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Aldehydes are a class of carbonyl compounds widely used as intermediates in the pharmaceutical, cosmetic and food industries. To date, there are few fully enzymatic methods for synthesizing these highly reactive chemicals. In the present work, we explore the biocatalytic potential of an amino oxidase extracted from the etiolated shoots of Lathyrus cicera for the synthesis of value-added aldehydes, starting from the corresponding primary amines. In this frame, we have developed a completely chromatography-free purification protocol based on crossflow ultrafiltration, which makes the production of this enzyme easily scalable. Furthermore, we determined the kinetic parameters of the amine oxidase toward 20 differently substituted aliphatic and aromatic primary amines, and we developed a biocatalytic process for their conversion into the corresponding aldehydes. The reaction occurs in aqueous media at neutral pH in the presence of catalase, which removes the hydrogen peroxide produced during the reaction itself, contributing to the recycling of oxygen. A high conversion (>95%) was achieved within 3 h for all the tested compounds.

The pervasive presence of nitric oxide (NO) in cells and its role in modifying cystein residues through protein S-nitrosylation is a remarkable redox based signalling mechanism regulating a variety of cellular processes. S-NITROSOGLUTATHIONE REDUCTASE (GSNOR) governs NO bioavailability by the breakdown of S-nitrosoglutathione (GSNO), fine-tunes NO signalling and controls total cellular S-nitrosylated proteins. Most of the published data on GSNOR functional analysis is based on the model plant Arabidopsis with no previous report for its effect on in vitro regeneration of tissue cultured plants. Moreover, the effect of GSNOR overexpression (O.E) on tomato growth, development and disease resistance remains enigmatic. Here we show that SlGSNOR O.E in tomato alters multiple developmental programs from in vitro culture establishment to plant growth and fruit set. Moreover, constitutive SlGSNOR O.E in tomato showed enhanced resistance against early blight (EB) disease caused by Alternaria solani and reduction in hypersensitive response (HR)-mediated cell death after Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) infiltrations. High GSNOR transcript levels led to the inhibition of in vitro shoot proliferation in transformed explants as revealed by the fluorescence microscopy after YFP labelling. Transgenic tomato lines overexpressing SlGSNOR showed defective phenotypes exhibiting stunted plant growth and bushy-type plants due to loss of apical dominance, along with reduced seed germination and delayed flowering. Furthermore, SlGSNOR O.E plants exhibited altered leaf arrangement, fruit shape and modified locules number in tomato fruit. These findings give a novel insight into a multifaceted regulatory role of SlGSNOR in tomato plant development, reproduction and response to pathogens., (Copyright © 2021 Elsevier GmbH. All rights reserved.)

Phosphorus is a crucial macronutrient for plant growth and development. The mechanisms for maintaining inorganic phosphate (Pi) homeostasis in rice are not well understood. The ubiquitin-conjugating enzyme variant protein OsUEV1B was previously found to interact with OsUbc13 and mediate lysine63-linked polyubiquitination. In the present study, we found OsUEV1B was specifically inhibited by Pi deficiency, and was localized in the nucleus and cytoplasm. Both osuev1b mutant and OsUEV1B-RNA interference (RNAi) lines displayed serious symptoms of toxicity due to Pi overaccumulation. Some Pi starvation inducible and phosphate transporter genes were upregulated in osuev1b mutant and OsUEV1B-RNAi plants in association with enhanced Pi acquisition, and representative Pi starvation responses, including stimulation of acid phosphatase activity and root hair growth, were also activated in the presence of sufficient Pi. A yeast two-hybrid screen revealed an interaction between OsUEV1B and OsVDAC1, which was confirmed by bimolecular fluorescence complementation and firefly split-luciferase complementation assays. OsVDAC1 encoded a voltage-dependent anion channel protein localized in the mitochondria, and OsUbc13 was shown to interact with OsVDAC1 via yeast two-hybrid and bimolecular fluorescence complementation assays. Under sufficient Pi conditions, similar to osuev1b, a mutation in OsVDAC1 resulted in significantly greater Pi concentrations in the roots and second leaves, improved acid phosphatase activity, and enhanced expression of the Pi starvation inducible and phosphate transporter genes compared with wild-type DongJin, whereas overexpression of OsVDAC1 had the opposite effects. OsUEV1B or OsVDAC1 knockout reduced the mitochondrial membrane potential and adenosine triphosphate levels. Moreover, overexpression of OsVDAC1 in osuev1b partially restored its high Pi concentration to a level between those of osuev1b and DongJin. Our results indicate that OsUEV1B is required for rice phosphate homeostasis., (© 2021 Society for Experimental Biology and John Wiley & Sons Ltd.)

The plant cell wall provides each cell with structural support and mechanical strength, and thus, it plays an important role in supporting the plant body against the gravitational force. We investigated the effects of microgravity on the composition of cell wall polysaccharides and on the expression levels of genes involved in cell wall metabolism using rice shoots cultivated under artificial 1 g and microgravity conditions on the International Space Station. The bulk amount of the cell wall obtained from microgravity-grown shoots was comparable with that from 1 g -grown shoots. However, the analysis of sugar constituents of matrix polysaccharides showed that microgravity specifically reduced the amount of glucose (Glc)-containing polysaccharides such as 1,3:1,4-β-glucans, in shoot cell walls. The expression level of a gene for endo-1,3:1,4-β-glucanase, which hydrolyzes 1,3:1,4-β-glucans, largely increased under microgravity conditions. However, the expression levels of genes involved in the biosynthesis of 1,3:1,4-β-glucans were almost the same under both gravity conditions. On the contrary, microgravity scarcely affected the level and the metabolism of arabinoxylans. These results suggest that a microgravity environment promotes the breakdown of 1,3:1,4-β-glucans, which, in turn, causes the reduced level of these polysaccharides in growing rice shoots. Changes in 1,3:1,4-β-glucan level may be involved in the modification of mechanical properties of cell walls under microgravity conditions in space.

