Multi-Omics Analysis of the Effects of Soil Amendment on Rapeseed (Brassica napus L.) Photosynthesis under Drip Irrigation with Brackish Water.

Drip irrigation with brackish water increases the risk of soil salinization while alleviating water shortage in arid areas. In order to alleviate soil salinity stress on crops, polymer soil amendments are increasingly used. But the regulation mechanism of a polymer soil amendment composed of polyacrylamide polyvinyl alcohol, and manganese sulfate (PPM) on rapeseed photosynthesis under drip irrigation with different types of brackish water is still unclear. In this field study, PPM was applied to study the responses of the rapeseed (Brassica napus L.) phenotype, photosynthetic physiology, transcriptomics, and metabolomics at the peak flowering stage under drip irrigation with water containing 6 g·L-1 NaCl (S) and Na2CO3 (A). The results showed that the inhibitory effect of the A treatment on rapeseed photosynthesis was greater than that of the S treatment, which was reflected in the higher Na+ content (73.30%) and lower photosynthetic-fluorescence parameters (6.30-61.54%) and antioxidant enzyme activity (53.13-77.10%) of the A-treated plants. The application of PPM increased the biomass (63.03-75.91%), photosynthetic parameters (10.55-34.06%), chlorophyll fluorescence parameters (33.83-62.52%), leaf pigment content (10.30-187.73%), and antioxidant enzyme activity (28.37-198.57%) under S and A treatments. However, the difference is that under the S treatment, PPM regulated the sulfur metabolism, carbon fixation and carbon metabolism pathways in rapeseed leaves. And it also regulated the photosynthesis-, oxidative phosphorylation-, and TCA cycle-related metabolic pathways in rapeseed leaves under A treatment. This study will provide new insights for the application of polymer materials to tackle the salinity stress on crops caused by drip irrigation with brackish water, and solve the difficulty in brackish water utilization.

Integrated Transcriptomic and Metabolomic Analysis of the Mechanism of Foliar Application of Hormone-Type Growth Regulator in the Improvement of Grape (Vitis vinifera L.) Coloration in Saline-Alkaline Soil.

(1) Background: To solve the problems of incomplete coloration and quality decline caused by unreasonable use of regulators in grapes, this study clarified the differences in the effects of a hormone-type growth regulator (AUT) and two commercial regulators on grape coloration and quality through field experiments. (2) Methods: The color indexes (brightness (L*), red/green color difference (a*), yellow/blue color difference (b*), and color index for red grapes (CIRG)) of grape fruit were measured using a CR-400 handheld color difference meter. The titratable acid content, total phenol content, and total sugar content were measured using anthrone colorimetry, folinol colorimetry, and NaOH titration, respectively, and the chalcone isomerase activity, phenylalanine ammoniase activity, dihydroflavol reductase activity, and anthocyanin content were measured using a UV spectrophotometer. (3) Results: The a*, total sugar and total phenol contents, and chalcone isomerase (CHI) and phenylalanine ammoniase (PAL) activities of grape fruit in the AUT treatment significantly increased, while the titratable acid content significantly decreased, compared to those in the CK treatment. The expressions of the differentially expressed genes (DEGs) trpB and argJ in AUT treatment were significantly up-regulated. The expressions of the differentially expressed metabolites (DEMs) phenylalanine and 4-oxoproline were significantly up-regulated, while those of 3,4-dihydroxybenzaldehyde and N-acetyl glutamate were significantly down-regulated. The CIRG significantly increased by 36.4% compared to that in the CK, indicating improved fruit coloration. (4) Conclusion: The AUT could shorten the color conversion period of grape fruit and improve the coloration, taste, and tolerance to saline and alkaline stresses.

Transcriptomic and Metabolomic Analyses Reveal the Differential Regulatory Mechanisms of Compound Material on the Responses of Brassica campestris to Saline and Alkaline Stresses.

Oilseed rape not only has the function of improve saline and alkaline soils, but also alleviate the local feed shortage. However, medium- and high-degree soil salinization and alkalinization always inhibit the growth of oilseed rape. Studies have shown that compound material can improve the tolerance to saline and alkaline stress of crops, but the difference in the regulation mechanism of compound material on oilseed rape in saline and alkaline soils is not clear. This study explored the difference through determining the leaf ion contents, physiological indexes, transcriptomics, and metabolomics of oilseed rape in salinized soil (NaCl 8 g kg-1) and alkalinized soil (Na2CO3 8 g kg-1) at full flowering stage, respectively after the application of compound material. The results showed that in salinized and alkalinized soil, the compound material upregulated the genes related to the regulation of potassium ion transport, and changed the amino acid metabolic pathway, which reduced the contents of Na+, malondialdehyde (MDA), and relative conductivity (REC) in leaves, and increased the contents of K+ and Mg2+ and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). However, there were differences in the regulation mechanism of compound material in salinized and alkalinized soil. In salinized soil, the compound material improved the tolerance of oilseed rape to saline stress by upregulating transcription factors mannose-1-phosphate guanylyltransferase (GPMM) and Glutamine--fructose-6-phosphate transaminase (GFPT) and downregulating phosphomannomutase (PMM) to change nucleotide metabolism pathway and lipid metabolism pathway. In alkalized soil, the compound material improved the tolerance of oilseed rape to alkaline stress by upregulating transcription factors Phenylalanine ammonia lyase (PAL) to change the biosynthesis pathway of other secondary metabolites. Therefore, the compound material can improve the tolerance of oilseed rape to saline and alkaline stress by regulating the genetic adaptability and apparent plasticity, but the mechanisms were different. This study provides a practical method for the ecological environment restoration and the development of animal husbandry.

