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1
Almeida, Julieta Andrea Silva de, Concetta Kascheres, and Maria de Fátima D. A. Pereira. "Ethylene and abscisic acid in the control of development of the rhizome of Kohleria eriantha (Benth.) Hanst. (Gesneriaceae)." Brazilian Journal of Plant Physiology 17, no. 4 (December 2005): 391–99. http://dx.doi.org/10.1590/s1677-04202005000400007.
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Kohleria eriantha has rhizomes which are underground stems with buds enclosed by modified leaves, that store starch. The buds of this rhizome can develop in two morphological patterns: an aerial shoot (similar to the mother plant) or a rhizome, depending on the water level present in the substrate. Development of the shoot was inhibited by low water availability (1 mL) in the substrate. It was verified that ethylene and ABA were involved in controlling the development of the rhizome pattern under low water availability. Treatments with ethrel, PEG and ABA induced shoot development whereas treatments with AgNO3 or AVG inhibited shoot development. Increased ethylene and ABA were observed under conditions that inhibited shoot development. Moreover, it is suggested that ABA may induce the production of ethylene in the sections of the rhizome under low water availability.
2
Astacio, Manuel G., and Marc W. van Iersel. "Concentrated Exogenous Abscisic Acid Drenches Reduce Root Hydraulic Conductance and Cause Wilting in Tomato." HortScience 46, no. 12 (December 2011): 1640–45. http://dx.doi.org/10.21273/hortsci.46.12.1640.
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Previous work has shown that exogenous abscisic acid (ABA) applications can reduce transpiration, delay wilting, and thereby extend the shelf life of unwatered plants. Paradoxically, we have seen that drenches with concentrated ABA solutions may actually induce wilting. These wilting symptoms occur despite the presence of ample water in the substrate, suggesting that ABA may interfere with the ability of roots to take up water. Our objective was to develop a better understanding of this wilting effect using tomato (Solanum lycopersicum) as a model. In the first study, ABA drenches (125–2000 mg·L−1) reduced transpiration and water use compared with the control plants, yet the relative water content (RWC) of the leaves of ABA-treated plants was lower than that of control plants at 24 h after the ABA drench. Control plants had a leaf RWC of 97%, whereas plants treated ABA had a RWC of 57% to 62%. ABA concentrations of 500 mg·L−1 or higher caused the plants to wilt within 24 h despite the presence of ample water in the substrate. Leaf ABA concentrations 24 h after the ABA application ranged from 2.6 (control) to 62.6 nmol·g−1 fresh weight (FW) in the 2000-mg·L−1 ABA treatment, indicating effective transport of ABA from the roots to the leaves. The reduced leaf RWC suggests that ABA drenches are limiting water transport through the roots to the leaves. The effects of ABA on the hydraulic conductance of the roots and stems of tomatoes were quantified to determine if ABA drenches limit water transport through the roots. The cumulative volume of water conducted by the root systems during a 4-day period ranged from 36.7 mL in the control treatments to 8.1 mL in roots systems drenched with 1000 mg·L−1 ABA, a reduction of 78%. When the conductance study was repeated using decapitated roots and excised stems, root water flux was again reduced by ABA, but water flux through internodal stem sections did not show an ABA effect. Results suggest that ABA-induced wilting is caused by a reduction in root conductance and we hypothesize that ABA affects aquaporins in the roots, limiting water uptake.
3
Gibson, James L., and Shannon Crowley. "ABSCISIC ACID DRENCHES IMPROVE POSTPRODUCTION SHELF LIFE OF IMPATIENS." HortScience 41, no. 3 (June 2006): 511E—512. http://dx.doi.org/10.21273/hortsci.41.3.511e.
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Foliar sprays or root dips of synthetic abscisic acid (s-ABA) have shown to reduce the transpiration rate and subsequently prolong postharvest longevity in a select group of herbaceous ornamental crops. The objective of our study was to determine the impact of s-ABA on postproduction performance of seed impatiens in greenhouse or low light conditions. Market ready Impatiens wallerana `Xtreme Scarlet' plants were sprayed or the root substrate was drenched with s-ABA at 250 or 500 mg·L–1 then boxed for 48 h to represent shipping conditions. Flower number was measured 3 days after application, and again after plants were hydrated following the day when the last treatment wilted 0, 2, 4, 8, 16, or 24 days after application. Visual quality ratings were made 0, 2, 3, 4, 8, 11, 16, or 19 days after application and again after plants were re-irrigated. Drenching the substrate with s-ABA at 500 mg·L–1 maintained foliage and flower turgidity up to 8 days in the greenhouse environment and 16 days in the low light environment. Substrate drenches at 500 mg·L–1 dramatically decreased flower number after removal from the shipping box under greenhouse conditions, and in the low light environment drenching the substrate at 250 mg·L–1 produced similar visual quality results to 500 mg·L–1 16 days after treatment. Plants drenched at 250 mg·L–1 also had the same number of flowers 3 and 20 days after treatment, when compared to 500 mg·L–1. Therefore, impatiens growers should drench the root substrate with s-ABA at 250 mg·L–1 to reduce labor costs associated with hand-watering and prolong postproduction performance in low light conditions, such as indoor retail conditions.
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Khan, Irfan Ullah, Akhtar Ali, Shah Zareen, Haris Ali Khan, Chae Jin Lim, Junghoon Park, Jose M. Pardo, and Dae-Jin Yun. "Non-Expresser of PR-Genes 1 Positively Regulates Abscisic Acid Signaling in Arabidopsis thaliana." Plants 11, no. 6 (March 18, 2022): 815. http://dx.doi.org/10.3390/plants11060815.
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The plant hormone, abscisic acid (ABA), is not only important for promoting abiotic stress responses but also plays a versatile and crucial role in plant immunity. The pathogen infection-induced dynamic accumulation of ABA mediates the degradation of non-expresser of PR genes 1 (NPR1) through the CUL3NPR3NPR4 proteasome pathway. However, the functional significance of NPR1 degradation by other E3 ligases in response to ABA remains unclear. Here, we report that NPR1 is induced transcriptionally by ABA and that npr1-1 mutation results in ABA insensitivity during seed germination and seedling growth. Mutants lacking NPR1 downregulate the expression of ABA-responsive transcription factors ABA INSENSITIVE4 (ABI4) and ABA INSENSITIVE5 (ABI5), and that of their downstream targets EM6, RAB18, RD26, and RD29B. The npr1-1 mutation also affects the transcriptional activity of WRKY18, which activates WRKY60 in the presence of ABA. Furthermore, NPR1 directly interacts with and is degraded by HOS15, a substrate receptor for the DDB1-CUL4 ubiquitin E3 ligase complex. Collectively, our findings demonstrate that NPR1 acts as a positive regulator of ABA-responsive genes, whereas HOS15 promotes NPR1 degradation in a proteasome-dependent manner.
5
Ramirez, Leonor, Pedro Negri, Laura Sturla, Lucrezia Guida, Tiziana Vigliarolo, Matías Maggi, Martín Eguaras, Elena Zocchi, and Lorenzo Lamattina. "Abscisic acid enhances cold tolerance in honeybee larvae." Proceedings of the Royal Society B: Biological Sciences 284, no. 1852 (April 5, 2017): 20162140. http://dx.doi.org/10.1098/rspb.2016.2140.
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The natural composition of nutrients present in food is a key factor determining the immune function and stress responses in the honeybee ( Apis mellifera ). We previously demonstrated that a supplement of abscisic acid (ABA), a natural component of nectar, pollen, and honey, increases honeybee colony survival overwinter. Here we further explored the role of ABA in in vitro -reared larvae exposed to low temperatures. Four-day-old larvae (L4) exposed to 25°C for 3 days showed lower survival rates and delayed development compared to individuals growing at a standard temperature (34°C). Cold-stressed larvae maintained higher levels of ABA for longer than do larvae reared at 34°C, suggesting a biological significance for ABA. Larvae fed with an ABA-supplemented diet completely prevent the low survival rate due to cold stress and accelerate adult emergence. ABA modulates the expression of genes involved in metabolic adjustments and stress responses: Hexamerin 70b, Insulin Receptor Substrate, Vitellogenin , and Heat Shock Proteins 70. AmLANCL2, the honeybee ABA receptor, is also regulated by cold stress and ABA. These results support a role for ABA increasing the tolerance of honeybee larvae to low temperatures through priming effects.
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Kang, Jong-Goo, Rhuanito Soranz Ferrarezi, Sue K. Dove, Geoffrey M. Weaver, and Marc W. van Iersel. "Increased Fertilizer Levels Do Not Prevent Abscisic Acid–Induced Chlorosis in Pansy." HortTechnology 26, no. 5 (October 2016): 647–50. http://dx.doi.org/10.21273/horttech03441-16.
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Abscisic acid (ABA) is a plant hormone involved in regulating stomatal responses to environmental stress. By inducing stomatal closure, applications of exogenous ABA can reduce plant water use and delay the onset of drought stress when plants are not watered. However, ABA can also cause unwanted side effects, including chlorosis. Pansy (Viola ×wittrockiana) has been shown to be particularly susceptible to ABA-induced chlorosis. The objective of this study was to determine if fertilization rate affects the severity of ABA-induced chlorosis in this species. ‘Delta Premium Pure Yellow’ pansy seedlings were fertilized with controlled-release fertilizer incorporated at rates from 0 to 8 g·L−1 of substrate. When plants had reached a salable size, half the plants were sprayed with a solution containing 1 g·L−1 ABA, whereas the other plants were sprayed with water. Leaf chlorophyll content was monitored for 2 weeks following ABA application. Leaf chlorophyll content increased greatly as fertilizer rate increased from 0 to 2 g·L−1, with little increase in leaf chlorophyll at even higher fertilizer rates. ABA induced chlorosis, irrespective of the fertilizer rate. Plant dry weight was lowest when no controlled-release fertilizer was incorporated, but similar in all fertilized treatments. ABA treatment reduced shoot dry weight by ≈24%, regardless of fertilization rate. This may be due to ABA-induced stomatal closure, which limits carbon dioxide (CO2) diffusion into the leaves. We conclude that ABA sprays induce chlorosis, regardless of which fertilizer rate is used. However, because leaf chlorophyll concentration increases with increasing fertilizer rates, higher fertilizer rates can mask ABA-induced chlorosis.
