Physiological and quantitative proteomic analysis of NtPRX63-overexpressing tobacco plants revealed that NtPRX63 functions in plant salt resistance.

High salinity is harmful to crop yield and productivity. Peroxidases (PRXs) play crucial roles in H2O2 scavenging. In our previous study, PRX63 significantly upregulated in tobacco plants under salt stress. Thus, in order to understand the function of PRX63 in tobacco salt response, we overexpressed this gene in tobacco (Nicotiana tabacum L.), investigated the morphological, physiological and proteomic profiles of NtPRX63-overexpressing tobacco transgenic lines and wild type. The results showed that, compared with the wild type, the transgenic tobacco plants presented enhanced salt tolerance and displayed lower ROS (reactive oxygen species), malondialdehyde (MDA) and Na+ contents; higher biomass, potassium content, soluble sugar content, and peroxidase activity; and higher expression levels of NtSOD, NtPOD and NtCAT. Protein abundance analysis revealed 123 differentially expressed proteins between the transgenic and wild-type plants. These proteins were functionally classified into 18 categories and are involved in 41 metabolic pathways. Furthermore, among the 123 proteins, eight proteins involved in the ROS-scavenging system, 12 involved in photosynthesis and energy metabolism processes, two stress response proteins, one signal transduction protein and one disulfide isomerase were significantly upregulated. Furthermore, three novel proteins that may be involved in the plant salt response were also identified. The results of our study indicate that an enhanced ROS-scavenging ability, together with the expression of proteins related to energy mobilization and the stress response, functions in the confirmed salt resistance of transgenic tobacco plants. Our data provide valuable information for research on the function of NtPRX63 in tobacco in response to abiotic stress.

[Comparison of drought risk between transplanting and direct-sowing rice in the Sichuan Basin, China]. / å››å·ç›†åŒºç›´æ’­ä¸Žç§»æ ½æ°´ç¨»æ—±ç¾é£Žé™©æ¯”è¾ƒ.

The quantitative evaluation and comparison of drought risks at each development stage and the whole growth period between transplanting rice and direct-sowing rice in Sichuan Basin can provide a scientific basis for the transformation and promotion of rice production technology in various regions. Based on the theory of natural disaster risk and the formation mechanism of rice drought risk, we evaluated and compared the drought risk in the whole growth period and the four development stages (sowing-jointing, jointing-booting, booting-full heading, full heading-maturity) between transplanting rice and direct-sowing rice, analyzed the vulnerability of disaster bodies, the sensitivity of disaster environment and the capacity of drought disaster prevention and reduction of rice drought in Sichuan Basin, using meteorological data in Sichuan Basin from 1961 to 2017, the observation data of rise production, agricultural statistics and the basic geographical information. The drought risk assessment model for Sichuan Basin was established, which was used to classify the results of evaluation. The results indicated that the drought risk of rice in Sichuan Basin was higher. The medium-risk areas in terms of the two planting methods were both the most widely distributed areas. The spatial-distribution characteristics of drought risk for the two kinds of rice were generally the same which was high in the middle and east of the basin, low in the southwest of the basin, and decreased from east to west and from the center to the surroundings. For the two planting methods, the greatest difference of rice drought risk appeared at the sowing-jointing stage. The drought risk of the direct-sowing rice at the sowing-jointing stage was significantly lower, and the distribution range was smaller than that of the transplanting rice. The distribution of the slight-low drought risk area of the direct-sowing rice was wider, but the high-risk area was slightly smaller.

Physiological Analysis and Proteome Quantification of Alligator Weed Stems in Response to Potassium Deficiency Stress.

The macronutrient potassium is essential to plant growth, development and stress response. Alligator weed (Alternanthera philoxeroides) has a high tolerance to potassium deficiency (LK) stress. The stem is the primary organ responsible for transporting molecules from the underground root system to the aboveground parts of the plant. However, proteomic changes in response to LK stress are largely unknown in alligator weed stems. In this study, we investigated the physiological and proteomic changes in alligator weed stems under LK stress. First, the chlorophyll and soluble protein content and SOD and POD activity were significantly altered after 15 days of LK treatment. The quantitative proteomic analysis suggested that a total of 296 proteins were differentially abundant proteins (DAPs). The functional annotation analysis revealed that LK stress elicited complex proteomic alterations that were involved in oxidative phosphorylation, plant-pathogen interactions, glycolysis/gluconeogenesis, sugar metabolism, and transport in stems. The subcellular locations analysis suggested 104 proteins showed chloroplastic localization, 81 proteins showed cytoplasmic localization and 40 showed nuclear localization. The protein⁻protein interaction analysis revealed that 56 proteins were involved in the interaction network, including 9 proteins involved in the ribosome network and 9 in the oxidative phosphorylation network. Additionally, the expressed changes of 5 DAPs were similar between the proteomic quantification analysis and the PRM-MS analysis, and the expression levels of eight genes that encode DAPs were further verified using an RT-qPCR analysis. These results provide valuable information on the adaptive mechanisms in alligator weed stems under LK stress and facilitate the development of efficient strategies for genetically engineering potassium-tolerant crops.

[Screening and Research Cyathula officinalis in Cold Hardy Physiological Characteristics].

