Ethylene response factor (ERF) is a key transcription factor of plant ethylene signaling pathway, which plays an important role in plant response to abiotic and biotic stresses by regulating the expression of downstream genes. However, little is known about the mechanisms of the regulation of gene expression by ERF proteins. Chloroplast is an essential organelle that is important for photosynthesis and biosynthesis of many essential metabolites. There exists an interaction between chloroplasts and the nucleus. Chloroplasts can send multiple kinds of signals to regulate the nuclear gene expression known as retrograde signaling. In our study, we have analyzed the expression of the components related to plastid retrograde signaling pathway to elucidate the mechanism of tomato ethylene responsive factor 1 (TERF1) in response to drought stress. Our results showed that TERF1 can regulate different biogenic and operational retrograde signals to regulate nuclear genes expression, which can improve plant tolerance to drought stress. We also propose a new potential of TERF1 in regulating nuclear gene expression, including regulation of different phytohormone signaling pathways and gene posttranscriptional modification triggered by different retrograde signals. Our results have enriched our knowledge about the function of ERF proteins and ethylene signaling pathway.

Growth responses of the moderately salt-tolerant velvet ash (Fraxinus velutina) and salt-sensitive poplar (Populus × euramericana) were investigated under heterogeneous root zone salinity. The salinity treatments imposed on the two root zones (lower-higher) were 137-137 (uniform), 103-171, 68-205, 34-239, and 0-273 mM NaCl for velvet ash, and 51-51 (uniform), 34-68, 17-85, and 0-103 mM NaCl for poplar. The leaf gas exchange of the plants was measured one month after these treatments were implemented, and the plants were sampled 75 d after treatment to measure other physiological parameters. Net photosynthetic rate, transpiration rate, total biomass, and fine root compensatory growth increased as the difference in salinity between the two root zones (i.e., salinity heterogeneity) increased in velvet ash. These parameters showed no significant difference among the treatments in poplar. The leaf Na⁺ content was lower under heterogeneous salinity than under uniform salinity in both tested species. The leaf proline content in velvet ash decreased under heterogeneous salinity compared to that under uniform salinity, whereas that of poplar increased. The soluble sugar content of velvet ash leaves increased under heterogeneous salinity, whereas no changes were observed in poplar. The increased fine root biomass in the lower salinity zone promoted velvet ash growth by decreasing the leaf Na⁺ and Cl^- content under heterogeneous salinity. The poplar's undifferentiated root distribution and gas exchange in response to the heterogeneous salinity were attributed to its salt sensitivity.

Crop plants are regularly exposed to an array of abiotic and biotic stresses, among them drought stress is a major environmental factor that shows adverse effects on plant growth and productivity. Because of this these factors are considered as hazardous for crop production. Drought stress elicits a plethora of responses in plants resulting in strict amendments in physiological, biochemical, and molecular processes. Photosynthesis is the most fundamental physiological process affected by drought due to a reduction in the CO₂ assimilation rate and disruption of primary photosynthetic reactions and pigments. Drought also expedites the generation of reactive oxygen species (ROS), triggering a cascade of antioxidative defense mechanisms, and affects many other metabolic processes as well as affecting gene expression. Details of the drought stress-induced changes, particularly in crop plants, are discussed in this review, with the major points: 1) leaf water potentials and water use efficiency in plants under drought stress; 2) increased production of ROS under drought leading to oxidative stress in plants and the role of ROS as signaling molecules; 3) molecular responses that lead to the enhanced expression of stress-inducible genes; 4) the decrease in photosynthesis leading to the decreased amount of assimilates, growth, and yield; 5) the antioxidant defense mechanisms comprising of enzymatic and non-enzymatic antioxidants and the other protective mechanisms; 6) progress made in identifying the drought stress tolerance mechanisms; 7) the production of transgenic crop plants with enhanced tolerance to drought stress.

The link between the MtTdp1α (tyrosyl-DNA phosphodiesterase) gene, involved in the repair of DNA topoisomerase I mediated DNA damage, and the plant defense response has been investigated in MtTdp1α-depleted Medicago truncatula transgenic lines obtained by intron-spliced hairpin RNA approach, compared to the control line (CTRL, empty vector). Reduction of cuticle permeability highlighted by chlorophyll efflux assays positively correlated with the level of MtTdp1α gene silencing. The increased cuticle thickness was confirmed by transmission electron microscopy, which revealed an apparent expansion of the epicuticular waxes deposited on the outer surface. RNA-Seq analysis, carried out in the MtTdp1α-depleted plants, revealed the different expression of resistance (R) genes, PAMP (pathogen-associated-molecular pattern) triggered immunity (PTI) genes and transcription factors (TFs) involved in the regulation of the plant defense response.

