Soil salinity leads to a reduction in plant growth, germination, relative water content, and production of wheat plants worldwide. Chitosan showed a positive effect on plant growth and development and improved plant stress tolerance. The current study aimed to examine the effect of different chitosan concentrations on the gamma-aminobutyric acid (GABA) shunt pathway in germinating seeds of wheat (Triticum durum L.) under salt stress (25 - 200 mM NaCl). We determined the seed germination pattern, seed moisture content, GABA shunt metabolites (GABA, glutamate, and alanine), oxidative damage in terms of malondialdehyde (MDA) accumulation, and the glutamate decarboxylase (GAD) mRNA transcription. Pre-treatment of wheat seeds with chitosan improved germination by enhancing germination percentage, seedling length, and seedling fresh and dry masses under salt stress. Data showed an increase in GABA shunt and their metabolites (alanine and glutamate), MDA content, and GAD mRNA transcription, and a decrease in germination percentage, seedling length, seedling fresh and dry masses for both untreated and chitosan-treated seeds under salt stress. Our results suggest that the elevation of GABA in chitosan-treated seeds was able to maintain metabolic stability under salt stress. The MDA content increased in chitosan-treated seeds as NaCl concentration increased, however, the increase was slightly lower than the MDA content in untreated seeds which confirmed that chitosan activates GAD mRNA expression that leads to activate GABA shunt to involve in the reduction of membrane damage and activation of reactive oxygen species scavenging systems under salt stress. Consequently, this study demonstrated that chitosan significantly enhanced the accumulation of GABA and amino acids metabolism to maintain the C:N balance and improved salt tolerance in wheat seeds during seed germination.

In order to produce human lactoferrin (Lf) in alfalfa (Medicago sativa L.), a construct containing human Lf cDNA under the control of cauliflower mosaic virus 35S promoter was engineered. As selectable marker bar gene, whose expression in plant cells confers tolerance to L-phosphinothricin (ppt) was used. Plants from a highly embryogenic alfalfa clone from the Bulgarian cultivar Obnova 10 were transformed using Agrobacterium tumefaciens mediated leaf disc method. Transgenic alfalfa plants were established from ppt-resistant calli via indirect somatic embryogenesis. The presence of human Lf cDNA in the genome of the selected regenerants was confirmed by polymerase chain reaction (PCR). Reverse transcriptase (RT)-PCR and Western blot showed expression of human Lf in leaf tissue. Studies on antibacterial effect of the recombinant glycoprotein were conducted and resistance of the transgenic alfalfa plants to two phytopathogens, Pseudomonas syringae pv. syringae and Clavibacter michiganensis, was demonstrated. The obtained results suggest that the expression of human Lf in alfalfa could be beneficial not only for producing recombinant protein for clinical application but also for crop quality improvement.

It has been hypothesized that xylanase inhibitors play important roles in plant defense against microbial pathogens. Currently, there is little information available about xylanase inhibitor OsXIP in rice and its gene expression. We cloned a xylanase inhibitor gene OsXIP from rice (Oryza sativa L. cv. Nipponbare) genomic DNA. To determine the function of OsXIP, we generated OsXIP-overexpressing transgenic rice plants. The transgenic plants had significantly higher OsXIP expression and showed enhanced defense response to Magnaporthe oryzae compared to the wild-type plants. The results also showed that the increased OsXIP expression was accompanied by the up-regulation of pathogenesisrelated genes. To clarify the OsXIP expression pattern, a ProOsXIP::GUS vector was constructed and transgenic plants were obtained. GUS staining results revealed that OsXIP showed organ-specific expressions in rice plants. OsXIP was primarily expressed in the roots and in the veins, but it was weakly expressed in the leaves. Analyses of the OsXIP expression in response to biotic and abiotic stresses indicated that it was drastically induced by biotic stresses and methyl jasmonate treatment. OsXIP, a member of a new class of antifungal proteins, may function as a barrier that prevents the cell wall degradation by xylanases excreted by fungal pathogens. The OsXIP was found to be a stressresponsive gene and it could take part in plant defense via a JA-mediated signaling pathway.

