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.

ABC transporters, which comprise one of the largest protein families, are involved in maintaining osmotic homeostasis, nutrient uptake, pathogen resistance, and metal tolerance. In this study, 30 ABC genes in dwarf polish wheat were characterized and classified into seven subfamilies (ABCA - ABCG). Among them, 24 ABC transporters were newly found in wheat. The expressions of 13 ABC genes in roots and leaves under six metal stresses were also analyzed. All these genes were differentially regulated by Cd (except ABCE2, ABCF4, and ABCF6 in roots), suggesting that these genes participate in Cd transport, sequestration, or uptake. These genes were also differentially regulated by other metals including Cu, Mg, Zn, Fe, and Ni. Results suggest that the expressions of ABC transporters in dwarf polish wheat played important roles in metal transport and detoxification.

The accumulation of polysaccharides, activities of sucrose metabolism enzymes, and the expression of sucrose biosynthetic genes in Dendrobium officinale were significantly affected by exogenous methyl jasmonate (MeJA). Application of MeJA increased the content of polysaccharides and the highest polysaccharide production occurred in the samples treated with 200 μM MeJa. The MeJA application influenced polysaccharide biosynthesis rather than degradation because the activities of sucrose metabolism enzymes and the expressions of sucrose biosynthetic genes were upregulated by MeJA. Interestingly, low MeJA concentrations promoted accumulation of Dendrobium polysaccharides, while high MeJA amounts played an inhibitory role. The content of major constituent of polysaccharides, glucose and mannose, also increased after MeJa treatment.

Root rot caused by Fusarium solani, is one of the most severe diseases in pepper (Capsicum annuum L.). Grafting has been attempted as an effective means to control the disease, but little is known about the disease resistance mechanism in grafted pepper. Therefore, we investigated the changes of biomass, cell structure, and the secondary metabolism in roots of control (non-grafted pepper) and grafted peppers using cvs. Weishi and Buyeding as rootstocks and the cv. Xinfeng 2 as a scion. After a manual inoculation, less F. solani invaded grafted pepper roots and consequently less serious injury to the root cell ultra-structure compared with the control was found. The roots of grafted pepper infected with F. solani exhibited greater biomass production and root activity than the roots of infected controls. Grafting led to an increased content of salicylic acid, benzoic acid, vanillin, lignin, and polyamines, as well as activities of phenylalanine ammonia lyase, polyphenoloxidase, and peroxidase. These results suggest that grafting improved the resistance of peppers to root rot.

The potential toxicity of nanoparticles (NPs) is under debate. Information about TiO₂ NPs phytotoxicity is still limited partly due to the different TiO₂ NP forms that may be found in the environment. The present work investigated the impact of different TiO₂ NPs forms (rutile and anatase) on germination, growth, cell cycle profile, ploidy level, and micronucleus formation in Lactuca sativa (lettuce) and Ocimum basilicum (basil). Seeds were exposed to anatase (ana) or rutile + anatase (rut+ana) at concentrations 5 - 150 mg dm^-3 for 5 d and after that different parameters were analyzed. Rut+ana showed high potential to impair germination and growth. On the other hand, ana alone showed a positive influence on seedling growth. Despite that, ana induced severe alterations in cell cycle dynamics. Regarding species, basil was more sensitive to TiO₂ NPs cytostatic effects (delay/arrest in G₀/G₁ phase), whereas in lettuce, TiO₂ NPs were more genotoxic (micronucleus formation increase). Finally, we propose that, besides germination and plant growth, cell cycle dynamics and micronucleus formation can be sensitive biomarkers of these NPs.

