Aluminium toxicity in acid soils is the main limitation to crop production worldwide. In wheat (Triticum aestivum L.), the Al-activated malate transporter (TaALMT1) gene located on chromosome 4DL is associated with malate efflux and Al-tolerance. To introgress Al-tolerance from the breeding line CAR3911 into the high yielding Al-sensitive cultivar Kumpa-INIA, phenotypic and molecular characterizations of gene/QTL underlying Al-tolerance in CAR3911 followed by marker-assisted backcrossing (MAS-BC) were undertaken. Al-tolerant backcross (BC) lines were selected using the functional marker ALMT1-4 designed immediately upstream of the TaALMT1 coding region. Foreground and background selections using ALMT1-4 and microsatellite markers were conducted. Linkage and sequence analyses suggest that the TaALMT1 gene could underly the Al-tolerance in CAR3911, possessing the same promoter type (V) as the Al-tolerant genotypes Carazinho and ET8. The MAS-BC strategy allowed the selection of Al-tolerant lines with the smallest introgressed region (6 cM) on 4D and the highest recurrent parent genome (RPG) (98 %) covering 2 194 cM of the wheat genome. The homozygous BC3F2 line named Kumpa-INIA-TaALMT1 expressed a 3-fold higher Al-tolerance than its isogenic line Kumpa-INIA at 40 μM Al in the hydroponic solution, and similarly to CAR3911 and Carazinho. The MAS-BC strategy was successful for the introgression of the TaALMT1 gene into Kumpa-INIA in only three BC generations, shortening the breeding cycle to 24 months, which promises to increase wheat production and a greater yield stability in the acid soils of Southern Chile.

SnRK2 are plant-specific serine/threonine kinases that are involved in plant responses to abiotic stresses. In this study, four novel genes SnRK2s:TpSnRK2.11, TpSnRK2.2, TpSnRK2.5, and TpSnRK2.10 from dwarf Polish wheat (Triticum polonicum L.) were characterized and classified into three groups. TpSnRK2.5 and TpSnRK2.11 were members of group 1; TpSnRK2.2 was member of group 2; TpSnRK2.10 belonged to group 3. The expression of TpSNRK2.2 was strongly regulated by polyethylene glycol (PEG), NaCl, and cold in roots and leaves, as well as by ABA in leaves. The transcript of TpSnRK2.5 was intensely induced by all the treatments in roots and leaves. The distinct expression patterns of TpSnRK2.10 indicate that this gene was very sensitive to ABA and NaCl, less sensitive to cold and PEG. The transcript of TpSnRK2.11 was activated significantly by PEG, NaCl, and cold, but weakly by ABA. Our results indicate that these four genes were probably involved in wheat responses to different abiotic stresses in different tissues.

In many polar and alpine ecosystems, lichens of genus Umbilicaria represent dominant species forming community structure. Photosynthetic and spectral properties of the lichens may change rapidly according to an actual hydration status of their thalli. In this study, we investigated responses of photochemical reflectance index (PRI), normalized difference vegetation index (NDVI), effective quantum yield of photosynthetic efficiency of photosystem (PS) II (Φ_PSII), and several photosynthetic parameters derived from fast induction kinetics of chlorophyll fluorescence (OJIP) to controlled dehydration. We used U. arctica and U. hyperborea collected close to Nuuk, Greenland. In both the species, PRI showed a curvilinear increase with dehydration, i.e., a decreasing water potential (Ψ_w). The increase was apparent within Ψ_w range of 0 to -10 MPa. The PRI increase was less pronounced in U. arctica than in U. hyperborea. NDVI decreased with a progressive thallus dehydration in both the species, however, throughout Ψ_w range of 0 to -30 MPa, U. hyperborea had lower NDVI values than U. arctica. The relationship between Φ_PSII and Ψ_w resulted in a typical S curve. A critical Ψ_w at which photosynthetic processes were fully inhibited was -30 MPa in both the species, however, species-specific differences in the S curve shape were found. Analyses of photosynthetic parameters derived from OJIPs revealed that the absorption of radiation energy and a trapping rate increased with dehydration in active reaction centres of PS II, the number of which decreased with a more pronounced lichen thallus dehydration. It is concluded that U. arctica and U. hyperborea possess effective physiological mechanisms to maintain an effective photosynthesis when partly dehydrated (the Ψ_w range of 0 to -15 MPa). In spite of similar ecological niches that these two lichens occupy in nature, their spectral and photosynthetic properties differred.

