•MsPG1 was localized in plasma membrane of epidermal cells of root apexes.•MsPG1 decreased aluminum accumulations in pectins and hemicellulose 1 in vivo and vitro and enhanced root elongation in the ...present of aluminum.•MsPG1 increased porosity and extensibility of cell walls in root apexes of alfalfa in present of aluminum.
Pectins are abundant in the primary cell walls and involve in regulating intercellular adhesion. MsPG1gene was cloned from alfalfa and its function of Al tolerance was tested in vivo and vitro. Results showed that the expression of MsPG1 was increased by Al, and the MsPG1 was localized in the plasma membrane of epidermal cells in root apexes. Overexpression of MsPG1 in hairy roots of alfalfa increased root growth in the present of Al, which was attributed to the decreased Al accumulations in pectins, hemicellulose 1 (HC1), cell walls and root apexes conferred by the decreased content of HC1 and ratios of negatively charged functional groups (−OH and −COOH) in cell wall. The decreased Al accumulations in pectins and cell walls were also observed in incubation MsPG1 with pectins and cell walls in vitro. TEM and FESEM assays showed that overexpression of MsPG1 protected the cell microstructure of root apexes, and increased the porosity and pore size of porous lattice-like structure of cell wall in the present of Al. These results indicated that MsPG1 could increase Al tolerance of alfalfa via decreasing Al accumulation in cell wall and increasing the porosity and extensibility of cell wall under excess Al stress.
Water stress is an important factor affecting herb quality and yield and exogenous spermidine (Spd) addition can enhance dehydration tolerance of plants. Anoectochilus roxburghii (Wall.) Lindl is a ...perennial herb widely used in medicine, health care, and beauty industry, yet, its dehydration resistance remains largely unknown. In this view, the current research aimed at elucidating the drought resistance mechanism of A. roxburghii under PEG-induced water stress at different levels (10%, 20%, and 30% PEG6000). In particular, the morphological, physiological, and biochemical changes occurring in leaves treated with (0.5 mM, 5 mM) or without Spd were discussed under moderate water stress (20% PEG6000). Results showed that water stress significantly inhibited the growth of A. roxburghii by decreasing the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), arginine decarboxylase (ADC), S-adenosylmethionine decarboxylase (SAMDC), and polyamine oxidase (PAO). The contents of soluble protein, soluble proline, hydrogen peroxide (H2O2), malondialdehyde (MDA), and the relative conductivity (REC) of leaves increased by 27.32%, 31.37%, 68.84%, 103.61%, and 63.64%, respectively. Under dehydration condition, foliar spraying Spd effectively improved plant growth with the contents of soluble protein and soluble proline increased, while the H2O2, REC, and MDA contents decreased. The SOD activity of 0.5 mM and 5 mM treatments were 1.13 and 1.01 times higher than only 20% PEG treatment, respectively. Similarly, the POD activity of 0.5 mM and 5 mM treatments increased by 52.82% and 34.11%, while the CAT activity of 0.5 mM and 5 mM treatments increased by 34.39 and 33.15 U/mgprot, respectively. In addition, exogenous Spd application significantly increased the key enzyme activities of polyamine metabolism (ADC, SAMDC, and PAO) under moderate water stress. In conclusion, exogenous Spd addition with low concentration (0.5 mM) improved the resistance of A. roxburghii against water stress by increasing the antioxidant enzymes activities and endogenous polyamines contents. This study helps to the understanding of dehydration resistance of A. roxburghii and provide guidelines for its cultivation under water deficit condition.
•Anoectochilus roxburghii has weak water deficit tolerance.•Exogenous spermidine (Spd) addition improved the dehydration resistance.•Spd increased the activities of antioxidant enzymes and polyamine metabolism.•Low Spd concentration (0.5 mM) was better than high one (5 mM).
Alfalfa is a good green manure source, but its effect on rice growth has not been fully elucidated. Two green manure species, alfalfa and broad bean (Vicia faba L.), and two N fertilizer levels, ...alone or combination, were applied to a rice field. The results indicated that alfalfa had more pronounced effects on increasing soil labile phosphorus (P) fractions (including NaHCO
-Pi, NaOH-Pi), P uptake and soil enzyme activities (dehydrogenase, urease, acid phosphatase and β-glucosidase) than broad bean and N fertilizer. The transformation of NaHCO
-Po to labile P regulated by alfalfa played a significant direct and indirect effect on grain yield. Although a much lower N input from alfalfa addition, a similar grain yield with N fertilizer treatment was achieved, and the integration of alfalfa with N fertilizer produced the highest grain yield and P availability, which was associated with the highest urease, acid phosphatase and β-glucosidase activity in soil. These results indicate that alfalfa green manure had a great ability of increasing grain yield through enhancing P availability in rice paddy, which could give us a way to reduce N fertilizer application by enhancing P availability.