Responses of two muskmelon (Cucumis melo L.) genotypes (drought tolerant SC-15 and drought susceptible EC-564755) were analyzed at 0, 7, 14, and 21 d of progressive water stress. Although water deficit caused a significant decline in relative water content, the magnitude of reduction was lower in SC-15. Electrolyte leakage, hydrogen peroxide, and malonydialdehyde generation were higher in EC-564755, whereas accumulation of proline was higher in SC-15. Higher activities of antioxidant enzymes, such as catalase, superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and glutathione reductase, and higher expression of the respective genes were recorded in SC-15 than in EC-564755. Expressions of DREB2C and DREB3 in SC-15 revealed a fluctuating pattern with down-regulation on days 7 and 21 of water stress, whereas up-regulation was observed on day 14. Concurrently, both genes in EC-564755 showed continuous down-regulation on days 7, 14, and 21 of water stress. Expressions of RD22 and dehydrin recorded on days 7, 14, and 21 were lower in SC-15. The cluster analysis showed that, these two genotypes had a clear distinction in physiological and biochemical properties and gene expressions under water stress and the genotype SC-15 had more efficient osmoprotectant mechanism than genotype EC-564755 under water deficit conditions.

NAM, ATAF1/2, and CUC2 (NAC) proteins are plant-specific transcription factors playing essential roles in plant development and various abiotic stress responses. In the present study, we identified 173 full-length NAC genes in soybean, which were phylogenetically clustered into 15 groups (NACa - NACo). The soybean NAC genes (GmNACs) were non-randomly located across the 20 chromosomes, and 128 genes (86.5 %) were preferentially located in duplicated regions of chromosome arms, which implied long segmental duplication and contributed to evolution of the GmNAC gene family. Most GmNACs genes showed a distinct tissue-specific expression pattern and the redundant expression patterns of active duplicate genes suggested that GmNACs have been retained by substantial subfunctionalization during soybean evolution. Furthermore, active GmNACs genes that had undergone strong artificial selection during soybean domestication were identified based on selection analysis. After low nitrogen treatment, enhanced expression of some selected GmNAC genes were noticed in soybean shoot and root, which implied that GmNACs might play an important role in nitrogen metabolism. Here, we summarize the sequence and expression analysis of the NAC gene family in the soybean.

Genes encoding plant WRKY transcription factors are important for stress response. In the current study, two WRKY transcription factor genes (JrWRKY6 and JrWRKY53) were identified from walnut (Juglans regia L.), and their function and involvement in stress responses were characterized. Under NaCl stress, JrWRKY6 and JrWRKY53 were upregulated in a short time (within 6 h of seedling exposure to salt) except in roots, in which the highest induction occurred at 24 and 48 h of salt exposure. The gene expression patterns under polyethylene glycol stress were similar to those under NaCl stress. Under heat stress, both genes were induced in all tissues, except for JrWRKY6 in leaf tissue of seedlings treated for 24 and 48 h. Both genes were also induced in all plants exposed to cold stress, except for JrWRKY6 in root tissue of seedlings exposed for 6 h and JrWRKY53 in root tissue exposed for 48 h. JrWRKY6 and JrWRKY53 also showed varied responses to abscisic acid (ABA), with the maximum expression being for JrWRKY6 in the roots of plants treated for 1 h, and JrWRKY53 in the leaves of plants treated for 3 h. Furthermore, under NaCl, sorbitol, heat, cold, and ABA treatments, yeast cells transformed with JrWRKY6 and JrWRKY53 showed an improved growth activity and density relative to the empty-vector-containing control yeast. Moreover, JrWRKY6 or JrWRKY53 could bind to the W-box motif. These results suggest that JrWRKY6 and JrWRKY53 can response positively to abiotic stressors and improve the plant tolerance to salinity, osmotic stress, and abnormal temperatures in a mechanism that likely involves the ABA signalling pathway and W-box binding activity.