Soil co-contaminated with cadmium (Cd) and decabromodiphenyl ether (BDE-209) is a widespread environmental problem, especially in electronic waste contaminated surroundings. Accumulation of Cd and BDE-209 in crops has possibly harmful effects on local human health. In order to assess the potential of arbuscular mycorrhizal (AM) fungi and amaranth (Amaranthus hypochondriacus L.) in remediation of soil co-contaminated with Cd and BDE-209, pot trials were performed to investigate interactive effects of AM fungi, Cd and BDE-209 on growth of amaranth, uptake of Cd and BDE-209, distribution of chemical forms of Cd and activities of antioxidant enzymes in shoots and dissipation of BDE-209 in soil. The present results showed that shoot biomass of non-mycorrhizal plants was significantly inhibited by increasing of Cd addition (5-15 mg kg -1 ), but were only slightly declined with BDE-209 addition (5 mg kg -1 ). The interaction of Cd and BDE-209 reduced the proportions of ethanol- and d-H 2 O-extractable Cd in shoots, consequently alleviated Cd toxicity to plants and enhanced root uptake of Cd and BDE-209. Inoculation of AM fungi resulted in significantly greater shoot biomass as well as higher concentrations of Cd and BDE-209 compared with non-mycorrhizal treatment. Moreover, AM fungi played a beneficial role in relieving oxidative stress on amaranth by increasing the activities of dismutase (SOD) and catalase (CAT) in shoots and significantly improved the dissipation of BDE-209 in soil. The present study suggested that combination of AM fungi and amaranth may be a potential option for remediation of Cd and BDE-209 co-contaminated soils., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Heavy metal accumulation in agricultural land causes crop production losses worldwide. Metal homeostasis within cells is tightly regulated. However, homeostasis breakdown leads to accumulation of reactive oxygen species (ROS). Overall plant fitness under stressful environment is determined by coordination between roots and shoots. But little is known about organ specific responses to heavy metals, whether it depends on the metal category (redox or non-redox reactive) and if these responses are associated with heavy metal accumulation in each organ or there are driven by other signals. Maize seedlings were subjected to sub-lethal concentrations of four metals (Zn, Ni, Cd and Cu) individually, and were quantified for growth, ABA level, and redox alterations in roots, mature leaves (L1,2) and young leaves (L3,4) at 14 and 21 days after sowing (DAS). The treatments caused significant increase in endogenous metal levels in all organs but to different degrees, where roots showed the highest levels. Biomass was significantly reduced under heavy metal stress. Although old leaves accumulated less heavy metal content than root, the reduction in their biomass (FW) was more pronounced. Metal exposure triggered ABA accumulation and stomatal closure mainly in older leaves, which consequently reduced photosynthesis. Heavy metals induced oxidative stress in the maize organs, but to different degrees. Tocopherols, polyphenols and flavonoids increased specifically in the shoot under Zn, Ni and Cu, while under Cd treatment they played a minor role. Under Cu and Cd stress, superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR) activities were induced in the roots, however ascorbate peroxidase (APX) activity was only increased in the older leaves. Overall, it can be concluded that root and shoot organs specific responses to heavy metal toxicity are not only associated with heavy metal accumulation and they are specialized at the level of antioxidants to cope with., Competing Interests: Declaration of competing interest There is no conflict of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Many areas exhibiting increased concentrations of soluble salts are simultaneously polluted with heavy metals (HM), and halophytes with extended tolerance to heavy metal toxicity seem to represent a promising tool for their phytoremediation. In this study, the response of the soil-grown C 3 -CAM (Crassulacean acid metabolism) intermediate halophyte Mesembryanthemum crystallinum (common ice plant) to increased concentrations of Cd (0.01-1 mM) was investigated. None of the tested Cd treatments affected growth parameters or tissue water content of either C 3 or CAM-performing plants. Chlorophyll a fluorescence confirmed high tolerance of the photosynthetic apparatus of both metabolic states towards Cd. Plants performing both photosynthesis types accumulated significant Cd amounts only under the highest (1 mM) treatment, and the metal was primarily deposited in the roots, which are features typical of an excluding strategy. Upon the application of 1 mM Cd solution CAM-performing plants, due to the NaCl pre-treatment applied for CAM induction, were exposed to significantly higher amounts of bioavailable Cd in comparison with those of C 3 -performing plants. As a result, roots of CAM plants accumulated over 4-fold higher Cd amounts when compared with C 3 plants. In our opinion, enhanced Cd-accumulating potential observed in CAM-performing plants was the effect of osmotic stress episode and resulting modifications e.g. in the detoxifying capacity of the antioxidative system. Increased antioxidative potential of NaCl pre-treated plants was pronounced with significantly higher activity of CuZnSOD (copper-zinc superoxide dismutase), not achievable in C 3 plants subjected to high Cd concentrations. Moreover, the applied Cd doses induced SOD activity in a compartment-dependent manner only in C 3 plants. We confirmed that none of the applied Cd concentrations initiated the metabolic shift from C 3 to CAM., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

Peroxidases play prominent roles in antioxidant responses and stress tolerance in plants; however, their functions in soybean tolerance to salt stress remain unclear. Here, we investigated the role of a peroxidase gene from the wild soybean ( Glycine soja ), GsPRX9 , in soybean tolerance to salt stress. GsPRX9 gene expression was induced by salt treatment in the roots of both salt-tolerant and -sensitive soybean varieties, and its relative expression level in the roots of salt-tolerant soybean varieties showed a significantly higher increase than in salt-sensitive varieties after NaCl treatment, suggesting its possible role in soybean response to salt stress. GsPRX9 -overexpressing yeast (strains of INVSc1 and G19) grew better than the control under salt and H 2 O 2 stress, and GsPRX9 -overexpressing soybean composite plants showed higher shoot fresh weight and leaf relative water content than control plants after NaCl treatment. Moreover, the GsPRX9 -overexpressing soybean hairy roots had higher root fresh weight, primary root length, activities of peroxidase and superoxide dismutase, and glutathione level, but lower H 2 O 2 content than those in control roots under salt stress. These findings suggest that the overexpression of the GsPRX9 gene enhanced the salt tolerance and antioxidant response in soybean. This study would provide new insights into the role of peroxidase in plant tolerance to salt stress.

Chromium (Cr) pollution is at a worrying level in a region of oilseed rape production in China. Sulfur (S) is an indispensable element for plants that has been confirmed to play an important role in regulating plant response to heavy metal stress. The present study was conducted to examine the role of S in alleviating Cr toxicity in oilseed rape. Cr stress strongly induced oxidative stress and inhibited plant growth. Application of S significantly enhanced the tolerance of oilseed rape exposed to Cr stress by activating several detoxification mechanisms including the ascorbate-glutathione (AsA-GSH) enzyme defense system and GSH production. The Cr and phytochelatins (PC) contents in the root under S treatment were markedly higher than those under Cr stress. The transcript abundances of the heavy metal transporters HMA2 and HMA4 were lower under S treatment than under Cr treatment. Most Cr was restricted to roots, and the translocation factor (TF) of Cr was markedly decreased in oilseed rape. In conclusion, our study revealed that S application is advantageous to oilseed rape defense against Cr toxicity and inhibits Cr translocation from roots to shoots.

Phenolic acid composition and activities of two associated enzymes such as PAL (phenylalanine ammonia-lyase) and CW-PRX (cell wall peroxidase) in brown rice (BR) were examined during a germination for 4 days. Shoot and kernel fractions of the germinated brown rice were separated, and soluble extracts and insoluble residues of the fractions were analyzed. In the shoot fraction, the PAL activity and soluble phenolic acid content reached to its maximum on the second day of atmospheric germination, and decreased thereafter. In contrast, the amount of insoluble phenolic acids and CW-PRX activity continuously increased during the germination for 4 days. Comparing the shoot fractions, the kernel fraction exhibited lower activities of PAL and CW-PRX, but showed an increase in total phenolic acid content during germination. Germination raised the antioxidant activity of brown rice, especially in the shoot fraction which contained more phenolic acids than the kernel fraction., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

With No Lysine (WNK) kinase belongs to ser/thr protein kinase group in which conserved catalytic lysine (K) residue of subdomain II is shifted to subdomain I. In this study, we cloned full-length coding region of WNK9 from Oryza sativa (OsWNK9) and performed in silico studies to confirm the presence of all kinase signature regulatory elements. The transcript analysis revealed that OsWNK9 was strongly down regulated under salinity, drought and ABA stress in shoots. Constitutive expression of OsWNK9 in Arabidopsis thaliana imparted increased tolerance to salt, drought, and ABA stress. Transgenic lines showed healthy phenotypes such as green leaves, achieved higher fresh weight and longer roots under salt, drought and ABA stress as compared to wild-type (WT). Transgenic plants showed better seed germination, higher chlorophyll retention and less water loss under salt and drought stress compared to WT. Promoter/gene expression studies revealed that OsWNK9 were expressed throughout plant tissues with higher expression in roots. Subcellular localization studies of OsWNK9 showed their presence in the nucleus. The transcript analysis of abiotic stress marker genes and ABA dependent genes showed they were highly expressed in transgenic lines compared to WT in response to salt and drought stress. The endogenous ABA level under salt and drought stress in transgenic lines was higher than WT. The results indicated that OsWNK9 may regulate salt and drought response in ABA dependent manner., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Strigolactones (SLs) are a class of phytohormones that regulate plant architecture. Carotenoid cleavage dioxygenase ( CCD ) genes are involved in the biosynthesis of SLs and are identified and characterized in many plants. However, the function of CCD genes in tobacco remains poorly understood. In this study, two closely related genes NtCCD8A and NtCCD8B were cloned from tobacco ( Nicotiana tabacum L.). The two NtCCD8 genes are orthologues of the tomato ( Solanum lycopersicum ) carotenoid cleavage dioxygenase 8 ( SlCCD8 ) gene. NtCCD8A and NtCCD8B were primarily expressed in tobacco roots, but low expression levels of these genes were detected in all plant tissues, and their transcript levels significantly increased in response to phosphate limitation. NtCCD8A and NtCCD8B mutations were introduced into tobacco using the CRISPR/Cas9 system and transgenic tobacco lines for both ntccd8 mutant alleles were identified. The ntccd8a and ntccd8b mutant alleles were inactivated by a deletion of three nucleotides and insertion of one nucleotide, respectively, both of which led to the production of premature stop codons. The ntccd8 mutants had increased shoot branching, reduced plant height, increased number of leaves and nodes, and reduced total plant biomass compared to wild-type plants; however, the root-to-shoot ratio was unchanged. In addition, mutant lines had shorter primary roots and more of lateral roots than wild type. These results suggest that NtCCD8 genes are important for changes in tobacco plant architecture., Competing Interests: The authors declare no conflict of interest.