Internal transcribed spacer (ITS) regions and maturase K (matK) sequence polymorphisms provide an efficient tool for discrimination and conservation of genetic resources of Anoectochilus species. The objectives of this study were to develop markers specifically distinguishing A. formosanus Hayata from closely related A. koshunensis Hayata, A. roxburghii (Wall.) Lindl., and Ludisia discolor (Ker Gawl.) A. Rich. and to identify a molecular phylogenetic relationship of a new intergeneric BC1F1 hybrid - Ludochilus Jin-Chai. Specific primers for nuclear ITS regions and chloroplast matK sequences were designed and converted into cleaved amplified polymorphic sequence (CAPS) markers. Results show that the matK sequences obtained corresponded to pseudogenes and that their digestion with enzyme HinfI revealed a polymorphic pattern in A. formosanus and A. koshunensis. The pedigree of Lud. Jin-Chai, which was derived from the cross between Lus. discolor and A. formosanus, was also confirmed based on ITS and matK CAPS markers.

Dramatic accumulation of proline is a common physiological response in plants exposed to various abiotic stresses. Accumulation of proline could be due to de novo synthesis, decreased degradation, lower utilization, or hydrolysis of proteins. Extensive intercellular proline transport occurs between the cytosol, chloroplasts, and mitochondria due to its compartmentalized metabolism. Although all functions of proline in stress tolerance are still a matter of debate, it is suggested that proline contributes to stabilization of sub-cellular structures, scavenging free radicals, and buffering cellular redox potential. It also chelates heavy metals, modulates cellular functions, and even triggers gene expression. Apparently, proline acts as stress-related signal exhibiting cross tolerance to a range of different stresses. Besides these significant roles, its metabolism is found to be coupled to several key pathways such as pentose phosphate, tricarboxylic acid, or urea cycles and contributes to, i.e., purine synthesis and the phenylpropanoid pathway. Although the molecular basis of regulation of proline metabolism is still largely obscure, the genetic engineering of proline content could lead to new opportunities to achieve plant stress tolerance.

The protective roles of glutathione (GSH) applied on salt stress-affected mung bean (Vigna radiata L.) seedlings were studied. The salt stress (200 mM NaCl) significantly increased the malondialdehyde (MDA), methylglyoxal (MG), H₂O₂, and proline (Pro) content, O₂ ^.- generation rate, and lipoxygenase (LOX) activity and reduced the leaf relative water content (RWC) and chlorophyll (Chl) content. The salt stress also significantly reduced the ascorbate (AsA) content, increased the endogenous GSH and glutathione disulfide (GSSG) content, and reduced the GSH/GSSG ratio. The activities of mono-dehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and catalase (CAT) decreased; and the activities of ascorbate peroxidase (APX), glutathione reductase (GR), superoxide dismutase (SOD), glutathione S-transferase (GST), and glutathione peroxidase (GPX) increased under the salt stress. The activities of glyoxalase I (Gly I) and glyoxalase II (Gly II) decreased under the salt stress (except the Gly II activity at 48 h). Mung bean seedlings which were treated with NaCl together with GSH showed an improved AsA and GSH content, GSH/GSSG ratio, higher activities of APX (only at 24 h), MDHAR, DHAR, GR, SOD (only at 24 h), CAT, GPX (only at 48 h), GST (only at 24 h), Gly I and Gly II under the salt stress compared with those treated with NaCl alone. The improved antioxidant and glyoxalase systems by GSH application decreased the MDA, H₂O₂, and MG content, O₂ ^.- generation rate, as well as increased the leaf RWC and Chl content. Thus, exogenous GSH improved the response of the mung bean seedlings to the salt stress.

