Immunohistochemical Detection of the Wall Components on the Example of Shoot Apical Meristem of Fagopyrum esculentum and Fagopyrum tataricum.

Immunohistochemistry is a method that allows the detection of individual components of cell walls in an extremely precise way at the level of a single cell and wall domains. The cell wall antibodies detect specific epitopes of pectins, arabinogalactan proteins (AGP), hemicelluloses, and extensins. The presented method visualization of the selected pectic and AGP epitopes using antibodies directed to wall components is described. The method of the analysis of the chemical composition of the wall is present on the example of the shoot apical meristems of Fagopurum esculentum and Fagopyrum tataricum. Recommended protocols for immunostaining and examination on fluorescence microscopy level are presented.

Ferric reduction by a CYBDOM protein counteracts increased iron availability in root meristems induced by phosphorus deficiency.

To mobilize sparingly available phosphorus (P) in the rhizosphere, many plant species secrete malate to release P sorbed onto (hydr)oxides of aluminum and iron (Fe). In the presence of Fe, malate can provoke Fe over-accumulation in the root apoplast, triggering a series of events that inhibit root growth. Here, we identified HYPERSENSITIVE TO LOW P1 (HYP1), a CYBDOM protein constituted of a DOMON and a cytochrome b561 domain, as critical to maintain cell elongation and meristem integrity under low P. We demonstrate that HYP1 mediates ascorbate-dependent trans-plasma membrane electron transport and can reduce ferric and cupric substrates in Xenopus laevis oocytes and in planta. HYP1 expression is up-regulated in response to P deficiency in the proximal zone of the root apical meristem. Disruption of HYP1 leads to increased Fe and callose accumulation in the root meristem and causes significant transcriptional changes in roots. We further demonstrate that HYP1 activity overcomes malate-induced Fe accumulation, thereby preventing Fe-dependent root growth arrest in response to low P. Collectively, our results uncover an ascorbate-dependent metalloreductase that is critical to protect root meristems of P-deficient plants from increased Fe availability and provide insights into the physiological function of the yet poorly characterized but ubiquitous CYBDOM proteins.

Soybean type-B response regulator GmRR1 mediates phosphorus uptake and yield by modifying root architecture.

Phosphorus (P) plays a pivotal role in plant growth and development. Low P stress can greatly hamper plant growth. Here, we identified a QTL (named QPH-9-1), which is associated with P efficiency across multiple environments through linkage analysis and genome-wide association study. Furthermore, we successfully cloned the underlying soybean (Glycine max) gene GmRR1 (a soybean type-B Response Regulator 1) that encodes a type-B response regulator protein. Knockout of GmRR1 resulted in a substantial increase in plant height, biomass, P uptake efficiency, and yield-related traits due to the modification of root structure. In contrast, overexpression of GmRR1 in plants resulted in a decrease in these phenotypes. Further analysis revealed that knockout of GmRR1 substantially increased the levels of auxin and ethylene in roots, thereby promoting root hair formation and growth by promoting the formation of root hair primordium and lengthening the root apical meristem. Yeast two-hybrid, bimolecular fluorescence complementation, and dual-luciferase assays demonstrated an interaction between GmRR1 and Histidine-containing Phosphotransmitter protein 1. Expression analysis suggested that these proteins coparticipated in response to low P stress. Analysis of genomic sequences showed that GmRR1 underwent a selection during soybean domestication. Taken together, this study provides further insights into how plants respond to low P stress by modifying root architecture through phytohormone pathways.

Screening the toxicity profile and genotoxicity mechanism of excess manganese confirmed by spectral shift.