All living organisms require a variety of essential elements for their basic biological functions. While the homeostasis of nutrients is highly intertwined, the molecular and genetic mechanisms of these dependencies remain poorly understood. Here, we report a discovery of a molecular pathway that controls phosphate (Pi) accumulation in plants under Zn deficiency. Using genome-wide association studies, we first identified allelic variation of the Lyso-PhosphatidylCholine (PC) AcylTransferase 1 ( LPCAT1 ) gene as the key determinant of shoot Pi accumulation under Zn deficiency. We then show that regulatory variation at the LPCAT1 locus contributes significantly to this natural variation and we further demonstrate that the regulation of LPCAT1 expression involves bZIP23 TF, for which we identified a new binding site sequence. Finally, we show that in Zn deficient conditions loss of function of LPCAT1 increases the phospholipid Lyso-PhosphatidylCholine/PhosphatidylCholine ratio, the expression of the Pi transporter PHT1;1, and that this leads to shoot Pi accumulation., Competing Interests: MK, NB, AS, AM, RA, DS, GF, GK, MA, WB, HR No competing interests declared, (© 2018, Kisko et al.)

DNA methylation plays a critical role in diverse biological processes of plants. Arabidopsis DNA METHYLTRANSFERASE1 (MET1) represses shoot regeneration by inhibiting WUSCHEL (WUS) expression, which is essential for shoot initiation. However, the upstream signals regulating MET1 expression during this process are unclear. We analyzed the signals regulating MET1 expression using a number of established strategies, such as genetic analysis, confocal microscopy, quantitative real-time PCR and chromatin immunoprecipitation. MET1 expression patterns underwent dynamic changes with the initiation of WUS during shoot regeneration. The cell cycle regulator E2FA was characterized as an upstream factor directly promoting MET1 expression. Moreover, cytokinin promoted MET1 expression partially by enhancing CYCD3 expression. Our findings reveal that MET1-mediated shoot regeneration is regulated by the cytokinin-induced cell cycle, and provide new insights into the regulation of DNA methylation in shoot regeneration., (© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.)

Annual dormancy-growth cycle is a developmental and physiological process essential for the survival of deciduous trees in temperate and boreal forests. Seasonal control of shoot growth in woody perennials requires specific genetic programmes responding to environmental signals. The environmental-controlled mechanisms that regulate the shift between winter dormancy and the growth-promoting genetic programmes are still unknown. Here, we show that dynamics in genomic DNA methylation levels are involved in the regulation of dormancy-growth cycle in poplar. The reactivation of growth in the apical shoot during bud break process in spring is preceded by a progressive reduction of genomic DNA methylation in apex tissue. The induction in apex tissue of a chilling-dependent poplar DEMETER-LIKE 10 (PtaDML10) DNA demethylase precedes shoot growth reactivation. Transgenic poplars showing downregulation of PtaDML8/10 caused delayed bud break. Genome-wide transcriptome and methylome analysis and data mining revealed that the gene targets of DEMETER-LIKE-dependent DNA demethylation are genetically associated with bud break. These data point to a chilling-dependent DEMETER-like DNA demethylase mechanisms being involved in the shift from winter dormancy to a condition that precedes shoot apical vegetative growth in poplar., (© 2017 John Wiley & Sons Ltd.)

Auxin is a main plant growth hormone crucial in a multitude of developmental processes in plants. Auxin biosynthesis via the tryptophan aminotransferase of arabidopsis (TAA)/YUCCA (YUC) route involving tryptophan aminotransferases and YUC flavin-dependent monooxygenases that produce the auxin indole-3-acetic acid (IAA) from tryptophan is currently the most researched auxin biosynthetic pathway. Previous data showed that, in maize and arabidopsis, TAA/YUC-dependent auxin biosynthesis can be detected in endoplasmic reticulum (ER) microsomal fractions, and a subset of auxin biosynthetic proteins are localized to the ER, mainly due to transmembrane domains (TMD). The phylogeny presented here for TAA/TAR (tryptophan aminotransferase related) and YUC proteins analyses phylogenetic groups as well as transmembrane domains for ER-membrane localisation. In addition, RNAseq datasets are analysed for transcript abundance of YUC and TAA/TAR proteins in Arabidopsis thaliana . We show that ER membrane localisation for TAA/YUC proteins involved in auxin biosynthesis is already present early on in the evolution of mosses and club mosses. ER membrane anchored YUC proteins can mainly be found in roots, while cytosolic proteins are more abundant in the shoot. The distribution between the different phylogenetic classes in root and shoot may well originate from gene duplications, and the phylogenetic groups detected also overlap with the biological function., Competing Interests: The authors declare no conflict of interest.

The effects of exogenous nitro oxide (NO) on chilling resistance and the metabolism of polyamine, proline, and γ-aminobutyric acid of bamboo shoots were investigated. Bamboo shoots were dipped in 0.07 mM sodium nitroprusside (SNP) and stored at 1 °C for 56 days. During the storage, the development of chilling injury of SNP treated bamboo shoots was inhibited with decreased accumulation of malonaldehyde and electrical leakage. At the end of storage, the chilling injury incidence of treated bamboo shoots decreased by 37.9% while their malonaldehyde content and electrical leakage were 8.8% and 18.6% lower than that of the control, respectively. Interestingly, the endogenous NO, polyamines, γ-aminobutyric acid, and proline contents of treated bamboo shoot also significantly increased. Consistently, the metabolisms of these nitrogenous compounds were stimulated in treated bamboo shoots, according to their higher (20.2%-49.8%) related enzyme activities, including nitric oxide synthase, arginine decarboxylase, ornithine decarboxylase, glutamate decarboxylase, orn-δ-aminotransferase, and Δ1-pyrroline-5-carboxylate synthetase. The results indicated that the SNP treatment enhanced chilling tolerance of bamboo shoots, which might associate with the activated metabolism of polyamines, γ-aminobutyric acid, and proline. SNP treatment might be an alternative technology to avoid chill injury during cold storage of bamboo shoots.

Arbuscular mycorrhizal (AM) fungi inoculation is considered a potential biotechnological tool for an eco-friendly remediation of hazardous contaminants. However, the mechanisms explaining how AM fungi attenuate the phytotoxicity of metal(oid)s, in particular arsenic (As), are still not fully understood. The influence of As on plant growth and the antioxidant system was studied in Leucaena leucocephala plants inoculated with different isolates of AM fungi and exposed to increasing concentrations of As (0, 35, and 75 mg dm -3 ) in a Typic Quartzipsamment soil. The study was conducted under greenhouse conditions using isolates of AM fungi selected from uncontaminated soils (Acaulospora morrowiae, Rhizophagus clarus, Gigaspora albida; and a mixed inoculum derived from combining these isolates, named AMF Mix) as well as a mix of three isolates from an As-contaminated soil (A. morrowiae, R. clarus, and Paraglomus occultum). After 21 weeks, the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were determined in the shoots in addition to measuring plant height and mineral contents. In general, AM fungi have shown multiple beneficial effects on L. leucocephala growth. Although the activity of most of the stress-related enzymes increased in plants associated with AM fungi, the percentage increase caused by adding As to the soil was even greater for non-mycorrhizal plants when compared to AM-fungi inoculated ones, which highlights the phytoprotective effect provided by the AM symbiosis. The highest P/As ratio observed in AM-fungi plants, compared to non-mycorrhizal ones, can be considered a good indicator that the AM fungi alter the pattern of As(V) uptake from As-contaminated soil. Our results underline the role of AM fungi in increasing the tolerance of L. leucocephala to As stress and emphasize the potential of the symbiosis L. leucocephala-R. clarus for As-phytostabilization at moderately As-contaminated soils., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Glutathione S-transferases (GSTs) play important roles in herbicide tolerance. However, studies on GST function in herbicide tolerance among plant tissues are still lacking. To explore the mechanism of metolachlor tolerance difference between maize shoots and roots, the effects of metolachlor on growth, GST activity, and the expression of the entire GST gene family were investigated. It was found that this differential tolerance to metolachlor was correlated with contrasting GST activity between the two tissues and can be eliminated by a GST inhibitor. An in vitro metolachlor-glutathione conjugation assay confirmed that the transformation of metolachlor is 2-fold faster in roots than in shoots. The expression analysis of the GST gene family revealed that most GST genes are expressed much higher in roots than shoots, both in control and in metolachlor-treated plants. Taken together, higher level expression of most GST genes, leading to higher GST activity and faster herbicide transformation, appears to be responsible for the higher tolerance to metolachlor of maize roots than shoots.