The enzyme 4-coumarate:coenzyme A ligase (4CL) plays an important role in phenylpropanoid metabolism. The 5'-upstream regions of two Sm4CL genes were isolated from danshen (Salvia miltiorrhiza Bunge) and their functions were characterized by promoter-directed GUS gene expression assay in transgenic Arabidopsis. Seedlings containing pSm4CL1 promoter:GUS fusions showed apparent GUS staining in hypocotyl and those harboring pSm4CL2 promoter:GUS fusions were clearly stained in cotyledon vasculars and roots. Mature Arabidopsis transformed with pSm4CL1 promoter:GUS exhibited GUS expression which was weak in the shoots and scarcely in roots and those modified with pSm4CL2 promoter:GUS displayed obvious GUS staining in roots, stigmatic papillae, stamens and sepal veins. Semi-quantitative RT-PCR revealed that Sm4CL2 was transcribed at the highest level in roots which was also shown to be the major accumulation site of salvianolic acid B. The results suggested that Sm4CL2 rather than Sm4CL1 might be responsible for the biosynthesis of salvianolic acid B in danshen roots.

Ethylene response factors (ERFs) are involved in many plant development events and stress defenses. In this study, an ERF gene, VvERF3b, was cloned from the leaves of Vitis vinifera. VvERF3b belongs to ERF group VIIIa. Expression of the gene was induced by abscisic acid, ethephon, and salicylic acid, but not by NaCl. Promoter sequence analysis of the VvERF3b gene revealed that there are several potential cis-acting elements that may be potentially recognized and bound by the transcription factors related to hormones and stress responses. Deletion analysis showed that the 5'-flanking sequence of -1047 to -585 from the transcriptional start site is essential to the high expression of the VvERF3b gene, whereas the sequence fragment of -1324 to -1047 revealed suppression effect. The result indicated that the region appears to contain cis-acting elements that can be bound by the proteins in a transcription complex to induce the inhibition of gene expression.

The cucumber genes CsPDR8/CsABCG36 and CsPDR12/CsABCG40 encode two similar pleiotropic drug resistance proteins (ABCG_PDRs) belonging to the large ABC family of multispecific ATP-dependent transporters. We have already shown that the amount of root CsPDR8/CsABCG36 and CsPDR12/CsABCG40 transcripts is markedly elevated by phytohormones related to the plant response to environmental constraints, suggesting the involvement of both genes in hormone-mediated reactions to stresses. To further characterize the function and regulation of CsPDR8/CsABCG36 and CsPDR12/CsABCG40, we determined the subcellular localization of the predicted CsPDR8/CsABCG36 and CsPDR12/CsABCG40 proteins in cucumber and performed a transcriptional analysis of genes encoding these proteins under different abiotic stresses (heavy metals, salinity, osmotic stress, and oxidative stress) and redox perturbations. In addition, the activities of antioxidative enzymes as well as the content of hydrogen peroxide and superoxide were measured in cucumber roots to monitor the redox perturbations under all experimental conditions. Western blot analysis of membrane fractions prepared from cucumber roots with specific antibodies raised against the peptides corresponding to sequences unique to CsPDR8/CsABCG36 and CsPDR12/CsABCG40 revealed that both proteins localize to the plasma membrane. The transcript abundance and the plasma membrane protein content closely correlated with the stress severity and the hydrogen peroxide content but not with the superoxide anion content. Based on the results obtained so far, we may conclude that CsPDR8/CsABCG36 and CsPDR12/CsABCG40 are up-regulated under multiple stress conditions and redox perturbations and that the H₂O₂ and stress-related phytohormones can act as signaling molecules affecting the expression of both cucumber genes.