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Lee, H.-S., and B. V. Milborrow. "Endogenous Biosynthetic Precursors of (+)-Abscisic Acid. V. Inhibition by Tungstate and its Removal by Cinchonine shows that Xanthoxal is Oxidised by a Molybdo-Aldehyde Oxidase." Functional Plant Biology 24, no. 6 (1997): 727. http://dx.doi.org/10.1071/pp96060.
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A cell-free preparation from avocado fruit incorporates [14C]mevalonate into ABA. A number of specific inhibitors have been used to probe the system and tungstate ions at 100 µM reduce the 14C in ABA by 80% The inhibitory effect was overcome by the alkaloid cinchonine (2000 µM) which binds tungstate strongly and selectively. More 14C from mevalonate was present in xanthoxal (4600 dpm), less in ABA (340 dpm) when the cell-free system was inhibited by tungstate (100 µM) than in controls (1810 dpm in xanthoxal, 1200 dpm in ABA), which shows that xanthoxal is the substrate for the aldehyde oxidase. Xanthoxic acid, therefore, is the next intermediate and AB-aldehyde is not a normal precursor. The potential for using the tungstate/cinchonine reaction to probe other biosynthetic pathways which require a molybdate ion is discussed.
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Julian, Jose, Alberto Coego, Jorge Lozano-Juste, Esther Lechner, Qian Wu, Xu Zhang, Ebe Merilo, et al. "The MATH-BTB BPM3 and BPM5 subunits of Cullin3-RING E3 ubiquitin ligases target PP2CA and other clade A PP2Cs for degradation." Proceedings of the National Academy of Sciences 116, no. 31 (July 15, 2019): 15725–34. http://dx.doi.org/10.1073/pnas.1908677116.
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Early abscisic acid signaling involves degradation of clade A protein phosphatases type 2C (PP2Cs) as a complementary mechanism to PYR/PYL/RCAR-mediated inhibition of PP2C activity. At later steps, ABA induces up-regulation of PP2C transcripts and protein levels as a negative feedback mechanism. Therefore, resetting of ABA signaling also requires PP2C degradation to avoid excessive ABA-induced accumulation of PP2Cs. It has been demonstrated that ABA induces the degradation of existing ABI1 and PP2CA through the PUB12/13 and RGLG1/5 E3 ligases, respectively. However, other unidentified E3 ligases are predicted to regulate protein stability of clade A PP2Cs as well. In this work, we identified BTB/POZ AND MATH DOMAIN proteins (BPMs), substrate adaptors of the multimeric cullin3 (CUL3)-RING-based E3 ligases (CRL3s), as PP2CA-interacting proteins. BPM3 and BPM5 interact in the nucleus with PP2CA as well as with ABI1, ABI2, and HAB1. BPM3 and BPM5 accelerate the turnover of PP2Cs in an ABA-dependent manner and their overexpression leads to enhanced ABA sensitivity, whereas bpm3 bpm5 plants show increased accumulation of PP2CA, ABI1 and HAB1, which leads to global diminished ABA sensitivity. Using biochemical and genetic assays, we demonstrated that ubiquitination of PP2CA depends on BPM function. Given the formation of receptor-ABA-phosphatase ternary complexes is markedly affected by the abundance of protein components and ABA concentration, we reveal that BPMs and multimeric CRL3 E3 ligases are important modulators of PP2C coreceptor levels to regulate early ABA signaling as well as the later desensitizing-resetting steps.
9
van Iersel, Marc W., Kate Seader, and Sue Dove. "Exogenous Abscisic Acid Application Effects on Stomatal Closure, Water Use, and Shelf Life of Hydrangea (Hydrangea macrophylla)." Journal of Environmental Horticulture 27, no. 4 (December 1, 2009): 234–38. http://dx.doi.org/10.24266/0738-2898-27.4.234.
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Abstract A lack of adequate watering reduces the shelf life of many ornamental plants during retail. Our goals were to determine whether sprays or drenches with abscisic acid (ABA) can reduce transpiration and extend the shelf life of hydrangea (Hydrangea macrophylla). During the first 5 days after treatment, ABA drenches of 125 to 1000 ppm reduced stomatal conductance (gs) by 50 to 80% as compared to water. ABA-induced stomatal closure reduced plant water uptake from the substrate; control plants took up half of the plant-available water during the first 7 days after treatment, while it took 14 days for plants drenched with 1000 ppm to take up half of the available water. Control plants wilted after 12 days and time to wilting of drenched plants increased with increasing ABA concentrations, up to 23 days in the 1000 ppm treatment. Spray treatments had little effect on gs and no detectable effect on water uptake or time to wilting. Some yellowing of older leaves was seen with ABA drenches of 500 or 1000 ppm. Despite this side effect, ABA drenches have potential to extend the shelf life of hydrangeas in retail environments.
10
Song, XiGui, XiaoPing She, and Juan Wang. "Inhibition of abscisic acid-induced stomatal closure by ethylene is related to the change of hydrogen peroxide levels in guard cells in broad bean." Australian Journal of Botany 59, no. 8 (2011): 781. http://dx.doi.org/10.1071/bt11144.
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We analysed the role and relationship between hydrogen peroxide (H2O2) reduction and the inhibition of abscisic acid (ABA)-induced stomatal closure by ethylene. Like ascorbic acid (ASA), the most important reducing substrate for H2O2 removal, catalase, one of the H2O2 scavenging enzymes and diphenylene iodonium, an inhibitor of the H2O2-generating enzyme NADPH oxidase, both ethylene-releasing compound 2-chloroethylene phosphonic acid (ethephon, ETH) and 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, were found to inhibit stomatal closure by ABA and to reduce H2O2 levels by ABA in guard cells, indicating that ethylene-caused inhibition of ABA-induced stomatal closure involves reduction of H2O2 levels in guard cells. Additionally, similar to ASA and catalase, ACC/ETH not only suppressed H2O2-induced stomatal closure and H2O2 levels in guard cells treated with exogenous H2O2 in light, but also reopened the stomata which had been closed by ABA and reduced H2O2 levels that had been generated by ABA. The abovementioned effects of ACC and ETH were dissimilar to that of diphenylene iodonium, an inhibitor of the H2O2-generating enzyme NADPH oxidase, which not only had incapability to reduce H2O2 levels by exogenous H2O2 but also could not abolish H2O2 that had been generated by ABA. So we suggest that ethylene probably induces H2O2 removal and reduces H2O2 levels in Vicia faba guard cells, and finally inhibits stomatal closure induced by ABA.
11
Smith, Daryl J., Marianna A. Patrauchan, Christine Florizone, Lindsay D. Eltis, and William W. Mohn. "Distinct Roles for Two CYP226 Family Cytochromes P450 in Abietane Diterpenoid Catabolism by Burkholderia xenovorans LB400." Journal of Bacteriology 190, no. 5 (December 21, 2007): 1575–83. http://dx.doi.org/10.1128/jb.01530-07.
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ABSTRACT The 80-kb dit cluster of Burkholderia xenovorans LB400 encodes the catabolism of abietane diterpenoids. This cluster includes ditQ and ditU, predicted to encode cytochromes P450 (P450s) belonging to the poorly characterized CYP226A subfamily. Using proteomics, we identified 16 dit-encoded proteins that were significantly more abundant in LB400 cells grown on dehydroabietic acid (DhA) or abietic acid (AbA) than in succinate-grown cells. A key difference in the catabolism of DhA and AbA lies in the differential expression of the P450s; DitU was detected only in the AbA-grown cells, whereas DitQ was expressed both during growth on DhA and during growth on AbA. Analyses of insertion mutants showed that ditQ was required for growth on DhA, ditU was required for growth on AbA, and neither gene was required for growth on the central intermediate, 7-oxo-DhA. In cell suspension assays, patterns of substrate removal and metabolite accumulation confirmed the role of DitU in AbA transformation and the role of DitQ in DhA transformation. Spectral assays revealed that DitQ binds both DhA (dissociation constant, 0.98 ± 0.01 μM) and palustric acid. Finally, DitQ transformed DhA to 7-hydroxy-DhA in vitro. These results demonstrate the distinct roles of the P450s DitQ and DitU in the transformation of DhA and AbA, respectively, to 7-oxo-DhA in a convergent degradation pathway.
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Cai, Guohua, Yuan Wang, Guoqing Tu, Pengwang Chen, Sheng Luan, and Wenzhi Lan. "Type A2 BTB Members Decrease the ABA Response during Seed Germination by Affecting the Stability of SnRK2.3 in Arabidopsis." International Journal of Molecular Sciences 21, no. 9 (April 30, 2020): 3153. http://dx.doi.org/10.3390/ijms21093153.
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The Arabidopsis genome comprises eighty genes encoding BTB (broad-complex, tramtrack, and bric-a-brac) family proteins that are characterized with the BTB domain and that potentially serve as substrate adaptors for cullin-based E3-ligases. In addition to the BTB domain, most BTB proteins also contain various other interaction motifs that probably act as target recognition elements. Here, we report three members of the BTB-A2 subfamily that distinctly only contain the BTB domain, BTB-A2.1, BTB-A2.2, and BTB-A2.3, that negatively regulates abscisic acid (ABA) signaling in Arabidopsis. BTB-A2.1, BTB-A2.2, and BTB-A2.3 encoded cytoplasm- and nucleus-localized proteins and displayed highly overlapping expression patterns in Arabidopsis tissues. Disruption of these three genes, but not single or double mutants, resulted in a decrease in ABA-induced inhibition of seed germination. Further analyses demonstrated the expression levels of these three genes were up-regulated by ABA, and their mutation increased ABA signalling. Importantly, protein-protein interaction assays showed that these three BTB-A2 proteins physically interacted with SnRK2.3. Moreover, biochemical and genetic assays indicated that BTB-A2.1, BTB-A2.2, and BTB-A2.3 decreased the stability of SnRK2.3 and attenuated the SnRK2.3 responsible for the ABA hypersensitive phenotype of seed germination. This report thus reveals that BTB-A2s serve as negative regulators for balancing the intensity of ABA signaling during seed germination.