Elucidation of mechanisms underlying plant tolerance to cadmium, a widespread toxic soil pollutant, and accumulation of Cd in plants are urgent tasks. For this purposes, the pea (Pisum sativum L.) mutant SGECd^t (obtained by treatment of the laboratory pea line SGE with ethylmethane sulfonate) was reciprocally grafted with the parental line SGE, and four scion/rootstock combinations were obtained: SGE/SGE, SGECd^t/SGECd^t, SGE/SGECd^t, and SGECd^t/SGE. They were grown in hydroponics in the presence of 1 μM CdCl₂ for 30 d. The SGE and SGECd^t scions on the SGECd^t rootstock had a higher root and shoot biomass and an elevated root and shoot Cd content compared with the grafts having SGE rootstock. Only the grafts with the SGE rootstock showed chlorosis and roots demonstrating symptoms of Cd toxicity. The content of nutrient elements in roots (Fe, K, Mg, Mn, Na, P, and Zn) was higher in the grafts having the SGECd^t rootstock, and three elements, namely Ca, Fe, and Mn, were efficiently transported by the SGECd^t root to the shoot of these grafts. The content of other measured elements (K, Mg, Na, P, and Zn) was similar in the root and shoot in all the grafts. Then, the non-grafted plants were grown in the presence of Cd and subjected to deficit or excess concentrations of Ca, Fe, or Mn. Exclusion of these elements from the nutrient solution retained or increased differences between SGE and SGECd^t in growth response to Cd toxicity, whereas excess of Ca, Fe, or Mn decreased or eliminated such differences. The obtained results assign a principal role of roots to realizing the increased Cd-tolerance and Cdaccumulation in the SGECd^t mutant. Efficient translocation of Ca, Fe, and Mn from roots to shoots appeared to counteract Cd toxicity, although Cd was actively taken up by roots and accumulated in shoots.

Candidate gene association studies implicate the detection of contributing single nucleotide polymorphism (SNP) for the target traits and have been recommended as a promising technique to anatomize the complex characters in plants. ERECTA gene in plants controls different physiological functions. In this study, we identified SNPs in 1.1 kb partial sequences of TaER-1 and TaER-2 of wheat (Triticum aestivum L.). Thirty-nine SNPs were identified in the coding regions of TaER-1 gene in 33 wheat genotypes, of which 20 SNPs caused non-synonymous mutations while 19 SNPs produced synonymous mutations; while 31 SNPs were located in the coding regions of TaER-2 gene in 26 genotypes, of which 18 SNPs caused non-synonymous mutations and 13 SNPs caused synonymous mutations. In addition, 32 SNPs in TaER-1 and 9 SNPs in TaER-2 were also identified in the non-coding regions. Moreover, the significant genetic associations of SNPs of TaER-1 and TaER-2 genes with carbon isotope discrimination, stomatal conductance, photosynthetic rate, transpiration rate, intrinsic water use efficiency (iWUE), leaf length, leaf width, stomatal density, epidermal cell density, and stomatal index were noted in wheat genotypes. This study confirms the importance of TaER-1 and TaER-2 genes which could improve iWUE of wheat by regulating leaf gas exchange and leaf structural traits. These identified SNPs may play a critical role in molecular breeding by means of marker-assisted selection.

Superoxide dismutase is a crucial reactive oxygen species (ROS) scavenger and converts the superoxide radical (O₂^-) to H₂O₂, so it is thought to enhance abiotic stress tolerance by reducing ROS accumulation and so avoiding oxidative damage. In this study, we isolated a salt- and oxidative stress-responsive Cu/Zn SOD gene TaSOD5 from wheat. The ectopic overexpression of TaSOD5 in Arabidopsis increased total and Cu/Zn SOD activities, and offered the plant tolerance to salt stress. Arabidopsis ectopically expressing TaSOD5 possessed a superior resistance to oxidative stress induced H₂O₂. The TaSOD5 ectopic overexpression elevated the activities of both ROS scavengers and O₂^- producer NADPH oxidase. These findings show that Cu/Zn SOD enhances salt tolerance via regulating the machinery of redox homeostasis rather than improving SOD activity alone.

Annexins play a crucial role in plant development and response to environmental stimuli. In this study, a total of 23 annexin genes (GmANN1 - GmANN23) were identified from the soybean genome database and for two of them (GmANN11 and GmANN14), complete cDNAs were cloned. GmANN1 - GmANN23 encoded a set of predicted proteins which showed high similarity to other known annexins. Most GmANN genes contained four putative annexin repeats. Generally, a type II Ca²⁺-binding site is found to exist in the first and fourth repeats. GmANN1, 10, 11, 12, and 14 showed different organ-specific expression patterns. Furthermore, expression of these five GmANNs was significantly induced by drought and abscisic acid. Expression of four annexins (GmANN1, 11, 12, and 14) was induced by cold and expression of three annexins (GmANN1, 11, and 12) responded to high salinity.

