOX3 in regulating both root hair initiation and elongation in rice, which is similar to RTH5 but different from RHD2, confirming the difference of genetic mechanisms regulating root hair morphogenesis in monocot and dicot plants.

Excess radiation is one of frequent natural environmental stresses that plants have to cope with on a daily basis. Therefore, plants have evolved many short- and long-term mechanisms to acclimate to high irradiance and tolerate it. Ureides, generated from purine degradation, have been proposed as compounds involved in environmental stress responses, including altered irradiance. In the present study, high irradiance was used to investigate ureide content and gene expression in Arabidopsis thaliana. Arabidopsis plants shifted to high irradiance showed high content of a specific ureide compound, allantoin. The accumulation of allantoin was associated with increased expression of uricase, an enzyme involved in its production. When an Arabidopsis mutant (aln-3), which constitutively accumulates elevated amounts of allantoin, was exposed to high irradiance, mutant plants demonstrated enhanced tolerance to the stress conditions compared to the wild-type plants. Our results provide evidence that accumulation of the allantoin might contribute in plants response to increased growth irradiance.

Salt stress is one of the most critical environmental factors limiting plant growth, and hydrogen sulfide (H2S) can play a role in plant responses to this stress. To investigate the effects of H2S on mitochondrial functions under salt stress, we treated Malus hupehensis Rehd. var. pingyiensis germinating seeds with an 85 mM NaCl solution with or without an H2S donor sodium hydrosulfide (NaHS) and H2S scavenger hypotaurine (HT). Then, hydrogen peroxide (H2O2) content and antioxidant enzyme activities were measured in mitochondria of seedling roots. Our results show that the application of 0.05 mM NaHS rescued an NaCl-induced inhibition of root elongation, decreased H2O2 content, and enhanced superoxide dismutase (SOD), guaiacol peroxidase (POD), and catalase (CAT) activities in the mitochondria compared to NaCl treatment alone. It was also found that 0.05 mM NaHS significantly decreased the mitochondrial permeability transition pore and increased mitochondrial membrane fluidity, mitochondrial membrane potential, and cytochrome c/a ratio under NaCl stress. However, 0.02 mM NaHS did not affect root growth, antioxidant enzyme activities, and mitochondrial function under NaCl stress, whereas high concentrations of NaHS (more than 0.2 mM) had a weaker or negative effects. Moreover, 15 µM HT eliminated the beneficial effects of NaHS under NaCl stress. Our results suggest that H2S protected plants against salt stress by decreasing H2O2 accumulation and by regulating membrane stability and antioxidant system in mitochondria.

Cadmium (Cd) is a major abiotic stressor that affects plant growth and reduces the productivity of field crops. Here, we examined the ultrastructural, physiological, and molecular changes in three wheat cultivars [Sumai 3, Jingdong 8 (JD 8), and Nannong 9918 (9918)] in response to different concentrations of Cd (0, 10, 50, and 100 μM) in 1/4 Hoagland nutrient solution. The results showed that JD 8 contained the lowest shoot Cd content and the highest root Cd content among the three cultivars at higher Cd concentrations and so JD 8 was proposed to be a relatively Cd-tolerant cultivar. Next, the stress responses of JD 8 and 9918 were compared. Cadmium reduced root growth and size and number of the leaves, inhibited root hair development, and promoted leaf cell death. The result of trypan blue staining showed that the dead leaf cells induced by Cd stress gradually emerged in the xylem, supporting the hypothesis that cell death could restrict Cd transport. The Cd-induced deterioration of the leaf ultrastructure led to the complete disorganization of the chloroplasts, which had lower amounts of transitory starch and an increased number of osmiophilic granules compared to those in the untreated controls. Autophagy-related genes and autophagy in the leaves were induced by Cd stress. At the same concentration and Cd treatment time, the Cd-tolerant genotype JD 8 exhibited less toxic symptoms compared to the Cd-sensitive genotype 9918. The results of this study provide insights into the ultrastructural and physiological damages induced by Cd stress, which may help in selecting Cd-tolerant wheat cultivars.