Based on information from the Arabidopsis model system, a putative transcriptional activator of cuticle formation (TaSHN1) was selected among the expressed sequence tags in wheat (Triticum aestivum L.). RT-PCR indicated the preferential expression of this gene in the basal, but not in the middle parts of wheat leaves. This leaf region is a likely site of cuticle formation in cereals. TaSHN1 was cloned and expressed in Arabidopsis, resulting in shiny leaf surfaces and the overproliferation of cuticular material as observed by electron microscopy. Unlike the Arabidopsis WAX INDUCER/SHINE1 (WIN/SHN1) gene, TaSHN1 triggered disorganized cuticular ultrastructure in the transgenic leaves, with the continuous layers replaced by large electrodense bodies embedded in amorphous lipid material. Toluidine blue staining and dark-adapted water release indicated increased cuticular permeability in TaSHN1-expressing Arabidopsis leaves. The expression of TaSHN1 resulted in a moderate decrease of the total number of stomata per unit leaf area in comparison with the wild type. Drought tolerance of Arabidopsis was unaffected by the transgene. The data indicate that this putative wheat orthologue of WIN/SHN transcription factors (TaSHN1) elicited both overlapping and new, distinctive phenotypes compared to other WIN/SHN-overexpressing plants. TaSHN1 transgenic Arabidopsis lines should provide a rich source of material for further comparative biochemical, physiological, and genetic studies.

Hydroponic experiments were conducted to investigate the effects of nitrogen forms on nitric oxide accumulation and glycinebetaine (GB) metabolism under osmotic stress (OS) simulated by the addition of polyethylene glycol (PEG-6000) to two maize (Zea mays L.) cultivars Zhengdan 958 (ZD958; drought-tolerant) and Jundan 20 (JD20; drought-sensitive). OS led to the accumulation of NO, GB, and choline, as well as to an increase of betaine aldehyde dehydrogenase (BADH) activity in both the cultivars. The responses of both the maize cultivars to OS were significantly higher under nitrate nutrition than under the mixed supply of ammonium and NO₃ ^- or sole NH₄ ⁺. Cultivar ZD958 was superior to JD20 under the osmotic stress. Furthermore, compared with sole NH₄ ⁺, sole NO₃ ^- and the mixed supply of NH₄ ⁺ and NO₃ ^- increased all the parameters in cv. ZD958 but only the GB and choline content in JD20. Therefore, it is concluded that ZD958 showed a higher accumulation of NO and enhanced GB metabolism under OS than JD20 regardless of N form.

Saussurea involucrata Kar. et Kir. tolerates severe abiotic stresses including cold, and the level of membrane fatty acid desaturation is associated with its cold acclimation. We discovered and characterized a full-length cDNA of stearoyl acyl-carrier-protein desaturase (sikSACPD) which encodes a protein consisted of 396 amino acids. A sequence alignment of the SikSACPD protein showed that it shares 91 and 86 % identity with the SACPDs of Carthamus tinctorius and Helianthus annuus, respectively. Semi-quantitative RT-PCR showed that the expression of sikSACPD increased in S. involucrata leaves as the temperature decreased from 20 to -10 °C. Agrobacterium tumefaciens was used to transform fatty acid biosynthesis 2 (FAB2):SikSACPD and FAB2:FAB2 constructs into tobacco to investigate resistance to a freezing stress and fatty acid composition of the transgenic plants. The FAB2:SikSACPD transgenic plants showed a slightly more resistance to the freezing stress than the FAB2:FAB2 transgenic plants and the wild-type. The proportion of oleic acid (C18:1) in the leaves of SikSACPD transgenic tobacco increased from approximately 5 to 20 % compared with the leaves of non-transgenic tobacco when both were exposed to cold stress treatments. This study demonstrates that the SikSACPD transgene, when expressed in tobacco, conferred a higher cold tolerance in comparison with that observed in non-transgenic tobacco. Thus, this gene may be a candidate for enhancing cold tolerance in other crop plants.