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Dee, M. W., F. Brock, A. D. Bowles, and C. Bronk Ramsey. "Using a Silica Substrate to Monitor the Effectiveness of Radiocarbon Pretreatment." Radiocarbon 53, no. 4 (2011): 705–11. http://dx.doi.org/10.1017/s0033822200039151.
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The objective of radiocarbon pretreatment is to eliminate any contaminant carbon from the sample material. Solvent washes and acid-base-acid (ABA) procedures are widely used for this purpose. However, quantitatively analyzing their effectiveness is surprisingly problematic, as it often requires large numbers of 14C measurements or high-precision compositional analysis. The technique presented here involves monitoring the impact of different forms of contamination by measuring their adherence to a non-carbonaceous substrate called Chromosorb®. Firstly, the substrate was used in place of a 14C sample in order to monitor the accrual of carbon contamination during a standard solvent wash and ABA pretreatment. This produced a contamination profile against which modifications to the pretreatment procedure could be compared. Secondly, stocks were prepared of Chromosorb that had been infused with environmental contaminants and with common glues, adhesives, and preservatives. By monitoring the elimination of carbon from these stocks, the effectiveness of different pretreatment procedures could be evaluated and the most problematic of the contaminants for 14C dating could be identified.
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Khakhina, Svetlana, Soraya S. Johnson, Raman Manoharlal, Sarah B. Russo, Corinne Blugeon, Sophie Lemoine, Anna B. Sunshine, et al. "Control of Plasma Membrane Permeability by ABC Transporters." Eukaryotic Cell 14, no. 5 (February 27, 2015): 442–53. http://dx.doi.org/10.1128/ec.00021-15.
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ABSTRACTATP-binding cassette transporters Pdr5 and Yor1 fromSaccharomyces cerevisiaecontrol the asymmetric distribution of phospholipids across the plasma membrane as well as serving as ATP-dependent drug efflux pumps. Mutant strains lacking these transporter proteins were found to exhibit very different resistance phenotypes to two inhibitors of sphingolipid biosynthesis that act either late (aureobasidin A [AbA]) or early (myriocin [Myr]) in the pathway leading to production of these important plasma membrane lipids. Thesepdr5Δ yor1strains were highly AbA resistant but extremely sensitive to Myr. We provide evidence that these phenotypic changes are likely due to modulation of the plasma membrane flippase complexes, Dnf1/Lem3 and Dnf2/Lem3. Flippases act to move phospholipids from the outer to the inner leaflet of the plasma membrane. Genetic analyses indicate thatlem3Δ mutant strains are highly AbA sensitive and Myr resistant. These phenotypes are fully epistatic to those seen inpdr5Δ yor1strains. Direct analysis of AbA-induced signaling demonstrated that loss of Pdr5 and Yor1 inhibited the AbA-triggered phosphorylation of the AGC kinase Ypk1 and its substrate Orm1. Microarray experiments found that apdr5Δ yor1strain induced a Pdr1-dependent induction of the entire Pdr regulon. Our data support the view that Pdr5/Yor1 negatively regulate flippase function and activity of the nuclear Pdr1 transcription factor. Together, these data argue that the interaction of the ABC transporters Pdr5 and Yor1 with the Lem3-dependent flippases regulates permeability of AbA via control of plasma membrane protein function as seen for the high-affinity tryptophan permease Tat2.
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Lv, Qianlong, Xingxing Li, Xinkai Jin, Ying Sun, Yuanyuan Wu, Wanmin Wang, and Junli Huang. "Rice OsPUB16 modulates the ‘SAPK9-OsMADS23-OsAOC’ pathway to reduce plant water-deficit tolerance by repressing ABA and JA biosynthesis." PLOS Genetics 18, no. 11 (November 28, 2022): e1010520. http://dx.doi.org/10.1371/journal.pgen.1010520.
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Ubiquitin-mediated proteolysis plays crucial roles in plant responses to environmental stress. However, the mechanism by which E3 ubiquitin ligases modulate plant stress response still needs to be elucidated. In this study, we found that rice PLANT U-BOX PROTEIN 16 (OsPUB16), a U-box E3 ubiquitin ligase, negatively regulates rice drought response. Loss-of-function mutants of OsPUB16 generated through CRISPR/Cas9 system exhibited the markedly enhanced water-deficit tolerance, while OsPUB16 overexpression lines were hypersensitive to water deficit stress. Moreover, OsPUB16 negatively regulated ABA and JA response, and ospub16 mutants produced more endogenous ABA and JA than wild type when exposed to water deficit. Mechanistic investigations revealed that OsPUB16 mediated the ubiquitination and degradation of OsMADS23, which is the substrate of OSMOTIC STRESS/ABA-ACTIVATED PROTEIN KINASE 9 (SAPK9) and increases rice drought tolerance by promoting ABA biosynthesis. Further, the ChIP-qPCR analysis and transient transactivation activity assays demonstrated that OsMADS23 activated the expression of JA-biosynthetic gene OsAOC by binding to its promoter. Interestingly, SAPK9-mediated phosphorylation on OsMADS23 reduced its ubiquitination level by interfering with the OsPUB16-OsMADS23 interaction, which thus enhanced OsMADS23 stability and promoted OsAOC expression. Collectively, our findings establish that OsPUB16 reduces plant water-deficit tolerance by modulating the ‘SAPK9-OsMADS23-OsAOC’ pathway to repress ABA and JA biosynthesis.
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Aeed, Paul A., Casey L. Young, Marek M. Nagiec, and Åke P. Elhammer. "Inhibition of Inositol Phosphorylceramide Synthase by the Cyclic Peptide Aureobasidin A." Antimicrobial Agents and Chemotherapy 53, no. 2 (February 2009): 496–504. http://dx.doi.org/10.1128/aac.00633-08.
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ABSTRACT By using a detergent-washed membrane preparation, the interaction of the fungal natural product inhibitor aureobasidin A (AbA) with inositol phosphorylceramide synthase (IPC synthase) was studied by kinetic analysis of wild-type and mutant enzyme-catalyzed reactions. AbA inhibited the wild-type enzyme from both Candida albicans and Saccharomyces cerevisiae in an irreversible, time-dependent manner, with apparent Ki values of 183 and 234 pM, respectively. Three synthetic chemistry-derived AbA derivatives, PHA-533179, PHA-556655, and PHA-556656, had affinities 4 to 5 orders of magnitude lower and were reversible inhibitors that competed with the donor substrate phosphatidylinositol (PI). AbA was a reversible, apparently noncompetitive inhibitor, with a Ki of 1.4 μM, of the IPC synthase from an AbA-resistant S. cerevisiae mutant. The Km values for both substrates (ceramide and PI) were similar when they interacted with the mutant and the wild-type enzymes. By contrast, the V max for the mutant enzyme was less than 10% of that for the wild-type enzyme. A comparison of the results obtained with AbA with those obtained with two other natural products inhibitors, rustmicin and khafrefungin, revealed that while rustmicin appeared to be a reversible, noncompetitive inhibitor of the wild-type enzyme, with a Ki of 16.0 nM, khafrefungin had the kinetic properties of a time-dependent inhibitor and an apparent Ki of 0.43 nM. An evaluation of the efficiencies of these compounds as inhibitors of the mutant enzyme revealed for both a drop in the apparent affinity for the enzyme of more than 2 orders of magnitude.
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Zhao, Lili, Jingwei Yan, Yang Xiang, Yue Sun, and Aying Zhang. "ZmWRKY104 Transcription Factor Phosphorylated by ZmMPK6 Functioning in ABA-Induced Antioxidant Defense and Enhance Drought Tolerance in Maize." Biology 10, no. 9 (September 10, 2021): 893. http://dx.doi.org/10.3390/biology10090893.
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Mitogen-activated protein kinase (MAPK) cascades are primary signaling pathways involved in various signaling pathways triggered by abiotic and biotic stresses in plants. The downstream substrate proteins of MAPKs in maize, however, are still limited. Here, we screened a WRKY IIa transcription factor (TF) in maize (Zeamays L.), ZmWRKY104, and found that it is a substrate of ZmMPK6. ZmWRKY104 physically interacts with ZmMPK6 in vitro and in vivo. Liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis results showed that threonine-59 (Thr-59, T59) was the major phosphorylation site of ZmWRKY104 by ZmMPK6. Subcellular localization analysis suggested that ZmWRKY104 acts in the nucleus and that ZmMPK6 acts in the nucleus and cytoplasmic membrane in the cytosol. Functional analysis revealed that the role of ZmWRKY104 in ABA-induced antioxidant defense depends on ZmMPK6. Moreover, overexpression of ZmWRKY104 in maize can enhance drought tolerance and relieve drought-induced oxidative damage in transgenic lines. The above results help define the mechanism of the function of ZmWRKY104 phosphorylated by ZmMPK6 in ABA-induced antioxidant defense and drought tolerance in maize.
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Liu, Chang, Hasi Yu, Xiaolan Rao, Laigeng Li, and Richard A. Dixon. "Abscisic acid regulates secondary cell-wall formation and lignin deposition in Arabidopsis thaliana through phosphorylation of NST1." Proceedings of the National Academy of Sciences 118, no. 5 (January 25, 2021): e2010911118. http://dx.doi.org/10.1073/pnas.2010911118.
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Plant secondary cell-wall (SCW) deposition and lignification are affected by both seasonal factors and abiotic stress, and these responses may involve the hormone abscisic acid (ABA). However, the mechanisms involved are not clear. Here we show that mutations that limit ABA synthesis or signaling reduce the extent of SCW thickness and lignification in Arabidopsis thaliana through the core ABA-signaling pathway involving SnRK2 kinases. SnRK2.2. 3 and 6 physically interact with the SCW regulator NAC SECONDARY WALL THICKENING PROMOTING FACTOR 1 (NST1), a NAC family transcription factor that orchestrates the transcriptional activation of a suite of downstream SCW biosynthesis genes, some of which are involved in the biosynthesis of cellulose and lignin. This interaction leads to phosphorylation of NST1 at Ser316, a residue that is highly conserved among NST1 proteins from dicots, but not monocots, and is required for transcriptional activation of downstream SCW-related gene promoters. Loss of function of NST1 in the snd1 mutant background results in lack of SCWs in the interfascicular fiber region of the stem, and the Ser316Ala mutant of NST1 fails to complement this phenotype and ABA-induced lignin pathway gene expression. The discovery of NST1 as a key substrate for phosphorylation by SnRK2 suggests that the ABA-mediated core-signaling cascade provided land plants with a hormone-modulated, competitive desiccation-tolerance strategy allowing them to differentiate water-conducting and supporting tissues built of cells with thicker cell walls.