The MYB transcription factor superfamily is a large gene family that plays central roles in developmental processes and defence responses in plants. Unlike in Arabidopsis, only few members of the R2R3-MYB gene family have been functionally well characterized in maize, especially in abiotic stress-response pathways. Subgroup-specific conserved motifs outside the MYB domain may reflect functional conservation. A comparative genomics study using Arabidopsis abiotic stress-responsive MYB protein sequences identified 46 ZmMYB genes that may be involve in abiotic stress responses of Zea mays. An expression pattern analysis of the 46 ZmMYB genes under abiotic stress treatments was used to identify 22 MYB genes that were induced by one or more of the stress treatments. ZmMYB30 was highly upregulated under the four stress treatments. The ectopic expression of ZmMYB30 in transgenic Arabidopsis plants promoted salt-stress tolerance and also increased the expression of a number of abiotic stress-related genes, allowing the plants to overcome adverse conditions.

Gibberellin 2-oxidases (GA2oxs) irreversibly convert bioactive gibberellins (GAs) and their immediate precursors into inactive GAs via 2-β hydroxylation and so regulate gibberellin content in plants. However, to the best of our knowledge, little has been known about the GA2oxs and its function in cool season turfgrass Poa pratensis. In this study, rapid amplification of cDNA end (RACE) was employed to isolate PpGA2ox from P. pratensis. The open reading frame of PpGA2ox was 1 047 bp in length, corresponding to 348 amino acids. PpGA2ox was localized in both nucleus and cytoplasm. The expression of PpGA2ox could be up-regulated by 10 μM gibberellic acid, 5 μM methyl jasmonate, or 10 μM indole-3-acetic acid. In addition, its native promoter could drive GUS expression in both leaf apex and shoot apical region. Moreover, overexpression of PpGA2ox in Arabidopsis led to GA-deficiency leading to dwarf phenotype, delayed flowering time, and increased chlorophyll content. Our study suggests that PpGA2ox could be a candidate gene for breeding new cultivars of P. pratensis.

WHIRLY transcription factors play critical roles in responses to biotic and abiotic stresses, but their other biological functions remain unclear. In this study, SlWHY2, a member of the WHIRLY family, was isolated from Solanum lycopersicum. The role of SlWHY2 was studied using transgenic tobacco plants. Real-time quantitative polymerase chain reaction analysis showed that SlWHY2 expression was induced by polyethylene glycol, NaCl, salicylic acid, hydrogen peroxide, and bacterial pathogens. SlWHY2 overexpression in tobacco caused enhanced tolerance to drought stress, as indicated by lower accumulation of malondialdehyde and relative electrolyte leakage, as well as higher relative water content and activities of superoxide dismutase and ascorbate peroxidase. Moreover, higher expression of cytochrome oxidase 1 (NtCOX1) and open reading frame 1 (NtORF1) were observed under drought in the transgenic lines. This suggested that overexpression of SlWHY2 enhanced tolerance to drought stress by regulating the transcription of mitochondrial genes and stabilizing mitochondrial function. Transgenic tobacco also displayed greater resistance to Pseudomonas solanacearum infection as evidenced by lower reactive oxygen species content and higher expression of defence-related genes. Overall, these findings suggest that SlWHY2 acts as a positive regulator in response to biotic and abiotic stresses.

The miR171 is a conserved microRNA (miRNA) family and has been shown to participate in plant growth and development. However, the precise function of miR171 in Pinus densata remains largely unclear. Mature miR171 sequence comparison reveals high similarity between Arabidopsis thaliana and P. densata and the pre-miR171 could fold into a characteristic stem-loop hairpin structure. Genes encoding GRAS (GAI-RGA-SCR) family transcription factors and actin binding protein were identified as targets of pde-miR171 using a modified RNA ligase mediated 5' rapid amplification of cDNA ends (RLM-RACE). Furthermore, the interaction between pde-miR171 and Arabidopsis SCL6 (SCARECROW-LIKE6) was further validated through transient co-expression of both genes in Nicotiana benthamiana leaves. Next, results of real-time quantitative PCR demonstrated that the expression of pde-miR171 was significantly up-regulated in miR171-overexpressing plants than in wild-type plants, which was inversely correlated with the expression of Arabidopsis SCL6 genes. In addition, overexpression of pde-miR171 in Arabidopsis induced larger leaves and earlier flowering under long-day conditions compared with the wild type. The findings presented here suggest that miR171 derived from a P. densata precursor together with its target gene SCL6 may play important roles in the regulation of primary root growth, leaf shape, and flowering time in plants.

