The response of physiological and xylem anatomical traits under cadmium stress in Pinus thunbergii seedlings.

Studying the response of physiological and xylem anatomical traits under cadmium stress is helpful to understand plants' response to heavy metal stress. Here, seedlings of Pinus thunbergii Parl. were treated with 50, 100 and 150 mg kg-1 Cd2+ for 28 days. Cadmium and nonstructural carbohydrate content of leaves, stems and roots, root Cd2+ flux, cadmium distribution pattern in stem xylem and phloem, stem xylem hydraulic traits, cell wall component fractions of stems and roots, phytohormonal content such as abscisic acid, gibberellic acid 3, molecule -indole-3-acetic acid, and jasmonic acid from both leaves and roots, as well as xylem anatomical traits from both stems and roots were measured. Root Cd2+ flux increased from 50 to 100 mmol L-1 Cd2+ stress, however it decreased at 150 mmol L-1 Cd2+. Cellulose and hemicellulose in leaves, stems and roots did not change significantly under cadmium stress, while pectin decreased significantly. The nonstructural carbohydrate content of both leaves and stems showed significant changes under cadmium stress while the root nonstructural carbohydrate content was not affected. In both leaves and roots, the abscisic acid content significantly increased under cadmium stress, while the gibberellic acid 3, indole-3-acetic acid and jasmonic acid methylester content significantly decreased. Both xylem specific hydraulic conductivity and xylem water potential decreased with cadmium stress, however tracheid diameter and double wall thickness of the stems and roots were not affected. High cadmium intensity was found in both the stem xylem and phloem in all cadmium stressed treatments. Our study highlighted the in situ observation of cadmium distribution in both the xylem and phloem, and demonstrated the instant response of physiological traits such as xylem water potential, xylem specific hydraulic conductivity, root Cd2+ flux, nonstructural carbohydrate content, as well as phytohormonal content under cadmium stress, and the less affected traits such as xylem anatomical traits, cellulose and hemicellulose.

Effects of Selenium on the Lignin Deposition Pattern and Stem Mechanical Properties of Alfalfa (Medicago sativa L.).

Lignin provides structural support to plants; however, it reduces their utilization rate. According to our previous studies, selenium (Se) reduces lignin accumulation in alfalfa, but the specific mechanism involved remains unclear. Therefore, at the seedling stage, four root irrigation treatments using 2.5, 50, and 5 µmol/L sodium selenite (S-RI), selenomethionine (SS-RI), Se nanoparticles (SSS-RI), and deionized water (CK-RI) were performed. At the branching stage, four treatments of foliar spraying with the three Se fertilizers described above at a concentration of 0.5 mmol/L (S-FS, SS-FS, and SSS-FS) and deionized water (CK-FS) were administered. The results revealed that all Se treatments chiefly reduced the level of deposition of syringyl (S) lignin in the first internode of alfalfa stems. SS-FS and SSS-FS treatments mainly reduced the deposition of S and guaiacyl (G) lignins in the sixth internode of alfalfa stems, respectively, while S-FS treatment only slightly reduced the deposition of G lignin. S, SS, and SSS-RI treatments reduced the level of deposition of S and G lignins in the sixth internode of alfalfa stems. Se application increased plant height, stem diameter, epidermis (cortex) thickness, primary xylem vessel number (diameter), and pith diameter of alfalfa but decreased primary xylem area and pith parenchyma cell wall thickness of the first internode, and SS(SSS)-FS treatment reduced the mechanical strength of alfalfa stems. Therefore, Se application could decrease lignin accumulation by regulating the organizational structure parameters of alfalfa stems and the deposition pattern of the lignin monomers.

Multimodal Spectroscopic Studies to Evaluate the Effect of Nod-Factor-Based Fertilizer on the Maize (Zea mays) Stem.