Chilling stress during germination often causes severe injury. In the present study, maize seed germination and shoot growth under chilling stress were negatively correlated with the dose of tebuconazole in an exponential manner as predicted by the model Y = A + B × e (-x/k) . Microencapsulation was an effective means of eliminating potential phytotoxic risk. The gibberellins (GAs) contents were higher after microencapsulation treatment than after conventional treatment when the dose of tebuconazole was higher than 0.12 g AI (active ingredient) kg -1 seed. Further analysis indicated that microencapsulation can stimulate ent-kaurene oxidase (KO) activity to some extent, whereas GA 3-oxidase (GA3ox) and GA 2-oxidase (GA2ox) activities remained similar to those in the control. Genes encoding GA metabolic enzymes exhibited different expression patterns. Transcript levels of ZmKO1 increased in the microcapsule treatments compared to the control. Even when incorporated into microcapsules, tebuconazole led to the upregulation of ZmGA3ox1 at doses of less than 0.12 g AI kg -1 seed and to the upregulation of ZmGA3ox2 when the dose was higher than 0.12 g AI kg -1 seed. With increasing doses of microencapsulated tebuconazole, the transcript levels of ZmGA2ox4, ZmGA2ox5 and ZmGA2ox6 exhibited upward trends, whereas the transcript levels of ZmGA2ox7 exhibited a downward trend.

Cytosolic glutamine synthetase 1;2 plays an important role in the primary nitrogen assimilation in roots. Based on characterization of the knockout mutant gln1;2 we have recently demonstrated that Gln1;2 is also essential for ammonium handling in shoots. Here we built reciprocally grafted plants between wild type (Wt) and gln1;2 in order to separate the root and shoot roles of Gln1;2. Significant reduction in silique number and seed yield were observed in the grafted plants 1;2 shoot /Wt root relative to Wt shoot /1;2 root and Wt shoot /Wt root . Shoot Gln1;2 thus played a crucial role for seed production. Tracing experiments with 15 N showed that the relative nitrogen remobilization from vegetative organs to seeds in gln1;2 was just as efficient as in the Wt plants. This was the case although the total quantity of nitrogen in gln1;2 was significantly lower compared to that in the Wt. We conclude that the functions of shoot Gln1;2 are primarily associated with internal N signaling for establishment of seed yield capacity rather than with nitrogen remobilization.

Axillary buds (AXBs) of hybrid aspen (Populus tremula×P. tremuloides) contain a developing dwarfed shoot that becomes para-dormant at the bud maturation point. Para-dormant AXBs can grow out after stem decapitation, while dormant AXBs pre-require long-term chilling to release them from dormancy. The latter is mediated by gibberellin (GA)-regulated 1,3-β-glucanases, but it is unknown if GA is also important in the development, activation, and outgrowth of para-dormant AXBs. The present data show that para-dormant AXBs up-regulate GA receptor genes during their maturation, but curtail GA biosynthesis by down-regulating the rate-limiting GIBBERELLIN 3-OXIDASE2 (GA3ox2), which is characteristically expressed in the growing apex. However, decapitation significantly up-regulated GA3ox2 and GA 4 -responsive 1,3-β-glucanases (GH17-family; α-clade). In contrast, decapitation down-regulated γ-clade 1,3-β-glucanases, which were strongly up-regulated in maturing AXBs concomitant with lipid body accumulation. Overexpression of selected GH17 members in hybrid aspen resulted in characteristic branching patterns. The α-clade member induced an acropetal branching pattern, whereas the γ-clade member activated AXBs in recurrent flushes during transient cessation of apex proliferation. The results support a model in which curtailing the final step in GA biosynthesis dwarfs the embryonic shoot, while high levels of GA precursors and GA receptors keep AXBs poised for growth. GA signaling, induced by decapitation, reinvigorates symplasmic supply routes through GA-inducible 1,3-β-glucanases that hydrolyze callose at sieve plates and plasmodesmata., (© The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Main Conclusion: Arabidopsis ppc3 mutant has a growth-arrest phenotype and is affected in phosphate- and salt-stress responses, showing that this protein is crucial under control or stress conditions. Phosphoenolpyruvate carboxylase (PEPC) and its dedicated kinase (PEPC-k) are ubiquitous plant proteins implicated in many physiological processes. This work investigates specific roles for the three plant-type PEPC (PTPC) and the two PEPC-k isoenzymes in Arabidopsis thaliana. The lack of any of the PEPC isoenzymes reduced growth parameters under optimal growth conditions. PEPC activity was decreased in shoots and roots of ppc2 and ppc3 mutants, respectively. Phosphate starvation increased the expression of all PTPC and PPCK genes in shoots, but only PPC3 and PPCK2 in roots. The absence of any of these two proteins was not compensated by other isoforms in roots. The effect of salt stress on PTPC and PPCK expression was modest in shoots, but PPC3 was markedly increased in roots. Interestingly, both stresses decreased root growth in each of the mutants except for ppc3. This mutant had a stressed phenotype in control conditions (reduced root growth and high level of stress molecular markers), but was unaffected in their response to high salinity. Salt stress increased PEPC activity, its phosphorylation state, and L-malate content in roots, all these responses were abolished in the ppc3 mutant. Our results highlight the importance of the PPC3 isoenzyme for the normal development of plants and for root responses to stress.

Although Trichoderma spp. have beneficial effects on numerous plants, there is not enough knowledge about the mechanism by which they improves plant growth. In this study, we evaluated the participation of plasma membrane (PM) H + -ATPase, a key enzyme involved in promoting cell growth, in the elongation induced by T. asperellum and compared it with the effect of 10 μM indol acetic acid (IAA) because IAA promotes elongation and PM H + -ATPase activation. Two seed treatments were tested: biopriming and noncontact. In neither were the tissues colonized by T. asperellum; however, the seedlings were longer than the control seedlings, which also accumulated IAA and increased root acidification. An auxin transport inhibitor (2,3,5 triiodobenzoic acid) reduced the plant elongation induced by Trichoderma spp. T. asperellum seed treatment increased the PM H + -ATPase activity in plant roots and shoots. Additionally, the T. asperellum extracellular extract (TE) activated the PM H + -ATPase activity of microsomal fractions of control plants, although it contained 0.3 μM IAA. Furthermore, the mechanism of activation of PM H + -ATPase was different for IAA and TE; in the latter, the activation depends on the phosphorylation state of the enzyme, suggesting that, in addition to IAA, T. asperellum excretes other molecules that stimulate PM H + -ATPase to induce plant growth.

Emerging evidences exhibit that mitogen-activated protein kinase (MAPK/MPK) signaling pathways are connected with many aspects of plant development. The complexity of MAPK cascades raises challenges not only to identify the MAPK module in planta but also to define the specific role of an individual module. So far, our knowledge of MAPK signaling has been largely restricted to a small subset of MAPK cascades. Our previous study has characterized an Arabidopsis bushy and dwarf1 (bud1) mutant, in which the MAP Kinase Kinase 7 (MKK7) was constitutively activated, resulting in multiple phenotypic alterations. In this study, we found that MPK3 and MPK6 are the substrates for phosphorylation by MKK7 in planta. Genetic analysis showed that MKK7-MPK6 cascade is specifically responsible for the regulation of shoot branching, hypocotyl gravitropism, filament elongation, and lateral root formation, while MKK7-MPK3 cascade is mainly involved in leaf morphology. We further demonstrated that the MKK7-MPK6 cascade controls shoot branching by phosphorylating Ser 337 on PIN1, which affects the basal localization of PIN1 in xylem parenchyma cells and polar auxin transport in the primary stem. Our results not only specify the functions of the MKK7-MPK6 cascade but also reveal a novel mechanism for PIN1 phosphorylation, establishing a molecular link between the MAPK cascade and auxin-regulated plant development., Competing Interests: The authors have declared that no competing interests exist.