Tissue/organ-specific promoters are important tools in genetic engineering and crop molecular breeding. They are well characterized in dicots, such as Arabidopsis, tobacco, and tomato, but not sufficiently in monocots, especially in wheat. In this study, the genes specifically expressed in seven different tissues, including coleoptile, root, leaf, pistil, anther, embryo, and endosperm were identified through analyzing the public transcriptome data from a wheat microarray using the ROKU method. The expression patterns of selected genes were validated by reverse transcription polymerase chain reaction. The results showed that these selected genes were expressed specifically or preferentially in each representative tissue/organ. Moreover, the function of their promoters was verified by transient expression in wheat or stable transformation in Arabidopsis. The results showed that these promoters can efficiently and predominantly drive uidA (β-glucuronidase) reporter gene expression in different tissues. Due to their tissue-specific nature, these promoters can be used as potential candidates in plant genetic engineering.

Gibberellic acid (GA) is a natural plant growth regulator (PGR) which stimulates germination, vegetative growth, flowering, and fruit formation. However, when high concentrations of GA are used, it inhibits plant growth and development and causes abnormalities in the plant tissue. In our study, we determined the effects of different concentrations of GA on Allium cepa L. var. cepa roots. Increasing concentrations of GA (50 - 5 000 mg dm^-3) were used in A. cepa root growth inhibition tests. Further, random amplified polymorphic DNA technique was used for determination of possible genotoxic effects of 600 - 1200 mg dm^-3 GA on A. cepa root tips. Our findings show cytotoxic and genotoxic effects of these concentrations of GA and indicate that the difference among control and treatment groups were statistically significant.

Arabidopsis thaliana L. ecotype Dijon-G (Di-G) showed a different symptom development during pathogenesis compared to ecotype Columbia-0 (Col-0). Previously, it has been shown that Di-G has a higher susceptibility to necrotrophic fungus Alternaria brassicicola than Col-0. In this study, Di-G showed enhanced disease susceptibility to necrotrophic fungi Botrytis cinerea, Sclerotinia sclerotiorum, and Sclerotium rolfsii known to secrete oxalic acid (OA) as a pathogenicity factor. Treatment with 50 and 100 mM OA resulted in a more leaf tissue collapse in Di-G than in Col-0. The OA also up-regulated expression of the salicylic acid (SA)-inducible pathogenesis-related gene 1 (PR1) and down-regulated expression of the jasmonic acid/ethylene-inducible defensin PDF1.2 gene in Di-G. By contrast, Di-G was resistant to hemibiotrophic fungus Colletotrichum higginsianum and biotrophic Turnip crinkle virus (TCV) infections. Application of 0.5 mM SA resulted in a higher accumulation of endogenous SA and in a preferential expression of SA-responsive genes in Di-G. Salicylic acid accelerated OA-triggered plant cell death and attenuated PDF1.2 expression in Di-G. These results suggest that the enhanced susceptibility of Di-G to necrotrophic pathogen infections might be mediated by attenuated JA-ethylene defence signalling and/or heightened SA-related defence signalling. Interaction of SA-signalling with OA secretion might be also involved in the enhanced susceptibility of Di-G.

Aquaporins control the specific transport of water and some other small molecules across membranes and are involved in various physiological processes. Plasma membrane aquaporins (PIPs) were shown to play an important role during tomato seed development. Therefore, we were interested in the participation of PIPs in seed germination and early seedling growth of wild type (WT) and the 7B-1 mutant, affected by blue light responses. We characterised the expression patterns of PIP-type aquaporin genes in these lines during different phases of seed germination and seedling growth after HgCl₂ (an aquaporin blocker) treatment. Further, we investigated whether blue radiation (BL) was involved in the regulation of these processes. Our experiments showed that 7B-1 mutant seed germination and root elongation are less responsive to HgCl₂ compared to WT. In both WT and 7B-1 mutant seeds, BL modulates the expression of PIP1;1 (upregulation) and PIP1;3 (downregulation) aquaporin isoforms. The PIP1;3 gene is downregulated not only by BL but also by HgCl₂ with a stronger effect in WT seeds. Thus, we show that BL can alter PIPs gene expression during tomato seed germination and seedling growth and that the 7B-1 mutation reduced the responsiveness to mercury blockage of aquaporins. Altogether, our data indicate that PIP aquaporins participate in tomato seed germination and radicle elongation and that the 7B-1 mutation and BL have an impact on these processes.