Maize (Zea mays) is one of the most cultivated plants in the world. Due to the large area, the scale of its production, and the demand to increase the yield, there is a need for new environmentally friendly fertilizers. One group of such candidates is bacteria-produced nodulation (or nod) factors. Limited research has explored the impact of nodulation, factors on maize within field conditions, with most studies restricted to greenhouse settings and early developmental stages. Additionally, there is a scarcity of investigations that elucidate the metabolic alterations in the maize stem due to nod-factor exposure. It was therefore the aim of this study. Maize stem's metabolites and fibers were analyzed with various imaging analytical techniques: matrix assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI), Raman spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR), and diffuse reflectance infrared Fourier transform spectroscopy. Moreover, the biochemical analyses were used to evaluate the proteins and soluble carbohydrates concentration and total phenolic content. These techniques were used to evaluate the influence of nod factor-based biofertilizer on the growth of a non-symbiotic plant, maize. The biofertilizer increased the grain yield and the stem mass. Moreover, the spectroscopic and biochemical investigation proved the appreciable biochemical changes in the stems of the maize in biofertilizer-treated plants. Noticeable changes were found in the spatial distribution and the increase in the concentration of flavonoids such as maysin, quercetin, and rutin. Moreover, the concentration of cell wall components (fibers) increased. Furthermore, it was shown that the use of untargeted analyses (such as Raman and ATR FT-IR, spectroscopic imaging, and MALDI-MSI) is useful for the investigation of the biochemical changes in plants.

Enhancement of Vindoline and Catharanthine Accumulation, Antioxidant Enzymes Activities, and Gene Expression Levels in Catharanthus roseus Leaves by Chitooligosaccharides Elicitation.

Catharanthus roseus (L.) G. Don is a plant belonging to the genus Catharanthus of the Apocynaceae family. It contains more than one hundred alkaloids, of which some exhibit significant pharmacological activities. Chitooligosaccharides are the only basic aminooligosaccharides with positively charged cations in nature, which can regulate plant growth and antioxidant properties. In this study, the leaves of Catharanthus roseus were sprayed with chitooligosaccharides of different molecular weights (1 kDa, 2 kDa, 3 kDa) and different concentrations (0.01 µg/mL, 0.1 µg/mL, 1 µg/mL and 10 µg/mL). The fresh weights of its root, stem and leaf were all improved after chitooligosaccharides treatments. More importantly, the chitooligosaccharides elicitor strongly stimulated the accumulation of vindoline and catharanthine in the leaves, especially with the treatment of 0.1 µg/mL 3 kDa chitooligosaccharides, the contents of them were increased by 60.68% and 141.54%, respectively. Furthermore, as the defensive responses, antioxidant enzymes activities (catalase, glutathione reductase, ascorbate peroxidase, peroxidase and superoxide dismutase) were enhanced under chitooligosaccharides treatments. To further elucidate the underlying mechanism, qRT-PCR was used to investigate the genes expression levels of secologanin synthase (SLS), strictosidine synthase (STR), strictosidine glucosidase (SGD), tabersonine 16-hydroxylase (T16H), desacetoxyvindoline-4-hydroxylase (D4H), deacetylvindoline-4-O-acetyltransferase (DAT), peroxidase 1 (PRX1) and octadecanoid-responsive Catharanthus AP2-domain protein 3 (ORCA3). All the genes were significantly up-regulated after chitooligosaccharides treatments, and the transcription abundance of ORCA3, SLS, STR, DAT and PRX1 reached a maximal level with 0.1 µg/mL 3 kDa chitooligosaccharides treatment. All these results suggest that spraying Catharanthus roseus leaves with chitooligosaccharides, especially 0.1 µg/mL of 3 kDa chitooligosaccharides, may effectively improve the pharmaceutical value of Catharanthus roseus.

Sulfur Induces Resistance against Canker Caused by Pseudomonas syringae pv. actinidae via Phenolic Components Increase and Morphological Structure Modification in the Kiwifruit Stems.

Bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) has led to considerable losses in all major kiwifruit-growing areas. There are no commercial products in the market to effectively control this disease. Therefore, the defense resistance of host plants is a prospective option. In our previous study, sulfur could improve the resistance of kiwifruit to Psa infection. However, the mechanisms of inducing resistance remain largely unclear. In this study, disease severity and protection efficiency were tested after applying sulfur, with different concentrations in the field. The results indicated that sulfur could reduce the disease index by 30.26 and 31.6 and recorded high protection efficiency of 76.67% and 77.00% after one and two years, respectively, when the concentration of induction treatments was 2.0 kg/m3. Ultrastructural changes in kiwifruit stems after induction were demonstrated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the activities of phenylalanine ammonia-lyase (PAL), peroxidase (POD) and polyphenol oxidase (PPO), and the accumulation of lignin were determined by biochemical analyses. Our results showed that the morphological characteristics of trichomes and lenticels of kiwifruit stem were in the best defensive state respectively when the sulfur concentration was 3.0 kg/m3 and 1.5 kg/m3. Meanwhile, in the range of 0.5 to 2.0 kg/m3, the sulfur could promote the chloroplast and mitochondria of kiwifruit stems infected with Psa to gradually return to health status, increasing the thickness of the cell wall. In addition, sulfur increased the activities of PAL, POD and PPO, and promoted the accumulation of lignin in kiwifruit stems. Moreover, the sulfur protection efficiency was positively correlated with PPO activity (p < 0.05) and lignin content (p < 0.01), which revealed that the synergistic effect of protective enzyme activity and the phenolic metabolism pathway was the physiological effect of sulfur-induced kiwifruit resistance to Psa. This evidence highlights the importance of lignin content in kiwifruit stems as a defense mechanism in sulfur-induced resistance. These results suggest that sulfur enhances kiwifruit canker resistance via an increase in phenolic components and morphology structure modification in the kiwifruit stems. Therefore, this study could provide insights into sulfur to control kiwifruit canker caused by Psa.

Silicon enhances stem strength by promoting lignin accumulation in herbaceous peony (Paeonia lactiflora Pall.).

Herbaceous peony (Paeonia lactiflora Pall.) is a popular high-end cut flower, but stem bending caused by low stem strength severely decreases its quality. To enhance stem strength, the regulatory effects of exogenous silicon were investigated in P. lactiflora. The results showed that silicon application enhanced stem strength by increasing the thickness of secondary cell walls and the layers of thickened secondary cells. Moreover, more lignin accumulated, particularly G-lignin and S-lignin, and the activities of lignin biosynthetic enzymes increased with silicon application. In addition, based on transcriptome analysis, silicon application induced the expression of genes participating in lignin biosynthesis pathway. Among them, hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyl transferase gene (HCT1) was isolated from P. lactiflora and found to be mainly localized in the cytoplasm of cells. Overexpression of PlHCT1 increased the layers of thickened secondary cells and lignin accumulation in tobacco, resulting in enhanced stem strength and demonstrably straight stems. Finally, silicon content, lignin content and PlHCT1 expression in P. lactiflora cultivars with high stem strengths were totally higher than those in cultivars with low stem strengths. These results indicated that silicon application enhanced stem strength by promoting lignin accumulation in P. lactiflora, which has prospects for stem quality improvement in general.

Effect of Sodium Azide on Quantitative and Qualitative Stem Traits in the M2 Generation of Ethiopian Sesame (Sesamum indicum L.) Genotypes.

The emerging oilseed crop Sesamum indicum, also known as the queen of oilseeds, is being grown globally for its oil content for medicinal and nutritional values. One of the key challenges of sesame cultivation is its low productivity. In the present study, sodium azide (NaN3) was used as a chemical mutagen. The aim of this study was to examine the effect of NaN3 on quantitative and qualitative stem traits in the M2 generation of Ethiopian sesame (Sesamum indicum L.) genotypes. Seeds of fourteen sesame genotypes were used in this study and germinated and grown under greenhouse conditions. Different qualitative and quantitative data were collected and analyzed. Traits such as plant height, ground distance to first distance, and internode length were significantly affected by NaN3 treatment. The highest plant height was recorded in the control on Humera 1 and Baha Necho genotypes, while the lowest was observed on Setit 2 and Hirhir treated with the chemical. The highest ground distance to the first branch was observed in Gumero, while the least ground distance was recorded in Setit 1 in the treated and control genotypes, respectively. The best internode length was recorded on Setit 2 and ADI in the control, while the lowest internode length was observed in Setit 1 genotype treated with sodium azide. Genotypes such as ACC44, ADI, Baha Necho, Borkena, Gonder 1, and Setit 1 treated with NaN3 have showed glabrous type of stem hairiness. All the fourteen genotypes (both treated and control) were clustered into four groups. In conclusion, we observed a highly significant variation among the genotypes due the effect of the chemical and genotypes themselves. Hence, this report would create more genetic diversity for further sesame genetic research improvements.