In this study, the toxicity induced by excessive doses of manganese (MnCl2), which is one of the essential trace elements for the continuation of the metabolic activities of the organisms, was investigated with the help of the Allium test. Toxicity was investigated by using physiological (percent germination, root length, weight gain), cytogenetic [mitotic index (MI), micronucleus (MN), chromosomal abnormalities (CAs)], biochemical [malondialdehyde (MDA), superoxide dismutase (SOD) catalase (CAT)] and anatomical (root tip meristematic cell damage) parameters. Allium cepa L. bulbs were divided into four groups as one control and three treatments. The control group was germinated with tap water, and the treatment groups were germinated with 250, 500 and 1000 µM doses of MnCl2. The germination process was continued for 72 h without interruption. At the end of the period, the root tips were collected, washed in distilled water and made ready for microscopic and spectrophotometric analyzes with the help of routine preparation techniques. As a result, the highest germination percentage, root length, weight gain and MI, and the lowest MN frequency, CAs numbers, MDA level, SOD and CAT enzyme activities were determined in the control group (group I). MnCl2 exposure caused a decrease in physiological parameter values and an increase in cytogenetic (except MI) and biochemical parameter values, depending on the dose. MnCl2 exposure induced MN and CAs such as fragment, sticky chromosome, vagrant chromosome, unequal distribution of chromatin and bridge. This genotoxic effect of MnCl2 was associated with DNA-MnCl2 interaction, and this interaction was also confirmed by bathochromic and hypochromic shifts in spectral analysis. Anatomical damages such as epidermis cell damage, flattened cell nucleus, cortex cell damage and cortex cell wall thickening were observed after MnCl2 treatment. As a result, it has been determined that excessive doses of the trace element Mn cause physiological, cytogenetic, biochemical and anatomical toxicity and A. cepa test material is a reliable bio-indicator in determining this toxicity.

Early sensing of phosphate deprivation triggers the formation of extra root cap cell layers via SOMBRERO through a process antagonized by auxin signaling.

KEY MESSAGE: The role of the root cap in the plant response to phosphate deprivation has been scarcely investigated. Here we describe early structural, physiological and molecular changes prior to the determinate growth program of the primary roots under low Pi and unveil a critical function of the transcription factor SOMBRERO in low Pi sensing. Mineral nutrient distribution in the soil is uneven and roots efficiently adapt to improve uptake and assimilation of sparingly available resources. Phosphate (Pi) accumulates in the upper layers and thus short and branched root systems proliferate to better exploit organic and inorganic Pi patches. Here we report an early adaptive response of the Arabidopsis primary root that precedes the entrance of the meristem into the determinate developmental program that is a hallmark of the low Pi sensing mechanism. In wild-type seedlings transferred to low Pi medium, the quiescent center domain in primary root tips increases as an early response, as revealed by WOX5:GFP expression and this correlates with a thicker root tip with extra root cap cell layers. The halted primary root growth in WT seedlings could be reversed upon transfer to medium supplemented with 250 µM Pi. Mutant and gene expression analysis indicates that auxin signaling negatively affects the cellular re-specification at the root tip and enabled identification of the transcription factor SOMBRERO as a critical element that orchestrates both the formation of extra root cap layers and primary root growth under Pi scarcity. Moreover, we provide evidence that low Pi-induced root thickening or the loss-of-function of SOMBRERO is associated with expression of phosphate transporters at the root tip. Our data uncover a developmental window where the root tip senses deprivation of a critical macronutrient to improve adaptation and surveillance.

Optimal BR signalling is required for adequate cell wall orientation in the Arabidopsis root meristem.

Plant brassinosteroid hormones (BRs) regulate growth in part through altering the properties of the cell wall, the extracellular matrix of plant cells. Conversely, feedback signalling from the wall connects the state of cell wall homeostasis to the BR receptor complex and modulates BR activity. Here, we report that both pectin-triggered cell wall signalling and impaired BR signalling result in altered cell wall orientation in the Arabidopsis root meristem. Furthermore, both depletion of endogenous BRs and exogenous supply of BRs triggered these defects. Cell wall signalling-induced alterations in the orientation of newly placed walls appear to occur late during cytokinesis, after initial positioning of the cortical division zone. Tissue-specific perturbations of BR signalling revealed that the cellular malfunction is unrelated to previously described whole organ growth defects. Thus, tissue type separates the pleiotropic effects of cell wall/BR signals and highlights their importance during cell wall placement.