Bamboo possesses many unique physiological characteristics, but the molecular understanding of many of these processes remains poorly understood till to date. One major reason is unavailability of sufficient sequence and expression data. Selection of suitable reference genes is pivotal to initiate any gene expression analyses. Although, suitable reference genes have been identified in the temperate bamboo Phyllostachys edulis, it has not been done for tropical bamboo. In this study, expression stability of 10 candidate reference genes were investigated in 4 widely grown tropical bamboo species (Bambusa tulda, B. balcooa, B. bambos, and B. vulgaris), different organs (young leaves from flowering and non flowering culms, flag leaf (leaf just below the mature inflorescence), possible flag leaf (leaf covering the immature inflorescence), culm sheath, internode, root, rhizome, and inflorescence bud), different parts (basal, middle, and tip regions of leaf; internodes located in the basal, middle, and tip region of the branch, and developmental stages early, middle, and late inflorescence buds) by using 3 reliable computational tools (geNorm, NormFinder, and RefFinder). A universal single reference gene for normalization of gene expression data was not identified. However, the eukaryotic initiation factor 4α (eIF4α), clathirin adaptor complexes medium subunit (CAC), and nucleotide tract-binding protein (NTB) were found stable in the selected organs across different bamboo species. On the other hand, eIF4α ranked top when different organs and peptidyl prolyl cis-trans isomerase/cyclophilin (CYP), eukaryotic elongation factor 1α (eEF1α) and ubiquitin 5 (UBQ5) ranked top when different developmental stages of B. tulda were analyzed. Taken together, this study not only identifies reference gene/s that are stable across species, organs, and developmental stages of bamboo, but it also assesses the impacts of major contributing factors regulating expression stability of the reference genes.

Cassava storage roots serve as an outstanding source of starch that is commonly utilized for nourishment and industrial applications. Despite the extensive studies, which indicated diverse important roles of miRNAs as post-transcriptional regulators of gene expression, the potential contribution of microRNAs to storage root development in cassava are sparse. Here, we characterized the key miRNAs and auxin content in two main types of cassava roots, fibrous roots and storage roots. The differential expression pattern of miRNAs and their mRNA targets, miR164/NAC and miR167/ARF6, ARF8, revealed the correlation in storage root development. A higher content of indole-3-acetic acid was observed in storage roots in contrast with fibrous roots, and the possible role was discussed. Altogether, this first finding suggested the roles of miR164/miR167 in the molecular mechanism underlying cassava storage root development.

The roles of ethylene responsive factors (ERFs) and their positive and negative regulations of abiotic stress tolerance have been widely reported. This study reports the characterization of ItERF from Iris typhifolia Kitag with respect to molecular and functional properties. The 867 bp cDNA fragment of ItERF was cloned by reverse transcription PCR from I. typhifolia. Real-time quantitative PCR revealed that ItERF expression was induced in the roots, stems, and leaves of I. typhifolia after NaCl treatment, and that ItERF expressions were significantly higher in the leaves and roots than in the stems. A green fluorescent protein marker revealed that ItERF was located to the nucleus. Plant survival and root growth of ItERF transgenic Arabidopsis thaliana L. seedlings were much better than those of the wild type under NaCl stress. Malondialdehyde content in the transgenic lines was significantly lower than that in the wild type. Growth of yeast transformants showed an enhanced tolerance to salt stress than non-transformed yeast cells. All of the results verified that the expression of ItERF had effects on plant growth under salt stress.

Fusarium head blight caused by the hemibiotrophic fungus Fusarium graminearum is one of the most devastating diseases of wheat which reduces both grain yield and quality. To better understand mechanism underlying wheat resistance to this pathogen, the expressions of five candidate genes encoding phenylalanine ammonia-lyase (PAL), glucanase-2 (Gl 2), class IV chitinase (Cht-4), cytochrome P₄₅₀ (CYP₎, and pleiotropic drug resistance (PDR) following spike inoculation with F. graminearum was compared in susceptible cv. Falat and resistant cv. Sumai3 at three time points (48, 96, 144 h after inoculation). Real-time quantitative PCR analysis indicated earlier and greater inductions of PAL, Glu-2, and Cht-4 in spikes of 'Sumai3' as compared to 'Falat' in response to F. graminearum inoculation. The expression of CYP in the resistant 'Sumai3' was about three times higher than in 'Falat' at 144 h after pathogen inoculation. Moreover, soil drench application of sodium salicylate (SA) one day before pathogen inoculation drastically curtailed pathogen infection in both the cultivars. Furthermore, SA treatment caused an induction of these genes in spikes of the susceptible cultivar to show a similar pattern as in the resistant one when inoculated with F. graminearum. Proteomics analysis of F. graminearum treated spikes 96 h after inoculation confirmed an increase of Glu and Cht spot volume in 'Sumai3' whereas a decrease in 'Falat'. The SA treatment also caused significant increases in Glu and Cht spot volumes in both the cultivars. Our findings show an association between SA improvement of wheat defense against F. graminearum infection and induction of genes encoding proteins involved in pathogen response (Glu-2, Cht-4), secondary metabolite biosyntheses (PAL), and xenobiotic detoxification (CYP and PDR).