Flow-sorted chromosomes have been used to simplify analyses of complex plant genomes. In bread wheat, majority of studies involve cultivar Chinese Spring, a genotype chosen for sequencing. Telosomic lines developed from this cultivar enable isolation by flow sorting chromosome arms, which represent less than 3.4 % of the genome. However, access to other wheat cultivars is needed to allow mapping and cloning useful genes. In these cultivars, cytogenetic stocks are not readily available and only one chromosome (3B) can be sorted. Remaining chromosomes form composite peaks on flow karyotypes and cannot be sorted. In order to overcome this difficulty, we tested a pragmatic approach in which composite chromosome peaks are dissected to smaller sections. The analysis of chromosome composition in sorted fractions confirmed feasibility of obtaining sub-genomic fractions comprising only a few chromosomes. Usually one of the chromosomes was more abundant and the frequencies of dominant chromosomes in sorted fractions ranged from 16 % (chromosome 7B) to 80 % (chromosome 2B). The enrichment factor, calculated as the relative proportion of chromosomal DNA in the wheat genome to the proportion of chromosomal DNA in a sorted fraction, ranged from 3.2-fold (7B) to 16.4-fold (5D). At least a 5-fold enrichment can be obtained for 17 out of 21 wheat chromosomes. Moreover, we show that 15 out of the 21 chromosomes can be sorted without being contaminated by their homoeologs. These observations provide opportunities for constructing sub-genomic large-insert DNA libraries, optical mapping, and targeted sequencing selected genome regions in various cultivars of wheat. The availability of fractions enriched for chromosomes of interest and free of contaminating homoeologs will increase the efficiency of research projects and reduce their costs as compared to whole genome approaches. The same methodology should be feasible in other plants where single chromosome types cannot be sorted.

Autophagy has been implicated as a cellular protein degradation process that is used to recycle cytoplasmic components under biotic and abiotic stresses and so restrict programmed cell death (PCD). In this study, we report a novel regulatory mechanism by which NADPH oxidase respiratory burst oxidase homolog D (RBOHD) regulated pathogen-induced autophagy and hypersensitive (HR) cell death. We found that the Pseudomonas syringae pv tomato bacteria DC₃000 expressing avrRps4 (Pst-avrRps4) induction of RBOHD-dependent reactive oxygen species (ROS) production promoted the onset of autophagy, whereas a pretreatment with an NADPH oxidase RBOHD inhibitor reversed this trend. The inhibitor significantly blocked pathogen-induced autophagosome formation and ROS increase. Moreover, we also show that in the wild-type and atrbohF mutant, Pst-avrRps4-induced cell death was limited, whereas in the case of the atrbohD mutant, the infection triggered a spreading-type necrosis. Our results demonstrate that the RBOHD-dependent ROS accumulation stimulated autophagosome formation and limited HR cell death.

The present study investigated differences in cadmium resistance of two wheat (Triticum aestivum L.) cultivars. The cvs. RAJ 4161 (Cd resistant) and PBW 343 (Cd sensitive) were treated with 200 mg(Cd) kg^-1(soil) for 3, 5, 7, and 10 d. The effect of the Cd stress was estimated by measuring growth parameters, accumulation of cadmium, sulphur, and glutathione (GSH), and by expression of some defence genes [phytochelatin synthase (PCS), glutathione reductase (GR), and ascorbate peroxidase (APX)]. The Cd treatment resulted in a significant reduction in plant growth and in an increase in the accumulation of S and GSH. Further, the expressions of PCS, GR, and APX were also mostly enhanced. The PCS was upregulated significantly in roots of RAJ 4161 (0.6-fold) and downregulated (0.9-fold) in PBW 343 on day 3 of the Cd treatment. In RAJ 4161, the expressions of APX and GR recorded a maximum increase of 2.1- and 2.4-fold in roots and leaves, respectively, after 10 d of the stress. The results show that a different ability of RAJ 4161 and PBW 343 to modulate mRNA expression after the Cd treatment was related to their Cd tolerance.

Salinity is one of the most severe problems in worldwide agricultural production. The effect of salt on dry mass, total glutathione content, its regulatory enzymes, and extent of DNA damage in growing mungbean (Vigna radiata L. Wilczek) seedlings was investigated. The salt stress decreased a dry mass accumulation in the seedlings. A total glutathione (GSH) content and the activities of the enzymes of GSH metabolism were adversely affected by the salt stress. The enhanced accumulation of reactive oxygen species under the NaCl stress caused an increase in DNA damage, measured using a comet assay, in both roots and leaves of the mungbean seedlings. The pretreatment of mungbean seeds with a sublethal dose of NaCl was able to overcome the adverse effects of the salt stress to variable extents by exhibiting significant alterations of all tested parameters, imparting better growth and metabolism of the mungbean seedlings.