Selenium restores mitochondrial dysfunction to reduce Cr-induced cell apoptosis in Chinese cabbage (Brassica campestris L. ssp. Pekinensis) root tips.

Chromium (Cr) disrupts the growth and physiology of plants. Selenium (Se) is considered as a promising option to help plants ameliorate Cr toxicity. To investigate the effects of exogenous Se on reactive oxygen species (ROS) burst and programmed cell death (PCD) in root tip cells under Cr stress, hydroponic experiments were carried out with Chinese cabbage seedlings grown in Hoagland solution containing 1 mg L-1 Cr and 0.1 mg L-1 Se. Results showed that Se scavenged the overproduction of H2O2 and O2－·, and alleviated the level of lipid peroxidation in root tips stressed by Cr. Moreover, Se effectively prevented DNA degradation and reduced the number of apoptotic cells in root tips. Compared with Cr treatment, Se supplementation reduced the content of ROS and malondialdehyde in mitochondria by 38.23% and 17.52%, respectively. Se application decreased the opening degree of mitochondrial permeability transition pores by 32.30%, increased mitochondrial membrane potential by 40.91%, alleviated the release of cyt c from mitochondria into cytosol by 18.42% and caused 57.40% decrease of caspase 3-like protease activity, and thus restored mitochondrial dysfunction caused by Cr stress. In addition, the alteration of Se on mitochondrial physiological properties maintained calcium homeostasis between mitochondria and cytosol, which further contributed to reducing the appearance of Cr-induced PCD. Findings suggested that Se restored mitochondrial dysfunction, which further rescued root tip cells from PCD, consequently activating defense strategies to protect plants from Cr toxicity and maintaining plant growth.

Induction of Callogenesis, Organogenesis, and Embryogenesis in Non-Meristematic Explants of Bleeding Heart and Evaluation of Chemical Diversity of Key Metabolites from Callus.

Lamprocapnos spectabilis (L.) Fukuhara is a perennial plant species valued in the horticultural, cosmetic, and pharmaceutical markets. To date, however, there were no studies on tissue culture systems in this species when adjusted from non-meristematic explants. The aim of this study is to induce callogenesis, organogenesis, and somatic embryogenesis in non-meristematic explants of Lamprocapnos spectabilis 'Alba' cultured in various media and to analyze the chemical diversity of the produced callus. Leaf, petiole, and internode explants were cultured on the modified Murashige and Skoog (MS) medium fortified with various combinations and concentrations of 6-benzyladenine (BA), indole-3-acetic acid (IAA), 1-naphthaleneacetic acid (NAA), 2,4-dichlorphenoxyacetic acid (2,4-D), and picloram (PIC). After 10 weeks of culturing, the morphogenetic response of explants was evaluated and the concentration of chlorophylls, carotenoids, anthocyanins, and polyphenols in callus was analyzed. There was no influence of explant type on the callogenesis efficiency (62.1-65.3%). The highest fresh weight of callus was produced on leaf explants in the presence of 2,4-D or PIC. In contrast, the highest share of dry weight was found in internode-derived calli and cultured on IAA-supplemented medium (up to 30.8%). Only 2.5% of all explants regenerated adventitious shoots, while rhizogenesis was reported in 4.5% of explants. Somatic embryos were produced indirectly by 0% to 100% of explants, depending on the culture medium and explant type. The highest mean number of embryos (11.4 per explant) was found on petioles cultured in the MS medium with 0.5 mg·L-1 BA and 1.0 mg·L-1 PIC. Calli cultured in media with NAA usually contained a higher content of primary and secondary metabolites. There was also a significant impact of explant type on the content of anthocyanins, polyphenols, and carotenoids in callus. Further studies should focus on the elicitation of metabolites production in callus culture systems of the bleeding heart.

Changes in gene expression in potato meristems treated with the sprout suppressor 1,4-dimethylnaphthalene are dependent on tuber age and dormancy status.