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Choi, Juyoung, Wonkyung Lee, Gynheung An, and Seong-Ryong Kim. "OsCBE1, a Substrate Receptor of Cullin4-Based E3 Ubiquitin Ligase, Functions as a Regulator of Abiotic Stress Response and Productivity in Rice." International Journal of Molecular Sciences 22, no. 5 (March 2, 2021): 2487. http://dx.doi.org/10.3390/ijms22052487.
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Ubiquitination is an important environmental stress response, and E3 ubiquitin ligases play a major role in the process. T-DNA insertion mutants of rice, Oscbe1-1, and Oscbe1-2, were identified through the screening of cold stress tolerance at seedling stage. Oscbe1 mutants showed a significantly higher cold stress tolerance in the fresh weight, chlorophyll content, and photosynthetic efficiency than wild type. Molecular prediction showed that OsCBE1 (Oryza sativa Cullin4-Based E3 ubiquitin ligase1) encoded a novel substrate receptor of Cullin4-based E3 ubiquitin ligase complex (C4E3). Whereas Oscbe1 mutants had fewer panicles and grains than wild type in the paddy field, the overexpression lines of OsCBE1 had more panicles and grains, suggesting that OsCBE1 is involved in the regulation of both abiotic stress response and development. Oscbe1 mutants also showed ABA hypersensitivity during seed germination, suggesting OsCBE1 function for the stress response via ABA signaling. In silico analysis of OsCBE1 activity predicted a CCCH-type transcription factor, OsC3H32, as a putative substrate. Co-IP (Co-immunoprecipitation) study showed that OsCBE1 interacts with OsDDB1, an expected binding component of OsCBE1 and OsC3H32. Additionally, expression of OsOLE16, OsOLE18, and OsBURP5 were negatively related with expression of OsCBE1. These results suggest that OsCBE1 functions as a regulator of the abiotic stress response via CCCH as a member of the C4E3.
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Schwartz, Steven H., Bao C. Tan, Donald R. McCarty, William Welch, and Jan A. D. Zeevaart. "Substrate specificity and kinetics for VP14, a carotenoid cleavage dioxygenase in the ABA biosynthetic pathway." Biochimica et Biophysica Acta (BBA) - General Subjects 1619, no. 1 (January 2003): 9–14. http://dx.doi.org/10.1016/s0304-4165(02)00422-1.
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Woo, Og-Geum, Soon-Hee Kim, Seok Keun Cho, Sang-Hoon Kim, Han Nim Lee, Taijoon Chung, Seong Wook Yang, and Jae-Hoon Lee. "BPH1, a novel substrate receptor of CRL3, plays a repressive role in ABA signal transduction." Plant Molecular Biology 96, no. 6 (March 21, 2018): 593–606. http://dx.doi.org/10.1007/s11103-018-0717-x.
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Oh, Tae Rin, Jong Hum Kim, Seok Keun Cho, Moon Young Ryu, Seong Wook Yang, and Woo Taek Kim. "AtAIRP2 E3 Ligase Affects ABA and High-Salinity Responses by Stimulating Its ATP1/SDIRIP1 Substrate Turnover." Plant Physiology 174, no. 4 (June 16, 2017): 2515–31. http://dx.doi.org/10.1104/pp.17.00467.
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Alagoa, Koru Joe. "An appraisal of heavy metals in water column and bottom substrate of Aba river, Abia state, Nigeria." GSC Biological and Pharmaceutical Sciences 6, no. 3 (March 30, 2019): 045–50. http://dx.doi.org/10.30574/gscbps.2019.6.3.0021.
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Yelgel, Celal, and Gyaneshwar P. Srivastava. "Atomic and Electronic Structure of Multilayer Graphene on a Monolayer Hexagonal Boron Nitride." MRS Proceedings 1549 (2013): 65–70. http://dx.doi.org/10.1557/opl.2013.710.
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ABSTRACTThe atomic and electronic structures of multilayer graphene on a monolayer boron nitride (MLBN) have been investigated by using the pseudopotential method and the local density approximation (LDA) of the density functional theory (DFT). We show that the LDA energy band gap can be tuned in the range 41-278 meV for a multilayer graphene by using MLBN as a substrate. The dispersion of the π/π* bands slightly away from the K point is linear with the electron speed of 0.9×106 and 0.93×106 for graphene (MLG)/MLBN and ABA trilayer graphene (TLG)/MLBN systems, respectively. This behaviour becomes quadratic with a relative effective mass of 0.0021 for the bilayer graphene (BLG)/MLBN system. The calculated binding energies are in the range of 10-43 meV per C atom.
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Bauerle, William L., William W. Inman, and Jerry B. Dudley. "(141) Leaf Abscisic Acid Accumulation in Response to Substrate Water Content: Variation Among Acer rubrum L. Genotypes." HortScience 41, no. 4 (July 2006): 1057D—1057. http://dx.doi.org/10.21273/hortsci.41.4.1057d.
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Quantitative differences in leaf abscisic acid (ABAL) among four cultivars of red (Acer rubrum L.) and one Freeman maple (Acer × freemanii E. Murray) were investigated. This study tested the hypothesis that ABAL concentration can be used to compare the effects of water stress on the gas exchange response of five different maple cultivars, including four red maple genotypes, `Summer Red', `October Glory', `Autumn Flame', and `Franksred' (Red Sunset), as well as one hybridized Freeman maple genotype, `Jeffersred' (Autumn Blaze). Cloned genotypes of red and Freeman maple were subjected to two treatments: 1) irrigated daily to container capacity or 2) irrigation withheld for one drought and recovery cycle. Leaf abscisic acid concentration, gas exchange, and whole-tree sap flow measurements were conducted under both conditions. Over the course of the drought stress and recovery phase, net photosynthesis (Anet), stomatal conductance (gs), and transpiration (E) declined as ABAL and instantaneous water use efficiency (A/gs) increased. This study found that ABAL tracked gs and that stomatal responsiveness to substrate moisture deficit is likely mediated by ABA accumulation in leaf tissue. This research demonstrates a leaf-level physiological response to substrate volumetric water content that appears to depend on ABAL concentration. In addition, the evidence in this study indicates that ABAL may be used as a potential surrogate for the gs response to substrate water stress and could become part of a cultivar drought tolerance selection strategy for red and Freeman maple.
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Wang, Lei, Shaoqing Wen, and Zhanxiong Li. "Synthesis of amphiphilic ABA triblock oligomer via ATRP and its surface properties." Canadian Journal of Chemistry 95, no. 5 (May 2017): 605–11. http://dx.doi.org/10.1139/cjc-2016-0591.
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A series of novel amphiphilic ABA-type poly(tridecafluorooctylacrylate)-poly(ethylene glycol)-poly(tridecafluorooctylacrylate) (henceforth referred to as p-TDFA-PEG-p-TDFA) triblock oligomers were successfully synthesized via atom transfer radical polymerization (ATRP) using well-defined Br-PEG-Br as macroinitiator and copper as catalyst. The block oligomers were characterized by Fourier transform infrared (FTIR) spectroscopy and 1H and 19F nuclear magnetic resonances (NMR). Gel permeation chromatography (GPC) showed that the block oligomers have been obtained with narrow molecular weight distributions of 1.22–1.33. X-ray photoelectron spectroscopy (XPS) was carried out to confirm the attachment of p-TDFA-PEG-p-TDFA onto the silicon substrate, together with the chemical compositions of p-TDFA-PEG-p-TDFA. The wetabilities of the oligomer films were measured by water contact angles (CAs). Water CAs of p-TDFA-PEG-p-TDFA film were measured and their morphologies were tested by atomic force microscopy (AFM). The result showed that the CAs of the oligomer films, which possess fluoroalkyl groups assembled on the outer surface, increase after heating due to the migration of fluoroalkyl groups and the resulted microphase separation of the p-TDFA-PEG-p-TDFA.
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Romero-Muñoz, Miriam, Alfonso Albacete, Amparo Gálvez, María Carmen Piñero, Francisco M. del Amor, and Josefa López-Marín. "The Use of Ecological Hydromulching Improves Growth in Escarole (Cichorium endivia L.) Plants Subjected to Drought Stress by Fine-Tuning Cytokinins and Abscisic Acid Balance." Agronomy 12, no. 2 (February 12, 2022): 459. http://dx.doi.org/10.3390/agronomy12020459.
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Drought is considered as one of the major limiting factors to plant growth and productivity. Drought stress reduces stomatal conductance, affecting water relations and decreasing CO2 assimilation rate and photosynthesis. Several strategies have been developed to alleviate the negative effects of drought in the agricultural industry. One of these strategies is the use of the mulching technology, which retains water in the soil surface. Knowing that hormones play a key role in plant growth and drought stress responses, we hypothesized that the use of a new ecological mulching technology called hydromulching would improve growth over bare soil under drought stress through changes in the hormonal balance. To test this hypothesis, escarole plants (Cichorium endivia L.) were grown in pots filled with coco fiber, non-covered (bare soil) or covered with polyethylene film (PE) and three types of hydromulches made up with recycled additives: wheat straw (WS), rice hulls (RH), and substrate used for mushroom cultivation (MS). Half of the plants were subjected to drought by reducing the volume of irrigation water to 70% of crop evapotranspiration. Despite drought stress impaired escarole growth-related parameters in all treatments, plants mulched with MS maintained significantly superior growth, due to improved plant water relations and photosynthetic function. This can be explained by an efficient interaction hydromulch/soil/plant in regulating the hormonal balance under water depletion. Indeed, the concentrations of the active cytokinins (CKs), trans-zeatin and isopentenyladenine, were higher in plants grown with MS treatment, associated with shoot growth-enhancing and photosynthetic rate maintenance under stress conditions. The concentrations of the stress-related hormone, abscisic acid (ABA), varied antagonistically to those of the active CKs. In this regard, ABA increased with drought but to a lower extent in MS plants thus regulating stomata opening, which, in crosstalk with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and salicylic acid, improved plant water relations. The results obtained demonstrate that hydromulching is an efficient and sustainable management strategy to ameliorate the drought effects on escarole plants through fine regulation of the CKs/ABA balance, which will be of utmost interest and applicability in the actual climate change scenario.
