Selenium (Se) is an essential trace element for humans and animals. A hydroponic experiment was performed to study the effects of sulphur (S) on Se uptake, translocation, and assimilation in wheat (Triticum aestivum L.) seedlings. Sulphur starvation had a positive effect on selenate uptake and the form of Se supplied greatly influenced Se speciation in plants. Compared with the control plants, Se uptake by the S-starved plants was enhanced by 4.81-fold in the selenate treatment, and selenate was readily transported from roots to shoots. By contrast, S starvation had no significant effect on selenite uptake, and selenite taken up by roots was rapidly converted to organic forms and tended to accumulate in roots. X-ray absorption near edge spectroscopy (XANES) analysis showed that organic forms of selenium, including selenocystine, Se-methyl-selenocysteine (MeSeCys), and selenomethionine-Se-oxide, were dominant in the plants exposed to selenite and accounted for approximately 90 % of the total Se. Whereas selenate remained as the dominant species in the roots and shoots exposed to selenate, with little selenate converted to selenite and MeSeCys. Besides, sulphur starvation increased the proportion of inorganic Se species in the selenate-supplied plants, but had no significant effects on Se speciation in plants exposed to selenite. The present study provides important knowledge to understand the associated mechanism of Se uptake and metabolism in plants.

Water use efficiency (WUE) is an worth attempting trait to discover the genomic regions governing it, especially in view of the diminishing water resources for the crop plants in general and rice in particular. In order to address this, the present investigation was aimed at identification of genomic regions governing WUE employing a recombinant inbred line population derived from a cross between INRC10192, a high WUE landrace, and IR64, a high yielding cultivar. A total of 36 quantitative trait loci (QTLs) were detected under control as well as drought conditions on chromosomes 1, 2, 4, 8, 9, 10, and 11. Among all, the QTLs with the marker intervals RM486-RM6703, RM6703-RM11484, RM404-RM447, RM24879-RM171, and RM229-RM332 on chromosomes 1, 8, 10, and 11 were found to govern the water use efficiency related traits such as carbon isotope discrimination, specific leaf area, leaf width, and relative water content. Nine major QTL intervals were targeted for candidate gene identification using gene ontology (GO) and transcriptome-based analyses. Overrepresented GO terms in the targeted QTLs were found to be associated with the genes/pathways controlling stomatal regulatory mechanism, stress responsive genes or transcription factors, and saccharide biosynthesis pathways under stress situation. Hence, these genes or genomic regions are potential candidates for development of high WUE rice cultivars.

The anther culture technique, although it has been widely used in wheat breeding programs, is associated with a high albinism rate that limits its application. The mechanism of albinism has not been studied explicitly at the molecular level. In this study, differently expressed genes (DEGs) and proteins (DEPs) of albino and green seedlings from a wheat anther culture were analyzed and compared using transcriptomic sequencing (RNA-Seq), two-dimensional electrophoresis, and mass spectrometry. A total of 1 892 DEGs (1 115 down-regulated and 777 up-regulated) and 43 DEPs (15 down-regulated and 28 up-regulated) that are primarily involved in photosynthetic pathways and porphyrin and chlorophyll metabolism was identified when the albino group library was used as the control. Most DEGs participated in constructing components of thylakoids and the chloroplast envelope as determined via gene ontology analysis. The expression patterns of 12 selected genes were evaluated using real-time quantitative PCR, and the results were in agreement with the RNA-Seq analysis. Our results may assist the development of new methods to decrease the albino seedling rates in wheat anther cultures.

This study is focused on examination of crown dehydrin content during overwintering and spring dehardening periods in three Poaceae family winter plants: rye, wheat, and triticale. Frost resistances of seedlings in laboratory and field conditions were compared. Immunoblotting demonstrates that winter wheat and winter triticale differed from winter rye based on their dehydrin qualitative content. Unlike wheat and triticale, rye lacked a protein with a molecular mass of 55.3 kDa. Winter wheat contained a polypeptide with a molecular mass of 29 kDa in autumn but lacked it in winter compared with triticale. Comparison of dehydrin spectra from the three winter crops suggests a relationship between synthesis of dehydrins with molecular masses of 29 and 55.3 kDa and frost resistance of the plant species.