A new cereal type II metacaspase full-length cDNA from wheat (Triticum aestivum L.) leaves, TaeMCAII, was for the first time successfully amplified and sequenced. The full-length sequence of the TaeMCAII cDNA of 1 551 bp contains a 1 218 bp open reading frame. The deduced protein encoded by the TaeMCAII cDNA consists of 405 amino acids with a calculated molecular mass of 44 kDa and an isoelectric point of 5.29. In response to wounding or heat shock, a similar sequence of ultrastructural events including the tonoplast rupture, chromatin condensation, degradation of chloroplasts and disappearance of cytoplasm and organelles were observed using transmission electron microscopy. As the observed changes in TaeMCAII mRNA level did not occur to be statistically significant wounding-induced programmed cell death (PCD) seems to be metacaspase-independent pathway. Interestingly, in PCD caused by a heat-shock treatment, the level of TaeMCAII mRNA remained unaltered until 48 h after the stress what suggests that TaeMCAII participates in later stages of PCD triggered by heat-shock. Phylogenetic analysis enabled to classify TaeMCAII as a type II metacaspase. Finally, homology modelling of the putative three-dimensional structure of the TaeMCAII protein and a topology analysis of its probable active site were performed.

The halophyte Thellungiella salsuginea is a new model plants due to its small genome size, short life cycle, and copious seed production. Although T. salsuginea shares a high sequence identity with its close relative Arabidopsis thaliana, it shows a greater tolerance to salinity, drought, freezing, heat, and cold. To elucidate the mechanism of abiotic stress resistance in T. salsuginea, we characterized its cytosolic Apx1 gene (TsApx1) and established A. thaliana transgenic lines overexpressing TsApx1. Under 300 mM NaCl, the content of H₂O₂, malondialdehyde, and proline were lower and the activities of superoxide dismutase, catalase, glutathione peroxidase, and ascorbate peroxidase were all higher in the transgenic plants overexpressing TsApx1 (35S:TsApx1-GFP) than in the wild-type plants. The atapx1 mutant plants of A. thaliana had a NaCl/mannitol-sensitive phenotype. The ectopic expression of TsApx1 in the atapx1 mutant effectively remedied the phenotype. These results suggest that TsApx1 plays an important role in scavenging reactive oxygen species in the cytoplasm under salinity or drought. Although TsApx1 in T. salsuginea was constantly expressed at a high level, this gene was clearly inducible. In summary, the high constitutive expression and rapid induction of TsApx1 may contribute to the tolerance to abiotic stresses in T. salsuginea.

Gamma-aminobutyric acid (GABA) is a non-protein amino acid that accumulates in a number of plant species under various environmental stresses. In this paper, the ability of applied GABA for the alleviation of NaCl stress was investigated in view of growth parameters, gas exchange, photosynthetic pigments, chlorophyll fluorescence, activities of antioxidant enzymes, malondialdehyde (MDA) content, and electrolyte conductivity (REC) in wheat seedlings. Germination rate and shoot dry mass decreased with an increasing NaCl concentration and this decrease was less pronounced when 0.5 mM GABA was applied. In the NaCl-treated seedlings, exogenous GABA partially enhanced photosynthetic capacity and antioxidant enzyme activities and decreased MDA content and REC. Therefore, GABA reduced the impact of salinity on the wheat seedlings.

The effect of UV-B irradiation at temperatures of 22 and 4 °C on flash induced oxygen yields, photochemical activity, and energy transfer in pea thylakoid membranes in the absence and presence of scavengers of reactive oxygen species (ROS) was studied. Three different scavengers were used: dimethyl sulfoxide (DMSO), histidine (His), and n-propyl gallate (nPG). As result of the UV-B treatment of isolated membranes, the flash oxygen yields were considerably affected - the amplitudes decreased and the oscillation pattern was lost. The analysis of the flash oxygen yields and initial oxygen burst showed alterations of a number of oxygen evolving centers in the S0 state as well as changes of decay kinetics of the oxygen burst under continuous irradiation. ROS scavengers exhibited more or less expressed protective effects, nPG being the most effective against UV-B induced damages of the flash oxygen yields. At both the temperatures, photosystem II (PS II) mediated electron transport was more sensitive to the UV-B treatment in comparison with photosystem I (PS I). The analysis of 77 K fluorescence spectra showed that the fluorescence ratio F735/F685 increased by the UV-B treatment probably due to a redistribution of excitation energy between both photosystems most likely caused by partial unstacking and due to a decrease of PS II fluorescence resulting from reaction center-type quenching. The nPG was the most powerful scavenger which protected the oxygen evolution capacity of PS II in the absence and presence of an exogenous electron acceptor to the highest extent.