Male sterile line is a useful material for hybridization, but its sterility mechanism, especially proteomic profile, is still not entirely clear. In wheat (Triticum aestivum L.), a male sterile Bainong (BNS) genotype whose sterility could be manipulated by temperature was recently selected. We focused on the proteomic profile change of anthers from the male sterile line (SL) and its conversional line (CL). Two-dimensional gel electrophoresis and MALDI-TOF-MS technologies were utilized for proteomic profiles analysis. Differently abundant protein spots (over 2-fold, P < 0.05) were selected for identification analysis. Compared to CL, 24 up-regulated and 23 down-regulated proteins were identified in SL. Protein metabolism-related proteins, which included a ubiquitin-conjugating enzyme E2 (23 kDa) and an ATP-dependent Clp protease proteolytic subunit, were over-accumulated in SL anthers. Alcohol dehydrogenase ADH1A, fructose-bisphosphate aldolase, chloroplast fructose-bisphosphate aldolase, and NADP-dependent malic enzyme were notably down-regulated in SL anthers. Up-regulated prohibitin protein Wph and a translationallycontrolled tumor protein homolog, and down-regulated histone acetyltransferases HAT1 and HAT2, and DNA directed RNA polymerase subunit α were identified in SL anthers. These dramatically changed proteins may play a crucial role in abnormal anther development and pollen abortion in BNS.

Jatropha curcas L. is a plant with various commercial uses, and drought is an important limiting factor for its distribution and production. In this study, we investigated the role of drought hardening in an increased drought tolerance in J. curcas, and the involvement of osmoregulation and biochemical pathways in this enhanced tolerance. Results show that a drought hardening treatment with 10 % (m/v) polyethylene glycol 6000 for two days significantly increased a survival rate, decreased the content of malondialdehyde, and alleviated electrolyte leakage in the J. curcas seedlings under the drought stress. Measurements of leaf water potential, osmotic potential, and pressure potential show that this drought hardening treatment can improve the water status of J. curcas seedlings during the early phase of drought stress. In addition, the drought hardening treatment gradually increased the concentrations of compatible solutes proline, glycinebetaine, and soluble sugars during drought hardening and subsequent drought stress. It also clearly raised the activity of betaine aldehyde dehydrogenase, a key enzyme for the glycinebataine biosynhthesis as well as the activity of enzymes Δ₁-pyrroline-5-carboxylate synthetase (P5CS), glutamate dehydrogenase, arginase, and ornithine aminotransferase, all key enzymes in the proline biosynthesis. The expression of P5CS gene in the J. curcas seedlings also increased during drought hardening and subsequent drought stress, but the activity of proline dehydrogenase decreased. These results show that the drought hardening treatment can enhance drought tolerance in J. curcas, and osmoregulation is a key factor in this increased drought tolerance.

Polyploidization is a major genome modification that results in plant species with multiple chromosome sets. Parental genome adjustment to co-habit a new nuclear environment results in additional innovation outcomes. We intended to assess genomic changes in polyploid model species with small genomes using inter retrotransposons amplified polymorphism (IRAP) and retrotransposon microsatellite amplified polymorphism (REMAP). Comparative analysis among diploid and autotetraploid A. thaliana and A. suecica lines with their parental lines revealed a marginal fraction of novel bands in both polyploids, and a vast loss of parental bands in allopolyploids. Sequence analysis of some remodelled bands shows that A. suecica parental band losses resulted mainly from sequence changes restricted to primer domains. Moreover, in A. suecica, both parental genomes presented rearrangement frequencies proportional to their sizes. Overall rates of genomic remodelling events detected in A. suecica were similar to those observed in species with a large genome supporting the role of retrotransposons and microsatellite sequences in the evolution of most allopolyploids.