The effect of lanthanum on the metabolism of ascorbate (AsA) and glutathione (GSH) in the leaves of maize seedlings under cadmium stress was investigated. The findings showed that Cd remarkably increased electrolyte leakage (EL), the activities of ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase (MDHAR), glutathione reductase, L-galactono-1,4-lactone dehydrogenase, and γ-glutamylcysteine synthetase, and the content of reduced AsA, reduced GSH, total AsA, total GSH, malondialdehyde (MDA), and Cd, compared with control. However, Cd significantly decreased the dry biomass of roots and shoots. Treatment with La + Cd evidently increased the activities of above enzymes except MDHAR, the content of reduced AsA, reduced GSH, total AsA and total GSH, and the dry biomass of roots and shoots, compared with Cd stress alone. Meanwhile, treatment with La + Cd remarkably decreased EL and the content of Cd and MDA compared with Cd stress alone. Our results suggested that La could be used as a regulator to improve the Cd tolerance of maize for its role in the alleviation of Cd-induced oxidative damage by regulating the metabolism of AsA and GSH.

Histone deacetylases (HDACs) catalyze histone deacetylation and play an important role in suppression of gene transcription in multiple cellular processes. HDACs are widely distributed in eukaryotes, however, detailed characterrization of HDACs in woody plants is not available. In this study, the sequences of reduced potassium dependency 3/histone deacetylase 1 (RPD3/HDA1) family proteins in black cottonwood (Populus trichocarpa Torr. & A. Gray) were characterized and their expression patterns in response to cold and salt stresses were determined. The RPD3/HDA1 proteins had conserved HDAC domains and can be divided into three classes based on sequence similarity and phylogenetic analysis. The transcripts of the HDAC genes were detected in different amounts in leaves, stems, and roots. The expressions of HDAC genes HDA902, HDA903, HDA904, HDA909, and HDA912 were up-regulated in a cold stress. Interestingly, in a salt stress, most of the HDAC genes were down-regulated. These results indicate that the poplar HDAC genes were regulated by the cold and salt stresses, and the members of the RPD3/HDA1 family play a role in stress responses.

Proline is emerging as a critical component of drought tolerance and fine tuning of its metabolism under stress affects the plants sensitivity and response to stress. Thus the study was carried out to analyse the effect of water deficit on the proline content and principal enzymes involved in its synthesis (Δ¹-pyrolline-carboxylate synthetase) and catabolism (proline dehydrogenase) at different developmental stages and in different organs (roots, nodules, leaves, pod wall, and seeds) of two chickpea (Cicer arietinum L.) cultivars differing in drought tolerance (drought tolerant ICC4958 and drought sensitive ILC3279). It was observed that increased Δ¹-pyrolline-carboxylate synthetase activity under moderate stress in roots and nodules of ICC4958 caused an increase in proline content during initiation of reproductive development whereas increased proline dehydrogenase activity in nodules and leaves at this period helped to maintain reducing power and energy supply in tissues and proper seed development as seed biomass increased consistently up to maturity. On the other hand, roots and nodules of ILC3279 responded to stress by increasing proline content after the developmental phase of reproductive organs was over (near maturity) which negatively affected the response of pod wall to stress. Concurrent increase in activities of Δ¹-pyrolline-carboxylate synthetase and proline dehydrogenase in pod wall of ILC3279 aggravated the oxidative stress and affected seed development as seed biomass initially increased rapidly under stress but was unaffected near maturity.

The tonoplast and plasma membrane localized sodium (potassium)/proton antiporters have been shown to play an important role in plant resistance to salt stress. In this study, AtNHX1 and AtNHX3, two tonoplast Na⁺(K⁺)/H⁺ antiporter encoding genes from Arabidopsis thaliana, were expressed in poplar to investigate their biological functions in the resistance to abiotic stresses in woody plants. Transgenic poplar plants expressing either gene exhibited increased resistance to both salt and water-deficit stresses. Compared to the wild type (WT) plants, transgenic plants accumulated more sodium and potassium ions in the presence of 100 mM NaCl and showed reduced electrolyte leakage in the leaves under water stress. Furthermore, the proton-translocating and cation-dependent H⁺ (Na⁺/H⁺ or K⁺/H⁺) exchange activities in the tonoplast vesicles isolated from the leaves of transgenic plants were higher than in those isolated from WT plants. Therefore, constitutive expression of either AtNHX1 or AtNHX3 genetically modified the salt and water stress tolerance of transgenic poplar plants, providing a potential tool for engineering tree species with enhanced resistance to multiple abitotic stresses.