Various ecophysiological investigations on carnivorous plants in wet soils are presented. Radial oxygen loss from roots of Droseraceae to an anoxic medium was relatively low 0.02 - 0.07 μmol(O₂) m^{- 2} s^-1 in the apical zone, while values of about one order of magnitude greater were found in both Sarracenia rubra roots and Genlisea violacea traps. Aerobic respiration rates were in the range of 1.6 - 5.6 μmol kg^-1 (f.m.) s^-1 for apical root segments of seven carnivorous plant species and 0.4 - 1.1 μmol kg^-1 (f.m.) s^-1 for Genlisea traps. The rate of anaerobic fermentation in roots of two Drosera species was only 5 - 14 % of the aerobic respiration. Neither 0.2 mM NaN₃ nor 0.5 mM KCN influenced respiration rate of roots and traps. In all species, the proportion of cyanide-resistant respiration was high and amounted to 65 - 89 % of the total value. Mean rates of water exudation from excised roots of 12 species ranged between 0.4 - 336 mm 3 kg^-1 (f.m.) s^-1 with the highest values being found in the Droseraceae. Exudation from roots was insensitive to respiration inhibitors. No significant difference was found between exudation rates from roots growing in situ in anoxic soil and those kept in an aerated aquatic medium. Carnivorous plant roots appear to be physiologically very active and well adapted to endure permanent soil anoxia.

The NAC (NAM, ATAF1/2, and CUC2) transcription factor family participates in responses to various kinds of environmental stimuli in plants. However, the roles of NAC protein in cold resistance, especially in the cold resistance of tomatoes, are not completely understood. This study examined the roles of a tomato (Solanum lycopersicum) NAC transcription factor (SlNAC35) in resisting chilling using transgenic tomatoes. GUS staining and expression analysis revealed that SlNAC35 expression was induced at 4 °C, thereby suggesting its involvement in plant responses to chilling stress. Moreover, transgenic lines over-expressing SlNAC35 exhibited high chlorophyll content, fresh mass, and low accumulation of reactive oxygen species and membrane damage under chilling stress. These results indicated that SlNAC35 overexpression enhanced the chilling tolerance of transgenic tomatoes. High expressions of cold tolerance markers SlCOR518 and SlCOR413IM1 were observed under chilling stress in transgenic lines. This observation suggested that SlNAC35 overexpression enhanced the chilling tolerance of transgenic lines by involving the c-repeat binding factor-cold stress response (CBF-COR) signaling pathway and by regulating SlCOR expression.

Sulphur (S) is incorporated into diverse primary and secondary metabolites that play important roles in proper growth and development of plants. In cereals, a fraction of the nitrogen (N) accumulated in developing grains is guaranteed by amino acid remobilization from vegetative tissues, a contribution that becomes critical when soil nutrients are deficient. Glutamine synthetase (GS) and amino acid transporters (AAT) are key components involved in N assimilation and recycling. The aim of the present study was to evaluate the effect of S availability on the expressions of HvGS and several selected HvAAT genes in barley plants and on the phloem exudation rate of amino acids. To this end, two independent experiments were designed to impose low S availability conditions to barley plants. Low S availability caused a decrease in the phloem exudation rate of amino acids as well as in the gene expression of all the HvGS genes and five of the six HvAAT genes analyzed. The strong correlation found between the phloem amino acid exudation rate and HvGS1-1, HvGS1-2, HvAAP7, and HvProT1 gene expression may indicate the participation of these genes in the regulation of amino acid remobilization through the phloem.

Sunflower broomrape (Orobanche cumana Wallr.) is considered a self-fertilizing species, but there is no indication as to whether it is strictly self-fertilized or that it presents some extent of cross-fertilization. The objective of this research was to measure the rate of cross-fertilization in O. cumana using an unpigmented recessive mutant as a visual marker. A pot and a field experiment in which single unpigmented plants were surrounded by a large number of pigmented plants were conducted. Occurrence of F₁ hybrids, readily distinguishable from unpigmented plants in the progenies of unpigmented plants provided a direct measurement of the cross-fertilization rate. Progenies of unpigmented plants contained 21.5 % of F₁ hybrids in the pot experiment and 28.8 % in the field experiment. The results revealed that O. cumana is a partially allogamous species, which has great relevance for understanding the genetic structure and dynamics of populations and, ultimately, race evolution in this parasitic plant.