Diosgenin, mainly extracted from some Dioscorea species, is the most important starting material for the production of steroidal drugs. It is believed that diosgenin in Dioscorea is synthesized from isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP, the isomer of IPP) produced by the cytosolic mevalonate pathway. So far, the possibility of the plastidic 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway for biosynthesis of diosgenin remains unclear. The key enzyme in the MEP pathway is 1-deoxy-D-xylulose 5-phosphate-reductoisomerase (DXR, EC: 1.1.1.267). In this study, a DXR gene, named DzDXR (GenBank accession number KY131955), was isolated from Dioscorea zingiberensis. The DzDXR has an open reading frame of 1 413 bp encoding a protein of 470 amino acid residues. The function of DzDXR was verified by a colour enhancement assay in the Escherichia coli cells harbouring the plasmid pAC-BETA. Bioinformatic analyses revealed that DzDXR had a putative plastid transit peptide at the N-terminal region and was highly homologous to other plant DXRs, especially to those in monocotyledons. During the growth period of D. zingiberensis, the expression of DzDXR was found significantly high in leaves and very low in tubers, and the highest expression was observed in mature leaves in summer. In contrast to the DzDXR transcription, diosgenin was present predominantly in tubers and in minute quantities in leaves. Because diosgenin is very likely formed mainly in the cytosol of mature leaf cells of Dioscorea and the plastidic IPP and DMAPP produced by the MEP pathway can be transported into the cytosol, the consistently high expression of DzDXR detected in mature leaf of D. zingiberensis implies that the MEP pathway might play a significant role in diosgenin biosynthesis.

Reactive oxygen species lead to cellular damage and in plants exposed to drought stress, an increasing expressions of genes encoding antioxidant enzymes play important protective roles. The aim of this study was to evaluate response of drought tolerant ('Arg' and 'Roshan') and drought sensitive ('Arta' and 'Navid') wheat cultivars to oxidative stress caused by drought. Relative water content (RWC), water loss rate (WLR), free proline content, malondialdehyde (MDA) accumulation, and peroxidase (POX) activity were measured after 2, 4, 6, and 8 h of dehydration. The tolerant cultivars had a higher RWC and lower MDA, proline content, POX activity and WLR as compared to the sensitive cultivars. Real-time quantitative PCR was used to measure the expressions of genes encoding antioxidant enzymes in chloroplastic thylakoids and stroma. The expressions of chloroplastic Cu/Zn superoxide dismutase, thylakoid-bound ascorbate peroxidase, mono-dehydroascorbate reductase, dehydroascorbate reductase, and chloroplastic glutathione reductase genes were up-regulated in the tolerant cultivars. A direct relationship between physiological traits and increased gene expressions was observed for both sensitive and tolerant cultivars. Overall, increasing gene expressions protect the plants from oxidative damage caused by dehydration stress and improves tolerance to this stress.

This review summarizes main difficulties involved in barley (Hordeum vulgare L.) transformation. The most commonly used procedures for genetic transformation in barley are Agrobacterium tumefaciens and particle bombardment mediated methods. While different barley cultivars are used for genetic engineering with varying sensitivity, recent improvements in regeneration and transformation techniques are described and summarized. Furthermore, some of the transformation complicating factors, in particular somaclonal variation and transgene insertion sites, are discussed in more detail.