The relationship between hydrogen peroxide (H₂O₂) and nitric oxide (NO) in the regulation of ascorbate and glutathione metabolism by jasmonic acid (JA) in Agropyron cristatum leaves were studied. Results showed that JA increased the production of H₂O₂ and NO, the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), L-galactono-1,4-lactone dehydrogenase (GalLDH), and γ-glutamylcysteine synthetase (γ-ECS), as well as transcription of the respective genes and also the content of reduced ascorbate (AsA) and reduced glutathione (GSH). Above increases were suppressed by pre-treatments with H₂O₂ synthesis inhibitor diphenylene iodonium (DPI), H₂O₂ scavenger dimethylthiourea (DMTU), NO synthesis inhibitor N ^G-nitro-L-Arg methyl ester (L-NAME), and NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). Pre-treatments with DPI and DMTU reduced H₂O₂ and NO production. Pre-treatments with L-NAME and cPTIO reduced NO production, but did not reduce the H₂O₂ production induced by JA. Our results suggested that NO acted downstream of H₂O₂ in JA signalling in the up-regulation of ascorbate and glutathione metabolism in A. cristatum leaves.

Carrot (Daucus carota L.) chromosomes are small and uniform in shape and length. Here, mitotic chromosomes were subjected to multicolour fluorescence in situ hybridization (mFISH) with probes derived from conserved plant repetitive DNA (18-25S and 5S rDNA, telomeres), a carrot-specific centromeric repeat (Cent-Dc), carrot-specific repetitive elements (DCREs), and miniature inverted-repeat transposable elements (MITEs). A set of major chromosomal landmarks comprising rDNA and telomeric and centromeric sequences in combination with chromosomal measurements enabled discrimination of carrot chromosomes. In addition, reproducible and unique FISH patterns generated by three carrot genome-specific repeats (DCRE22, DCRE16, and DCRE9) and two transposon families (DcSto and Krak) in combination with telomeric and centromeric reference probes allowed identification of chromosome pairs and construction of detailed carrot karyotypes. Hybridization patterns for DCREs were observed as pericentromeric and interstitial dotted tracks (DCRE22), signals in pericentromeric regions (DCRE16), or scattered signals (DCRE9) along chromosomes similar to those observed for both MITE families.

Members of the Brassicaceae family disperse their seeds through a mechanism commonly referred to as fruit dehiscence or pod shatter. Pod shatter is influenced by variations in valve margin structure and by the molecular control pathways related to valve development. Anatomical patterns of the dehiscence zone from Brassica napus L., Brassica rapa L., Brassica carinata L., and Sinapis alba L., representing fruit types differing in pod shatter resistance, were compared using histological staining. The pod shatter-susceptible plant B. napus showed an increased lignin deposition at the vascular bundle of the replum as well as an increased separation of cell layers. In pod shatter-resistant plants S. alba, B. rapa, and B. carinata, we observed two layers of lignified valve margin cells. From these four species, we isolated and identified homologs of SHATTERPROOF (SHP1, SHP2), INDEHISCENT (IND), ALCATRAZ (ALC), FRUITFULL (FUL), AGAMOUS (AG), NAC SECONDARY WALL THICKENING PROMOTING FACTOR1 (NST1), and SEEDSTICK (STK) genes involved in fruit development and pod shatter in Arabidopsis. Transcriptional analysis of these eight genes was performed by real-time polymerase chain reaction and the results demonstrate that differences in the expression patterns of the eight genes may be associated with dehiscence variation within these four species.