The current work compared the physiological characteristics of plantain (Musa AAB) plantlets micropropagated in temporary immersion bioreactors (TIB) and on a gelled medium (GM). The plantlets were evaluated during in vitro growth (in the shoot elongation phase) and at the end of ex vitro acclimatization. TIB improved rooting and gave rise to longer shoots and higher dry mass. Respiration rate was the highest at the beginning of shoot elongation in both the TIB and GM plantlets. Photosynthetic rate in TIB was significantly higher than in GM from the midpoint of acclimatization, whereas a pyruvate kinase (PK) activity was lower. Starch accumulation was ca. two fold higher in corms than in leaves and always higher in the TIB than GM plantlets. The higher expression of genes coding for carbon metabolism enzymes PK and phosphoenolpyruvate carboxylase (PEPC) in TIB than in PM indicates a more important role of an autotrophic metabolism in the TIB plantlets when compared to the GM ones. The accumulated reserves were used during the first days of acclimatization leading to the higher survival rates and to the better plant quality of the TIB plantlets.

High temperatures have become a major threat that seriously affects crop growth and yield. The present work aimed to investigate the acclimation process in adjusting plant responses to high root temperatures. Tomato (Solanum lycopersicum L., cv. Micro-Tom) during the flowering time was subjected to heat treatments (day/night temperatures at the root level of 40 or 45 °C for 4 d) while control plants were maintained at 25 °C, and the heat-stress treatment effects were analysed in the tomato leaves. The results showed a reduction in the content of chlorophylls a and b as well as chlorophyll a/b ratio at both high temperatures. Further, the increase in the amount of malondialdehyde as an indicator of lipid peroxidation was greater at 45 °C. The leaf content of hydrogen peroxide was induced in tomato plants subjected to 45 °C whereas it was markedly decreased in plants maintained at 40 °C as compared to control plants. Antioxidant enzymes showed higher activity in tomatoes treated at 45 °C compared to those treated at 40 °C. Moreover, the highest amount of antioxidants such as carotenoids and ascorbate in tomato plants were found at a temperature of 45 °C. Collectively, we provide evidence that physiological and biochemical components can be altered depending on the heat level, exposure time, and developmental stage. The interaction of root and shoot under high temperatures must be further characterized in terms of understanding the challenging climate changes.

In a previous study, we have identified and characterized gene from wheat (Triticum aestivum L.) encoding F-box protein and named it TaFBA. In this paper, transgenic tobacco (Nicotiana tabacum L.) plants overexpressing TaFBA1 displayed accelerated growth early, but the rate slowed gradually at later stages of growth, and the mature transgenic plants were even shorter in stature and flowered later than did the wild type (WT). Treatment with gibberellin (GA) conferred an accelerated growth rate to the transgenic tobacco plants at later stages, similar to that of WT, whereas growth was inhibited more seriously in WT than in transgenic tobacco when plants were treated with a GA biosynthesis inhibitor. The content of GA in transgenic tobacco plants was higher at early developmental stages, but it was lower at later growth stages than in WT. Some GA biosynthesis genes were down regulated, which was accompanied with elevated expression of a GA catabolism gene. Thus, our results suggest that TaFBA1 is possibly involved in the regulation of plant growth and development, and that it may be related to the production, metabolism, and proper function of GA.

Uridine diphosphate glucose dehydrogenase (UGDH) plays an important role in biosynthesis of hemicellulose by catalyzing oxidation of UDP-glucose (UDP-Glc) to UDP-glucuronate (UDP-GlcA), a key sugar nucleotide involved in biosynthesis of the plant cell wall. In this study, a UGDH ortholog referred to as LgUGDH was isolated from Larix gmelinii using PCR and rapid amplification of cDNA ends techniques. Real-time PCR shows that the LgUGDH gene was expressed primarily in larch stems in addition to its roots and leaves, and Southern blot analysis indicates that UGDH is encoded by two paralogous genes in L. gmelinii. Overexpression of LgUGDH increased the content of soluble sugars and hemicelluloses and enhanced vegetative growth and cold tolerance in transgenic Arabidopsis thaliana. These results reveal that L. gmelinii UGDH participates in sucrose/polysaccharide metabolism and cell wall biosynthesis and may be a good candidate gene for enhancing plant growth, cold tolerance, and hemicellulose content.