Commercial storage of potatoes often relies on the use of sprout inhibitors to prolong storage and reduce spoilage. The compound 1,4-dimethylnaphthalene (DMN) has seen increase application as a sprout inhibitor in the potato industry as older chemistries are being phased out. The mode of action of DMN is poorly understood as is the sensitivity of potato tissues to this new class of inhibitor. During storage potato tubers transition from a state of endo-dormant to eco-dormant and it is not known if the DMN response is consistent across this developmental transition. RNA-seq gene expression profiling was used to establish if stored potato tubers (Solanum tuberosum cv La Chipper) have differential sensitivity to DMN as tubers age. DMN was applied at three different times during storage; just after harvest when tubers are in endo-dormancy, midwinter at early eco-dormancy, and in spring during late eco-dormancy when sprouting was prevented via exposure to cold storage temperatures. Changes in gene expression were lowest during endo-dormancy while midwinter and spring treatments exhibited a greater and more diverse expression response. Functional analysis of differential gene expression demonstrated gene sets associated with DNA replication, cell division, and DNA methylation are suppressed after DMN treatment. However, gene sets associated with salicylic acid, jasmonic acid, abiotic and biotic stress responses are elevated by DMN only after endodormancy terminates. Gene clusters associated with pathogenesis related proteins PR-4 and PR-5 are also upregulated in response to DMN. These results indicate that DMN sensitivity changes as potato tubers age and transition from endo-dormant to eco-dormant in storage and the overall response is a shift in gene classes that regulate growth and response to stress.

LaALMT1 mediates malate release from phosphorus-deficient white lupin root tips and metal root to shoot translocation.

Under phosphorus (P) deficiency, Lupinus albus (white lupin) releases large amounts of organic acid anions from specialized root structures, so-called cluster or proteoid roots, to mobilize and acquire sparingly soluble phosphates from a restricted soil volume. The molecular mechanisms underlying this release and its regulation are, however, poorly understood. Here, we identified a gene belonging to the aluminium (Al)-activated malate transporter (ALMT) family that specifically contributes to malate, but not citrate release. This gene, LaALMT1, was most prominently expressed in the root apices under P deficiency, including those of cluster roots and was also detected in the root stele. Contrary to several ALMT homologs in other species, the expression was not stimulated, but moderately repressed by Al. Aluminium-independent malate currents were recorded from the plasma membrane localized LaALMT1 expressed in Xenopus oocytes. In composite lupins with transgenic roots, LaALMT1 was efficiently mutated by CRISPR-Cas9, leading to diminished malate efflux and lower xylem sap malate concentrations. When grown in an alkaline P-deficient soil, mutant shoot phosphate concentrations were similar, but iron and potassium concentrations were diminished in old leaves, suggesting a role for ALMT1 in metal root to shoot translocation, a function that was also supported by growth in hydroponics.

Functional Analysis of Coilin in Virus Resistance and Stress Tolerance of Potato Solanum tuberosum using CRISPR-Cas9 Editing.

The role of the nuclear protein coilin in the mechanisms of resistance of potato Solanum tuberosum cultivar Chicago to biotic and abiotic stresses was studied using the CRISPR-Cas9 technology. For the coilin gene editing, a complex consisting of the Cas9 endonuclease and a short guide RNA was immobilized on gold or chitosan microparticles and delivered into apical meristem cells by bioballistics or vacuum infiltration methods, respectively. Editing at least one allele of the coilin gene considerably increased the resistance of the edited lines to infection with the potato virus Y and their tolerance to salt and osmotic stress.

Toxicity assay of lanthanum and cerium in solutions and soil.

Lanthanum (La) and cerium (Ce) are one of the most abundant rare earth elements (REEs). In spite of quite extensive studying of the effects of these lanthanides on biota, some contradictions remain in the results. Also little is known about the effect of lanthanum and cerium on plant cells and their mitotic cycle, especially in soils. In this study, the effects of La and Ce in solutions and soil samples on root growth, mitotic index (MI) and frequency of aberrant cells (FAC) were assayed using one of the most convenient objects for testing of cytotoxicity - onion Allium cepa L. Bulbs were germinated on media containing La and Ce in concentrations 0-200 mg/l and 0-50 mg/l respectively for solutions and 0-200 mg/kg for soil samples. After 5 days of germination in solutions, a significant decrease in root elongation and MI in apical meristem cells are shown. We have also observed an increase in the number of cells with aberrations at 50 mg/l La and Ce concentration. The number of observed stickiness and disturbed metaphase has increased significantly. Soil samples turned out to be less toxic compared to the solutions probably due to the decreased availability of REEs. In spite of this, significant cytotoxicity of soil samples containing the highest concentration of La and Ce (200 mg/kg) is observed. The latter may indicate the importance of considering the cytotoxicity of soils containing high lanthanides concentrations - in extraction and production areas and actively fertilized fields.