Globally, drought is the main factor that reduces common bean yield. For this reason, breeding alternatives, such as molecular marker-assisted selection, that focus on various functional genes directly involved in the response to water stress, such as those encoding late embryogenesis abundant (LEA), early response to dehydration (ERD), and dehydrin proteins, have been implemented. The aim of this study was to identify differentially expressed genes of Phaseolus vulgaris in drought-tolerant cultivars Pinto Saltillo (PS) and Pinto Villa (PV), and drought-susceptible cultivars Bayo Madero (BM) and Canario 60 (C60) in vegetative and reproductive stages. Relative water content (RWC) in leaf tissue was measured. Twenty-eight P. vulgaris genes obtained from GenBank and from a subtractive suppressive library from the PS cultivar were analysed, and their expression profiles were examined by reverse transcription polymerase chain reaction (RT-PCR). Then, cDNA arrays were developed and hybridised to confirm expression which was finally validated by quantitative PCR (qPCR). The usefulness of the identified genes as selection criteria for the tolerance of different genotypes to drought was examined using cDNA arrays. Expression of 21 genes was induced by drought. The cDNA arrays confirmed that expression of 19 of these genes increased in the vegetative stage upon exposure to the drought, and a higher expression was observed in the reproductive stage compared with vegetative stage V4. Only five genes induced by the drought were found to have a lower expression in the susceptible cultivars compared with the tolerant ones. During recovery after the drought in the reproductive stage, 13 of the 21 induced genes remained transcriptionally active including LEA3 and dehydrin. The RWC during the drought in vegetative stage V4 decreased by about 55 % in all cultivars, but at the onset of flowering, it increased to 80 % in PV and PS. In contrast, in the susceptible cultivars, it remained at 55 %. Using qPCR validation, expression induction was confirmed in the drought-tolerant cultivars. Polyubiquitin2, LEA3, LEA4, and dehydrin were useful genes for selecting drought-tolerant genotypes under field conditions.

The first rate-limiting enzyme of the mevalonate pathway during isoprenoid biosynthesis is 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR). In this study, the expression pattern of the MdHMGR2 gene in Malus domestica suggests that MdHMGR2 was expressed in a tissue-specific manner and was significantly induced by ethephon (ETH), indoleacetic acid (IAA), methyl jasmonate (MeJA), and salicylic acid (SA). The MdHMGR2 promoter was isolated, sequenced, and analyzed through bioinformatics tools, and the results suggest the presence of various putative cis-acting elements responsive to different hormones. Activity of β-glucuronidase (GUS) driven by the full length MdHMGR2 promoter and its 5'deletion fragments was detected in transgenic Arabidopsis thaliana. A strong GUS activity was observed in seedlings, roots, newly growing true leaves, anthers, and stigmas in transgenic Arabidopsis containing the full MdHMGR2 promoter. The results indicate that a region from -1050 to -827 was crucial for promoter activity. In addition, the MdHMGR2 promoter was induced in response to ETH, IAA, MeJA, and SA. The analysis suggests that an ethylene-responsive element in the region from -1050 to -1005 was required for the ethylene inducibility.

Kinetin-induced programmed cell death of field bean (Vicia faba spp. minor) root cortex cells led to aerenchyma formation. The process was accompanied by appearance of a greater amount of reactive oxygen species (ROS), greater superoxide dismutase (SOD) and catalase (CAT) activities, as well as by thickening cell walls and changes in sugar amounts, particularly in cell wall-bound sugars. The obtained results justify the supposition that ROS scavengers together with an increased amount of sugars (soluble, storage, and cell wall-bound) and thick cell walls protected the cells against death. Thus, kinetin played a dual role because it induced programmed death of chosen cells and simultaneously stimulated protective mechanisms against death in other cells. These results confirm an earlier suggestion that cell death induced by kinetin is a specific process during which its progression is hallmarked by metabolic and morphological features.

Litchi is one of the most important subtropical evergreen fruit trees in Southern Asia. Litchi floral buds are a mix of axillary or apical panicle primordia, leaf primordia, and rudimentary leaves. Under usual winter and early spring conditions, the axillary panicle primordia prevail, and the rudimentary leaves abscise when low temperatures reach a certain threshold. The floral buds ultimately develop into pure panicles. Understanding the regulatory mechanism of rudimentary leaf senescence is of great importance for litchi flowering. In this study, litchi potted trees at the floral differentiation stage were treated with low and high temperatures in order to induce senescence or development of leaves. The microstructure of the petiole base of the rudimentary leaves was determined. The results show several layers of flattened cells forming in the abscission zone of the rudimentary leaves that were treated with low temperatures as well as an obvious boundary regarded as the abscission layer zone. We also determined the gene expression in the leaves with different developmental fate. The results show that the LcRboh, LcMC-1-like, and LcPirin genes were significantly induced in the rudimentary leaves treated with low temperatures, and the expression increased with the proceeding of senescence. The expression of the genes encoding class Ι β-1,3-glucanase and β-xylosidase also increased with the senescence, suggesting their possible involvement in the low temperature-induced senescence of the rudimentary leaves.