In the present study, we found that the expression patterns of the vegetative profilins and actin depolymerizing factors (ADFs) were specifically altered under low temperature (17 °C) stress using a real-time PCR. Our results show that also reorganization of the actin cytoskeleton was triggered by a low temperature. Facilitation of microfilament (MF) assembly by phalloidin treatment resulted in an enhanced low temperature stress tolerance, whereas blocking MF assembly with latrunculin B resulted in enhanced low temperature stress sensitivity. Our results show that the specific members of the vegetative profilins and ADFs might participate in regulating the response of plants to a low temperature stress, and the actin cytoskeleton is vital for the tolerance of Arabidopsis seedlings to low temperature stress.

To investigate whether brassinosteroids (BR) affects cytokinin (CK)-induced anthocyanin biosynthesis, seedlings of the Arabidopsis dwarf4 (dwf4) mutants including partially suppressing coi1 (psc1) and dwf4-102, which are defective in the BR biosynthesis, and the brassinosteroid-insensitive 1-4 (bri1-4) mutant defective in BR signalling were used for the analysis of CK-induced anthocyanin accumulation and the expression of anthocyanin biosynthetic genes and WD-repeat/Myb/bHLH transcription factors. The results show that the CK-induced anthocyanin accumulation was remarkably reduced in dwf4 and bri1-4 mutants, but distinctly increased in the wild type (WT) treated with BR. Moreover, the CK-induced expressions of the late anthocyanin biosynthetic genes including dihydroflavonol reductase, leucoanthocyanidin dioxygenase, and UDP-glucose: flavonoid-3-O-glucosyl transferase were significantly reduced in bri1-4 and dwf4-102 mutants compared to WT. In addition, the expressions of transcription factors production of anthocyanin pigment 1 (PAP1), glabra 3 (GL3), and enhancer of glabra 3 (EGL3) were induced by CK in WT but not in the bri1-4 and dwf4-102 mutants. These results indicate that BR enhanced the CK-induced anthocyanin biosynthesis by up-regulating the late anthocyanin biosynthetic genes and this regulation might be mediated by the transcription factors PAP1, GL3, and EGL3.

The Wx gene, which encodes waxy proteins, is the sole gene responsible for amylose synthesis in the wheat seed endosperm. In this study, we characterized, at the molecular level, several Wx alleles in durum wheat (Triticum turgidum L. ssp. durum Desf.) that had previously been catalogued at the protein level. Our data show a misclassification of the alleles in both Wx genes: Wx-A1 alleles from Blanqueta (Wx-A1a) and Astrodur (Wx-A1b) have been reclassified as Wx-A1a and Wx-A1h, respectively. A sequence comparison of the Wx-B1e allele shows that there were up to five different alleles under this denomination, which confirms that the protein analysis by SDS-PAGE separation needs to be combined with the PCR amplification-sequencing analysis in order to obtain a correct classification of the alleles, which will facilitate their use in wheat quality improvement.

Cotton (Gossypium hirsutum L.) net photosynthetic rate (P_N) decreased with leaf age and low irradiance, and the interaction of these factors might lead to decreased yields mainly in crops with a high plant density. Shade decreased leaf gas exchange, mainly in young leaves, which did not recover after exposure to an increasing irradiance. Old leaves reached P_N saturation at a lower irradiance than young leaves. Also stomatal conductance decreased with leaf age and shading. Intercellular CO₂ concentration and irradiance were inversely related. The responses of P_N to irradiance decreased as leaf aged, and it did not interact with shade suggesting that self-shading is not primarily responsible for the decreased photosynthetic rate in older cotton leaves.

Nutritional stress is one of the main limits to sugar beet yield. This study evaluated morphological and molecular responses of sugar beet to changes in sulfate availability. Morphological characteristics of the root system and the accumulation of microRNA395 (miR395) were examined in sulfate(S)-supplemented and S-deprived seedlings under hydroponic conditions. We also investigated the functional role of miR395 in regulating the expression of APS1 gene coding for ATP-sulfurylase in roots and leaves. The S-deprived seedlings showed a significant increase in the number of root tips, in the miR395 expression in leaves but not in roots, and in the expression of APS1 gene. Our results indicate that miR395 may be a useful biomarker for sulfate status in sugar beet.