The aim of this study was to identify single nucleotide polymorphism (SNP) markers genetically linked to root elongation rate (RER) in sugar beet (Beta vulgaris L.). A population of 244 F₃ individuals, obtained from the cross between lines L01 (a low RER) and L18 (a high RER), was phenotyped by measuring RER of 11-d-old seedlings grown in a hydroponic culture. Two DNA bulks of 50 F₃ individuals with extreme phenotypes were used for bulk segregant analysis by restriction-associated DNA sequencing. A total of 20 376 SNPs were identified. Single nucleotide polymorphisms were filtered to reduce the number of the false positive and mapped on candidate chromosomal regions of the B. vulgaris reference genome. One of the total of SNPs selected, SNP10139, was strongly linked to RER (P < 0.01). The pattern of association between the SNP10139 genotype and RER was also evaluated on a breeding line panel comprising 40 low and 40 high RER individuals with different allele frequencies between groups (P < 0.01). The SNP10139 sequence was mapped on the B. vulgaris peptide transporter (PTR) gene, a carrier that influences root elongation in Arabidopsis thaliana. Our results suggest that SNP10139 influence RER in sugar beet, and sequence information can be used in marker-assisted selection programs.

The interaction between phosphorus (P) and other media components alters root development and masks the plant response and thus limits the ability to correctly identify P-deficiency response (pdr) mutants. This study aims to assess changes in root development caused by different composition of growth media normally used in Arabidopsis research and to study their effects on pdr-mutant screening. Primary root growth of four genotypes was analyzed in media differing in P concentrations: half-strength Murashige and Skoog (1/2 MS) and Somerville and Ogren (SO). The effects of nitrogen source and Fe on root growth were investigated in each medium separately and in a mixture. We found that the primary root length of all genotypes grown on 1/2 MS was reduced in comparison with plants grown on SO medium. The mutant pdr9 was the most sensitive in 1/2 MS, This mutant was also hypersensitive to Fe that intensified its sensitivity to ammonium. Ammonium increased the root inhibition caused by Fe also in wild-type plants. In conclusion, on the basis of our study we recommend to use SO medium, which ensures an efficient selection to screen for pdr mutants through root growth. Moreover, nitrogen sources in the media other than nitrate should be taken carefully.

With the extensive utilization of graphene nanomaterials, they inevitably enter our environment. The potential phytotoxicity and environmental impact of graphene oxide (GO) have recently attracted much attention. We designed the experiment based on seed germination, seedling morphology, physio-biochemical properties, and antioxidant enzyme activities of five rice genotypes (9311, MH63, R527, K866, and Nipponbare) under six concentrations of GO (0, 5, 10, 50, 100, and 150 mg dm^-3). We studied the effects of different concentrations of GO on germination index (GI), shoot length (SL) and root length (RL), adventitious root number, shoot and root fresh masses, root/shoot ratio, chlorophyll (Chl) content, malondialdehyde content, and activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Graphene oxide treatments significantly enhanced seed germination and root growth and inhibited shoot growth of all genotypes. Furthermore, we found a significant genotype-dependent response to GO treatments. According to the relative increment trend of GI, SL, and RL, root/shoot ratio, antioxidant enzyme activities (CAT, POD, and SOD), and Chl content, 'R527' showed more tolerance to GO treatments than the other four genotypes. The 'MH63' and 'K866' were more sensitive than 'Nipponbare' and '9311'. It indicates that the GO-tolerant genotype might avoid free radicals damage from GO by increased antioxidant enzyme activities. Moreover, we should consider the genotype differences when evaluating the potential phytotoxicity of GO and environmental risk to ecosystems.