Physiological responses of Oryza sativa L. to lead excess (10 and 50 μM) were studied in a hydroponic system after 48- and 96-h exposure. Accumulation of Pb in stressed rice shoots was concomitant with an increased metal concentration in the growth media and duration of exposure. The Pb stress resulted in an enhanced lipid peroxidation accompanied by altered activities of antioxidants. A substantial increase in α-tocopherol content of the Pb stressed rice shoots was observed suggesting its important role as an antioxidant. Among the antioxidant enzymes studied, activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) increased in the Pb-treated rice shoots, whereas that of catalase (CAT) declined. Activity of an important ascorbate-glutathione cycle enzyme, glutathione reductase (GR), also increased significantly in the Pb-treated shoots. The results suggest that Pb toxicity resulted in induction of oxidative stress in rice shoots, and α-tocopherol accumulation and upregulation of SOD, APX, and GR activities play an effective role in acclimatization to Pb stress.

The mechanisms of growth inhibition and antioxidative response were investigated in wheat roots exposed to 300 μM iron together with different zinc concentrations (0, 50, and 250 μM). All Zn concentrations decreased Fe content but increased Zn content in the roots and leaves of Fe-treated seedlings. Compared with Fe stress alone, 50 or 250 μM Zn + Fe treatment stimulated root growth, and increased cell viability but decreased malondialdehyde content, which were correlated with the decreases of total and apoplastic hydrogen peroxide and superoxide anion radical (O₂ ^.-) content along with apoplastic hydroxyl radical content. Generation of O₂ ^.- in response to 10 μM diphenylene iodonium suggested that NADPH oxidase activity was lower in Zn + Fe-treated roots than in other roots. In addition, cell wallbound peroxidase, diamine oxidase, and polyamine oxidase in Fe-treated roots were insensitive to Zn addition. Further study showed the stimulation of total superoxide dismutase and glutathione reductase (GR) activities as well as apoplastic catalase, ascorbate peroxidase, and GR in Zn + Fe-stressed roots in comparison with Fe-alone-treated ones. Taken together, Zn could alleviate iron-inhibitory effect on root growth, which might be associated with the decrease of lipid peroxidation, the increase of cell viability and the reductions of reactive oxygen species generation.

Very little is known about lipid transfer proteins from flax (Linum usitatissimum L.). In the present work, three genes encoding a lipid transfer protein (LTP) were isolated from flax, two of which encoded Type-1 and one Type-2 LTPs with molecular masses of about 9 and 7 kDa, respectively. The analysis of deduced amino acid sequence reveals that only Type 2 of the L. usitatissimum leaf specific LTP (LuLTP_Ls) had an N terminal signal peptide consisting of 23 amino acids. The phylogenetic analyses of LuLTP_Ls suggest their closest relatedness with respective proteins from Dimocarpus longan and Vitis vinifera. The gene expression analysis shows that LTP Type 1 genes, which include LuLTP_Ls1 and LuLTP_Ls3, were progressively expressed during leaf development, whereas LuLTP_Ls4 (Type 2) was expressed only at initial and terminal senescence stages of cotyledons. The results suggest that both types of LuLTP_Ls were differentially yet significantly expressed in cotyledons implicating their function in transport and scavenging lipidic skeletons for the benefit of other developing parts of the plant.

Podophyllum hexandrum Royle is an important medicinal herb of North-Western Himalayas, and podophyllotoxin, being its major metabolite, has been used extensively in the preparation of several anticancer drugs. Podophyllotoxin accumulates in rhizomes; however, no information exists on the role of ATP-binding cassette (ABC) transporters vis-à-vis podophyllotoxin content. The present study reports identification, validation, and expression analysis of ABC transporter genes from P. hexandrum. Total 252 ABC transporter genes were identified as unigenes out of which 22 were further validated using real time qPCR in different tissues of varying podophyllotoxin content. Differential expression analysis and Pearson's correlation coefficient revealed two candidate genes PhABC6 and PhABCIII having a positive correlation with the podophyllotoxin content. PhABCIV showed the highest expression in rhizomes (20.53-folds compared to shoots) suggesting its possible role in transport and accumulation of podophyllotoxin.