Encapsulation of Synthesized Plant Growth Regulator Based on Copper(II) Complex in Chitosan/Alginate Microcapsules.

A new copper complex, trans-diaqua-trans-bis [1-hydroxy-1,2-di (methoxycarbonyl) ethenato] copper (abbreviation Cu(II) complex), was synthesized and its plant growth regulation properties were investigated. The results show a sharp dependence of growth regulation activity of the Cu(II) complex on the type of culture and its concentration. New plant growth regulator accelerated the development of the corn root system (the increase in both length and weight) but showed a smaller effect on the development of the wheat and barley root systems. Stimulation of corn growth decreased with increasing Cu(II) complex concentration from 0.0001% to 0.01% (inhibition at high concentrations-0.01%). The development of corn stems was also accelerated but to a lesser extent. Chitosan-coated calcium alginate microcapsules suitable for delivery of Cu(II) complex to plants were prepared and characterized. Analysis of the FTIR spectrum showed that complex molecular interactions between functional groups of microcapsule constituents include mainly electrostatic interactions and hydrogen bonds. Microcapsules surface exhibits a soft granular surface structure with substructures consisting of abundant smaller particles with reduced surface roughness. Release profile analysis showed Fickian diffusion is the rate-controlling mechanism of Cu(II) complex releasing. The obtained results give new insights into the complexity of the interaction between the Cu(II) complex and microcapsule formulation constituents, which can be of great help in accelerating product development for the application in agriculture.

Mode of Action of 1-Naphthylphthalamic Acid in Conspicuous Local Stem Swelling of Succulent Plant, Bryophyllum calycinum: Relevance to the Aspects of Its Histological Observation and Comprehensive Analyses of Plant Hormones.

The mode of action of 1-naphthylphthalamic acid (NPA) to induce conspicuous local stem swelling in the area of its application to the growing internode in intact Bryophyllum calycinum was studied based on the aspects of histological observation and comprehensive analyses of plant hormones. Histological analyses revealed that NPA induced an increase in cell size and numerous cell divisions in the cortex and pith, respectively, compared to untreated stem. In the area of NPA application, vascular tissues had significantly wider cambial zones consisting of 5-6 cell layers, whereas phloem and xylem seemed not to be affected. This indicates that stem swelling in the area of NPA application is caused by stimulation of cell division and cell enlargement mainly in the cambial zone, cortex, and pith. Comprehensive analyses of plant hormones revealed that NPA substantially increased endogenous levels of indole-3-acetic acid (IAA) in the swelling area. NPA also increased endogenous levels of cytokinins, jasmonic acid, and its precursor, 12-oxo-phytodienoic acid, but did not increase abscisic acid and gibberellin levels. It was shown, using radiolabeled 14C-IAA, that NPA applied to the middle of internode segments had little effect on polar auxin transport, while 2,3,5-triiodobenzoic acid substantially inhibited it. These results strongly suggest that NPA induces changes in endogenous levels of plant hormones, such as IAA, cytokinins, and jasmonic acid, and their hormonal crosstalk results in a conspicuous local stem swelling. The possible different mode of action of NPA from other polar auxin transport inhibitors in succulent plants is extensively discussed.

Transcriptome dynamic landscape underlying the improvement of maize lodging resistance under coronatine treatment.