3-Hydroxy-3-methylglutaryl-CoA reductase (HMG1) catalyzes the formation of mevalonic acid, the key intermediate of the cytosolic isoprenoid synthesis pathway. The parameters of stem and leaf growth were studied in the transgenic tobacco plants that express the HMG1 gene in both sense and antisense orientations towards the constitutive promoter. The transgenic plant height did not significantly differ from that of the control plants, though the plants carrying the sense copy of the HMG1 gene were considerably taller than plants that carried the antisense gene copy. Plants carrying an extra copy of the HMG1 gene were also characterized by increased leaf area. The number of mesophyll cells calculated per square unit of transgenic plants leaves was smaller than in the control plant leaves, though their volume was not considerably changed in any of the variants, suggesting changes in the cell packing density in leaves.

Tea leaves contain abundant flavan-3-ols, which include dihydroxylated and trihydroxylated catechins. Flavonoid 3'-hydroxylase (F3'H: EC 1.14.13.21) is one of the enzymes in the establishment of the hydroxylation pattern. A gene encoding F3'H, designated as CsF3'H, was isolated from Camellia sinensis with a homology-based cloning technique and deposited in the GenBank (GenBank ID: KT180309). Bioinformatic analysis revealed that CsF3'H was highly homologous with the characterized F3'Hs from other plant species. Four conserved cytochrome P450-featured motifs and three F3'H-specific conserved motifs were discovered in the protein sequence of CsF3'H. Enzymatic analysis of the heterologously expressed CsF3'H in yeast demonstrated that tea F3'H catalyzed the 3'-hydroxylation of naringenin, dihydrokaempferol and kaempferol. Apparent Km values for these substrates were 17.08, 143.64 and 68.06 μM, and their apparent Vmax values were 0.98, 0.19 and 0.44 pM·min(-1), respectively. Transcription level of CsF3'H in the new shoots, during tea seed germination was measured, along with that of other key genes for flavonoid biosynthesis using real-time PCR technique. The changes in 3',4'-flavan-3-ols, 3',4',5'-flavan-3-ols and flavan-3-ols, were consistent with the expression level of CsF3'H and other related genes in the leaves. In the study of nitrogen supply for the tea plant growth, our results showed the expression level of CsF3'H and all other tested genes increased in response to nitrogen depletion after 12 days of treatment, in agreement with a corresponding increase in 3',4'-catechins, 3',4',5'-catechins and flavan 3-ols content in the leaves. All these results suggest the importance of CsF3'H in the biosynthesis of 3',4'-catechins, 3',4',5'-catechins and flavan 3-ols in tea leaves.

Dimerization of rhamnogalacturonan-II (RG-II) via boron cross-links contributes to the assembly and biophysical properties of the cell wall. Pure RG-II is efficiently dimerized by boric acid (B(OH)3 ) in vitro only if nonbiological agents for example Pb(2+) are added. By contrast, newly synthesized RG-II domains dimerize very rapidly in vivo. We investigated biological agents that might enable this. We tested for three such agents: novel enzymes, borate-transferring ligands and cationic 'chaperones' that facilitate the close approach of two polyanionic RG-II molecules. Dimerization was monitored electrophoretically. Parsley shoot cell-wall enzymes did not affect RG-II dimerization in vitro. Borate-binding ligands (apiose, dehydroascorbic acid, alditols) and small organic cations (including polyamines) also lacked consistent effects. Polylysine bound permanently to RG-II, precluding electrophoretic analysis. However, another polycation, polyhistidine, strongly promoted RG-II dimerization by B(OH)3 without irreversible polyhistidine-RG-II complexation. Likewise, partially purified spinach extensins (histidine/lysine-rich cationic glycoproteins), strongly promoted RG-II dimerization by B(OH)3 in vitro. Thus certain polycations, including polyhistidine and wall glycoproteins, can chaperone RG-II, manoeuvring this polyanionic polysaccharide domain such that boron-bridging is favoured. These chaperones dissociate from RG-II after facilitating its dimerization, indicating that they act catalytically rather than stoichiometrically. We propose a natural role for extensin-RG-II interaction in steering cell-wall assembly., (© 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.)

Nitrate is a major nitrogen resource for cereal crops; thus, understanding nitrate signaling in cereal crops is valuable for engineering crops with improved nitrogen use efficiency. Although several regulators have been identified in nitrate sensing and signaling in Arabidopsis (Arabidopsis thaliana), the equivalent information in cereals is missing. Here, we isolated a nitrate-inducible and cereal-specific NAM, ATAF, and CUC (NAC) transcription factor, TaNAC2-5A, from wheat (Triticum aestivum). A chromatin immunoprecipitation assay showed that TaNAC2-5A could directly bind to the promoter regions of the genes encoding nitrate transporter and glutamine synthetase. Overexpression of TaNAC2-5A in wheat enhanced root growth and nitrate influx rate and, hence, increased the root's ability to acquire nitrogen. Furthermore, we found that TaNAC2-5A-overexpressing transgenic wheat lines had higher grain yield and higher nitrogen accumulation in aerial parts and allocated more nitrogen in grains in a field experiment. These results suggest that TaNAC2-5A is involved in nitrate signaling and show that it is an exciting gene resource for breeding crops with more efficient use of fertilizer., (© 2015 American Society of Plant Biologists. All Rights Reserved.)

Jasmonates are oxygenated lipids (oxylipins) that control defense gene expression in response to cell damage in plants. How mobile are these potent mediators within tissues? Exploiting a series of 13-lipoxygenase (13-lox) mutants in Arabidopsis (Arabidopsis thaliana) that displays impaired jasmonic acid (JA) synthesis in specific cell types and using JA-inducible reporters, we mapped the extent of the transport of endogenous jasmonates across the plant vegetative growth phase. In seedlings, we found that jasmonate (or JA precursors) could translocate axially from wounded shoots to unwounded roots in a LOX2-dependent manner. Grafting experiments with the wild type and JA-deficient mutants confirmed shoot-to-root oxylipin transport. Next, we used rosettes to investigate radial cell-to-cell transport of jasmonates. After finding that the LOX6 protein localized to xylem contact cells was not wound inducible, we used the lox234 triple mutant to genetically isolate LOX6 as the only JA precursor-producing LOX in the plant. When a leaf of this mutant was wounded, the JA reporter gene was expressed in distal leaves. Leaf sectioning showed that JA reporter expression extended from contact cells throughout the vascular bundle and into extravascular cells, revealing a radial movement of jasmonates. Our results add a crucial element to a growing picture of how the distal wound response is regulated in rosettes, showing that both axial (shoot-to-root) and radial (cell-to-cell) transport of oxylipins plays a major role in the wound response. The strategies developed herein provide unique tools with which to identify intercellular jasmonate transport routes., (© 2015 American Society of Plant Biologists. All Rights Reserved.)

The impact of severe drought stress (13% soil moisture) on the physiological responses, metabolic profile, and pathogenesis-related (PR) proteins in wheat above- and below-ground biomass after 20 days of treatment was studied. Drought depleted growth, assimilation pigments, and majority of free amino acids in the shoots (but proline increased considerably, +160%). On the contrary, root growth parameters were elevated, and free amino acids did not decrease, indicating investment of metabolites into the growth of roots under water deficiency. Mineral nutrients were only slightly influenced. Profiling of pathogenesis-related (PR) proteins revealed that chitinases (EC 3.2.1.14) and glucanases (EC 3.2.1.39) were activated in wheat by drought. Individual isoforms and their activity were rather stimulated under drought, especially in shoots. The expression of selected genes is in agreement with enzymatic data and suggests an organ (tissue) specific- and opposing behavior of these two types of defense components in drought-stressed wheat. Metabolic analyses at the level of phenolics showed an increase in the free and bound fraction of phenolic acids almost exclusively in the shoots and flavonoid isoorientin increased considerably: protective action against oxidative stress and dehydration of the leaves seems to be the main reason for this finding. The role of PR proteins and phenolics in drought-stressed tissue is discussed.