This study aimed to develop a new vector system to remove selection genes and to introduce two or more genes of interest into plants in order to express them in a coordinated manner. A multigene expression vector was established based on pCamBIA2300 using a selectable marker gene (SMG)-free system based on the combination of the isocaudamer technique and double T-DNA. The vector DT7 containing seven target genes was constructed and introduced into tobacco using Agrobacterium-mediated transformation. Twenty-one of 27 positive transgenic plants contained both T-DNA regions. The co-transformation frequency was 77.8 %. The frequency of unlinked integration of two intact T-DNAs was 22.22 % (6/27). The frequency of removal of SMG from transgenic T1 plants was 19.10 %. These results suggest that this vector system was functional and effective for multigene expression and SMG-free transgenic plant cultivation. At least seven target genes can be co-expressed using this system. Overall, these findings provide a new and highly effective platform for multigene and marker-free transgenic plant production.

As key nuclear transcription factors, the ethylene-insensitive3/EIN3-like (EIN3/EIL) proteins play important roles in ethylene signal transduction pathway in various plants. In order to better understand the role of EIN3/EILs, one EIN3-like gene (designated ZmEIL1) was isolated from maize (Zea mays L.). The full-length cDNA of ZmEIL1 was 1 999 bp in length and encoded 647 amino acids. Sequence comparison of ZmEIL1 protein with other EIN3/EILs proteins revealed high conservation of five α-helices that could form a V-shaped cleft in a 3-D model, just like AtEIL3 in Arabidopsis thaliana. This protein showed transcriptional activation and activation domain located on the 507 - 647 amino acids in yeast. Furthermore, ZmEIL1 could interact with ZmERF1 in the yeast systems, which was downstream response factor in ethylene signal transduction pathway. Its mRNA could be highly induced in maize seedlings by ethephon and 1-methylcyclopropene treatments. Meanwhile, ZmEIL1 showed relatively high expression at 20 d after pollination in maize kernel. These results show that ZmEIL1 played an important role in the growth and development by participating in ethylene signalling pathway in maize.

Drought and salinity are severe environmental stresses and limit soybean growth. In this study, a comparative analysis of physiological and molecular responses of two soybean (Glycine max L.) genotypes to these stresses was carried out. Plants of drought-tolerant genotype RD (cv. FD92) and sensitive genotype SD (cv. Z1303) were exposed to 15 % (m/v) PEG 6000, which simulated drought stress, or 150 mM NaCl. The RD plants maintained larger leaf area and higher net photosynthetic rate, chlorophyll content, stomatal conductance, and relative water content compared with the SD plants. Leaf proline content increased under both stresses more in RD than in SD. The drought tolerance of RD plants was also correlated with greater antioxidant activity and lower content of hydrogen peroxide and malondialdehyde under stress conditions. Amounts of abscisic acid, jasmonic acid, and salicylic acid under stress increased to a greater extent in RD than in SD plants. At the molecular level, the effects of 20-d stress treatments were manifested by relatively higher expression of drought- or salt-related genes: GmP5CS, GmDREB1a, GmGOLS, GmBADH, and GmNCED1 in RD plants than in SD plants. These results form the basis for understanding the mechanisms of the drought- and salt-stress tolerance in soybean.

Salt stress is one of the abiotic stresses limiting the yield of crops worldwide. However, the molecular mechanisms underlying the regulation of plant response to salt stress are not completely elucidated. Ethylene response factors (ERFs) are a subfamily of the AP2 (APETALA2)/ERF transcription factor family that regulates multiple aspects of plant growth and development, and plant responses to biotic and abiotic stresses. ERF96 is one of the small ERFs that is involved in plant defense response and abscisic acid signaling in Arabidopsis. By using real time quantitative PCR, we found that the expression of ERF96 in the wild type Arabidopsis thaliana (cv. Col-0) seedlings was induced by NaCl treatment. The transgenic plants overexpressing ERF96 were more tolerant to salt stress in terms of NaCl inhibited seed germination, early seedling development, and fresh mass. Consistent with these observations, elevated expressions of some NaCl-responsive genes including responsive drought 29 (RD29A), Δ¹-pyrroline-5-carboxylate synthetase (P5CS), cold responsive 15A (COR15A), and kinase 1 (KIN1) were observed in the transgenic plants in the presence of NaCl. We also found that the Na⁺ and K⁺ content and expressions of genes related to Na⁺/K⁺ homeostasis including stelar K⁺ outward rectifier (SKOR) and potassium transport 2/3 (AKT2/3) were altered in the ERF96 transgenic plants in response to NaCl treatment. Taken together, these results showed that overexpression of ERF96 enhanced plant tolerance to salt stress, indicating that ERF96 is a positive regulator of salt tolerance in Arabidopsis.