Long-term low temperatures restrict the regrowth of winter wheat (Triticum aestivum L.), thus decreasing agricultural output. Non-enzymatic expansins, which are related to plant growth, have been reported to respond to drought, salinity, and low-temperature stress. We obtained an expansin 3 gene, TaEXPA9. It is located in winter wheat cv. Dongnong with high cold hardiness. We analyzed the expression patterns of TaEXPA9-A/B/D in this cultivar and conducted a subcellular localization analysis of TaEXPA9-A/B/D in the onion epidermis. Transgenic Arabidopsis thaliana line with EXPA9-A/B/D overexpression was obtained to examine the effects of the orthologous genes of these expansins on plant growth and low-temperature stress resistance. The results showed that EXPA9-A/B/D expression significantly increased at 4 °C, it was higher in the roots than in shoots, and EXPA9-A/B/D was localized in the cell wall. The roots were well-developed in the transgenic A. thaliana, and the growth-related markers and setting rate were better than in the wild-type. Recovery was stronger in the transgenic plants after freezing stress. At low-temperature stress, the antioxidant enzyme activities and content of osmoregulatory substances in the TaEXPA9-A/B/D-overexpressing A. thaliana plants were significantly higher than in the wild-type plants, and the degree of membrane lipid peroxidation was lower. In summary, TaEXPA9 orthologous genes participate in the low-temperature stress response, and they might be of great importance in molecular breeding.

In this study, the total and actual nitrate reductase (NR) activity, and NR activation state, in tomato seedlings (Solanum lycopersicum cvs. Kmicic and Faworyt) treated with okadaic acid (OA) was evaluated. Seedlings were grown in a half-strength Murashige and Skoog (MS) medium in a growth chamber at day/night temperatures of 22/20 °C, a photon flux density of 150 µmol m^-2 s^-1, and a 16-h photoperiod. After 10 days, plants were transferred into MS medium with 0 (control), 0.01, 0.05, 0.1, 0.5, 1.0 µM OA. It was found that the total and actual NR activity increased in Kmicic leaves treated with 0.1, 0.5, and 1.0 µM OA compared to control. However, the NR activation state did not change in both roots and leaves of OA-treated tomato seedlings.

The effects of nitric oxide (NO) and/or iron (Fe) supplied to Fe deficient plants have been investigated in peanut (Arachis hypogaea L.) grown in Hoagland nutrient solution with or without Fe. Two weeks after Fe deprivation, recovery was induced by addition of 250 μM sodium nitroprusside (SNP, a NO donor) and/or 50 μM Fe (Fe-EDTA) to the Fe deprived (-Fe) nutrient solution. Activities of antioxidant enzymes, leaf chlorophyll (Chl), and active Fe content decreased, whereas activities of H⁺-ATPase, ferric-chelate reductase (FCR), nitrate reductase, and nitric oxide synthase and NO production increased in Fe deficient plants, consequently an Fe chlorosis symptom appeared obviously. In contrast, these symptoms disappeared gradually after two weeks with NO and/or Fe supply, which caused an increases in leaf Chl and active Fe content, especially following by co-treatment with NO and Fe to values found in Fe sufficient plants. Increased activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and decreased accumulation of reactive oxygen species (H₂O₂, O₂^*- ) and malondialdehyde enhanced the ability of resistance to oxidative stress. Supplied NO alone had the obvious effect on increased NO production and on activity of H⁺-ATPase and FCR, whereas root length and root/shoot ratio were most effectively increased by Fe supplied alone. Co-treatment with NO and Fe did the best effects on recovery peanut chlorosis symptoms by significantly increased Chl and available Fe content and adjusted distribution of Fe and other mineral elements (Ca, Mg, and Zn) in both leaves and roots.

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.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) serves not only as a key enzyme in glycolysis, but also as a multifunctional protein in other biological processes, especially in response to abiotic stresses in plants. Cytosolic GAPDH (GAPC) is a typical redox protein with selected catalytic cysteine, which undergoes reversible redox post-translational modifications (RPTMs) on its thiol group by reacting with hydrogen peroxide and nitric oxide related species. Moreover, the modified GAPC may interact with certain signal transmitters such as phosphatidic acid, phospholipase D, and osmotic stress-activated protein kinase. All these observations suggest that GAPC serve as a key mediator in redox signal transduction in plants. In this review, we provide an up-to-date insight into molecular mechanisms after H₂O₂- and NO-dependent oxidation of GAPC. We also discuss GAPC catalytic functions and potential functions as a modified protein by RPTMs.