BACKGROUND: Lodging is one of the important factors causing maize yield. Plant height is an important factor in determining plant architecture in maize (Zea mays L.), which is closely related to lodging resistance under high planting density. Coronatine (COR), which is a phytotoxin and produced by the pathogen Pseudomonas syringae, is a functional and structural analogue of jasmonic acid (JA). RESULTS: In this study, we found COR, as a new plant growth regulator, could effectively reduce plant height and ear height of both hybrids (ZD958 and XY335) and inbred (B73) maize by inhibiting internode growth during elongation, thus improve maize lodging resistance. To study gene expression changes in internode after COR treatment, we collected spatio-temporal transcriptome of inbred B73 internode under normal condition and COR treatment, including the three different regions of internode (fixed, meristem and elongation regions) at three different developmental stages. The gene expression levels of the three regions at normal condition were described and then compared with that upon COR treatment. In total, 8605 COR-responsive genes (COR-RGs) were found, consist of 802 genes specifically expressed in internode. For these COR-RGs, 614, 870, 2123 of which showed expression changes in only fixed, meristem and elongation region, respectively. Both the number and function were significantly changed for COR-RGs identified in different regions, indicating genes with different functions were regulated at the three regions. Besides, we found more than 80% genes of gibberellin and jasmonic acid were changed under COR treatment. CONCLUSIONS: These data provide a gene expression profiling in different regions of internode development and molecular mechanism of COR affecting internode elongation. A putative schematic of the internode response to COR treatment is proposed which shows the basic process of COR affecting internode elongation. This research provides a useful resource for studying maize internode development and improves our understanding of the COR regulation mechanism based on plant height.

Comparative analysis of physical and functional properties of cellulose nanofibers isolated from alkaline pre-treated wheat straw in optimized hydrochloric acid and enzymatic processes.

Two methods, HCl and enzymatic treatments, were evaluated for diversification of morphological and functional properties of cellulose nanofibers (CNF) from two- stage-alkaline pre-treated wheat straw (WS). The extraction conditions were optimized by a central composite designed experimental approach varying time (4-8 h) and temperature (80-120 °C) for the HCl-based treatment and time (4-8 h), and FiberCare dosage (50-100 endo-1,4-ß-glucanase unit/g) and Viscozyme (10-20 fungal ß-glucanase units/g) for the enzyme-based treatment. The CNF yields, morphological (polydispersity index (PdI), length and diameter), and functional (crystallinity and thermal degradation) properties were compared. The CNF produced by the HCl (HCN) and enzymatically (ECN) attained diameters ~17 nm had PdI, length, and crystallinity of 0.53, 514 nm & 70%, and 0.92, 1.0 µm & 48%, respectively. Thus, the HCN morphology suits homogenous nano-applications, whereas that of the ECN, would suit heterogenous nano-applications. The HCN and ECN yields were similar (~20%) with optimal production time of 7.41 and 4.64 h, respectively. Both the HCN & ECN can be classified as thermally stable nanocolloids with maximum thermal degradation temperatures of ~380 °C and Zeta potential ~-16 mV. The two CNF production methods have potential synergetic effects on CNF production, morphological, and functional properties.

Characteristics of a recombinant Fusarium verticillioides cutinase and its effects on enzymatic hydrolysis of rice straw.

The current study heterologously expressed a cutinase from Fusarium verticillioides by Pichia pastoris and investigated its properties and effects on the hydrolysis of rice straw. The optimal pH and temperature for F. verticillioides cutinase were 8.0 and 50 °C, respectively. F. verticillioides cutinase had poor thermal stability and could be inhibited by some metal ions, inhibitors, and detergents (5 mM), including Ni2+, Zn2+, Cu2+, Ca2+, Mn2+, sodium dodecyl sulfate, EDTA, and Tween-20. F. verticillioides cutinase could tolerate 15% methanol and dimethyl sulfoxide but was significantly repressed by 15% ethanol and acetone with 48% and 63% residual activity, respectively. F. verticillioides cutinase could degrade the cuticle of rice straw with palmitic acid and stearic acid as the main products. However, the dissolving sugars released from the rice straw treated with F. verticillioides cutinase were significantly reduced by 29.2 µg/mL compared with the control (107.9 µg/mL). Similarly, the reducing sugars produced from the cellulase hydrolysis of rice straw pretreated with F. verticillioides cutinase were reduced by 63.5 µg/mL relative to the control (253.6 µg/mL). Scanning electron microscopy results showed that numerous tuberculate or warty protrusions were present nearly everywhere on the surface of rice straw treated with F. verticillioides cutinase, and some protrusions even covered and blocked the stomata of the rice straw surface. Current limited data indicate that F. verticillioides cutinase might not be an appropriate choice for improving the utilization of agricultural straws.