Due to possible climate changes, heat stress has obtained a serious concern all over the world. Tolerance to this stress via knowledge of metabolic pathways will help us in engineering heat tolerant plants. A group of proteins called heat shock proteins are synthesized following stress and their synthesis is regulated by transcription factors. Under high temperature (HT), reactive oxygen species (ROS) are often induced and can cause damage to lipids, proteins, and nucleic acids. To scavenge the ROS and maintain cell membrane stability, synthesis of antioxidants, osmolytes, and heat shock proteins is of a vital importance. In view of above mentioned, this review highlights the detailed mechanism of pathways involving crucial steps that change during HT stress.

The effect of benzothiadiazole (BTH) and arbutin (ARB) on sugar metabolism and plant fitness in cucumber growing hydroponically in media with different doses of NO₃ ^- and urea as nitrogen sources (100 % NO₃ ^-, 75 % NO₃ ^- + 25 % urea, and 50 % NO₃ ^- + 50 % urea) was studied on the 7^th and 14^th day after the treatment. The glucose, sucrose, and chlorophyll (Chl) content, acid and alkaline invertases and lactate dehydrogenase activities, as well as leaf area of the 3^rd and 5^th leaves were determined. Urea changed the plant sugar metabolism in a dose-, time- and leaf-age-dependent manners and influenced a cucumber response to the BTH and ARB treatments. The BTH caused a significant cessation of growth, a decrease in Chl content, a reduction of leaf area, and an enhancement of lactate dehydrogenase and alkaline invertase activities. In the older leaves of the BTH-treated plants, a high accumulation of glucose and sucrose was found. At the lower dose of urea, the metabolic changes were limited. In the ARB-treated plants, the Chl content remained unchanged in all the nitrogen variants. In these plants, decrease in glucose and sucrose content and in both invertase activities was observed mainly in younger leaves of the plants grown on the high dose of urea. The ARB improved the fitness of the cucumber plants grown in the presence of urea.

Plant microRNAs (miRNAs) play important roles in regulating plant growth, development, and responses to abiotic stresses. In this study, 38 miRNAs (TaMIRs) from wheat (Triticum aestivum L.), 36 from the miRBase database, and two from our previous work were characterized and subjected to an expression pattern analysis under normal conditions and a drought stress. A semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR), real-time quantitative PCR (qPCR), and small RNA blot analyses revealed that two TaMIRs (TaMIR1120 and TaMIR1123) were root-predominant and two TaMIRs (TaMIR1121 and TaMIR1134) were leaf-predominant. Seven TaMIR precursors showed altered expressions after the drought; of these, TaMIR1136 was upregulated, whereas TaMIR156, TaMIR408, TaMIR1119, TaMIR1129, TaMIR1133, and TaMIR1139 were downregulated. These seven drought-responsive TaMIRs showed dose-dependent and typical temporal expression patterns during drought induction, and they gradually returned back under the normal growth conditions. The drought-responsive and the tissue-predominant TaMIRs had varying numbers of target genes. Randomly selected target genes exhibited opposite expression patterns to their corresponding TaMIRs suggesting that they were regulated by distinct TaMIRs through a post-transcriptional cleavage. The target genes regulated by drought-responsive and tissue-predominant TaMIRs are involved in various cellular processes, such as signal transduction, transcriptional regulation, primary and secondary metabolisms, development, and defense responses. These results provide a novel insight into the miRNA-mediated responses of wheat to drought stress.

The effects of short-term osmotic stress [a polyethylene glycol (PEG) treatment] on photosystem II (PS II) of upland and lowland rice seedlings were investigated using chlorophyll (Chl) fluorescence imaging. Spatial heterogeneity in the top fully expanded leaf for all Chl fluorescence parameters was found under stress conditions. After exposure to PEG, a decrease in the effective quantum yield of PS II photochemistry (φPS II) and photochemical quenching (qP), and an increase in non-photochemical quenching (NPQ) proceeded from the upper section to the base of the leaf. The most sensitive position in the leaf was different between the two ecotypes. Chl fluorescence parameters, net photosynthetic rates (P_N), and stomatal conductance (g_s) were more sensitive to the PEG stress in upland rice than in lowland rice. These results also indicate different leaf anatomy and development in the two rice ecotypes. Additionally, the findings suggest a more rapid stress response in upland rice.