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Tan, Wenrong, Dawei Zhang, Huapeng Zhou, Ting Zheng, Yanhai Yin, and Honghui Lin. "Transcription factor HAT1 is a substrate of SnRK2.3 kinase and negatively regulates ABA synthesis and signaling in Arabidopsis responding to drought." PLOS Genetics 14, no. 4 (April 16, 2018): e1007336. http://dx.doi.org/10.1371/journal.pgen.1007336.
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Bauerle, William L., William W. Inman, and Jerry B. Dudley. "Leaf Abscisic Acid Accumulation in Response To Substrate Water Content: Linking Leaf Gas Exchange Regulation with Leaf Abscisic Acid Concentration." Journal of the American Society for Horticultural Science 131, no. 2 (March 2006): 295–301. http://dx.doi.org/10.21273/jashs.131.2.295.
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Quantitative differences in leaf abscisic acid (ABAL) among four cultivars of red maple (Acer rubrum L.) and one freeman maple (Acer ×freemanii E. Murray) cultivar were investigated. This study tested the hypothesis that ABAL concentration can be used to compare the effects of water stress on the gas exchange response of five different maple genotypes, including four red maple cultivars [`Summer Red', `October Glory', `Autumn Flame', and `Franksred' ('Red Sunset')] and one hybridized freeman maple cultivar ['Jeffersred' ('Autumn Blaze')]. Two-year-old cloned genotypes of red maple and freeman maple were subjected to two treatments: irrigated daily to container capacity or irrigation withheld for one drought and recovery cycle. Leaf abscisic acid concentration, gas exchange, and wholetree sap flow measurements were conducted under well-watered and drought stress conditions. Over the course of the drought stress and recovery phase, net photosynthesis (Anet), stomatal conductance (gs), and transpiration (E) declined as ABAL and instantaneous water use efficiency (A/gs) increased. Until severe water stress conditions were prominent, water use was higher in `Summer Red' as compared to `October Glory'. This study found that ABAL tracked gs and that stomatal responsiveness to substrate moisture deficit is likely mediated by ABA accumulation in leaf tissue. This research demonstrates a leaf level physiological response to substrate volumetric water content that appears to depend on ABAL concentration. In addition, the evidence in this study indicates that ABAL may be used as a potential surrogate for the gs response to substrate water stress and could become part of a cultivar drought tolerance selection strategy for red maple and freeman maple.
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Shao, Chen, Chengliang Wang, and Jianye Zang. "Structural basis for the substrate selectivity of PvuRts1I, a 5-hydroxymethylcytosine DNA restriction endonuclease." Acta Crystallographica Section D Biological Crystallography 70, no. 9 (August 29, 2014): 2477–86. http://dx.doi.org/10.1107/s139900471401606x.
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5-Hydroxymethylation is a curious modification of cytosine that was discovered some decades ago, but its functional role in eukaryotes still awaits elucidation. 5-Hydroxymethylcytosine is an epigenetic marker that is crucial for multiple biological processes. The profile is altered under certain disease conditions such as cancer, Huntington's disease and Alzheimer's disease. Using the DNA-modification-dependent restriction endonuclease AbaSI coupled with sequencing (Aba-seq), the hydroxymethylome can be deciphered at the resolution of individual bases. The method is based on the enzymatic properties of AbaSI, a member of the PvuRts1I family of endonucleases. PvuRts1I is a modification-dependent endonuclease with high selectivity for 5-hydroxymethylcytosine over 5-methylcytosine and cytosine. In this study, the crystal structure of PvuRts1I was determined in order to understand and improve the substrate selectivity. A nuclease domain and an SRA-like domain are located at the N- and C-termini, respectively. Through comparison with other SRA-domain structures, the SRA-like domain was proposed to be the 5-hmC recognition module. Several mutants of PvuRts1I with enzymatic activity restricted to 5-hydroxymethylcytosine only were generated based on the structural analysis, and these enzyme variants are appropriate for separating the hydroxymethylome from the wider methylome.
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Mello, Jaime Wilson Vargas de, Luiz Eduardo Dias, Alfredo Mucci Daniel, Walter Antonio Pereira Abrahão, Eleonora Deschamps, and Carlos Ernesto G. Reynald Schaefer. "Preliminary evaluation of acid mine drainage in Minas Gerais State, Brazil." Revista Brasileira de Ciência do Solo 30, no. 2 (April 2006): 365–75. http://dx.doi.org/10.1590/s0100-06832006000200016.
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Mining in the State of Minas Gerais-Brazil is one of the activities with the strongest impact on the environment, in spite of its economical importance. Amongst mining activities, acid drainage poses a serious environmental problem due to its widespread practice in gold-extracting areas. It originates from metal-sulfide oxidation, which causes water acidification, increasing the risk of toxic element mobilization and water resource pollution. This research aimed to evaluate the acid drainage problem in Minas Gerais State. The study began with a bibliographic survey at FEAM (Environment Foundation of Minas Gerais State) to identify mining sites where sulfides occur. Substrate samples were collected from these sites to determine AP (acidity potential) and NP (neutralization potential). The AP was evaluated by the procedure of the total sulfide content and by oxygen peroxide oxidation, followed by acidity titration. The NP was evaluated by the calcium carbonate equivalent. Petrographic thin sections were also mounted and described with a special view to sulfides and carbonates. Based on the chemical analysis, the acid-base accounting (ABA) was determined by the difference of AP and NP, and the acid drainage potential obtained by the ABA value and the total volume of material at each site. Results allowed the identification of substrates with potential to generate acid drainage in Minas Gerais state. Altogether these activities represent a potential to produce between 3.1 to 10.4 billions of m³ of water at pH 2 or 31.4 to 103.7 billions of m³ of water at pH 3. This, in turn, would imply in costs of US$ 7.8 to 25.9 millions to neutralize the acidity with commercial limestone. These figures are probably underestimated because some mines were not surveyed, whereas, in other cases, surface samples may not represent reality. A more reliable state-wide evaluation of the acid drainage potential would require further studies, including a larger number of samples. Such investigations should consider other mining operations beyond the scope of this study as well as the kinetics of the acid generation by simulated weathering procedures.
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Shaji, Ashin, Maja Micetic, Yuriy Halahovets, Peter Nadazdy, Igor Matko, Matej Jergel, Eva Majkova, and Peter Siffalovic. "Real-time tracking of the self-assembled growth of a 3D Ge quantum dot lattice in an alumina matrix." Journal of Applied Crystallography 53, no. 4 (July 24, 2020): 1029–38. http://dx.doi.org/10.1107/s1600576720007815.
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A laboratory in situ grazing-incidence small-angle X-ray scattering (GISAXS) tracking of the self-assembled growth of a regular 3D Ge quantum dot (QD) structure in an amorphous Al2O3 matrix during the ion beam sputter deposition of a periodic Ge/Al2O3 multilayer on silicon is reported. A 573 K substrate temperature proved to be necessary to achieve the self-assembly effect. Relying on a fast repeated acquisition of GISAXS patterns, the temporal evolution of the growing 3D Ge QD structure was analyzed bilayer by bilayer to determine its type, lateral and vertical correlation lengths, and inter-QD distance. The QD structure was found to have body-centered tetragonal lattice type with ABA stacking, with the lattice parameters refined by fitting the final GISAXS pattern relying on a paracrystal model. A single set of paracrystal parameters enables one to simulate the temporal evolution of the in situ GISAXS patterns throughout the deposition process, suggesting that the Ge QD self-assembly is driven from the very beginning solely by the growing surface morphology. Ex situ GISAXS and X-ray reflectivity measurements along with a cross-section high-resolution transmission electron microscopy analysis complete the study.
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Belkheiri, Oumelkheir, and Maurizio Mulas. "Effect of water stress on growth, water use efficiency and gas exchange as related to osmotic adjustment of two halophytes Atriplex spp." Functional Plant Biology 40, no. 5 (2013): 466. http://dx.doi.org/10.1071/fp12245.
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Atriplex halimus L. is known in the Mediterranean basin and along the coastal areas of Sardinia for its adaptability to salinity, although less information is available on the resistance of this species to water stress in absence of salinity. The effect of water stress on growth and water utilisation was investigated in two Atriplex species: A. halimus originating of south Sardinian island and the exotic species Atriplex nummularia Lindl., originating in Australia and widely used in land restoration of arid areas. Water stress was applied to young plants growing in 20 L pots with a sufficient water reserve to store a potentially sufficient water reserve to maintain substrate near to field capacity (30%) between irrigations. Watering was at 70% (control) or 40% (stress) of field capacity. In order to simulate the grazing by livestock, four plant biomass cuttings were conducted at times T0, T1, T2 and T3, corresponding to one cutting at the end of well watered phase (T0) before water stress induction, two cuttings after cycles of 5 weeks each during full summer (T1) and late summer (T2) and one cutting during autumn (T3). All plants remained alive until the end of treatment although growth was strongly reduced. Leaf dry weight (DW) and water use efficiency (WUE) were determined for all cuttings; relative water content (RWC), turgid weight : dry weight ratio (TW : DW), water potential (Ψw), osmotic potential (Ψs), CO2 assimilation, osmotic adjustment (OA), abscisic acid (ABA) and sugar accumulation were determined for the late summer cutting at T2. Water stress induced a decrease in DW, RWC, Ψw, Ψs, TW : DW and CO2 assimilation for both species, but an increase in WUE expressed in terms of dry matter production and a high accumulation of ABA and total sugars mainly for A. halimus. This suggests a more developed adaptive mechanism in this selection. Indeed, the clone was selected from the southern part of the island, where natural populations of saltbush are more exposed to abiotic stresses, mainly the water stress generated not by salinity. A. nummularia showed a greater OA and a positive net solute accumulation as than A. halimus, suggesting that water stress resistance in A. halimus is linked to a higher WUE rather than a greater osmotic adjustment.