N4-methylcytidine ribosomal RNA methylation in chloroplasts is crucial for chloroplast function, development, and abscisic acid response in Arabidopsis.

Although the essential role of messenger RNA methylation in the nucleus is increasingly understood, the nature of ribosomal RNA (rRNA) methyltransferases and the role of rRNA methylation in chloroplasts remain largely unknown. A recent study revealed that CMAL (for Chloroplast mr aW- Like) is a chloroplast-localized rRNA methyltransferase that is responsible for N4-methylcytidine (m4 C) in 16S chloroplast rRNA in Arabidopsis thaliana. In this study, we further examined the role of CMAL in chloroplast biogenesis and function, development, and hormone response. The cmal mutant showed reduced chlorophyll biosynthesis, photosynthetic activity, and growth-defect phenotypes, including severely stunted stems, fewer siliques, and lower seed yield. The cmal mutant was hypersensitive to chloroplast translation inhibitors, such as lincomycin and erythromycin, indicating that the m4 C-methylation defect in the 16S rRNA leads to a reduced translational activity in chloroplasts. Importantly, the stunted stem of the cmal mutant was partially rescued by exogenous gibberellic acid or auxin. The cmal mutant grew poorer than wild type, whereas the CMAL-overexpressing transgenic Arabidopsis plants grew better than wild type in the presence of abscisic acid. Altogether, these results indicate that CMAL is an indispensable rRNA methyltransferase in chloroplasts and is crucial for chloroplast biogenesis and function, photosynthesis, and hormone response during plant growth and development.

Physiological, Biochemical, and Transcriptomic Responses of Neolamarckia cadamba to Aluminum Stress.

Aluminum is the most abundant metal of the Earth's crust accounting for 7% of its mass, and release of toxic Al3+ in acid soils restricts plant growth. Neolamarckia cadamba, a fast-growing tree, only grows in tropical regions with acidic soils. In this study, N. cadamba was treated with high concentrations of aluminum under acidic condition (pH 4.5) to study its physiological, biochemical, and molecular response mechanisms against high aluminum stress. High aluminum concentration resulted in significant inhibition of root growth with time in N. cadamba. The concentration of Al3+ ions in the root tip increased significantly and the distribution of absorbed Al3+ was observed in the root tip after Al stress. Meanwhile, the concentration of Ca, Mg, Mn, and Fe was significantly decreased, but P concentration increased. Aluminum stress increased activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase from micrococcus lysodeiktic (CAT), and peroxidase (POD) in the root tip, while the content of MDA was decreased. Transcriptome analysis showed 37,478 differential expression genes (DEGs) and 4096 GOs terms significantly associated with treatments. The expression of genes regulating aluminum transport and abscisic acid synthesis was significantly upregulated; however, the genes involved in auxin synthesis were downregulated. Of note, the transcripts of several key enzymes affecting lignin monomer synthesis in phenylalanine pathway were upregulated. Our results shed light on the physiological and molecular mechanisms of aluminum stress tolerance in N. cadamba.

Long-Term Cd Exposure Alters the Metabolite Profile in Stem Tissue of Medicago sativa.