Woody plants faced multiple abiotic stresses in forest plantation that can influence their growth and development. Dalbergia odorifera T. Chen is a vulnerably endangered tree species, and references about its responses to abiotic stresses are very rare in literature. Furthermore, the mechanisms underlying the abiotic stress tolerance in plants induced by exogenous glycine betaine (GB) remains unclear. Indeed, the alternative oxidase (AOX) is one of the major components of antioxidant enzymatic machinery, and there are no studies that focused on the effects of GB on the amount of AOX protein in plants under drought or cold stresses. Thus, the aim of this study was to investigate the effect of exogenous GB on the phenotype, osmoprotectants, photosynthetic pigments, and antioxidant systems in D. odorifera under cold and drought stresses. The layout of the trial was a factorial experiment in a completely randomized design using two factors including abiotic stress (drought and cold) and GB. Moreover, the principal component analysis based on the measured parameters manifested how the selected ROS scavengers were dispersed throughout the treatments. The results showed huge beneficial impacts of GB on the phenotypic traits of D. odorifera; GB also influences positively the antioxidant machinery, photosynthetic pigments, redox-homeostasis, and water status in D. odorifera seedlings under both stresses. Moreover, exogenous GB affects more the AOX pathway in D. odorifera under cold stress than under drought stress.

Midvein is an important structure of the upright leaf of rice, and its normal development is essential to the formation of a common plant type of rice (Oryza sativa L.). To reveal the effect of midvein deficiency on photosynthesis-related characteristics, leaf microstructure, and vein characteristics, the photosynthetic features between the midvein-deficient mutant dl-14 and wild-type Huanghuazhan plants were analyzed. The results indicated that the midvein area of the dl-4 mutant lacked large intercellular space and instead it was filled with mesophyll cells. Moreover, the vein density of the dl-14 mutant was significantly higher than that in cv. Huanghuazhan. Chlorophyll (Chl) a, Chl b, and carotenoid content were markedly elevated in dl-14. In terms of photosynthetic characteristics, we observed that under high irradiance and high CO₂ concentration, the net photosynthetic rate of dl-14 plants was significantly higher than that of Huanghuazhan plants, but its water use efficiency was significantly lower. In addition, several major photosynthetic parameters, including characteristics of chlorophyll fluorescence (the efficiency of excitation capture of open PS II center, photochemical quenching, effective quantum yield of PS II photochemistry, and electron transfer rate) were significantly higher in dl-14 plants compared to Huanghuazhan plants, but the nonphotochemical quenching of dl-14 mutant was significantly lower than that of Huanghuazhan. These findings indicate that the dl-14 mutant has higher vein density, stronger photon conversion ability, and weaker radiation dissipation ability. This study can provide theoretical support for breeders to use the midvein-deficient mutant.

To reveal the regulation mechanism of terpenoid biosynthesis in the leaves of Eucalyptus camaldulensis, the content of volatiles in eucalyptus leaves and the transcriptome databases of young and mature leaves were analyzed. The results showed that E. camaldulensis contains 92 and 89 kinds of volatile substances in the young and mature leaves, respectively. Among them, the content of 1,8-cineole, β-pinene, and other substances was significantly different in young and mature leaves. A total of 99 802 unigenes were obtained from the transcriptome database of young and mature leaves of E. camaldulensis and 18 441 genes displayed obviously differential expressions during both developmental stages. There were 6 982 up-regulated unigenes and 11 461 down-regulated unigenes in the young leaf stage compared to the mature leaf stage. The key genes for terpenoid biosynthesis, including limonene synthase-10, limonene synthase-11, myrcene synthase-1, α- pinene synthase-2, and 1,8-cineole synthase-2, were selected for further analysis to explore the mechanism of gene regulation and genetic transformation. The expressions of key genes were validated by RT-qPCR, and their expressions were consistent with RNA-seq data. WRKY, MYB, NAC, and bHLH transcription factors (TFs) displayed important regulatory effects on the above key genes. Thus, a regulatory network model of terpenoid biosynthesis was constructed using target genes and TFs during leaf development in E. camaldulensis. These results provide theoretical evidence for understanding the terpenoid biosynthesis in plants and reference for terpenoids utilization by genetic engineering methods in E. camaldulensis.