Background: Idesia polycarpa var. vestita Diels is an oil-bearing woody plant of significant economic value. Aims: To accelerate the propagation of its elite germplasm, this study aimed to establish an efficient and stable in vitro rapid propagation system using one-year-old stem segments from elite plants. Methods: Young stem explants were disinfected with 75% ethanol for 40 s, followed by 0.1% HgCl₂ for 6 min. MS or 1/2 MS served as basal media, and various combinations of plant growth regulators were tested for axillary bud induction, proliferation, and rooting. Results: The optimal disinfection protocol yielded a 38.10% survival rate. The best axillary bud induction medium was MS + 1.5 mg/L 6-BA + 0.05 mg/L NAA + 0.08 mg/L TDZ, achieving 100% induction. For proliferation, MS + 1.5 mg/L 6-BA + 0.06 mg/L NAA + 0.01 mg/L TDZ (proliferation coefficient 5.81) was optimal. Rooting was best with 1/2 MS + 0.3 mg/L IAA + 0.1 mg/L NAA (100% rooting, 14 roots/plant). Conclusions: This study established a reliable micropropagation system for Idesia polycarpa var. vestita, providing technical support for the efficient production of high-quality seedlings.

Previous studies on microwave exposure on plants have revealed variations in sensitivity of plants to different microwave frequencies, exposure durations, and power intensities. However, the effects of different polarizations of microwaves on plants have not been studied. Therefore, we investigated the effect of horizontally and vertically polarized 2 GHz continuous microwaves on Myriophyllum aquaticum plants at 1.8 W m^-2 power density. The electric potential variation along the vascular tissues were investigated for 1.5 h and growth parameters, pigmentation, and H₂O₂ formation were studied during 48 h microwave exposure. Exposure to horizontally polarized microwaves, decreased standard deviation of electric potential variation and increased H₂O₂ content significantly. Vertically polarized microwaves increased the standard deviation of electric potential variation and photosynthetic pigments significantly. However, none of the polarizations altered growth parameters (shoot length, stem diameter, and internodal length). Thermographic images taken for 1 h continuous microwave exposure did not indicate alteration in the temperature of the plants for both vertical and horizontal polarities.

Background: Platycladus orientalis L. is a drought-tolerant conifer valued for its ornamental and medicinal properties. However, efficient regeneration systems for this species remain limited, hindering its propagation and conservation. Aims: The aim of this study was to develop a reliable protocol for indirect organogenesis of Platycladus orientalis under in vitro conditions, evaluating the influence of explant type, culture medium, light exposure, and pretreatment on regeneration efficiency. Methods: Cotyledon, hypocotyl, and radicle explants were cultured on different media formulations. The effects of light and darkness during callus induction and shoot elongation were compared. Seeds underwent or avoided vernalization and scarification treatments to assess their influence on germination and callus formation. Results: Cotyledon explants achieved the highest callus induction rate, reaching 74.06%, particularly under dark conditions. Exposure to light during elongation significantly enhanced callus proliferation and shoots differentiation. Quoirin and LePoivre medium promoted the greatest number of adventitious shoots, with an average of 7.9 shoots per explant, while other media tested showed lower effectiveness. Germination was higher in non-vernalized and non-scarified seeds cultured in Quoirin and LePoivre medium. Conclusions: The established protocol enables efficient indirect organogenesis and shoot regeneration of Platycladus orientalis using cotyledon explants and Quoirin and LePoivre medium. The finding provides a valuable tool for clonal propagation and conservation of this species, supporting both ornamental cultivation and the preservation of its genetic resources.

Background and aims: Tire wear microplastics (TWMs) are emerging environmental contaminants, but their ecological risks to agricultural systems remain poorly understood. Methods: Rice seedlings were exposed to 0, 10, 100, and 1 000 mg L^-1 TWMs for 10 days. Growth parameters, chlorophyll fluorescence, and antioxidant enzyme activities were measured. Results: TWMs promoted growth; exposure to 1 000 mg L^-1 TWMs increased plant height and root length by 8.06% and 57.38%, respectively. Chlorophyll fluorescence analysis revealed that TWMs significantly suppressed rETR_max by 32.53 - 43.62% and altered qP and NPQ. TWMs inhibited Y(NPQ) while enhancing Y(NO) loss, indicating impaired photoprotective dissipation and aggravated photodamage. TWMs also inhibited SOD, POD, CAT, and APX activities in both leaves and roots, with root CAT and APX decreasing by up to 37.35% and 40.34%, reflecting a direct impairment of the antioxidant defense system. Conclusions: Rice seedlings achieve TWM-induced short-term growth at the expense of compromised photosynthetic efficiency and antioxidant defense, leading to an unsustainable compensatory state. This study provides physiological evidence for assessing TWMs phytotoxicity in agricultural systems.