Objective: To explore the mechanism in cold-resistant of Cyathula officinalis seedlings,in order to provide a theoretical basis for variety breeding and resistance cultivation of Cyathula officinalis. Methods: Collected the materials in main producing areas of Cyathula officinalis,and the Cyathula officinalis growing into seedling with five pairs of leaves were used to research. The seeds were deal with low temperature stress,and the seedlings of morphological and physiological indicators of Cyathula officinalis were measured,membership function method and low temperature variation index were used to screen and evaluate the cold-tolerance of the Cyathula officinalis. Results: Soluble sugar,proline,soluble protein,fresh weight,plant height can be used as the evaluation indexes of cold-resistant Cyathula officinalis. The red and white Cyathula officinalis from Baoxing county in Chongxing village and the white Cyathula officinalis from Hanyuan county all had a good cold-resistance. Conclusion: The cold-resistant in Cyathula officinalis are different in different areas, and cold tolerance is positively correlated with the content of osmotic adjustment substance of Cyathula officinalis seedlings.

Optimisation of high-pressure ultrasonic-assisted extraction and antioxidant capacity of polysaccharides from the rhizome of Ligusticum chuanxiong.

High-pressure ultrasound-assisted extraction was used to extract polysaccharides from the Ligusticum chuanxiong rhizomes. Three independent variables, namely, extraction temperature (X1), ultrasonic power (X2) and extraction time (X3) were investigated. Response surface methodology was performed based on the results of single-factor tests. Experimental data were fitted to a second-order polynomial equation using multiple regression analysis, and results were examined using appropriate statistical methods. The optimal conditions were as follows: extraction temperature of 85°C, ultrasonic power of 187 W and extraction time of 29 min. Under these conditions, the experimental yield of polysaccharides was 5.33%, which is close to the predicted yield of 5.41%. The extracted and purified polysaccharides showed excellent antioxidative effects on 2,2-diphenyl-1-picryl-hydrazy, hydroxyl and superoxide radicals in vitro.

[Quantitative determination of 5 active ingredients in different harvest periods of Ligusticum chuanxiong by HPLC].

A simple and quick method is described for the determination of ferulic acid, senkyunolide I, senkyunolide H, senkyunolide A and ligustilide in rhizomes of Ligusticum chuanxiong. The 5 active ingredients in the sample was extracted using 40% ethanol and analyzed by reversed-phase high performance liquid chromatography (HPLC). Chromatography separation was performed using Agilent 1100 series HPLC system with a Symmetry C18 column and gradient elution with a mixture of three solvents : solvent A, acetonitrile, solvent B, methanol and solvent C, 1% aqueous acetic acid, 0 min to 5 min A: B: C 20: 40: 40, 5 min to 30 min A: B: C 60 to 100 : 0 : 40 to 0. The effluent was monitored using a VWD detector set at 321 nm (0-4.3 min) and 275 nm (4.31-30 min). The flow rate was set at 1 mL x min(-1) and the injection volume was 10 microL. The column temperature was maintained at 35 degrees C. The calibration curve was linear (r > or = 0.99) over the tested ranges. The average recovery was 94.44%-103.1% (n = 6). The method has been successfully applied to the analysis in different harvest periods of L. chuanxiong samples. In this paper, single-factor randomized block design to study the 5 components content of L. chuanxiong on ten collecting stages. For the L. chuanxiong collected from April 15th to May 30rd, the content of 5 ingredients increased primarily, and then decreased. Determine the appropriate harvest time has important significance to the promotion of the quality of L. chuanxiong.

Optimization of high-pressure ultrasonic-assisted simultaneous extraction of six major constituents from Ligusticum chuanxiong rhizome using response surface methodology.

High-pressure ultrasound-assisted extraction technology was applied to extract ferulic acid, senkyunolide I, senkyunolide H, senkyunolide A, ligustilide and levistolide A from Ligusticum chuanxiong rhizomes. Seven independent variables, including solvent type, pressure, particle size, liquid-to-solid ratio, extraction temperature, ultrasound power, and extraction time were examined. Response Surface Methodology (RSM) using a Central Composite Design (CCD) was employed to optimize the experimental conditions (extraction temperature, ultrasonic power, and extraction time) on the basis of the results of single factor tests for the extraction of these six major components in L. chuanxiong rhizomes. The experimental data were fitted to a second-order polynomial equation using multiple regression analysis and were also examined using appropriate statistical methods. The best extraction conditions were as follows: extraction solvent: 40% ethanol; pressure: 10 MPa; particle size: 80 mesh; liquid-to-solid ratio: 100:1; extraction temperature: 70 °C; ultrasonic power, 180 W; and extraction time, 74 min.

[Photosynthetic characteristics and dry matter accumulation of hybrid rice varieties under different light conditions].

The study on the photosynthetic characteristics and dry matter accumulation of twelve hybrid rice varieties in the eco-environments with low- and high light intensity showed that the adaptation abiility of the varieties to eco-environment was mainly (depended on the varieties themselves, and there existed greater (differenees among them. The differences in net photosynthetic rate (Pn) and chlorophyll content (Chl) were more significant among the varieties than between the eco-environments. The grain yield had significant positive correlations with Pn and total dry matter mass (TDM), the determination coefficient R2 being 0.584 and 0.590, respectively, but no significant correlations with the export percentage of the matter in stem-sheath (EPMSS) and the transformation percentage of the matter in stem-sheath (TPMSS). In the eco-environment with high light intensity, the leaf thickness and dry matter accumulation increased, while the EPMSS and TPMSS decreased. Under enough sunlight condition, the high proportion of matter in grain yield was mainly come from the photosynthesis at late growth stages; while under insufficient sunlight condition, it was mainly originated from the early growth stages photosynthesis.