Plant stem cell niches (SCNs) can be maintained in time through asymmetric cell divisions (ACDs) that allow the production of new cell types while constantly renewing the pools of stem cells (SCs). ACDs in plants require the asymmetric distribution of molecular components inside the cells as well as external asymmetric positional information. These two types of asymmetric information are controlled by inter- and intracellular signalling events. Phosphorylation of proteins is a major intermediate step in these signalling events, serving either as an activator or repressor of signalling, via fast auto- and trans-phosphorylation mechanisms. Whereas protein kinases, which phosphorylate proteins on serine, threonine or tyrosine residues, have been thoroughly studied, less attention has been given to protein phosphatases, which de-phosphorylate their protein targets on these same residues. Phosphatases modulate the activity of signalling pathways by balancing the action of kinases, and are therefore critical in the regulation of ACDs in plants. In this review, we first present the different types of ACDs that operate during Arabidopsis embryonic and post-embryonic development and participate in the construction and maintenance of its root and shoot SCNs; we then give a brief description of the main protein phosphatases so far described in the Arabidopsis genome; and finally discuss their functions toward the regulation of the ACDs introduced in the first part of the paper., (© 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Nitrogen dioxide (NO2) is one of the most common and harmful air pollutants. To analyze the response of plants to NO2 stress, we investigated the morphological change, reactive oxygen species (ROS) production and antioxidant enzyme activity in Arabidopsis thaliana (Col-0) exposed to 1.7, 4, 8.5, and 18.8 mg/m(3) NO2. The results indicate that NO2 exposure affected plant growth and chlorophyll (Chl) content, and increased oxygen free radical (O2(-)) production rate in Arabidopsis shoots. Furthermore, NO2 elevated the levels of lipid peroxidation and protein oxidation, accompanied by the induction of antioxidant enzyme activities and change of ascorbate (AsA) and glutathione (GSH) contents. Following this, we mimicked nitric acid mist under experimental conditions, and confirmed the antioxidant mechanism of the plant to the stress. Our results imply that NO2 and its acid mist caused pollution risk to plant systems. During the process, increased ROS acted as a signal to induce a defense response, and antioxidant status played an important role in plant protection against NO2/nitric acid mist-caused oxidative damage., (Copyright © 2015. Published by Elsevier B.V.)

Little information is available on the role of glycinebetaine (GB) in chromium (Cr) tolerance while Cr toxicity is widespread problem in crops grown on Cr-contaminated soils. In this study, we investigated the influence of GB on Cr tolerance in wheat (Triticum aestivum L.) grown in sand and soil mediums. Three concentrations of chromium (0, 0.25, and 0.5 mM) were tested with and without foliar application of GB (0.1 M). Chromium alone led to a significant growth inhibition and content of chlorophyll a, b, proteins and enhanced the activity of antioxidant enzymes. Glycinebetaine foliar application successfully alleviated the toxic effects of Cr on wheat plants and enhanced growth characteristics, biomass, proteins, and chlorophyll contents. Glycinebetaine also reduced Cr accumulation in wheat plants especially in grains and enhanced the activity of antioxidant enzymes in both shoots and roots. This study provides evidence that GB application contributes to decreased Cr concentrations in wheat plants and its importance in the detoxification of heavy metals.

Lead (Pb) is a highly toxic heavy metal for both plants and animals; the environment is increasingly polluted with heavy metals and reduces crop productivity. Plants possess homeostatic mechanisms that allow them to keep correct concentrations of essential metal ions in cellular compartments and to minimize the damaging effects of an excess of nonessential ones. One of their adverse effects on plants are the generation of harmful active oxygen species, leading to oxidative stress and the antioxidative activity seems to be of fundamental importance for adaptive response of plant against environmental stress. The present study explores the effects of lead (soil treated twice/ week) with (10, 30 and 60 mM) on the specific activities of phosphatases which might lead to reducing power assay in (Triticum aestivum PBW344) seedling. A significant decrease in the redox potential of shoot compared to root was observed at the similar concentration of lead. A similar trend on leaves was also noted. Acid and alkaline phosphatase activities were significantly higher in roots than in shoot at all the three concentration of lead i.e. 10, 30 and 60 mM, compared to controls. The above mentioned changes were more pronounced at 60 mM concentration of lead than two other concentrations. These results lead us to suggest that increased lead concentration in soil might lead to adverse effects on plant growth and phosphatase activities.

Phloem loading is a critical process in plant physiology. The potential of regulating the translocation of photoassimilates from source to sink tissues represents an opportunity to increase crop yield. Pyrophosphate homeostasis is crucial for normal phloem function in apoplasmic loaders. The involvement of Arabidopsis (Arabidopsis thaliana) type I proton-pumping pyrophosphatase (AVP1) in phloem loading was analyzed at genetic, histochemical, and physiological levels. A transcriptional AVP1 promoter::GUS fusion revealed phloem activity in source leaves. Ubiquitous AVP1 overexpression (35S::AVP1 cassette) enhanced shoot biomass, photoassimilate production and transport, rhizosphere acidification, and expression of sugar-induced root ion transporter genes (POTASSIUM TRANSPORTER2 [KUP2], NITRATE TRANSPORTER2.1 [NRT2.1], NRT2.4, and PHOSPHATE TRANSPORTER1.4 [PHT1.4]). Phloem-specific AVP1 overexpression (Commelina Yellow Mottle Virus promoter [pCOYMV]::AVP1) elicited similar phenotypes. By contrast, phloem-specific AVP1 knockdown (pCoYMV::RNAiAVP1) resulted in stunted seedlings in sucrose-deprived medium. We also present a promoter mutant avp1-2 (SALK046492) with a 70% reduction of expression that did not show severe growth impairment. Interestingly, AVP1 protein in this mutant is prominent in the phloem. Moreover, expression of an Escherichia coli-soluble pyrophosphatase in the phloem (pCoYMV::pyrophosphatase) of avp1-2 plants resulted in severe dwarf phenotype and abnormal leaf morphology. We conclude that the Proton-Pumping Pyrophosphatase AVP1 localized at the plasma membrane of the sieve element-companion cell complexes functions as a synthase, and that this activity is critical for the maintenance of pyrophosphate homeostasis required for phloem function., (© 2015 American Society of Plant Biologists. All Rights Reserved.)

Autochthonous microorganisms [a consortium of arbuscular-mycorrhizal (AM) fungi and Bacillus thuringiensis (Bt)] were assayed and compared to Rhizophagus intraradices (Ri), Bacillus megaterium (Bm) or Pseudomonas putida (Psp) and non-inoculation on Trifolium repens in a natural arid soil under drought conditions. The autochthonous bacteria Bt and the allochthonous bacteria Psp increased nutrients and the relative water content and decreased stomatal conductance, electrolyte leakage, proline and APX activity, indicating their abilities to alleviate the drought stress. Mycorrhizal inoculation significantly enhanced plant growth, nutrient uptake and the relative water content, particularly when associated with specific bacteria minimizing drought stress-imposed effects. Specific combinations of autochthonous or allochthonous inoculants also contributed to plant drought tolerance by changing proline and antioxidative activities. However, non-inoculated plants had low relative water and nutrients contents, shoot proline accumulation and glutathione reductase activity, but the highest superoxide dismutase activity, stomatal conductance and electrolyte leakage. Microbial activities irrespective of the microbial origin seem to be coordinately functioning in the plant as an adaptive response to modulated water stress tolerance and minimizing the stress damage. The autochthonous AM fungi with Bt or Psp and those allochthonous Ri with Bm or Psp inoculants increased water stress alleviation. The autochthonous Bt showed the greatest ability to survive under high osmotic stress compared to the allochthonous strains, but when single inoculated or associated with Ri or AM fungi were similarly efficient in terms of physiological and nutritional status and in increasing plant drought tolerance, attenuating and compensating for the detrimental effect of water limitation., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Using a cuvette for simultaneous measurement of net photosynthesis in above ground plant organs and root respiration we investigated the effect of reduced leaf glucokinase activity on plant carbon balance. The gin2-1 mutant of Arabidopsis thaliana is characterized by a 50% reduction of glucokinase activity in the shoot, while activity in roots is about fivefold higher and similar to wild type plants. High levels of sucrose accumulating in leaves during the light period correlated with elevated root respiration in gin2-1. Despite substantial respiratory losses in roots, growth retardation was moderate, probably because photosynthetic carbon fixation was simultaneously elevated in gin2-1. Our data indicate that futile cycling of sucrose in shoots exerts a reduction on net CO2 gain, but this is over-compensated by the prevention of exaggerated root respiration resulting from high sucrose concentration in leaf tissue.