As a common pollutant, cadmium (Cd) is one of the most toxic heavy metals accumulating in agricultural soils through anthropogenic activities. The uptake of Cd by plants is the main entry route into the human food chain, whilst in plants it elicits oxidative stress by unbalancing the cellular redox status. Medicago sativa was subjected to chronic Cd stress for five months. Targeted and untargeted metabolic analyses were performed. Long-term Cd exposure altered the amino acid composition with levels of asparagine, histidine and proline decreasing in stems but increasing in leaves. This suggests tissue-specific metabolic stress responses, which are often not considered in environmental studies focused on leaves. In stem tissue, profiles of secondary metabolites were clearly separated between control and Cd-exposed plants. Fifty-one secondary metabolites were identified that changed significantly upon Cd exposure, of which the majority are (iso)flavonoid conjugates. Cadmium exposure stimulated the phenylpropanoid pathway that led to the accumulation of secondary metabolites in stems rather than cell wall lignification. Those metabolites are antioxidants mitigating oxidative stress and preventing cellular damage. By an adequate adjustment of its metabolic composition, M. sativa reaches a new steady state, which enables the plant to acclimate under chronic Cd stress.

Expression profiling of MADS-box gene family revealed its role in vegetative development and stem ripening in S. spontaneum.

Sugarcane is the most important sugar and biofuel crop. MADS-box genes encode transcription factors that are involved in developmental control and signal transduction in plants. Systematic analyses of MADS-box genes have been reported in many plant species, but its identification and characterization were not possible until a reference genome of autotetraploid wild type sugarcane specie, Saccharum spontaneum is available recently. We identified 182 MADS-box sequences in the S. spontaneum genome, which were annotated into 63 genes, including 6 (9.5%) genes with four alleles, 21 (33.3%) with three, 29 (46%) with two, 7 (11.1%) with one allele. Paralogs (tandem duplication and disperse duplicated) were also identified and characterized. These MADS-box genes were divided into two groups; Type-I (21 Mα, 4 Mß, 4 Mγ) and Type-II (32 MIKCc, 2 MIKC*) through phylogenetic analysis with orthologs in Arabidopsis and sorghum. Structural diversity and distribution of motifs were studied in detail. Chromosomal localizations revealed that S. spontaneum MADS-box genes were randomly distributed across eight homologous chromosome groups. The expression profiles of these MADS-box genes were analyzed in leaves, roots, stem sections and after hormones treatment. Important alleles based on promoter analysis and expression variations were dissected. qRT-PCR analysis was performed to verify the expression pattern of pivotal S. spontaneum MADS-box genes and suggested that flower timing genes (SOC1 and SVP) may regulate vegetative development.

Salt stress induces endoplasmic reticulum stress-responsive genes in a grapevine rootstock.

Grapevines, although adapted to occasional drought or salt stress, are relatively sensitive to growth- and yield-limiting salinity stress. To understand the molecular mechanisms of salt tolerance and endoplasmic reticulum (ER) stress and identify genes commonly regulated by both stresses in grapevine, we investigated transcript profiles in leaves of the salt-tolerant grapevine rootstock 1616C under salt- and ER-stress. Among 1643 differentially expressed transcripts at 6 h post-treatment in leaves, 29 were unique to ER stress, 378 were unique to salt stress, and 16 were common to both stresses. At 24 h post-treatment, 243 transcripts were unique to ER stress, 1150 were unique to salt stress, and 168 were common to both stresses. GO term analysis identified genes in categories including 'oxidative stress', 'protein folding', 'transmembrane transport', 'protein phosphorylation', 'lipid transport', 'proteolysis', 'photosynthesis', and 'regulation of transcription'. The expression of genes encoding transporters, transcription factors, and proteins involved in hormone biosynthesis increased in response to both ER and salt stresses. KEGG pathway analysis of differentially expressed genes for both ER and salt stress were divided into four main categories including; carbohydrate metabolism, amino acid metabolism, signal transduction and lipid metabolism. Differential expression of several genes was confirmed by qRT-PCR analysis, which validated our microarray results. We identified transcripts for genes that might be involved in salt tolerance and also many genes differentially expressed under both ER and salt stresses. Our results could provide new insights into the mechanisms of salt tolerance and ER stress in plants and should be useful for genetic improvement of salt tolerance in grapevine.

Zinc and Copper Enhance Cucumber Tolerance to Fusaric Acid by Mediating Its Distribution and Toxicity and Modifying the Antioxidant System.