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Sun, Dan, Xilin Zhao, Jun Ai, Zhenxing Wang, Guangli Shi, Yumeng Liu, Xiang Li, and Chengcheng Zhao. "Study on the Rooting Physiological Mechanism of Schisandra chinensis (Turcz.) Baill. Green-Branched Cuttings." Forests 14, no. 7 (July 3, 2023): 1365. http://dx.doi.org/10.3390/f14071365.
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Schisandra chinensis (Turcz.) Baill. is an important medicinal plant in northeast China. Cutting propagation is an effective method for the rapid propagation of many tree species. This research aimed to determine a suitable growing medium and appropriate root hormone type, concentration and treatment time through the utilization of different substrates and hormones to treat one-year-old branches of S. chinensis. The optimal treatment achieved a rooting rate of 60% with 225 ppm ABT and 75 ppm NAA for 2.5 h. The substrate of vermiculite/perlite = 1:1 (urea+potassium) was beneficial to the adventitious root formation, which reached 79%. The adventitious root primordium of S. chinensis originated from the junction of the xylem and cambium. ABT and NAA treatments altered the peak timing of POD, PPO and IAAO in S. chinensis cuttings. During the adventitious root formation of S. chinensis cuttings, the high endogenous IAA concentration promoted the occurrence of adventitious roots in the early stage and the lower endogenous IAA and GA3 concentrations promoted the elongation and growth of adventitious roots in the later period. Low ABA and ZR concentrations enabled adventitious root formation and elongation. An efficient cutting propagation system would enable the mass propagation of S. chinensis seedlings.
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López-Cuevas, J., M. I. Pech-Canul, J. L. Rodríguez-Galicia, and J. C. Rendón-Angeles. "A Practical Procedure for Measuring Contact Angles in Wettability Studies by the Sessile Drop Method." MRS Advances 4, no. 57-58 (2019): 3143–52. http://dx.doi.org/10.1557/adv.2019.373.
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ABSTRACTAn old procedure used to carry out a graphical derivation of curves, which is based on the optical properties of plane mirrors, has been adapted for the measurement of the contact angle (θ) formed between a liquid drop and a flat solid substrate in wettability experiments carried out by the so-called “sessile drop” method. The method was tested for mercury on soda-lime glass at room temperature in air as well as for Cusil (Ag-28wt.%Cu) and Incusil-ABA (Ag-27wt.%Cu-12wt.%In-2wt.%Ti) brazing alloys on pressureless-sintered silicon carbide (PLS-SiC) at 850 °C, under a vacuum of 10-4/10-5 Torr. The proposed method is fast, simple and accurate enough from high (∼140°) to relatively low (∼10°) contact angles. Although the proposed method has been tested for metal-ceramic systems, it is of general application, so that it would be useful for any liquid-solid system. The method is applicable for any temperature, pressure and atmospheric experimental conditions employed, as well as for any chemical composition of liquid and solid. It is also useful for both low and high contact angles, as well as for reactive and non-reactive systems, as long as a photograph of a liquid drop resting on a flat solid surface is available for the studied system.
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Inman, William W., and William L. Bauerle. "(142) Hydraulic Resistance: A Determinant of Short-term Stomatal Conductance Signaling in Disparate Xylem Anatomy of Red Maple (Acer rubrum L.) and Shumard Oak (Quercus shumardii Buckl.)." HortScience 41, no. 4 (July 2006): 1058A—1058. http://dx.doi.org/10.21273/hortsci.41.4.1058a.
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Recent work has shown that stomatal conductance (gs) and net photosynthesis (Anet) are responsive to the hydraulic conductance of the soil to leaf pathway (Xp). Two tree species with differing xylem structures were used to study the effect of systematic manipulations in Xp that elevated xylem hydraulic resistance. Simultaneous measures of gs, Anet, bulk leaf abscisic acid concentration (ABAL), leaf water potential (L), and whole plant transpiration (Ew) were taken under controlled environment conditions. Quercus shumardii Buckl. (shumard oak), a ring porous species and Acer rubrum L. `Summer Red' (red maple), a diffuse porous species, were studied to investigate the short-term hydraulic and chemical messenger response to drought. Both species decreased Anet, gs, L, and Ew in response to an immediate substrate moisture alteration. Relative to initial well-watered values, red maple Anet, gs, and Ew declined more than shumard oak. However, gs and Anet vs. whole-plant leaf specific hydraulic resistance was greater in shumard oak. In addition, the larger hydraulic resistance in shumard oak was attributed to higher shoot, as opposed to root, system resistance. The results indicate hydraulic resistance differences that may be attributed to the disparate xylem anatomy between the two species. This study also provides evidence to support the short-term hydraulic signal negative feedback link hypothesis between gs and the cavitation threshold, as opposed to chemical signaling via rapid accumulation from root-synthesized ABA.
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Romero-Muñoz, Miriam, Amparo Gálvez, Purificación A. Martínez-Melgarejo, María Carmen Piñero, Francisco M. del Amor, Alfonso Albacete, and Josefa López-Marín. "The Interaction between Hydromulching and Arbuscular Mycorrhiza Improves Escarole Growth and Productivity by Regulating Nutrient Uptake and Hormonal Balance." Plants 11, no. 20 (October 21, 2022): 2795. http://dx.doi.org/10.3390/plants11202795.
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To improve water and nutrient use efficiencies some strategies have been proposed, such as the use of mulching techniques or arbuscular mycorrhizal fungi (AMF) inoculation. To gain insights into the interaction between the use of hydromulch and AMF inoculation on plant growth and productivity, escarole plants (Cichorium endivia, L.) were inoculated with the AMF Rhizophagus irregularis and grown with non-inoculated plants under different soil cover treatments: ecological hydromulching based on the substrate of mushroom cultivation (MS), low-density black polyethylene (PE), and non-covered soil (BS). AMF inoculation or the use of mulching alone, but especially their interaction, increased the plant growth. The growth improvement observed in AMF-inoculated escarole plants grown under hydromulching conditions was mainly associated with the upgrading of nitrogen and phosphorous use efficiency through the regulation of the hormonal balance. Both hydromulching and AMF inoculation were found to increase the active gibberellins (GAs) and cytokinins (CKs), resulting in a positive correlation between these hormones and the growth-related parameters. In contrast, the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and abscisic acid (ABA) decreased in AMF-inoculated plants and especially in those grown with the MS treatment. This study demonstrates that there exists a positive interaction between AMF and hydromulching which enhances the growth of escarole plants by improving nutrient use efficiency and hormonal balance.
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Panapimonlawat, Tayanee, Sukon Phanichphant, and Saengrawee Sriwichai. "Electrochemical Dopamine Biosensor Based on Poly(3-aminobenzylamine) Layer-by-Layer Self-Assembled Multilayer Thin Film." Polymers 13, no. 9 (May 6, 2021): 1488. http://dx.doi.org/10.3390/polym13091488.
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Dopamine (DA) is an important neurotransmitter which indicates the risk of several neurological diseases. The selective determination with low detection limit is necessary for early diagnosis and prevention of neurological diseases associated with abnormal concentration of DA. The purpose of this study is to fabricate a poly(3-aminobenzylamine)/poly(sodium 4-styrenesulfonate) (PABA/PSS) multilayer thin film for use as an electrochemical DA biosensor. The PABA was firstly synthesized using a chemical oxidation method of 3-aminobenzylamine (ABA) monomer with ammonium persulfate (APS) as an oxidant. For electrochemical biosensor, the PABA/PSS thin film was fabricated on fluorine doped tin oxide (FTO)-coated glass substrate using the layer-by-layer (LBL) self-assembly method. The optimized number of bilayers was achieved using SEM and cyclic voltammetry (CV) results. The electroactivity of the optimized LBL thin film toward detection of DA in neutral solution was studied by CV and amperometry. The PABA/PSS thin film showed good sensitivity for DA sensing with sensitivity of 6.922 nA·cm−2·µM−1 and linear range of 0.1–1.0 µM (R2 = 0.9934), with low detection limit of 0.0628 µM, long-term stability and good reproducibility. In addition, the selectivity of the PABA/PSS thin film for detection of DA under the common interferences (i.e., ascorbic acid, uric acid and glucose) was also presented. The prepared PABA/PSS thin film showed the powerful efficiency for future use as DA biosensor in real sample analysis.
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Wang, Jin, Yang, Zong, and Peng. "Graphene Adhesion Mechanics on Iron Substrates: Insight from Molecular Dynamic Simulations." Crystals 9, no. 11 (November 6, 2019): 579. http://dx.doi.org/10.3390/cryst9110579.
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The adhesion feature of graphene on metal substrates is important in graphene synthesis, transfer and applications, as well as for graphene-reinforced metal matrix composites. We investigate the adhesion energy of graphene nanosheets (GNs) on iron substrate using molecular dynamic (MD) simulations. Two Fe–C potentials are examined as Lennard–Jones (LJ) pair potential and embedded-atom method (EAM) potential. For LJ potential, the adhesion energies of monolayer GN are 0.47, 0.62, 0.70 and 0.74 J/m2 on the iron {110}, {111}, {112} and {100} surfaces, respectively, compared to the values of 26.83, 24.87, 25.13 and 25.01 J/m2 from EAM potential. When the number of GN layers increases from one to three, the adhesion energy from EAM potential increases. Such a trend is not captured by LJ potential. The iron {110} surface is the most adhesive surface for monolayer, bilayer and trilayer GNs from EAM potential. The results suggest that the LJ potential describes a weak bond of Fe–C, opposed to a hybrid chemical and strong bond from EAM potential. The average vertical distances between monolayer GN and four iron surfaces are 2.0–2.2 Å from LJ potential and 1.3–1.4 Å from EAM potential. These separations are nearly unchanged with an increasing number of layers. The ABA-stacked GN is likely to form on lower-index {110} and {100} surfaces, while the ABC-stacked GN is preferred on higher-index {111} surface. Our insights of the graphene adhesion mechanics might be beneficial in graphene growing, surface engineering and enhancement of iron using graphene sheets.