The life cycle of flowering plants is partially defined by environmental cues like day length and temperature. In the model plant Arabidopsis thaliana and temperate cereals, such as barley (Hordeum vulgare) and wheat (Triticum spp.), differences in life cycle control have been associated with a natural variation in FLOWERING LOCUS C (FLC) and VERNALIZATION 1-3 (VRN1-3). In sugar beet (Beta vulgaris L.), variation in vernalization requirement and life cycle is determined by a major gene at the B locus. This gene has recently been identified as a pseudo-response regulator (PRR) gene BOLTING TIME CONTROL 1 (BTC1). A second gene in beet with homology to BTC1 and ARABIDOPSIS PSEUDO RESPONSE REGULATOR 7 (APRR7) in Arabidopsis was identified and termed Beta vulgaris PSEUDO RESPONSE REGULATOR 7 (BvPRR7). We functionally characterized BvPRR7 by transgenic analysis in Arabidopsis and expression profiling during development in beet. We show that BvPRR7 was diurnally regulated and responded to cold. Constitutive expression of BvPRR7 distorted diurnal rhythms and caused late flowering in Arabidopsis suggesting a conserved function of BvPRR7 in clock regulation. Conceivably, the retention of a functional role of BvPRR7 in clock regulation may have facilitated the evolution of a distinct role as major floral regulator of the second PRR7 homolog in beet, BTC1.

Auxin controls numerous processes in plant development and auxin/indoleacetic acid (Aux/IAA), an auxin response factor (ARF), and a lateral organ boundaries domain (LBD) were considered as early auxin response transcription factors (TFs). Till now, no Aux/IAA, ARF, and LBD TFs were identified in ramie (Boehmeria nivea L. Gaud). In this study, we used Arabidopsis and mulberry sequences as query to search against the ramie transcriptome database and the searched sequences were analyzed for a full-length coding sequence. In total, we obtained 16 BnAux/IAA, 14 BnARF, and 16 BnLBD TFs on which evolutionary analysis and expression profiling were conducted. Analysis of sequence conservation revealed close evolution relationships between ramie and mulberry. Expression analysis shows these genes were actively expressed in major ramie tissues, and several were auxin responsive. The expressions of these genes were also investigated under drought and a high temperature, main abiotic stresses during ramie life cycle. We found that most genes of the three families were stress-responsive and showed distinct expression patterns under the drought and high temperature stresses.

In northern China, freezing injury is observed frequently in the rare species Magnolia wufengensis but not in the more common species Magnolia denudata. To investigate the role of the phytohormone abscisic acid (ABA) on frost tolerance in these two species, exogenous ABA was applied to the seedlings and then physiological and biochemical responses were measured during cold acclimation. Shoot growth cessation was stimulated by ABA in M. wufengensis but not in M. denudata. Abscisic acid inhibited shoot growth in M. wufengensis but not in M. denudata. Treatment with ABA stimulated leaf senescence in both species, and this effect was greater in M. denudata. For both species, ABA-treated plants exhibited bud dormancy sooner and had an increased tolerance to freezing, decreased water content and increased accumulation of proline, glucose, and fructose in shoots. These effects were generally greater for M. denudata. Freezing tolerance was significantly correlated with content of water, proline, glucose, and fructose for both species, but freezing tolerance was significantly correlated with raffinose content only in M. wufengensis. We conclude that exogenous ABA could increase cold acclimation and improve cold hardiness of both Magnolia species, although M. denudata was more responsive to ABA than M. wufengensis, which might result from a greater dehydration and accumulation of proline and certain soluble sugars.