Calcium is a critical component in a number of plant signal transduction pathways and the calcineurin B-like protein (CBL) family is a unique group of calcium sensors regulating a family of CBL-interacting protein kinases (CIPKs). In this study, two poplar CBL genes, PeCBL6 (GenBank acc. No. DQ907710) and PeCBL10 (GenBank acc. No. DQ899956), were characterized in transgenic Arabidopsis thaliana, particularly with regard to its role in abiotic stress resistance. Expression of the two CBL genes in poplar was induced by cold, drought, or high salinity, but not by abscisic acid (ABA) treatment. In Arabidopsis thaliana, PeCBL6 was found in the nucleus and PeCBL10 in the tonoplast. Transgenic Arabidopsis plants overexpressing PeCBL6 or PeCBL10 showed enhanced tolerance to high salinity, drought and low temperature. These results suggested that PeCBL6 and PeCBL10 may function as positive regulators of salt, drought and temperature responses.

Biochemical and transcriptional approaches can provide crucial evidence about the physiological changes which can occur in organic and conventional cultivated common orange [Citrus sinensis (L.) Osbeck]. This study aimed to investigate the change in physicochemical parameters, the concentrations of free amino acids and other N-containing compounds, and the expressions of key genes coding for enzymes linked to N assimilation in fruits of common orange cv. "Valencia Late". Two enzymes involved in different ways in N assimilation were considered: nitrate reductase (NR), catalyzing the conversion of nitrate into nitrite, and glutamate dehydrogenase (GDH), operating in the assimilation of ammonium (interacting with glutamate synthase), and in ammonium re-assimilation through glutamate deamination. Results showed that the different fertilizers did not affect the physicochemical characteristics of fruits but induced the different accumulation of free amino acids, with higher concentrations of proline and contemporarily lower concentrations of glutamate, in addition to upregulated the expression of GDH gene in fruits from organically managed tress. This study identified a possible adaptive response of common orange plants to organic or conventional fertilizers. The present work is intended as a first step to make the mechanisms underlying plant responses to N supply clearer by comparing organic and conventional cultivation. It also can support breeders to select the best citrus cultivars and agronomists to improve crop fertilization and production management.

Late embryogenesis abundant (LEA) proteins are important for promoting the growth and stress tolerance of plants. They are widely involved in plant growth regulation and responses to hormones and environmental factors. However, knowledge of the functions of the LEA gene in ginseng species remains limited. In this study, a Panax ginseng LEA gene (PgLEA) expression vector was constructed, and stable transgenic Arabidopsis lines were established. The PgLEA protein was classified in the LEA-2 subgroup. Reverse-transcription quantitative PCR analysis showed that the expression of PgLEA increased under 300 mM NaCl or 10 % (m/v) polyethylene glycol treatments. Under salt and osmotic stresses, overexpression of PgLEA in transgenic Arabidopsis plants improved germination rate, root length, and survival rate compared to wild-type plants. In response to drought or salt stress, transgenic plants increased proline accumulation, decreased malonaldehyde content and ion leakage. Furthermore, the transgenic plants exhibited significantly increased activity of superoxide dismutase, peroxidase, and catalase, and reduced accumulation of hydrogen peroxide and superoxide. Moreover, overexpression of PgLEA affected the expression of genes related to salt/drought stress. Taken together, PgLEA is a positive regulator of drought and salinity stress, and positively functioned in pleiotropic effects through regulating osmotic balance, reactive oxygen species scavenging and inducing transcription of stress-related genes. PgLEA may enable ginseng plants to adapt to adverse environments. The data presented herein imply that PgLEA may be useful for breeding new stress-tolerant ginseng cultivars.