Target-site and non-target-site herbicide tolerance are caused by the prevention of herbicide binding to the target enzyme and the reduction to a nonlethal dose of herbicide reaching the target enzyme, respectively. There is little information on the molecular mechanisms involved in non-target-site herbicide tolerance, although it poses the greater threat in the evolution of herbicide-resistant weeds and could potentially be useful for the production of herbicide-tolerant crops because it is often involved in tolerance to multiherbicides. Bispyribac sodium (BS) is an herbicide that inhibits the activity of acetolactate synthase. Rice (Oryza sativa) of the indica variety show BS tolerance, while japonica rice varieties are BS sensitive. Map-based cloning and complementation tests revealed that a novel cytochrome P450 monooxygenase, CYP72A31, is involved in BS tolerance. Interestingly, BS tolerance was correlated with CYP72A31 messenger RNA levels in transgenic plants of rice and Arabidopsis (Arabidopsis thaliana). Moreover, Arabidopsis overexpressing CYP72A31 showed tolerance to bensulfuron-methyl (BSM), which belongs to a different class of acetolactate synthase-inhibiting herbicides, suggesting that CYP72A31 can metabolize BS and BSM to a compound with reduced phytotoxicity. On the other hand, we showed that the cytochrome P450 monooxygenase CYP81A6, which has been reported to confer BSM tolerance, is barely involved, if at all, in BS tolerance, suggesting that the CYP72A31 enzyme has different herbicide specificities compared with CYP81A6. Thus, the CYP72A31 gene is a potentially useful genetic resource in the fields of weed control, herbicide development, and molecular breeding in a broad range of crop species., (© 2014 American Society of Plant Biologists. All Rights Reserved.)

Pectin in the primary plant cell wall is thought to be responsible for its porosity, charge density, and microfibril spacing and is the main component of the middle lamella. Plant-parasitic nematodes secrete cell wall-degrading enzymes that macerate the plant tissue, facilitating the penetration and migration within the roots. In sedentary endoparasitic nematodes, these enzymes are released only during the migration of infective juveniles through the root. Later, nematodes manipulate the expression of host plant genes, including various cell wall enzymes, in order to induce specific feeding sites. In this study, we investigated expression of two Arabidopsis pectate lyase-like genes (PLL), PLL18 (At3g27400) and PLL19 (At4g24780), together with pectic epitopes with different degrees of methylesterification in both syncytia induced by the cyst nematode Heterodera schachtii and giant cells induced by the root-knot nematode Meloidogyne incognita. We confirmed upregulation of PLL18 and PLL19 in both types of feeding sites with quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and in situ RT-PCR. Furthermore, the functional analysis of mutants demonstrated the important role of both PLL genes in the development and maintenance of syncytia but not giant cells. Our results show that both enzymes play distinct roles in different infected root tissues as well as during parasitism of different nematodes.

Our previous study demonstrated that the oral administration of low molecular weight chitosans (LMWC), prepared by hydrolyzing crab shell chitosans with bamboo shoots chitosanase in an appropriate dose, reduced aristolochic acid-induced renal lesions in mice. The objectives of this study were to evaluate the safety of LMWC using genetic and animal toxicity assays. Two assays for genotoxicity were performed: the chromosomal aberration of Chinese hamster ovary cells (CHO-K1 cells) (in vitro) and micronucleus assays in mice (in vivo). Acute oral toxicity and 28-day repeated feeding toxicity tests were performed via the oral gavage method in Sprague-Dawley (SD) rats. LMWC did not induce an increase in micronucleus ratios in vivo, and the chromosome aberration assay indicated that the LMWC was safe in terms of clastogenicity in doses up to 5.0 mg/ml. No acute lethal effect at a maximum tested dose of 5.0 g LMWC/kg body weight (bw) was observed in rats. The results of the 28-day study revealed no adverse effects on the body weight, feed consumption, hematology, blood biochemical parameters, organ weights or pathology. The no observed adverse effect level (NOAEL) of LMWC in rats was 1.0 g/kg bw for the subacute toxicity study., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Cytokinin signaling is vital for plant growth and development which function via the two-component system (TCS). As one of the key component of TCS, transmembrane histidine kinases (HK) are encoded by a small gene family in plants. In this study, we focused on expression and functional analysis of cytokinin receptor-like HK genes (ZmHK) in maize. Firstly, bioinformatics analysis revealed that seven cloned ZmHK genes have different expression patterns during maize development. Secondly, ectopic expression by CaMV35S promoter in Arabidopsis further revealed that functional differentiation exists among these seven members. Among them, the ZmHK1a2-OX transgenic line has the lowest germination rate in the dark, ZmHK1-OX and ZmHK2a2-OX can delay leaf senescence, and seed size of ZmHK1-OX, ZmHK1a2-OX, ZmHK2-OX, ZmHK3b-OX and ZmHK2a2-OX was obviously reduced as compared to wild type. Additionally, ZmHK genes play opposite roles in shoot and root development; all ZmHK-OX transgenic lines display obvious shorter root length and reduced number of lateral roots, but enhanced shoot development compared with the wild type. Most notably, Arabidopsis response regulator ARR5 gene was up-regulated in ZmHK1-OX, ZmHK1a2-OX, ZmHK2-OX, ZmHK3b-OX and ZmHK2a2-OX as compared to wild type. Although the causal link between ZmHK genes and cytokinin signaling pathway is still an area to be further elucidated, these findings reflected that the diversification of ZmHK genes expression patterns and functions occurred in the course of maize evolution, indicating that some ZmHK genes might play different roles during maize development.

Thymus caespititius Brot. is an Iberian endemic species, whose essential oils possess high polymorphism. They consist mostly of mono- and sesquiterpene, some of them with interest for the pharmaceutical and food industries. The search for terpene synthase genes was performed in three in vitro T. caespititius genotypes. For these plants, the expression of a previously described γ-terpinene synthase gene, Tctps2, was confirmed, occurring concomitantly with a new gene encoding an enzyme with similar activity, named Thymus caespititius terpene synthase 4 (Tctps4). The two isogenes were isolated and functionally characterized in the three plant genotypes. Alignment of the two Tctps revealed a transit peptide much shorter in Tctps4 than in Tctps2 (3-4 amino acids instead of 47). The Tctps4 open reading frame is shorter than Tctps2 (1665 bp versus 1794 bp). The amino acid sequence of both γ-terpinene synthases shared an 88% pairwise identity. The fact that T. caespititius carries two isogenes for γ-terpinene synthases, suggests gene duplication along the evolutionary process, followed by mutations leading to the differentiation of both genes. These mutations didn't compromise protein activity. A high accumulation of transcripts from both genes was found in shoots of in vitro plantlets, while in roots they could not be detected. Still, γ-terpinene levels in aerial parts were reduced, probably due to fast conversion into carvacrol and thymol, the main components from T. caespititius essential oils. This study is a contribution to the identification of terpene synthase genes in Lamiaceae., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

It has been perplexing that DNA topoisomerases, enzymes that release DNA supercoils, play specific roles in development. In this study, using a floral stem cell model in Arabidopsis thaliana, we uncovered a role for TOPOISOMERASE1α (TOP1α) in Polycomb Group (PcG) protein-mediated histone 3 lysine 27 trimethylation (H3K27me3) at, and transcriptional repression of, the stem cell maintenance gene WUSCHEL (WUS). We demonstrated that H3K27me3 deposition at other PcG targets also requires TOP1α. Intriguingly, the repression of some, as well as the expression of many, PcG target genes requires TOP1α. The mechanism that unifies the opposing effects of TOP1α appears to lie in its role in decreasing nucleosome density, which probably allows the binding of factors that either recruit PcG, as we demonstrated for AGAMOUS at the WUS locus, or counteract PcG-mediated regulation. Although TOP1α reduces nucleosome density at all genes, the lack of a 5' nucleosome-free region is a feature that distinguishes PcG targets from nontargets and may condition the requirement for TOP1α for their expression. This study uncovers a connection between TOP1α and PcG, which explains the specific developmental functions of TOP1α., (© 2014 American Society of Plant Biologists. All rights reserved.)