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Blanchard, D., J. P. Aubry, J. E. de Vries, and H. Spits. "The role of Ca2+ and Mg2+ in the cytotoxic T lymphocyte reaction and in the secretion of N alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester-serine esterase by human T cell clones." Journal of Immunology 142, no. 7 (April 1, 1989): 2173–80. http://dx.doi.org/10.4049/jimmunol.142.7.2173.
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Abstract Human T cell clones contain enzymes that can cleave the substrate N-alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester (BLT). All CTL clones tested in this study secreted BLT-serine esterase activity, whereas only one of three tested non-cytolytic T cell clones secreted this enzymatic activity upon Ag-specific activation. BLT-serine esterase secretion could also be induced by the Fc gamma+ target cell Daudi in the presence of mAb specific for the TCR/CD3 complex, CD2, or the T cell activation Ag Tp 103. In addition, anti-CD3 and a mitogenic combination of anti-CD2 mAb, induced secretion of BLT-serine esterase in the absence of target cells, whereas anti-Tp 103 failed to do so. The secreted BLT-serine esterase activity induced by the various ligands was inhibited by the serine esterase inhibitors PMSF and m-ABA, but not by N-alpha-p-tosyl-L-lysine chloromethyl ketone. Significant BLT-serine esterase activity was induced by target cells or soluble anti-CD3 in the absence of extracellular Ca2+ ions, provided that extracellular Mg2+ ions were present. The cytotoxic activities by the human CTL clones were completely blocked under these conditions. All ligands that induced BLT-serine esterase secretion in the absence of extracellular Ca2+, induced a transient rise of intracellular Ca2+. Soluble anti-CD3 mAb did not induce a transient rise in intracellular Ca2+ or secretion of BLT serine esterase in CTL preincubated for 2 h with 5 mM EGTA. These findings indicate that mobilization of intracellular Ca2+ in human CTL clones is required for induction of secretion of BLT-serine esterase.
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Doupis, George, Konstantinos S. Chartzoulakis, Demetris Taskos, and Angelos Patakas. "The effects of drought and supplemental UV-B radiation on physiological and biochemical traits of the grapevine cultivar “Soultanina”." OENO One 54, no. 4 (October 7, 2020): 687–98. http://dx.doi.org/10.20870/oeno-one.2020.54.4.3581.
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Aim: In the Mediterranean region, grapevines usually undergo drought and high UV-B intensities during their summer growth season. The present study was conducted in order to evaluate the effects of these two abiotic stressors on the physiological and biochemical characteristics of a major Greek raisin variety (Vitis vinifera L. cv Soultanina).Methods and results: The experimental plants were three-years-old, grafted onto 110R rootstock and grown outdoors in 25 L pots containing a peat:perlite:sand (3:1:1, v/v/v) potting mixture. Grapevines were subjected to two irrigation treatments: (1) Well-Watered (plants were uniformly irrigated on a daily basis to soil substrate capacity), and (2) Water-Stressed (plants were equally irrigated with 50 % of the amount of water provided to Well-Watered plants), and to two levels of UV-B radiation: (1) ambient UV-B radiation, and (2) ambient plus 15 % UV-B radiation. Although the combination of drought and supplemental UV-B radiation appeared to have synergistic effects on gas exchange characteristics and H2O2 production, the development of biochemical limitations to photosynthesis was not detectable. Compared to the other stress treatments, WW±15 % UV-B plants exhibited higher stomatal conductance (gs) and photosynthetic rate (PN).Conclusion: Under elevated UV-B radiation, superoxide dismutase (SOD) activation, chlorophyll degradation and enhanced synthesis of carotenoids all helped the plant to maintain its physiological functions, while in Water-Stressed plants irrespective of the level of UV-B, a more pronounced role of abscisic acid (ABA) and trans-zeatin-riboside (t-ZR) in mediating stomatal responses was revealed.Significance of the study: Our results imply that the environmental conditions were not stressful enough to report the occurrence of non-diffusional limitations to photosynthesis. In addition, two different adaptive responses in relation to the applied abiotic stressor were shown.
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Mohammadi Ballakuti, Narjes, and Faezeh Ghanati. "Developed network between taxoid and phenylpropanoid pathways in Cryptosporiopsis tarraconensis, taxan-producing endophytic fungus by Debiased Sparse Partial Correlation (DSPC) algorithm." PLOS ONE 18, no. 2 (February 23, 2023): e0282010. http://dx.doi.org/10.1371/journal.pone.0282010.
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Although bioproduction of Paclitaxel by endophytic fungi is highly considered as an alternative promising source, but its yield is usually very low in comparison with other taxoids. Different strategies i.e., chemical and physical elicitations have been developed in order to overcome the shortage of Paclitaxel production. Paclitaxel biosynthesis is started with terpenoid pathway followed by phenylpropanoid metabolism where a benzoylphenylisoserine moiety is attached to C13 of baccatin III skeleton. This point which is catalyzed by the function of PAM seems to be a bottleneck that limits the rate of Paclitaxel production. Whether phenylpropanoids pathway regulates the taxanes biosynthesis in Cryptosporiopsis tarraconensis endophytic fungus elicited with benzoic acid (BA) was hypothesized in the present paper. The involvement of certain signal molecules and key enzymes of terpenoid and phenylpropanoid metabolism were investigated. According to the results, application of BA promoted a signaling pathway which was started with increase of H2O2 and ABA and continued by increase of NO and MJ, and finally resulted in increase of both phenylpropanoids and taxanes. However, again the rate of Paclitaxel production was lower than other taxoids, and the latter was much lower than phenolics. Therefore, supplying benzoic acid provided the precursor for the common taxan ring production. It is unlikely that Paclitaxel production is merely controlled by side chain production stage. It is more likely that in C. tarraconensis endophytic fungus, similar to Taxus sp., the competition between phenylpropanoid and taxoid pathways for substrate ended in favor of the former. The interaction network which was constructed based on DSPC algorithm confirmed that most compounds with close proximity have shared metabolic pathway relationships. Therefore, it is unlikely that the feeding with a given precursor directly result in increase of a desired metabolite which is composed of different merits.
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Koyro, Hans-Werner, and Bernhard Huchzermeyer. "From Soil Amendments to Controlling Autophagy: Supporting Plant Metabolism under Conditions of Water Shortage and Salinity." Plants 11, no. 13 (June 22, 2022): 1654. http://dx.doi.org/10.3390/plants11131654.
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Crop resistance to environmental stress is a major issue. The globally increasing land degradation and desertification enhance the demand on management practices to balance both food and environmental objectives, including strategies that tighten nutrient cycles and maintain yields. Agriculture needs to provide, among other things, future additional ecosystem services, such as water quantity and quality, runoff control, soil fertility maintenance, carbon storage, climate regulation, and biodiversity. Numerous research projects have focused on the food–soil–climate nexus, and results were summarized in several reviews during the last decades. Based on this impressive piece of information, we have selected only a few aspects with the intention of studying plant–soil interactions and methods for optimization. In the short term, the use of soil amendments is currently attracting great interest to cover the current demand in agriculture. We will discuss the impact of biochar at water shortage, and plant growth promoting bacteria (PGPB) at improving nutrient supply to plants. In this review, our focus is on the interplay of both soil amendments on primary reactions of photosynthesis, plant growth conditions, and signaling during adaptation to environmental stress. Moreover, we aim at providing a general overview of how dehydration and salinity affect signaling in cells. With the use of the example of abscisic acid (ABA) and ethylene, we discuss the effects that can be observed when biochar and PGPB are used in the presence of stress. The stress response of plants is a multifactorial trait. Nevertheless, we will show that plants follow a general concept to adapt to unfavorable environmental conditions in the short and long term. However, plant species differ in the upper and lower regulatory limits of gene expression. Therefore, the presented data may help in the identification of traits for future breeding of stress-resistant crops. One target for breeding could be the removal and efficient recycling of damaged as well as needless compounds and structures. Furthermore, in this context, we will show that autophagy can be a useful goal of breeding measures, since the recycling of building blocks helps the cells to overcome a period of imbalanced substrate supply during stress adjustment.
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Musadiq Oladimeji Usman, Ogechi Ozioma Anyanwu, and Innocent Oghale Ajawobu. "Proximate composition and heavy metal content of Pleurotus tuberregium mushroom grown on different substrates in (Aba) Nigeria." GSC Biological and Pharmaceutical Sciences 20, no. 3 (September 30, 2022): 213–22. http://dx.doi.org/10.30574/gscbps.2022.20.3.0330.
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Mushrooms have been widely used as food and food supplements in Nigeria and other countries of the world for millennia. They are highly nutritious so they contain good quality carbohydrates, proteins, vitamins and minerals. This study determined the proximate, the effects of some substrates (best medium) on the yield and the heavy metal content of mushrooms of Pleurotus tuberregium (Fr.) Sing., grown in the laboratory. Four different substrates were used in the experiment to grow the mushrooms namely: topsoil, sawdust, riversand, and mixture of riversand and sawdust respectively. The quality of the fruit body produced was measured with the use of ruler and vernier calipers. Some heavy metals (Cd, Cr and Pb) were analyzed using Atomic Absorption Spectrophotometer. The parameters measured were: number of fruiting bodies, height of stipe, fresh weight, diameter of pileus and diameter of stipe. The result of the experiment on production of mushroom revealed that mushrooms on riversand substrate had the highest mean stipe height, the widest mean pileus and the significantly (p<0.05) highest yield. Nutritional parameters were measured and it was found that highest crude fiber content was found in the mushroom grown in mixture of riversand and sawdust substrate; mushrooms on riversand substrate had the highest carbohydrate percentage content and ash content was highest in Pleurotus tuberregium mushroom grown on topsoil substrate. The contents of Cd, Cr and Pb were all below the detection limit of the instrumentation for Pleurotus tuberregium mushroom grown on all substrates. From this study, the choice of substrate for the growth of mushroom for human and industrial use should be considered to enhance yield and prevent exposure to heavy metal contaminants.