Phytosynthesis of gold and silver nanoparticles enhance in vitro antioxidant and mitostimulatory activity of Aconitum toxicum Reichenb. rhizomes alcoholic extracts.

Extracts obtained from different plant species proved to be a valuable tool in various biomedical applications. In the same time, the phytosynthesis of noble metal nanoparticles represents an already well-established route for obtaining nanoparticles with biological activity. The present paper studies the antioxidant activity and the cytogenetic effects of the alcoholic extracts from rhizomes of Aconitum toxicum Rchb., before and after the phytosynthesis of gold and silver nanoparticles, on the meristematic root cells of Allium cepa L., and on the general mitotic index and the progression rate through the mitotic phases, respectively, as well as on the genetic material organized in chromosomes. The extracts were characterized in terms of total polyphenolics content (1.49% and, respectively, 2.29%) and aconitine content (by HPLC - 4.891 mg/L and, respectively, 18.211 mg/L), while the phytosynthesis of metallic nanoparticles was monitored by UV-Vis spectrometry, X-ray diffraction, X-ray fluorescence and electron microscopy. Both the extracts and the obtained nanoparticles were evaluated for antioxidant potential (the antioxidant activity ranging between 78% and 84.32%) and cytogenetic effects. The obtained results prove the phytosynthesis of AgNPs and AuNPs with dimensions ranging from 9 nm to 15 nm for AuNPs, respectively from 53 nm to 67 nm for AgNPs. The extracts obtained from rhizomes of A. toxicum Rchb. induced mitotic stress, as well as a series of nuclear and mitotic aberrations. The biosynthesis of AgNPs and AuNPs intensified the antioxidant and mitostimulatory activity of the extracts.

Evidence for the Regulation of Gynoecium Morphogenesis by ETTIN via Cell Wall Dynamics.

ETTIN (ETT) is an atypical member of the AUXIN RESPONSE FACTOR family of transcription factors that plays a crucial role in tissue patterning in the Arabidopsis (Arabidopsis thaliana) gynoecium. Though recent insights have provided valuable information on ETT's interactions with other components of auxin signaling, the biophysical mechanisms linking ETT to its ultimate effects on gynoecium morphology were until now unknown. Here, using techniques to assess cell-wall dynamics during gynoecium growth and development, we provide a coherent body of evidence to support a model in which ETT controls the elongation of the valve tissues of the gynoecium through the positive regulation of pectin methylesterase (PME) activity in the cell wall. This increase in PME activity results in an increase in the level of demethylesterified pectins and a consequent reduction in cell wall stiffness, leading to elongation of the valves. Though similar biophysical mechanisms have been shown to act in the stem apical meristem, leading to the expansion of organ primordia, our findings demonstrate that regulation of cell wall stiffness through the covalent modification of pectin also contributes to tissue patterning within a developing plant organ.

Plant nucleoside diphosphate kinase 1: A housekeeping enzyme with moonlighting activity.

Nucleoside diphosphate kinase (NDPK) catalyzes the interconversion of nucleoside diphosphates and triphosphates using ATP as phosphate donor. This housekeeping enzyme is present in several subcellular compartments. The main isoform (NDPK1) is located in the cytosol and is highly expressed in meristems and provascular tissues. The manipulation of NDPK1 levels in transgenic potato roots demonstrates that this enzyme plays a key role in the transfer of energy between the cytosolic adenine and uridine nucleotide pools and in the distribution of carbon between starch and cellulose. Modulation of the expression of NDPK1 also alters the homeostasis of root respiration, glycolytic flux, reactive oxygen species production and growth. Herein, we propose a model summarizing the effects of the manipulation of NDPK1 levels on root metabolism. The model also accounts for G-quadruplex DNA binding, a moonlighting activity recently attributed to NDPK1, which possibly contributes to the metabolic phenotype of transgenic roots.