Background: In saffron (Crocus sativus), new corms develop at the base of every shoot developed from the maternal corm, a globular underground storage stem. Since the degree of bud sprouts influences the number and size of new corms, and strigolactones (SLs) suppress growth of pre-formed axillary bud, it was considered appropriate to investigate SL involvement in physiology and molecular biology in saffron. We focused on two of the genes within the SL pathway, CCD7 and CCD8, encoding carotenoid cleavage enzymes required for the production of SLs., Results: The CsCCD7 and CsCCD8 genes are the first ones isolated and characterized from a non-grass monocotyledonous plant. CsCCD7 and CsCCD8 expression showed some overlapping, although they were not identical. CsCCD8 was highly expressed in quiescent axillary buds and decapitation dramatically reduced its expression levels, suggesting its involvement in the suppression of axillary bud outgrowth. Furthermore, in vitro experiments showed also the involvement of auxin, cytokinin and jasmonic acid on the sprouting of axillary buds from corms in which the apical bud was removed. In addition, CsCCD8 expression, but not CsCCD7, was higher in the newly developed vascular tissue of axillary buds compared to the vascular tissue of the apical bud., Conclusions: We showed that production and transport of auxin in saffron corms could act synergistically with SLs to arrest the outgrowth of the axillary buds, similar to the control of above-ground shoot branching. In addition, jasmonic acid seems to play a prominent role in bud dormancy in saffron. While cytokinins from roots promote bud outgrowth. In addition the expression results of CsCCD8 suggest that SLs could positively regulate procambial activity and the development of new vascular tissues connecting leaves with the mother corm.

Health-promoting compounds, antioxidant and myrosinase activity in the sprouts of three broccoli cultivars under 40 mM, 80 mM and 160 mM NaCl were investigated. LangYan (LY) sprouts had the richest health-promoting compounds among the evaluated cultivars. Treatment of 40 mM and 80 mM NaCl significantly decreased the content of ascorbic acid and total phenolic as well as antioxidant activity, but did not affect glucoraphanin, sulforaphane and myrosinase activity compared to the control. However, 160 mM NaCl treatment significantly enhanced the level of total phenolic, glucoraphanin, sulforaphane, antioxidant and myrosinase activity, while significantly decreased ascorbic acid content. The results suggest that 160 mM NaCl treatment would enhance antioxidant activity and sulforaphane yield in broccoli sprouts. The health-promoting value of broccoli sprouts depends on plant genotype and could be affected by NaCl stress.

Cereal varieties with improved salinity tolerance are needed to achieve profitable grain yields in saline soils. The expression of AVP1, an Arabidopsis gene encoding a vacuolar proton pumping pyrophosphatase (H⁺-PPase), has been shown to improve the salinity tolerance of transgenic plants in greenhouse conditions. However, the potential for this gene to improve the grain yield of cereal crops in a saline field has yet to be evaluated. Recent advances in high-throughput nondestructive phenotyping technologies also offer an opportunity to quantitatively evaluate the growth of transgenic plants under abiotic stress through time. In this study, the growth of transgenic barley expressing AVP1 was evaluated under saline conditions in a pot experiment using nondestructive plant imaging and in a saline field trial. Greenhouse-grown transgenic barley expressing AVP1 produced a larger shoot biomass compared to null segregants, as determined by an increase in projected shoot area, when grown in soil with 150 mM NaCl. This increase in shoot biomass of transgenic AVP1 barley occurred from an early growth stage and also in nonsaline conditions. In a saline field, the transgenic barley expressing AVP1 also showed an increase in shoot biomass and, importantly, produced a greater grain yield per plant compared to wild-type plants. Interestingly, the expression of AVP1 did not alter barley leaf sodium concentrations in either greenhouse- or field-grown plants. This study validates our greenhouse-based experiments and indicates that transgenic barley expressing AVP1 is a promising option for increasing cereal crop productivity in saline fields., (© 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.)

Chickpea (Cicer arietinum) is an important pulse crop in many countries in the world. The symbioses between chickpea and Mesorhizobia, which fix N₂ inside the root nodules, are of particular importance for chickpea's productivity. With the aim of enhancing symbiotic efficiency in chickpea, we compared the symbiotic efficiency of C-15, Ch-191 and CP-36 strains of Mesorhizobium ciceri in association with the local elite chickpea cultivar 'Bivanij' as well as studied the mechanism underlying the improvement of N₂ fixation efficiency. Our data revealed that C-15 strain manifested the most efficient N₂ fixation in comparison with Ch-191 or CP-36. This finding was supported by higher plant productivity and expression levels of the nifHDK genes in C-15 nodules. Nodule specific activity was significantly higher in C-15 combination, partially as a result of higher electron allocation to N₂ versus H⁺. Interestingly, a striking difference in nodule carbon and nitrogen composition was observed. Sucrose cleavage enzymes displayed comparatively lower activity in nodules established by either Ch-191 or CP-36. Organic acid formation, particularly that of malate, was remarkably higher in nodules induced by C-15 strain. As a result, the best symbiotic efficiency observed with C-15-induced nodules was reflected in a higher concentration of the total and several major amino metabolites, namely asparagine, glutamine, glutamate and aspartate. Collectively, our findings demonstrated that the improved efficiency in chickpea symbiotic system, established with C-15, was associated with the enhanced capacity of organic acid formation and the activities of the key enzymes connected to the nodule carbon and nitrogen metabolism., (© 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.)

Growth is a complex trait that adapts to the prevailing conditions by integrating many internal and external signals. Understanding the molecular origin of this variation remains a challenging issue. In this study, natural variation of shoot growth under mannitol-induced stress was analyzed by standard quantitative trait locus mapping methods in a recombinant inbred line population derived from a cross between the Col-0 and Cvi-0 Arabidopsis thaliana accessions. Cloning of a major QTL specific to mannitol-induced stress condition led to identification of EGM1 and EGM2, a pair of tandem-duplicated genes encoding receptor-like kinases that are potentially involved in signaling of mannitol-associated stress responses. Using various genetic approaches, we identified two non-synonymous mutations in the EGM2[Cvi] allele that are shared by at least ten accessions from various origins and are probably responsible for a specific tolerance to mannitol. We have shown that the enhanced shoot growth phenotype contributed by the Cvi allele is not linked to generic osmotic properties but instead to a specific chemical property of mannitol itself. This result raises the question of the function of such a gene in A. thaliana, a species that does not synthesize mannitol. Our findings suggest that the receptor-like kinases encoded by EGM genes may be activated by mannitol produced by pathogens such as fungi, and may contribute to plant defense responses whenever mannitol is present., (© 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.)

The expression pattern of pathogenesis-related genes PR-1, PR-2 and PR-5, considered as markers for salicylic acid (SA)-dependent systemic acquired resistance (SAR), was examined in the roots and shoots of tomato plants pre-treated with SA and subsequently infected with root-knot nematodes (RKNs) (Meloidogyne incognita). PR-1 was up-regulated in both roots and shoots of SA-treated plants, whereas the expression of PR-5 was enhanced only in roots. The over-expression of PR-1 in the whole plant occurred as soon as 1 day after SA treatment. Up-regulation of the PR-1 gene was considered to be the main marker of SAR elicitation. One day after treatment, plants were inoculated with active juveniles (J2s) of M. incognita. The number of J2s that entered the roots and started to develop was significantly lower in SA-treated than in untreated plants at 5 and 15 days after inoculation. The expression pattern of PR-1, PR-2 and PR-5 was also examined in the roots and shoots of susceptible and Mi-1-carrying resistant tomato plants infected by RKNs. Nematode infection produced a down-regulation of PR genes in both roots and shoots of SA-treated and untreated plants, and in roots of Mi-carrying resistant plants. Moreover, in resistant infected plants, PR gene expression, in particular PR-1 gene expression, was highly induced in shoots. Thus, nematode infection was demonstrated to elicit SAR in shoots of resistant plants. The data presented in this study show that the repression of host defence SA signalling is associated with the successful development of RKNs, and that SA exogenously added as a soil drench is able to trigger a SAR-like response to RKNs in tomato., (© 2013 BSPP AND JOHN WILEY & SONS LTD.)