Fusaric acid (FA), the fungal toxin produced by Fusarium oxysporum, plays a predominant role in the virulence and symptom development of Fusarium wilt disease. As mineral nutrients can be protective agents against Fusarium wilt, hydroponic experiments employing zinc (Zn) and copper (Cu) followed by FA treatment were conducted in a glasshouse. FA exhibited strong phytotoxicity on cucumber plants, which was reversed by the addition of Zn or Cu. Thus, Zn or Cu dramatically reduced the wilt index, alleviated the leaf or root cell membrane injury and mitigated against the FA inhibition of plant growth and photosynthesis. Cucumber plants grown with Zn exhibited decreased FA transportation to shoots and a 17% increase in toxicity mitigation and showed minimal hydrogen peroxide, lipid peroxidation level with the increased of antioxidant enzymes activity in both roots and leaves. Cucumber grown with additional Cu absorbed less FA but showed more toxicity mitigation at 20% compared to with additional Zn and exhibited decreased hydrogen peroxide level and increased antioxidant enzymes activity. Thus, adding Zn or Cu can decrease the toxicity of the FA by affecting the absorption or transportation of the FA in plants and mitigate toxicity possibly through chelation. Zn and Cu modify the antioxidant system to scavenge hydrogen peroxide for suppressing FA induction of oxidative damage. Our experiments could provide a theoretical basis for the direct application of micro-fertilizer as protective agents in farming.

Valorization of Hemp Core Residues: Impact of NaOH Treatment on the Flexural Strength of PP Composites and Intrinsic Flexural Strength of Hemp Core Fibers.

Hemp core is a lignocellulosic residue in the production chain of hemp strands. Huge amounts of hemp core are gathered annually in Europe (43,000 tons) with no major application end. Such lignocellulosic wastes have potential as filling or reinforcing material to replace synthetic fibers and wood fibers in polymer composites. In this study, hemp core biomass was treated under different NaOH concentrations and then defibrated by means of Sprout Waldron equipment to obtain single fibers. Polypropylene matrix was reinforced up to 50 wt.% and the resulting hemp core fibers and the flexural properties were investigated. The results show that the flexural strength of composites increased with the intensity of NaOH treatment. The effect of NaOH was attributed to the removal of extractives and lignin in the fiber cell wall leading to improved interfacial adhesion characteristics. Besides, a methodology was established for the estimation of the intrinsic flexural strength of hemp core fibers. The intrinsic flexural strength of hemp core fibers was calculated to be 940 MPa for fibers treated at 10 wt.% of NaOH. In addition, a relationship between the lignin content and the intrinsic strength of the fibers was established.

Heterologous Expression of a Glycine soja C2H2 Zinc Finger Gene Improves Aluminum Tolerance in Arabidopsis.

Aluminum (Al) toxicity limits plant growth and has a major impact on the agricultural productivity in acidic soils. The zinc-finger protein (ZFP) family plays multiple roles in plant development and abiotic stresses. Although previous reports have confirmed the function of these genes, their transcriptional mechanisms in wild soybean (Glycine soja) are unclear. In this study, GsGIS3 was isolated from Al-tolerant wild soybean gene expression profiles to be functionally characterized in Arabidopsis. Laser confocal microscopic observations demonstrated that GsGIS3 is a nuclear protein, containing one C2H2 zinc-finger structure. Our results show that the expression of GsGIS3 was of a much higher level in the stem than in the leaf and root and was upregulated under AlCl3, NaCl or GA3 treatment. Compared to the control, overexpression of GsGIS3 in Arabidopsis improved Al tolerance in transgenic lines with more root growth, higher proline and lower Malondialdehyde (MDA) accumulation under concentrations of AlCl3. Analysis of hematoxylin staining indicated that GsGIS3 enhanced the resistance of transgenic plants to Al toxicity by reducing Al accumulation in Arabidopsis roots. Moreover, GsGIS3 expression in Arabidopsis enhanced the expression of Al-tolerance-related genes. Taken together, our findings indicate that GsGIS3, as a C2H2 ZFP, may enhance tolerance to Al toxicity through positive regulation of Al-tolerance-related genes.