Polymer amendment regulates cadmium migration in cadmium contaminated cotton field: Insights from genetic adaptation and phenotypic plasticity.

Polymer materials have been widely used in the remediation of soil heavy metal contamination for their good performance in the absorption of metal ions. To reveal the effect of polymer amendment (PA) on the remediation of cadmium-contaminated cotton fields, the cadmium (Cd) fractions in soil, Cd concentration in cotton organs, bioconcentration factor (BCF) of Cd, translocation factor (TF) of Cd, and the antioxidant capacity and photosynthesis of functional leaves were evaluated combining with the transcriptomic and metabolomic analyses, in barrel experiments in the field at the flowering and boll-forming stage of cotton. The results showed that, cotton improved the tolerance to Cd through self-regulation in Cd-contaminated soil. The expression of oxoglutaric acid and jasmonic acid were down-regulated by the application of PA to improve the photosynthetic rate (7.71%-46.20%), chlorophyll content (17.59%-63.18%), chlorophyll fluorescence (7.66%-32.25%), and antioxidant enzyme activity (15.49%-45.50%) of functional leaves, and the down-regulation of the expression of jasmonic acid and up-regulation of the expression of stearic acid reduced the exchangeable Cd concentration in the soil, which reduced the transport of Cd from the root to the bolls (54.39%). Thereby, the balance of the genetic adaptation and phenotypic plasticity of cotton was achieved, and the cell structure of leaves was restored. This study deepens our understanding of the molecular mechanism of PA in the remediation of Cd contamination in cotton fields, and provides guidance for the remediation of heavy metal contamination in farmland soil and agricultural safety under drip irrigation.

Metabolic regulation in soil microbial succession and niche differentiation by the polymer amendment under cadmium stress.

Cadmium (Cd) contamination seriously threatens the agricultural production, so exploring the response of soil microenvironment to amendments in Cd-contaminated soils is of importance. In this study, the mechanism of remediation of Cd-contaminated soil using the polymer amendment was studied in cotton flowering stage. The results showed that the concentration of Cd in cotton root and various Cd forms in Cd-contaminated soils were obviously high. High concentration of Cd, especially exchangeable Cd, could seriously affect the soil microenvironment. The root growth of cotton could be promoted, the carbon and nitrogen concentration and storage in soil were increased by 21.72-50.00%, while the exchangeable Cd concentration in soil were decreased by 41.43%, after applying the polymer amendment. In addition, the polymer amendment affected the soil microbial niche, increased the relative abundance of soil bacteria (Flaviaesturariibacter, Rubellimicrobium, and Cnuella), fungi (Verticillium and Tricharina), actinomycetes (Blastococcus and Nocardioides), and fungivores nematodes (Aphelenchus), and improved soil microbial metabolic functions (metabolism of nucleotides and carbohydrates). Therefore, this polymer amendment could be used to remediate severe Cd-contaminated soils, and the changes in the microbial and nematode communities help us understand the detoxification mechanism of the polymer amendment in Cd-contaminated soils.

Application of compound material alleviates saline and alkaline stress in cotton leaves through regulation of the transcriptome.

BACKGROUND: Soil salinization and alkalinization are the main factors that affect the agricultural productivity. Evaluating the persistence of the compound material applied in field soils is an important part of the regulation of the responses of cotton to saline and alkaline stresses. RESULT: To determine the molecular effects of compound material on the cotton's responses to saline stress and alkaline stress, cotton was planted in the salinized soil (NaCl 8 g kg- 1) and alkalized soil (Na2CO3 8 g kg- 1) after application of the compound material, and ion content, physiological characteristics, and transcription of new cotton leaves at flowering and boll-forming stage were analyzed. The results showed that compared with saline stress, alkaline stress increased the contents of Na+, K+, SOD, and MDA in leaves. The application of the compound material reduced the content of Na+ but increased the K+/Na+ ratio, the activities of SOD, POD, and CAT, and REC. Transcriptome analysis revealed that after the application of the compound material, the Na+/H+ exchanger gene in cotton leaves was down-regulated, while the K+ transporter, K+ channel, and POD genes were up-regulated. Besides, the down-regulation of genes related to lignin synthesis in phenylalanine biosynthesis pathway had a close relationship with the ion content and physiological characteristics in leaves. The quantitative analysis with PCR proved the reliability of the results of RNA sequencing. CONCLUSION: These findings suggest that the compound material alleviated saline stress and alkaline stress on cotton leaves by regulating candidate genes in key biological pathways, which improves our understanding of the molecular mechanism of the compound material regulating the responses of cotton to saline stress and alkaline stress.