Dehydrin improves plant resistance to many abiotic stresses. In this study, the expression profiles of a dehydrin gene, CdDHN4, were estimated under various stresses and abscisic acid (ABA) ...treatments in two bermudagrasses (Cynodon dactylon L.): Tifway (drought-tolerant) and C299 (drought-sensitive). The expression of CdDHN4 was up-regulated by high temperatures, low temperatures, drought, salt and ABA. The sensitivity of CdDHN4 to ABA and the expression of CdDHN4 under drought conditions were higher in Tifway than in C299. A 1239-bp fragment, CdDHN4-P, the partial upstream sequence of the CdDHN4 gene, was cloned by genomic walking from Tifway. Bioinformatic analysis showed that the CdDHN4-P sequence possessed features typical of a plant promoter and contained many typical cis elements, including a transcription initiation site, a TATA-box, an ABRE, an MBS, a MYC, an LTRE, a TATC-box and a GT1-motif. Transient expression in tobacco leaves demonstrated that the promoter CdDHN4-P can be activated by ABA, drought and cold. These results indicate that CdDHN4 is regulated by an ABA-dependent signal pathway and that the high sensitivity of CdDHN4 to ABA might be an important mechanism enhancing the drought tolerance of bermudagrass.
Dehydrins play positive roles in regulating plant abiotic stress responses. The objective of this study was to characterize two dehydrin genes, CdDHN4-L and CdDHN4-S, generated by alternative ...splicing of CdDHN4 in bermudagrass.
Overexpression of CdDHN4-L with φ-segment and CdDHN4-S lacking of φ-segment in Arabidopsis significantly increased tolerance against abiotic stresses. The growth phenotype of Arabidopsis exposed to NaCl at 100 mM was better in plants overexpressing CdDHN4-L than those overexpressing CdDHN4-S, as well as better in E.coli cells overexpressing CdDHN4-L than those overexpressing CdDHN4-S in 300 and 400 mM NaCl, and under extreme temperature conditions at - 20 °C and 50 °C. The CdDHN4-L had higher disordered characterization on structures than CdDHN4-S at temperatures from 10 to 90 °C. The recovery activities of lactic dehydrogenase (LDH) and alcohol dehydrogenase (ADH) in presence of CdDHN4-L and CdDHN4-S were higher than that of LDH and ADH alone under freeze-thaw damage and heat. Protein-binding and bimolecular fluorescence complementation showed that both proteins could bind to proteins with positive isoelectric point via electrostatic forces.
These results indicate that CdDHN4-L has higher protective ability against abiotic stresses due to its higher flexible unfolded structure and thermostability in comparison with CdDHN4-S. These provided direct evidence of the function of the φ-segment in dehydrins for protecting plants against abiotic stress and to show the electrostatic interaction between dehydrins and client proteins.
(AR) is an herb and food source with great economic, medicinal, and ecological value.
(DC.) Koidz. (AC) and
(Thunb.) DC. (AL) are its two botanical sources. The commercial fraud of AR adulterated ...with
Koidz. ex Kitam (AJ) frequently occurs in pursuit of higher profit. To quickly determine the content of adulteration in AC and AL powder, two spectroscopic techniques, near-infrared spectroscopy (NIRS) and hyperspectral imaging (HSI), were introduced. The partial least squares regression (PLSR) algorithm was selected for predictive modeling of AR adulteration levels. Preprocessing and feature variable extraction were used to optimize the prediction model. Then data and image feature fusions were developed to obtain the best predictive model. The results showed that if only single-spectral techniques were considered, NIRS was more suitable for both tasks than HSI techniques. In addition, by comparing the models built after the data fusion of NIRS and HSI with those built by the single spectrum, we found that the mid-level fusion strategy obtained the best models in both tasks. On this basis, combined with the color-texture features, the prediction ability of the model was further optimized. Among them, for the adulteration level prediction task of AC, the best strategy was combining MLF data (at CARS level) and color-texture features (C-TF), at which time the R
, RMSET, R
, and RMSEP were 99.85%, 1.25%, 98.61%, and 5.06%, respectively. For AL, the best approach was combining MLF data (at SPA level) and C-TF, with the highest R
(99.92%) and R
(99.00%), as well as the lowest RMSET (1.16%) and RMSEP (2.16%). Therefore, combining data and image features from NIRS and HSI is a potential strategy to predict the adulteration content quickly, non-destructively, and accurately.