A photoperiod-sensitive soybean [Glycine max (L.) Merr] cv. ZhongDou 24 (ZD24) exhibiting delayed flowering when grown under long-days (LD, a 16-h photoperiod) was used to identify the genetic control of flowering delay. A differential expression profiling technique enabled identification of a gene fragment that was up-regulated under LD. This fragment was homologous to a gene encoding methionine synthase (MS) in soybean and was named GmMS. The RNA content confirmed that GmMS was expressed in roots, stems, and leaves of soybean grown under LD. The highest expression was in stems. Full length GmMS, encoding 763 amino acids, was transferred into tobacco plants. The ectopic expression of GmMS in tobacco resulted in delayed flowering. Other effects included stunting, an increased MS activity and methionine content, a higher content of alcohol-soluble proteins and of chlorophylls, and a lower content of anthocyanins.

Tospoviruses are devastating plant viruses causing severe economic losses in a diverse range of crops worldwide. Here, we describe the development and evaluation of an RNA interference (RNAi) broad-spectrum virus resistance strategy based on a unique and short hairpin-RNA-generating construct (pNhpRNA). This construct was designed from a region of the nucleocapsid gene (N) of Tomato spotted wilt virus (TSWV) that showed a high sequence identity to the corresponding region in the related species Groundnut ringspot virus (GRSV) and Tomato chlorotic spot virus (TCSV). To test the effectiveness of the pNhpRNA construct, we developed a silencing reporter assay based on three fusion proteins in which the complete viral N gene sequence from each of the three tospoviruses was fused in frame to the green fluorescent protein (GFP) sequence. Co-agroinoculation of these constructs with pNhpRNA into leaves of Nicotiana benthamiana resulted in a strong silencing phenotype determined by GFP decay and suppression of the three N genes at the RNA and protein levels. To test the potential of the pNhpRNA construct to generate virus-resistant plants, we infiltrated the whole shoots of N. benthamiana with pNhpRNA. When these infiltrated plants were mechanically inoculated with the mentioned viruses 100, 70, and 60 % resistance phenotypes to TSWV, GRSV, and TCSV, respectively, were observed. The induction of a broad tospovirus resistance with a simple construct and a minimized off-target effect are the main contributions of pNhpRNA.

Leaf anatomy and irradiance-dependent leaf transmittance changes serving as irradiance acclimation mechanisms in leaves were studied in two ecologically contrasting Tradescantia species, a shade plant T. fluminensis Vell. and a sun plant T. sillamontana Matuda, grown at different irradiances. A dramatic increase in leaf thickness (2 to 4-fold) under a high growth irradiance (800 μmol m^-2 s^-1) compared with a low growth irradiance (60 μmol m^-2 s^-1), achieved mainly by expansion of the epidermis, was recorded in both species. The effect took place on the background of modest changes in mesophyll thickness (1.8-fold in T. fluminensis and 1.15-fold in T. sillamontana) and chloroplast size (0.8-fold in T. fluminensis and an insignificant change in T. sillamontana). Mesophyll structure and growth irradiance response did not seem to facilitate significantly light-dependent chloroplast (avoidance) movement in these species. Nevertheless, an exceptionally large (2 to 4-fold) irradiance-induced increase in light transmittance attributable to chloroplast avoidance movement was revealed. This increase by far exceeded that in other higher plants according to available literature. The magnitude of the irradiance-dependent transmittance changes positively correlated both with the rate of photosystem II recovery and with the extent of xanthophyll deepoxidation in the leaves. This was opposite to a negative correlation observed between the same parameters in different plant species. We hypothesize that, at the evolutionary timescale, chloroplast avoidance movement might adjust independently from other photoprotective mechanisms, e.g., non-photochemical quenching, whereas, on the ontogenetic timescale, adjustment of these mechanisms inevitably follows the same trend.