The "Specific Tissue" (ST) are proteins of unknown function present only in some plant families, mainly Fabaceae and Asteraceae. They are included in the PF10950 protein family and characterized by the presence of at least one domain of unknown function (DUF)2775. In this work we studied the involvement of the six members of the Medicago truncatula ST family (ST1 to ST6) in the development of flowers, fruits, and seeds by analysing the activity of their promoters (pST) after the construction of M. truncatula transgenic plants expressing the b-glucuronidase (GUS) reporter gene under the control of the six pSTs. The GUS activity was analysed in whole flowers and fruits and also in histological sections of these organs. The pST expression in the reproductive organs was mainly associated with the vascular bundles, especially throughout fruit development. These results pointed to an important role of ST proteins during the reproductive development stage, related to nutrient mobilization during the fruit and seed formation, that could be facilitated by their presence in the pod vascular bundles, as well as in the connective tissue of the anthers (ST3, ST4, ST6), in the placenta, the funiculus, and the outer parts of the developing seed (ST2, ST3, ST6). The observations made in this study were in agreement with the functions previously established for the three groups of M. truncatula ST proteins, as in the proposed function for ST1 in the transport and assimilation of nutrients, or the involvement of ST4, ST5, and ST6 in floral defence.

Fructose-1,6-bisphosphate aldolase (FBA), an essential enzyme involved in the glycolytic pathway, gluconeogenesis, and the Calvin cycle, plays significant roles in the regulation of plant growth, development, and stress responses. In this study, a novel gene, AhFBA (GenBank accession number KF470788), containing a 1077-bp open reading frame and encoding a protein of 358 amino acids, was isolated from Arachis hypogaea L. Bioinformatic analysis revealed that AhFBA belonged to class-I aldolases and preferentially localized in the cytoplasm. Real-time quantitative PCR analysis indicated that AhFBA had a higher expression in young fruits than in leaves and stems, and NaCl could trigger the highest expression of AhFBA in roots and leaves after 3-h and 6-h treatments. The salinity tolerance and survival of Escherichia coli transformed with AhFBA were notably enhanced compared with the control. Transgenic tobacco (Nicotiana tabacum L.) overexpressing the AhFBA gene exhibited a lower hydrogen peroxide content, electrolyte leakage, and malondialdehyde content and a higher photosynthetic efficiency, net photosynthetic rate, relative water content, and sucrose and proline content compared with control plants. Taken together, the results demonstrate that AhFBA functioned as a positive factor enhancing the tolerance of E. coli and N. tabacum to salinity stress, possibly by maintaining the osmotic balance and scavenging hydrogen peroxide.

The metalloid arsenic (As) is highly phytotoxic, in part due to the similarity of the arsenates to phosphates, but also due to its ability to induce reactive oxygen species (ROS) formation, and in the form of arsenite directly interact with certain enzymes. Here we aimed to determine the effects of a short period of As exposure on Arabidopsis thaliana. Particular focus was given to shoot responses, which have received less attention in previous studies. A. thaliana (ecotype Col-0) plants (28-d-old) were cultivated hydroponically in the presence of 0, 27, 108, and 216 µM arsenic in the form of sodium arsenate for five days. Translocation of As from root to shoot increased with increasing As concentration in the medium and caused a reduction in growth. Photosynthesis was severely affected due to stomatal closure, increased ROS accumulation, and alterations in expression of genes involved in oxidative stress responses and As detoxification. Primary metabolism was also perturbed, suggesting both the direct inhibition of certain enzymes as well as active defensive responses. Overall the effects of As toxicity depended greatly on the degree of translocation from root to shoot and involved both direct effects on biological processes and secondary effects caused by the accumulation of ROS.

Tea plant (Camellia sinensis) is a typical plant that accumulates abundant aluminum (Al) and fluoride (F). Al and F play vital roles in the growth and development in tea plant. MYB (myeloblastosis) is one of the largest transcription factor families in plant, which plays an important role in the stress responses. As the largest and multifunctional subfamily of MYB, R2R3-MYB subfamily participates in multiple abiotic stresses in plant. However, there are few studies about R2R3-MYB in tea plant, especially in the accumulation of Al and F during its growth. Here, we identified 43 CsMYB genes from the transcriptome database of tea plant and analyzed the relative expression in Al and F treatments. According to the Arabidopsis thaliana classification, 43 CsMYB genes are divided into 18 subgroups via phylogenetic tree analysis. All 43 CsMYB proteins have the typical R2R3-MYB domain by MEME prediction. Moreover, 9 CsMYB genes (CsMYB11, CsMYB17, CsMYB29, CsMYB38 to CsMYB43) that related to abiotic stress were selected from 43 CsMYB genes for a further study, and the relative expressions showed that they are tissue-specifically expressed. In addition, the results of different concentrations of Al treatments showed that CsMYB11, -17, -29, -38 and -41 are stimulated by Al treatment. The results of different concentrations of F treatments showed that the CsMYB11, -17, -38, -39, -40, -41, -42 and -43 participate in F accumulation of C. sinensis roots. Our research establishes a solid foundation for further investigation into the molecular functions of R2R3-MYB transcription factors in C. sinensis.