Cytochrome P₄₅₀, CYP93A1, is involved in the synthesis of the phytoalexin glyceollin in soybean (Glycine max L. Merr). The gene encoding CYP93A1 has been used as defense marker in soybean cell cultures, however, little is known regarding how this gene is expressed in the intact plant. To further understand the tissue-specific role of CYP93A1 in soybean defense, we analyzed the expression of this gene in mechanically damaged leaves and stems. In leaves, CYP93A1 was constitutively expressed; its expression did not change in response to mechanical damage. In stems, however, expression of CYP93A1 was induced as quickly as 4 h after mechanical damage and remained upregulated for at least 48 h. The induction of CYP93A1 was associated with the synthesis of glyceollins. In comparison to several other defense-related genes encoding cysteine protease inhibitors L1 and R1 and storage proteins vspA and vspB, CYP93A1 was the most strongly induced by stem wounding. The induction of CYP93A1 was observed only locally, not systemically. Similar stem expression patterns were consistently observed among three different soybean genotypes. The strong induction of CYP93A1 in mechanically damaged stems suggests an important role in the soybean stem defense response; therefore, this study expands the use of CYP93A1 as a defense response marker to stems, not just soybean cell cultures.

Abscisic acid (ABA) regulates various plant physiological processes, especially participates in the plant responses to harsh environments. The 9-cis-epoxycarotenoid dioxygenase (NCED) is a key enzyme in ABA biosynthesis pathway. Here, a TaNCED with an 1 887-bp open reading frame was cloned from wheat, which encodes a peptide of 628 amino acids. A chloroplast transit peptide sequence was found at the N-terminus of the TaNCED protein. Multiple sequence alignments indicate that the TaNCED protein shared high similarities with other NCEDs from different species. Real-time quantitative PCR analysis shows that expression of TaNCED was strongly up-regulated by treatments with ABA, polyethylene glycol, and drought stress, and it was down-regulated during germination of the wheat seeds. Ectopic overexpression of the TaNCED gene in Arabidopsis resulted in an increase of endogenous ABA and free proline content. A lower water loss rate and stomatal conductance of leaves were found in the transgenic plants in comparison with the wild type. Subsequently, the transgenic plants displayed an enhanced tolerance to drought stress but delayed seed germination. These data provide evidence that the TaNCED might play a primary role in regulation of ABA content during water stress and seed dormancy.

Cassava (Manihot esculenta Crantz) is an important crop, and its starch formation is regulated by sucrose metabolism and transport. To understand the roles of sucrose metabolism and transport in cassava under water stress, we studied not only sucrose metabolism and transport in cassava abscission zones (AZs) but also expression of respective genes. Sucrose was transported from leaves to roots in the early stage of water stress, and a reverse sucrose flow was detected in the later stages of the stress. The decrease in sucrose content was related to leaf senescence and inhibition of photosynthesis. Microarray analyses showed seven genes encoding sucrose synthase, nine genes encoding sucrose transporters, and eight genes encoding invertase in the cassava AZs under the water stress. Reverse transcription quantitative PCR confirmed two sucrose synthase and two invertase genes significantly upregulated under the stress, whereas one sucrose transporter gene was downregulated. The sucrose synthase and invertase gene expressions were negatively correlated with sucrose content under water stress, whereas sucrose transporter gene expressions were positively correlated with sucrose content.

The present study was conducted to examine differential responses of roots and leaves of Artemisia annua to different arsenic concentrations (50, 100, and 150 μΜ) and treatment durations (1, 3, 5, or 7 d). The values of bioconcentration factor and translocation factor calculated on the basis of total As-accumulation in roots and shoots suggested that A. annua is a good As-accumulator. Above and below ground plant biomass was enhanced at 100 μΜ As but at 150 μΜ As was significantly reduced. As-treatment caused membrane damage more in the roots than in the leaves as reflected by higher degree of lipid peroxidation in the roots than in the leaves. In response to As stress, plants activated antioxidative defense for detoxification of induced reactive oxygen species (ROS), As sequestration via phytochelatins (PCS) as well as production of a wide range of secondary metabolites. All of them were activated differently in roots and leaves. Among enzymatic antioxidants, leaves significantly elevated superoxide dismutase (SOD), ascorbate peroxidase, and glutathione reductase, whereas in roots SOD, catalase, and peroxidase played significant role in ROS detoxification. Plants activated As-sequestration pathway through thiols, glutathione, and PCS and their respective genes were more induced in leaves than in roots. Further gas chromatography in tandem with mass spectroscopy analysis revealed differential modulation of secondary metabolites in leaves and roots to sustain As-stress. For example, roots synthesized linoleic acid (4.85 %) under As-treatment that probably stimulated stress-signalling pathways and in turn activated differential defense mechanisms in roots to cope up with the adverse effects of As.