Heat stress severely reduces rice yield and quality; however, differences between the superior, early-flowering and inferior, later-flowering spikelets of indica rice in response to high-temperature stress during grain filling remain unclear. This study investigated the effects of high temperature (HT, 33.6/20.7 °C day/night) on growth, endosperm structure, and hormone and polyamine content of superior and inferior spikelets of heat-sensitive (SG-1) and heat-tolerant (HHZ) indica cultivars. The HT decreased fertilization rate, caused earlier grain filling, and reduced duration of grain filling, thus resulting in decreased grain mass and a poor endosperm structure. In addition, soluble sugar and sucrose content increased, and starch synthesis decreased by HT at the early stage of grain filling. The HT increased polyamine [spermidine (Spd) and spermine (Spm)] and abscisic acid (ABA) content, but reduced zeatin (Z) + zeatin riboside (ZR) and indole-3-acetic acid (IAA) content in the grains. Such effects were more apparent in the inferior than superior spikelets; however, the inferior spikelets of SG-1 were more affected than those of HHZ. At the middle grain filling stage, HT produced little difference between the two cultivars. Our results suggest that the poor development of inferior spikelets of SG-1 under the HT could be attributed, at least in part, to the changed content and ratios of free polyamines [putrescine (Put), Spd, and Spm] and phytohormones (Z+ZR, IAA, and ABA) and the conversion efficiency of sucrose into starch.

Caffeine (1,3,7-trimethylxanthine) is purine alkaloid, and it is secondary metabolite produced naturally in plants. It plays a crucial role in defense and stress tolerance. A hydroponic experiment was carried out to study the morphological, biochemical, and ultrastructural effects of caffeine treatment on seedlings of tobacco (Nicotiana tabacum L. cv. Turkish). The plants were grown in a growth chamber for 14 d in Hoagland's nutrient solution supplemented with 0 (control), 25, 50, 100, 1000, and 5000 μM caffeine. Shoot heights as well as root lengths significantly decreased in the plants treated with 1000 and 5000 μM caffeine. Total protein and sugar content in leaves increased significantly in the 5000 μM caffeine-treated plants. Moreover, electron microscopic analysis shows that in plants exposed to 1000 and 5000 μM caffeine, mesophyll cells possessed enlarged chloroplasts with disrupted thylakoid membranes associated with large starch grains and plastoglobules. Scanning electron micrographs exhibit that the vast majority of stomata in the plants treated with 1000 and 5000 μM were closed. In contrast, the 25 and 50 μM caffeine-treated plants showed an enhanced growth and no signs of injury.

Plant cell lines represent useful models in plant cell biology. They allow simple analysis of the effects of various factors including modulated gene expression at cellular and subcellular levels. The tobacco BY-2 cell line is a favoured model due to its high proliferation rate, capability of effective synchronization, and accessibility to transformation. A relatively high uniformity of BY-2 cultures allows morphological phenotyping and assessment of growth parameters like mitotic index, viability, or cell density. Here we review already published and newly introduced optimized guidelines to carry out reliable, reproducible and efficient characterization of BY-2 cultures from suggestions of appropriate methods to acquire primary data, proper statistical treatment, and biological interpretation. The presented experimental data demonstrate the extent of natural variability and the effect of initial cell density on various cell culture features. Supportive equations allow to estimate some derived phenotypic parameters like cell cycle duration or fresh biomass of the culture and to determine the size of data sets for reliable documentation of a certain phenotypic change. The optimized protocols and accompanying discussion of weak points of different approaches should serve as practical guide for both beginners and experienced researchers working on BY-2 cells.