Histone variants can epigenetically regulate gene transcription through chromatin modulation. This regulation have been occasionally found in responses to abiotic stresses in plants, but their roles are not quite clear. Here, we describe 12 salt-responsive histone variant genes isolated from wheat. There was no sequence polymorphism in these 12 genes between the wheat cultivar 'JN177'and its salinity and drought tolerant derivative 'SR3' indicating that histone variant genes are highly conserved. However, these genes displayed differential patterns of transcription in 'JN177' and 'SR3'. When transformed into Arabidopsis thaliana, eight of the genes were silenced. The heterologous expression of the four active transgenes had no discernible effect on the Arabidopsis phenotype neither under control conditions nor under different abiotic stresses suggesting that histone variants could not be considered as candidate genes for molecular breeding by ectopic expression.

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

A transcription factor gene Arachis hypogaea abscisic acid (ABA) responsive element binding protein 1 (AhAREB1) has been isolated from peanut previously. Here, the function of different domains from AhAREB1 was investigated using construct series containing AhAREB1 full-length and truncated fragments to transform peanut hairy roots and pAhNCED1 (promoter of Arachis hypogaea 9-cis-epoxycarotenoid dioxygenase 1) GUS/Col Arabidopsis thaliana, respectively. The results of real-time quantitative PCR, transient expression, and chromosome immunoprecipitation (ChIP) assay all showed that AhAREB1 negatively regulated the expression of the AhNCED1 gene. β-Glucuronidase (GUS) staining shows that AhAREB1 and the AhAREB1 gene truncated fragment A1 may be bound to ABA responsive element  motifs in the promoter region of AhNCED1 and involved in the negative regulation of the upstream AhNCED1 gene promoter, reflected by the inhibited expression of the AhNCED1 promoter reporter gene and significantly reduced GUS activity in transgenic A. thaliana plants. Furthermore, only the full variant of AhAREB1 and a fragment without a C1 domain had repression activity on the AhNCED1 promoter. On the contrary, the AhAREB1 gene truncated fragments A2 and A3 variant without a C2 domain had no such repression activity. Moreover, the negative regulation of AhNCED1 was detected only when the C2 domain was present suggesting that the C2 domain was required for AhAREB1 activity. Subcellular localization analysis shows that the deletion of conserved domains C1, C2, C3 had no effects on the nuclear localization of AhAREB1. In addition, ChIP analysis indicates that the deletion of domains C1 and C3 significantly affected the binding of the AhAREB1 transcription factor to the AhNCED1 promoter. Taken together, the results indicate that the different N-terminal domains of the AhAREB1 protein, which played different roles in the negative regulations of AhNCED1, were necessary for AhNCED1 transcription.

Plant defensins and defensin like protein (DEFL) form a large family of small cysteine-rich proteins. They are major components of plant immune systems, being involved in host defenses against biotic and abiotic stresses. In this study, a novel defensin like protein (DEFL) gene PnDEFL1 was isolated from Panax notoginseng, a traditional Chinese medicinal herb. The expression patterns of PnDEFL1 after treatment with methyl jasmonate, salicylic acid, ethephon, and H₂O₂, as well as during Fusarium solani infection, were analyzed using reverse transcription qPCR. The up-regulated expression of PnDEFL1 indicated that it responded to F. solani infection and all four defense-related signalling molecules. The PnDEFL1 gene was further fused with the green fluorescent protein gene in a plant expression vector and transformed into onion (Allium cepa) epidermal cells. The laser scanning confocal microscope confirmed that the PnDEFL1 protein localized to the extracellular region. In addition, the recombinant PnDEFL1 protein was expressed in Escherichia coli and purified by affinity chromatography. It had antifungal activities against F. solani, F. oxysporum, Botrosphaeria dothidea, and Sclerotinia sclerotiorum. The PnDEFL1 gene was transferred into tobacco (Nicotiana tabacum) to verify its function. The overexpression of PnDEFL1 in tobacco conferred a high resistance to F. solani infection. Thus, the PnDEFL1 gene is involved in the defense responses of P. notoginseng to F. solani infection.