Trehalose is a nonreducing disaccharide that is involved in the regulation of plant responses to a variety of environmental stresses. Trehalose 6-phosphate synthase (TPS) and trehalose 6-phosphate phosphatase (TPP) are two key enzymes in trehalose synthesis and they are widely distributed in higher plants. At present, TPS family genes have been systematically identified and analyzed in many plant species, but the TPP family genes have been rarely studied. In this study, ten TPS and six TPP genes in cannabis (Cannabis sativa L.) were identified at the genomic level. The phylogenetic tree of TPS and TPP family members in cannabis, Arabidopsis, and rice was constructed, and all the genes were divided into three subgroups: Class I, Class II, and Class III. The number of exons and motif types among Class I members was exactly the same, as were Class II members, but the gene structure and motif types of Class III members were slightly different. There were four pairs of CsTPSs and CsTPPs that had gene duplication, indicating that gene duplication events played an important role in the amplification of TPS and TPP families in cannabis. The results of expression analysis under abiotic stresses showed that 68.75 % of CsTPS and CsTPP genes were significantly induced by at least one abiotic stress. Among these genes, the expression of CsTPS1, CsTPS9, and CsTPPA was highest under at least one abiotic stress. These three genes may play a key role in abiotic stress responses. Most of the CsTPS and CsTPP genes that are closely located in the evolutionary tree have the same or similar functions. To our knowledge, this is the first paper that systematically reports the TPS and TPP gene families in cannabis.

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.

Thioredoxins (Trx) are small multifunctional redox proteins that contain thioredoxin conserved domain and active site WCXXC. The Trx family has an important role in multiple processes, including electron transport, seed germination, redox regulation, biotic and abiotic stresses resistance, etc. Although Trx genes have been extensively characterized in some plants, they have not been reported in peanut until now. The identification of AhTrx genes provides potential candidate genes for studying their effects and regulatory mechanisms in peanut (Arachis hypogaea L.) growth and development, especially under aluminium (Al) stress. It is also helpful to further analyze the Al resistance pathway in plants. Seventy AhTrx genes were identified using a genome-wide search method and conservative domain analysis. Then the basic physicochemical properties, phylogenetic relationship, gene structure, chromosomal localization, and promoter prediction were studied by the bioinformatic methods. Furthermore, the expressions of AhTrx genes under different Al treatment times in two peanut cultivars were tested using a real-time quantitative polymerase chain reaction. Seventy AhTrx genes were identified and characterized. Phylogenetic tree analysis showed that all AhTrx members could be classified into 9 groups with different conserved domains. Motif 1 was found to exist in every sequence, with an active site. Furthermore, the gene structures showed that the AhTrx family was complicated and changeable during evolution. The chromosomal localization indicated that the distribution and density of the Trx family on 20 peanut chromosomes were uneven. Predictive promoter analysis indicated that AhTrx proteins might play a role in phytohormones synthesis and stress response. Finally, the expression patterns of the AhTrx genes showed that every gene was differently expressed under Al treatment in different peanut cultivars, some were obvious, others had no significant difference, some were at a high level, while others were at a low level. This study systematically identifies the Trx gene family in peanut, providing some candidates for further study on its effects and regulatory mechanism under Al stress in peanut.

Cytokinins have been implicated in delaying leaf senescence. We previously generated transgenic cotton (Gossypium hirsutum L.) plants that harbor the Agrobacterium isopentenyl transferase gene (ipt) directed by a proteinase gene promoter. Here, we report that mRNAs were isolated from ipt cotton leaves and azygous leaves and were subsequently sequenced using Illumina Solexa technology. The sequence tags were searched against the TIGR database and the related gene expression profiles were compared resulting in the identification of 1 218 differentially expressed genes (DEGs): 719 up-regulated and 499 down-regulated. Analyzing the DEGs in the ipt cotton leaves showed that these genes belonged to four pathways: flavone biosynthesis, arginine and proline metabolism, glyoxylate and dicarboxylate metabolism, and RNA degradation. These pathways increased the activities of antioxidants, inhibited the effect of ethylene, and prevented degradation of macromolecules during senescence. The expression patterns of 17 genes were evaluated by real-time PCR and results were in agreement with the patterns of sequencing analysis. The identification of the DEGs may help us to understand a role of cytokinins in leaf senescence.