Nitric oxide (NO) is an important molecule involved in the perception of stress induced by toxic compounds such as arsenic (As). The present study investigated the role of NO applied as sodium nitroprusside (SNP) in cell signalling and the ability of NO to attenuate the toxic effects of As (in the form of sodium arsenate) in water hyacinth (Eichhornia crassipes). Water hyacinth plants were collected and assigned to one of the following treatments: control; 100 μM SNP; 20 μM As; or 20 μM As + 100 μM SNP. The plants remained under these conditions for 0, 4, 12, and 24 h. After each time interval, the plants were collected and As absorption, production of reactive oxygen species (ROS), integrity of membranes, and antioxidant enzyme activities were evaluated. The plants were able to absorb and accumulate large amounts of As, even after only four hours of exposure to the pollutant. The absorption and bioaccumulation factor of As was even greater when plants were exposed to both As and SNP. The accumulation of As triggered increases in ROS production and cell membrane damage. In the presence of SNP, the tolerance index to As increased and damage was mitigated. Therefore, from the present work, it was possible to conclude that exogenous NO influenced the ability of plants to tolerate As; this finding has implications for phytoremediation in areas contaminated by As.

Limited information is available on the role of brassinosteroids (BRs) in response of plants to nutrient deficiency. To understand the functions of BRs in response to iron deficiency, we investigated the effect of 24-epibrassinolide (EBR) on activities of ferric-chelate reductase (FCR), H⁺-ATPase, Ca²⁺-ATPase, nitrate reductase (NR), antioxidant enzymes, Fe and other minerals content and distribution, chlorophylls, soluble protein, free proline, reactive oxygen species, and malondialdehyde in peanut (Arachis hypogea L.) plants subjected to Fe deficiency (10^-5 M Fe(III)-EDTA) with foliar application of EBR (0, 10^-8, 5.0×10^-8, 10^-7, 5.0×10^-7, and10^-6 M). Results show that EBR increased Fe translocation from roots to shoots and increased Fe content in cell organelles. Activities of antioxidant enzymes increased and so the ability of resistance to oxidative stress was enhanced. As result of enhancement of H⁺-ATPase and Ca²⁺-ATPase activities, the inhibition of Fe, Ca, Mg, and Zn uptake and distribution was ameliorated. Chlorophyll, soluble protein, and free proline content also increased and consequently, chlorosis induced by Fe deficiency was alleviated. The results demonstrate that EBR had a positive role in regulating peanut growth and development under Fe deficiency and an optimal concentration appeared to be 10^-7 M.

Plant WRKY genes encode a complex and ancient class of zinc-finger transcription factors that are involved in multiple biological processes, especially in regulating defense against abiotic stresses. Despite a growing number of studies on the genomic organization of the WRKY gene family in various species, little information is available about this family in hemp (Cannabis sativa L.). In this study, based on the hemp genome sequence, 40 hemp WRKY (CsWRKY) genes were classified into three main groups and five subgroups according to their orthologs in Arabidopsis. Among these, 23, 15, and 14 CsWRKY genes were responsive to drought, NaCl, and Cd stress, respectively. Interestingly, the expressions of all of the 23 drought stress-responsive genes were up-regulated. Moreover, 18 CsWRKY genes were induced by abscisic acid (ABA) treatment. A total of six up-regulated genes related to all three stresses were identified. Among these, five were up-regulated, and one was down-regulated by ABA. These results indicate a diverse function of the CsWRKY genes, which provides a basis for future clarification of their function in hemp tolerance to abiotic stresses.