Reduction of the geomagnetic field delays Arabidopsis thaliana flowering time through downregulation of flowering-related genes.

Variations in magnetic field (MF) intensity are known to induce plant morphological and gene expression changes. In Arabidopsis thaliana Col-0, near-null magnetic field (NNMF, i.e., <100 nT MF) causes a delay in the transition to flowering, but the expression of genes involved in this response has been poorly studied. Here, we showed a time-course quantitative analysis of the expression of both leaf (including clock genes, photoperiod pathway, GA20ox, SVP, and vernalization pathway) and floral meristem (including GA2ox, SOC1, AGL24, LFY, AP1, FD, and FLC) genes involved in the transition to flowering in A. thaliana under NNMF. NNMF induced a delayed flowering time and a significant reduction of leaf area index and flowering stem length, with respect to controls under geomagnetic field. Generation experiments (F1 - and F2 -NNMF) showed retention of flowering delay. The quantitative expression (qPCR) of some A. thaliana genes expressed in leaves and floral meristem was studied during transition to flowering. In leaves and flowering meristem, NNMF caused an early downregulation of clock, photoperiod, gibberellin, and vernalization pathways and a later downregulation of TSF, AP1, and FLC. In the floral meristem, the downregulation of AP1, AGL24, FT, and FLC in early phases of floral development was accompanied by a downregulation of the gibberellin pathway. The progressive upregulation of AGL24 and AP1 was also correlated to the delayed flowering by NNMF. The flowering delay is associated with the strong downregulation of FT, FLC, and GA20ox in the floral meristem and FT, TSF, FLC, and GA20ox in leaves. Bioelectromagnetics. 39:361-374, 2018. © 2018 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc.

A rich source of potential bioactive compounds with anticancer activities by Catharanthus roseus cambium meristematic stem cell cultures.

ETHNOPHARMACOLOGICAL IMPORTANCE: Catharanthus roseus (L.) G. Don. is an important medicinal plant with rich sources of remarkable health benefits consisting more than 100 alkaloids and significant amounts of bioactive compounds, which have been widely used as a folk medicine for treatment of several pathologies. THE AIM OF THE STUDY: In the present study, we isolated and cultured innately undifferentiated cambium meristematic cells (CMCs), which were observed stable cell growth, enhancement of bioactive compounds from C.roseus. MATERIALS AND METHODS: We attempted to determine the effect of association between time-course growth rates, bioactive compounds and terpenoids indole alkaloid (TIA) contents as well as antioxidant and anticancer efficacies of C. roseus CMC suspension culture treated by UV-C. RESULTS: The bioactive compounds, vincristine contents, and antioxidant power were noticed significantly higher in 60 min exposure at 5 cm distances and with the directly collected sample (T7). A similar trend has also been noticed from the anticancer activity. Demonstration of TIA accumulation was found higher at 5 min exposure, at 20 cm distances and 48 h of incubation (T21) and the result of TIA contents had the highest correlation effects of anticancer activities. CONCLUSION: In the current study, we demonstrated that UV-C light could enhance the production of the essential compounds and bioactivities in the CMCs of C. roseus, and thus, C. roseus CMCs have the potential to serve as an industrial platform for the production of bioactive alkaloids and antioxidant, anticancer activity. Moreover, additional efforts should be made to irradiate CMC suspension cultures from C. roseus with UV-C to achieve better pharmacological profiles.

Differential expression of gibberellin- and abscisic acid-related genes implies their roles in the bud activity-dormancy transition of tea plants.