Proline, an amino acid, plays an important role in plants, and it is involved in stress resistance and development. Earlier, to study the proline role in maintaining stress resistance in plants, we obtained genetically modified transgenic lines of tobacco (Nicotiana tabacum L.) with reduced activity of proline dehydrogenase (PDH, the proline degradation gene) and increased content of proline. Transgenic tobacco plants demonstrated greater resistance to high concentrations of NaCl, drought, low temperatures, and heavy metals vs. control plants. The visual assessment showed that the leaf pubescence in transgenic plants varied noticeably. Here we apply automated analysis of the tobacco leaf folds to estimate quantitative characteristics of pubescence in genetically modified tobacco plants and the control SR1 line under non-stress conditions. Our results showed differences in the number of trichomes and their length between transgenic and control plants. The trichome number significantly increased in transgenic plants (from 1.5 to 3 times). The largest differences in the trichome numbers were observed for trichomes with lengths from 0 to 380 µm. When assessing the trichome length, the opposite was observed. In all three transgenic lines, the trichome length was significantly lower than that of the control SR1 line. The data obtained indicate the effect of proline as an important metabolome component affecting the plant phenotype. Our results demonstrate perspectives of tobacco transgenic lines as promising genetic models for studying the proline role in plant morphogenesis.

Drought and salinity, which can alter the water balance, disrupt the ionic equilibrium, and create reactive oxygen species (ROS), are capable of destroying plant tissues. In this study, transcriptomics, proteomics, and metabolomics have been used to elucidate various abiotic stress responses. In transcriptional signaling pathways, abscisic acid (ABA) is one of the plant phytohormones that regulate the stress response. On the other hand, several regulons and factors of transcription contributed in the reaction to osmotic stresses, as well as in ABA-dependent/independent signaling pathways. However, the findings display that intricate molecular reaction of plants under stress conditions may be controlled by complicated regulative networks of gene expression and signal transduction, as well as by the interaction between them. From the point of view of proteomics, protein modifications in response to stress can be considered as a molecular tool to improve the resistance of plants to environmental stresses. These studies have provided new information about the significance of several gene and protein networks involved in the response of plants to salinity and drought, and the induction of tolerance. Moreover, identifying the crucial pathways which are involved in salinity and drought resistance can open doors for the establishment of commercial-resistant crop cultivars, and might be very useful in the next-generation crop breeding strategies to produce plants with salinity and drought-resistant traits.

Paspalum fasciculatum Willd. ex Flüggé grows in mining soils which are Cd- and Pb-contaminated where it exhibits tolerance to Pb and the ability to extract Pb from these soils. To elucidate tolerance mechanisms to Pb-stress, liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used to quantify changes in the accumulation of proteins in leaves. We identified 323 proteins involved in primary metabolism and response to biotic or abiotic stresses. Although proteins involved in the processes of photosynthesis and saccharide and energy metabolism presented the greatest amount of down-regulated proteins, the plant was able to maintain photosynthetic functions and obtain energy to sustain the vital balance. P. fasciculatum based their tolerance on increased antioxidant defenses, improving the protection and repair of proteins and transduction signals to coordinate physiological response to Pb-stress. Our results provide important information to understand the tolerance mechanisms in P. fasciculatum and could be important in future molecular studies on the resistance and accumulation of Pb in plants.

Dehydration responsive element binding factor (DREB) is believed to be a stress-tolerance enhancer in plants. In the present study, a cold-binding factor (CBF)/DREB homologous gene NnDREB1 (XP_010242642.1) was isolated from lotus roots using rapid amplification of cDNA ends (RACE) and reverse transcription (RT)-PCR methods. Analysis of the deduced amino acid sequence and phylogeny classified NnDREB1 into the A-1 group of the DREB1 subfamily. Expression profiling using a quantitative PCR method revealed that NnRDEB1 was significantly induced by NaCl, mannitol, and polyethylene glycol, but not by low temperature and abscisic acid. To evaluate function of NnRDEB1, Arabidopsis thaliana was transformed with the NnDREB1 gene in a binary vector construct. The transgenic plants exhibited higher resistance to drought compared with the wild-type plants in terms of survival rates, dry and fresh masses, and chlorophyll content. In addition, overexpression of NnDREB1 resulted in higher germination rates compared with the wild type plants on MS medium containing mannitol. The expressions of downstream target stressrelated genes, including cold-regulated15B (COR15B), rare cold inducible 2B (RCI2B) and repeat domain 26 (RD26), were activated in the transgenic plants. Taken together, the results suggest that NnDREB1 might be an important protein in lotus root drought tolerance.