Polyamines play important roles in plant responses to various environmental stresses. In this study, changes in free polyamine content and transcription of genes participating in polyamine metabolism were investigated in sweet orange (Citrus sinensis Osbeck cv. Jincheng) seedlings under drought (DR), high-temperature (HT), and combined DR and HT (DRHT) stresses. Content of putrescine (Put) and spermidine (Spd) was the highest and that of spermine (Spm) was the lowest under the DR stress, whereas Put and Spd content was the lowest, and Spm content was the highest under the HT stress. Content of the three polyamines under the DRHT stress ranged between the values detected under the DR and HT at most time points. The fluctuation of Put content during the three stresses was irregular; significant amounts of Spd under the DRHT and Spm under all the three stresses were accumulated. Expression of genes encoding arginine decarboxylase, Spd synthase, and Spm synthase was significantly induced under the DR but not under the HT. The relief from all the stresses did not cause an expected decrease or increase in polyamine content and expression of related genes.

Anthocyanins from mulberry fruits are used in medicine. However, little anthocyanin can be detected in other tissues and sometimes also mulberry fruits are colorless. The aim of this study was to investigate which gene or genes have the strongest correlation with the anthocyanin biosynthesis. The expression of several anthocyanin synthesis genes were determined in different tissues of two white and two purple fruit cultivars. Genes encoding dihydroflavonol reductase (MaDFR) and anthocyanidin synthase (MaANS) showed a high expression only in fruit tissue of purple-fruit cultivars. During the development of mulberry fruits, the anthocyanin content was well correlated with the transcripts abundance of MaDFR, MaANS, and MaCHS (encoding chalcone synthase). The skin of female mulberry flowers turns red under irradiance because of up-regulated expressions of MaCHS, MaDFR, and MaANS. These three genes may control the anthocyanin biosynthesis in mulberry and up-regulation of them may greatly increase the anthocyanin content.

Apple (Malus × domestica Borkh.) is a perennial woody plant that undergoes a period of dormancy (in cv. Jonathan between late September and mid-December) to survive freezing temperatures of winter. DORMANCY-ASSOCIATED MADS-BOX (DAM) genes play important roles in the regulation of growth cessation and terminal bud formation in peach. To understand the role of DAM orthologs in apple, we isolated and characterized four DAM-like genes (designated as MdDAMa, MdDAMb, MdDAMc, and MdDAMd) and monitored their expression in apical buds throughout the season by real-time quantitative polymerase chain reaction analyses. The transcription of MdDAMa peaked in October and that of MdDAMc was elevated from August to October, whereas MdDAMb and MdDAMd were practically undetectable. The tandemly arranged genes MdDAMa/MdDAMb and MdDAMc/MdDAMd were localized to chromosomes 16 and 8, respectively. Based on these observations, we infer that MdDAMa and MdDAMc acted in a dominant fashion on each locus and were correlated with the period of endodormancy.

The JNK motif is repeated 4 000 times in an additional heterochromatin band. Flanking sequences of a JNK region, which form extra heterochromatin in 2R rye (Secale vavilovii Grossh.) chromosomes, were studied using a genome walking technique. The results clearly indicate that there were blocks of JNK sequences adjacent to the R173 family of repeated sequences. Moreover, it appears that the R173 are sequences flanking in both directions, i.e., upstream and downstream. Downstream, the R173 is adjacent to the JNKs in an anti-parallel orientation, whereas upstream it is adjacent in a parallel orientation. In order to confirm the presence of the R173 sequence, fluorescence in situ hybridization was carried out. Using both JNK and R173 molecular probes, overlapping hybridization signals in the 2RL pair of chromosomes were observed, indicating an identical location of the two sequence elements.

Jatropha curcas L. is a perennial, drought-resistant, and non-food oilseed crop. The fatty acid composition of seed oil, especially the ratio of 16- to 18-carbon fatty acids, has a direct impact on the biodiesel quality. In plants, fatty acid chain lengths are mainly determined by the plastidial fatty acid synthase complex which includes three β-ketoacyl-acyl carrier protein synthases (KASs), KASI, KASII, and KASIII. The KASIII is thought to play a rate-limiting role in fatty acid synthesis. Here, we report the functional characterization of a putative JcKASIII gene from Jatropha curcas using Arabidopsis thaliana L. as model system. The transcripts of JcKASIII were detected in all tissues examined and increased in seeds. Overexpression of JcKASIII in Arabidopsis led to an increased content of palmitic acid and a higher ratio of 16- to 18-carbon fatty acids. Moreover, functional analysis of JcAKSIII in kasI or kasII knock down Arabidopsis mutants revealed that the composition of seed oil changed. Taken together, these results suggest that heterologous JcKASIII could function as one of the major regulators of fatty acid composition.