KEY MESSAGE: Thirty genes involved in GA and ABA metabolism and signalling were identified, and the expression profiles indicated that they play crucial roles in the bud activity-dormancy transition in tea plants. Gibberellin (GA) and abscisic acid (ABA) are fundamental phytohormones that extensively regulate plant growth and development, especially bud dormancy and sprouting transition in perennial plants. However, there is little information on GA- and ABA-related genes and their expression profiles during the activity-dormancy transition in tea plants. In the present study, 30 genes involved in the metabolism and signalling pathways of GA and ABA were first identified, and their expression patterns in different tissues were assessed. Further evaluation of the expression patterns of selected genes in response to GA3 and ABA application showed that CsGA3ox, CsGA20ox, CsGA2ox, CsZEP and CsNCED transcripts were differentially expressed after exogenous treatment. The expression profiles of the studied genes during winter dormancy and spring sprouting were investigated, and somewhat diverse expression patterns were found for GA- and ABA-related genes. This diversity was associated with the bud activity-dormancy cycle of tea plants. These results indicate that the genes involved in the metabolism and signalling of GA and ABA are important for regulating the bud activity-dormancy transition in tea plants.

Genome-Wide Analysis of Long Non-Coding RNAs in Potato and Their Potential Role in Tuber Sprouting Process.

Sprouting is a key factor affecting the quality of potato tubers. The present study aimed to compare the differential expression of long non-coding RNAs (lncRNAs) in the apical meristem during the dormancy release and sprouting stages by using lncRNA sequencing. Microscopic observations and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed the changes in the morphology and expression of lncRNAs in potato tubers during sprouting. Meristematic cells of potato tuber apical buds divided continuously and exhibited vegetative cone bulging and vascularisation. In all, 3175 lncRNAs were identified from the apical buds of potato tubers, among which 383 lncRNAs were up-regulated and 340 were down-regulated during sprouting. The GO enrichment analysis revealed that sprouting mainly influenced the expression of lncRNAs related to the cellular components of potato apical buds (e.g., cytoplasm and organelles) and cellular metabolic processes. The KEGG enrichment analysis also showed significant enrichment of specific metabolic pathways. In addition, 386 differentially expressed lncRNAs during sprouting were identified as putative targets of 235 potato miRNAs. Quantitative real-time polymerase chain reaction results agreed with the sequencing data. Our study provides the first systematic study of numerous lncRNAs involved in the potato tuber sprouting process and lays the foundation for further studies to elucidate their precise functions.

Cell wall pectin methyl-esterification and organic acids of root tips involve in aluminum tolerance in Camellia sinensis.

Tea plant (Camellia sinensis (O.) Kuntze) can survive from high levels of aluminum (Al) in strongly acidic soils. However, the mechanism driving its tolerance to Al, the predominant factor limiting plant growth in acid condition, is still not fully understood. Here, two-year-old rooted cuttings of C. sinensis cultivar 'Longjingchangye' were used for Al resistance experiments. We found that the tea plants grew better in the presence of 0.4 mM Al than those grew under lower concentration of Al treatments (0 and 0.1 mM) as well as higher levels treatment (2 and 4 mM), confirming that appropriate Al increased tea plant growth. Hematoxylin staining assay showed that the apical region was the main accumulator in tea plant root. Subsequently, immunolocalization of pectins in the root tip cell wall showed a rise in low-methyl-ester pectin levels and a reduction of high-methyl-ester pectin content with the increasing Al concentration of treatments. Furthermore, we observed the increased expressions of C. sinensis pectin methylesterase (CsPME) genes along with the increasing de-esterified pectin levels during response to Al treatments. Additionally, the levels of organic acids increased steadily after treatment with 0.1, 0.4 or 2 mM Al, while they dropped after treatment with 4 mM Al. The organic acids secretion from root followed a similar trend. Similarly, a gradual increase in malate dehydrogenase (MDH), citrate synthase (CS) and glycolate oxidase (GO) enzyme activities and relevant metabolic genes expression were detected after the treatment of 0.1, 0.4 or 2 mM Al, while a sharp decrease was resulted from treatment with 4 mM Al. These results confirm that both pectin methylesterases and organic acids contribute to Al tolerance in C. sinensis.