Green manure application has been a good fertility management for crop growth and soil quality, but its effect on greenhouse gas intensity (
GHGI
) and net ecosystem carbon budget (
NECB
) of rice ...ecosystem is not well understood. Two green manure species, alfalfa (
Medicago sativa
L.) and broad beans (
Vicia faba
L.), and two N fertilization levels (0 and 200 kg ha
−1
), alone or in combination, were applied to rice paddy soils in 2012 and 2013. The results show that the grain yields increased by 25.36, 29.81, and 41.85 % for the N fertilizer, N + broad bean, and N + alfalfa treatments, respectively, compared with the no fertilizer. CH
4
and N
2
O emissions increased by 50.77 and 36.11 %, 30.70 and 75.04 % in N + broad bean and N + alfalfa treatments, respectively, compared to N fertilizer treatment. The average CH
4
and N
2
O emissions were 37.47 and 63.22 % higher in 2013 than in 2012, respectively, whereas the average soil temperature during the rice growth period was 2.1 °C higher in 2013 than in 2012. The highest value in
GHGI
was associated with the N + broad bean treatment (with a high C/N ratio), while the
NECB
and mass of soil total carbon change (
MSTC)
were highest in the N + alfalfa treatment (with a low C/N ratio). This result indicates that high C/N ratio green manures had high grain yields yet increased
GHGI
, while low C/N ratio green manures had even higher grains yields with increased
NECB
and
MSTC
.
According to the solution of dual-porosity model, a diffusivity filter model of carbonate reservoir was established, which can effectively illustrate the injection signal attenuation and lag ...characteristic. The interwell dynamic connectivity inversion model combines a multivariate linear regression (MLR) analysis with a correction coefficient to eliminate the effect of fluctuating bottom-hole pressure (BHP). The modified MLR model was validated by synthetic field with fluctuating BHP. The method was applied to Tahe oilfield which showed that the inversion result was reliable. The interwell dynamic connectivity coefficients could reflect the real interwell connectivity of reservoir. The method is easy to use and proved to be effective in field applications.
Acid-Aluminum (Al) is toxic to plants and greatly affects crop production worldwide. To understand the responses of plants to acid soils and Aluminum toxicity, we examined global gene expression ...using microarray data in alfalfa seedlings with the treatment of acid-Aluminum. 3,926 genes that were identified significantly up- or downregulated in response to Al3+ ions with pH 4.5 treatment, 66.33% of which were found in roots. Their functional categories were mainly involved with phytohormone regulation, reactive oxygen species, and transporters. Both gene ontology (GO) enrichment and KEGG analysis indicated that phenylpropanoid biosynthesis, phenylalanine metabolism, and flavonoid biosynthesis played a critical role on defense to Aluminum stress in alfalfa. In addition, we found that transcription factors such as the MYB and WRKY family proteins may be also involved in the regulation of reactive oxygen species reactions and flavonoid biosynthesis. Thus, the finding of global gene expression profile provided insights into the mechanisms of plant defense to acid-Al stress in alfalfa. Understanding the key regulatory genes and pathways would be advantageous for improving crop production not only in alfalfa but also in other crops under acid-Aluminum stress.
Isolated fractures usually exist in fractured media systems, where the capillary pressure in the fracture is lower than that of the matrix, causing the discrepancy in oil recoveries between fractured ...and non-fractured porous media. Experiments, analytical solutions and conventional simulation methods based on the continuum model approach are incompetent or insufficient in describing media containing isolated fractures. In this paper, the simulation of the counter-current imbibition in fractured media is based on the discrete-fracture model (DFM). The interlocking or arrangement of matrix and fracture system within the model resembles the traditional discrete fracture network model and the hybrid-mixed-finite-element method is employed to solve the associated equations. The Behbahani experimental data validates our simulation solution for consistency. The simulation results of the fractured media show that the isolated-fractures affect the imbibition in the matrix block. Moreover, the isolated fracture parameters such as fracture length and fracture location influence the trend of the recovery curves. Thus, the counter-current imbibition behavior of media with isolated fractures can be predicted using this method based on the discrete-fracture model.
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