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Yu, Yongtao, Sergi Portolés, Yi Ren, Guangyu Sun, Xiao-Fang Wang, Huihui Zhang, and Shaogui Guo. "The key clock component ZEITLUPE (ZTL) negatively regulates ABA signaling by degradation of CHLH in Arabidopsis." Frontiers in Plant Science 13 (September 13, 2022). http://dx.doi.org/10.3389/fpls.2022.995907.
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Ubiquitination-mediated protein degradation plays important roles in ABA signal transduction and delivering responses to chloroplast stress signals in plants, but additional E3 ligases of protein ubiquitination remain to be identified to understand the complex signaling network. Here we reported that ZEITLUPE (ZTL), an F-box protein, negatively regulates abscisic acid (ABA) signaling during ABA-inhibited early seedling growth and ABA-induced stomatal closure in Arabidopsis thaliana. Using molecular biology and biochemistry approaches, we demonstrated that ZTL interacts with and ubiquitinates its substrate, CHLH/ABAR (Mg-chelatase H subunit/putative ABA receptor), to modulate CHLH stability via the 26S proteasome pathway. CHLH acts genetically downstream of ZTL in ABA and drought stress signaling. Interestingly, ABA conversely induces ZTL phosphorylation, and high levels of ABA also induce CHLH proteasomal degradation, implying that phosphorylated ZTL protein may enhance the affinity to CHLH, leading to the increased degradation of CHLH after ABA treatment. Taken together, our results revealed a possible mechanism of reciprocal regulation between ABA signaling and the circadian clock, which is thought to be essential for plant fitness and survival.
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Peng, Jing, Meijiao Wang, Xiaoji Wang, Lijuan Qi, Can Guo, Hong Li, Cong Li, et al. "COP1 positively regulates ABA signaling during Arabidopsis seedling growth in darkness by mediating ABA-induced ABI5 accumulation." Plant Cell, February 28, 2022. http://dx.doi.org/10.1093/plcell/koac073.
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Abstract CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1), a well-characterized E3 ubiquitin ligase, is a central repressor of seedling photomorphogenic development in darkness. However, whether COP1 is involved in modulating abscisic acid (ABA) signaling in darkness remains largely obscure. Here, we report that COP1 is a positive regulator of ABA signaling during Arabidopsis seedling growth in the dark. COP1 mediates ABA-induced accumulation of ABI5, a transcription factor playing a key role in ABA signaling, through transcriptional and post-translational regulatory mechanisms. We further show that COP1 physically interacts with ABA-hypersensitive DCAF1 (ABD1), a substrate receptor of the CUL4-DDB1 E3 ligase targeting ABI5 for degradation. Accordingly, COP1 directly ubiquitinates ABD1 in vitro, and negatively regulates ABD1 protein abundance in vivo in the dark but not in the light. Therefore, COP1 promotes ABI5 protein stability post-translationally in darkness by destabilizing ABD1 in response to ABA. Interestingly, we reveal that ABA induces the nuclear accumulation of COP1 in darkness, thus enhancing its activity in propagating the ABA signal. Together, our study uncovers that COP1 modulates ABA signaling during seedling growth in darkness by mediating ABA-induced ABI5 accumulation, demonstrating that plants adjust their ABA signaling mechanisms according to their light environment.
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Wang, Pan, Sijia Qi, Xiaohong Wang, Liru Dou, Meng-ao Jia, Tonglin Mao, Yushuang Guo, and Xiangfeng Wang. "The OPEN STOMATA1–SPIRAL1 module regulates microtubule stability during abscisic acid–induced stomatal closure in Arabidopsis." Plant Cell, October 18, 2022. http://dx.doi.org/10.1093/plcell/koac307.
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Abstract Drought stress triggers abscisic acid (ABA) signaling in guard cells and induces stomatal closure to prevent water loss in land plants. Stomatal movement is accompanied by reorganization of the cytoskeleton. Cortical microtubules disassemble in response to ABA, which is required for stomatal closure. However, how ABA signaling regulates microtubule disassembly is unclear, and the microtubule-associated proteins (MAPs) involved in this process remain to be identified. In this study, we show that OPEN STOMATA 1 (OST1), a central component in ABA signaling, mediates microtubule disassembly during ABA-induced stomatal closure in Arabidopsis thaliana. We identified the MAP SPIRAL1 (SPR1) as the substrate of OST1. OST1 interacts with and phosphorylates SPR1 at Ser6, which promotes the disassociation of SPR1 from microtubules and facilitates microtubule disassembly. Compared to the wild type, the spr1 mutant exhibited significantly greater water loss and reduced ABA responses, including stomatal closure and microtubule disassembly in guard cells. These phenotypes were restored by introducing the phosphorylated active form of SPR1. Our findings demonstrate that SPR1 positively regulate microtubule disassembly during ABA-induced stomatal closure, which depends on OST1-mediated phosphorylation. These findings reveal a specific connection between a core component of ABA signaling and MAPs.
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Barduche, Douglas, Renato Paiva, Mauricio A. Lopes, and Edilson Paiva. "Effect of ABA and GA3 on protein mobilization in embryos and cotyledons of angico [Anadenanthera peregrina (L.) speg] seeds during germination." Brazilian Archives of Biology and Technology 42, no. 2 (1999). http://dx.doi.org/10.1590/s1516-89131999000200002.
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In this work, a woody species [A. peregrina (L.) Speg.] was studied in order to observe the effect of ABA and GA3 at the biochemical level during the process of seed germination. Embryos incubated in sucrose solution containing ABA and/or GA3 were analyzed through SDS-PAGE to observe the mobilization pattern of storage proteins during the beginning of germination. Cotyledons isolated from seeds incubated in aqueous solutions containing ABA and/or GA3, were also analyzed through SDS-PAGE and by PAGE/Activity Gels (polyacrylamide gels copolymerized with substrate for enzymes) to observe the mobilization pattern of storage proteins and protease activity after the beginning of the germination. Results of these experiments show that ABA blocks protein mobilization by inhibiting protease activity in cotyledons. This inhibition is not sufficient to prevent germination showing that the effect of ABA on germination is not dependent on protease activity. The blockage of storage protein mobilization was also observed in embryos, but no protease activity inhibition was clearly detected. ABA was able to induce the synthesis of proteins in cotyledons but not in embryos. A polypeptide with an approximate molecular weight of 17 kD, was degraded within 6 hours in control embryos, but this degradation was blocked by ABA and GA3. Using the same concentrations of ABA and GA3 on embryos and cotyledons, the effect of ABA was counteracted by GA3 in embryos, but not in cotyledons. Although the effects of ABA and GA3 were not so different from those shown in the literature, the behavior of 17 kD-polypeptide contradicts these reports suggesting that specific studies should be performed.
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Zhang, Zhiwei, Yang Liu, Jing Zhao, Wenqiang Li, Ruiwen Hu, Xia Li, Aitao Li, Yaping Wang, and Lixin Ma. "Active-site engineering of ω-transaminase from Ochrobactrum anthropi for preparation of L-2-aminobutyric acid." BMC Biotechnology 21, no. 1 (September 25, 2021). http://dx.doi.org/10.1186/s12896-021-00713-7.
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Abstract Background The unnatural amino acid, L-2-aminobutyric acid (L-ABA) is an essential chiral building block for various pharmaceutical drugs, such as the antiepileptic drug levetiracetam and the antituberculosis drug ethambutol. The present study aims at obtaining variants of ω-transaminase from Ochrobactrum anthropi (OATA) with high catalytic activity to α-ketobutyric acid through protein engineering. Results Based on the docking model using α-ketobutyric acid as the ligand, 6 amino acid residues, consisting of Y20, L57, W58, G229, A230 and M419, were chosen for saturation mutagenesis. The results indicated that L57C, M419I, and A230S substitutions demonstrated the highest elevation of enzymatic activity among 114 variants. Subsequently, double substitutions combining L57C and M419I caused a further increase of the catalytic efficiency to 3.2-fold. This variant was applied for threonine deaminase/OATA coupled reaction in a 50-mL reaction system with 300 mM L-threonine as the substrate. The reaction was finished in 12 h and the conversion efficiency of L-threonine into L-ABA was 94%. The purity of L-ABA is 75%, > 99% ee. The yield of L-ABA was 1.15 g. Conclusion This study provides a basis for further engineering of ω-transaminase for producing chiral amines from keto acids substrates.
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Wei, Rongchang, Dongping Tu, Xiyang Huang, Zuliang Luo, Xiaohua Huang, Nan Cui, Juan Xu, Faqian Xiong, Haifeng Yan, and Xiaojun Ma. "Genome-scale transcriptomic insights into the gene co-expression network of seed abortion in triploid Siraitia grosvenorii." BMC Plant Biology 22, no. 1 (April 5, 2022). http://dx.doi.org/10.1186/s12870-022-03562-4.
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Abstract Background Siraitia grosvenorii (Swingle) C. Jeffrey, also known as Luohanguo or monk fruit, is a famous traditional Chinese medicine ingredient with important medicinal value and broad development prospects. Diploid S. grosvenorii has too many seeds, which will increase the utilization cost of active ingredients. Thus, studying the molecular mechanism of seed abortion in triploid S. grosvenorii, identifying the abortion-related genes, and regulating their expression will be a new direction to obtain seedless S. grosvenorii. Herein, we examined the submicroscopic structure of triploid S. grosvenorii seeds during abortion. Results Upon measuring the endogenous hormone content, we found that abscisic acid (ABA) and trans-zeatin (ZR) levels were significantly downregulated after days 15 and 20 of flowering. RNA sequencing of triploid seeds at different developmental stages was performed to identify key genes regulating abortion in triploid S. grosvenorii seeds. Multiple genes with differential expression between adjacent stages were identified; seven genes were differentially expressed across all stages. Weight gene co-expression network analysis revealed that the enhancement of monoterpene and terpene metabolic processes might lead to seed abortion by reducing the substrate flow to ABA and ZR. Conclusions These findings provide insights into the gene-regulatory network of seed abortion in triploid S. grosvenorii from different perspectives, thereby facilitating the innovation of the breeding technology of S. grosvenorii.