In the present study, three Arabidopsis thaliana pop2 mutant lines with different T-DNA insertions in a gene coding γ-aminobutyric acid transaminase (GABA-TA) were screened for seed germination percentage, stress-induced oxidative damage, and GABA content and metabolism under various abiotic stresses including high temperature (42 °C), low temperature (4 °C), salinity (NaCl), and osmotic stress (mannitol). All mutant lines showed a decreased germination under all the stress treatments with a significant reduction in the pop2-1 and pop2-3 mutant lines. Content of GABA and MDA increased significantly in all pop2 mutants and wild type (WT) seedlings in response to all the treatments. However, content of GABA and MDA was lower in all pop2 mutants comparing to the WT under the same treatments. GABA increased already after 30 min and increased significantly after 2 h at 42 °C especially in the pop2-3 and WT seedlings. In response to the cold treatment, GABA content increased up to 4-fold compared to the control in all pop2 mutants and WT seedlings. In response to the NaCl treatment, GABA accumulated slightly in the WT and all pop2 mutants. On the contrary, GABA content increased significantly in the pop2, pop2-1, and pop2-3 mutants and WT under all mannitol treatments.

As result of a close evolutionary relationship between Triticeae B, G, and S genomes, the exchange of genetic material between them is possible and may be beneficial for broadening the genetic diversity of cultivated bread wheat. However, the extent to which regulatory networks are conserved remains poorly researched. Here, the structural organization and transcriptional activity of the B, S, and G genome copies of a gene encoding flavonoid biosynthesis enzyme chalcone-flavanone isomerase (CHI) were explored using introgression lines which differ from the wild type by carrying a non-bread wheat Chi-1 gene. Chi-S1, Chi-G1, and Chi-B1 all mapped to a comparable region of chromosomes 5S, 5G, and 5B, respectively. Nucleotide sequences of Aegilops speltoides Chi-S1 and Triticum timopheevii Chi-G1 were determined and compared with T. aestivum Chi-B1 sequences. The enzymes encoded by these three genes shared the same predicted tertiary structure and active sites. However, the replacement of Chi-B1 by Chi-S1 or Chi-G1 in a wheat background resulted in a significant decrease in the global amount of the Chi-1 transcript present in the seedling shoot indicating divergence in regulation of expression of the orthologous Chi-1 genes among Triticeae ssp.

One of the largest families of transcriptional regulators contains WRKY proteins. They play important roles in plant defense responses. In this study, a novel WRKY gene, CsWRKY2, was isolated from the tea [Camellia sinensis (L.) O. Kuntze] plant. The full-length cDNA of CsWRKY2 was 2 050 bp in length and encoded a 522-amino acid peptide chain containing two typical WRKY domains and two zinc finger motifs, suggesting that CsWRKY2 was member of the WRKY group I family. A subcellular localization assay shows that CsWRKY2 was localized to the nucleus. Real time qPCR analysis shows that CsWRKY2 expression was higher in leaves than in other organs and was induced by cold (4 °C), drought stress, and exogenous abscisic acid (ABA). Additionally, ABA content was enhanced after the cold or drought stress and the effects were relieved by an ABA biosynthesis inhibitor. Furthermore, the expression of CsWRKY2 was up-regulated by exogenous ABA under the cold and drought stresses and down-regulated by an ABA biosynthesis inhibitor. Our findings indicate that CsWRKY2 played an important role in plant defense responses to the cold and drought stresses by participating in the ABA signaling pathway, downstream to ABA.