In this study, the anthocyanin content and real-time quantitative expression of the anthocyanin biosynthesis-related genes were investigated in leaves, stems, and tubers of purple yam (Dioscorea alata L.). The anthocyanin content, its accumulation, and the expression of genes encoding phenylalanine ammonia lyase (PAL), flavanone-3-hydroxylase (F3H), anthocyanidin synthase (ANS), and UDP-glycose flavonoid glycosyl transferase (UFGT) were studied. The anthocyanin content in the leaves and stems was high at early stages of growth, but it decreased and remained at a similar level from the 35^th day onward. The anthocyanin content in the tubers firstly increased, reached a high peak at the 110^th day of growth, after which decreased. Anthocyanin accumulation rates and the expressions of the anthocyanin biosynthesis genes were high at the early stages of growth in the leaves and stems, but in tubers, two peaks were observed: at days 80 and 140 for the gene expression and at days 125 and 170 for the anthocyanin accumulation rate. Thus, there was coordination between the gene expressions and the anthocyanin accumulation rates in the various organs as well as in the entire plants.

Germin and germin-like proteins (GLPs) are a broad and diverse family of developmentally regulated proteins widely distributed in plants. Oryza sativa L. harbours a large family of GLPs and serves as a good model for their study. In the present study, a germin-like protein gene (OsRGLP1) of rice origin was characterized by its heterologous expression in tobacco. The real-time PCR established almost a uniform expression of OsRGLP1 in leaves, stem, and roots of T₁ Nicotiana tabacum cv. Samsun. Although no morphological difference was apparent between T₀ transgenic and wild-type plants, leaves of mature transgenic plants showed necrotic lesions associated with an elevated content of H₂O₂, which was evidenced by in situ 3,3'-diaminobenzidine staining. A significantly higher activity of heat resistant superoxide dismutase (SOD) was observed in the transgenic plants as compared to the wild-type. The SOD activity in the transgenic plants was insensitive to potassium cyanide and sensitive to H₂O₂.

Phospholipase D (PLD) and its product phosphatidic acid are now considered to be one of the key elements of numerous physiological processes in plants including the salicylic acid signalling pathway. The presented study investigates the transcriptional regulation of Brassica napus PLDs following treatments with defense-related stimuli. We cloned eight B. napus genes encoding members of PLDβ, γ, and δ isoforms and performed phylogenetic analysis with its ancestor species Brassica rapa and Brassica oleracea, and with the model plant Arabidopsis thaliana. Transcription of the identified genes was monitored after treatment with benzothiadiazole (BTH), methyl jasmonate (MeJA), bacterial elicitor flg22, wounding, and after infection with fungal pathogens Sclerotinia sclerotiorum and Leptosphaeria maculans. Most of the genes responded specifically to a particular treatment. Remarkably the genes encoding the PLDγ and PLDβ isoforms were up-regulated by stimuli associated with the salicylic acid signalling pathway. The generality of this finding was confirmed by the analysis of public transcriptional data from Arabidopsis thaliana.

Analysis of structural changes of octoploid triticale genomes was conducted in F₂ and F₃ generations. The plants were derived from crosses of five cultivars and breeding lines of hexaploid wheat (Triticum aestivum L.) with one cultivar of rye (Secale cereale L). The study used four marker systems: inter-simple sequence repeat (ISSR), inter-retrotransposon amplified polymorphism (IRAP), retrotransposon-microsatellite amplified polymorphism (REMAP), and a technique named inter-transposon amplified polymorphism (ITAP) developed by the authors. Most frequently, elimination of specific bands was observed, especially of rye bands. Depending on the cross combination, the percentage of eliminated rye bands ranged from 73.6 to 80.6 %. A lower percentage of wheat bands was eliminated, i.e., from 57.6 to 76.48 %, depending on the combination of crosses. The emergence of new types of bands in hybrids absent in the parental forms was the rarest phenomenon (14.5-17.9 %). The results indicate the ongoing process of genome rearrangements at the molecular level in the early generations of plant crosses that also involve repeated nucleotide sequences of DNA.