Phenolic compounds are considered to be an important autotoxic substances. The interactions between them and soil microbes are increasingly becoming a focus of the allelopathic research studies. In the present study, we have evaluated the effect of 4-hydroxybenzoic acid on soil microbial community structure and functional diversity. Bulk soil without grapevine cuttings (Group 1) and rhizosphere soil with Beta (Vitis riparia × Vitis labrusca) grapevine cuttings (Group 2) were used as research subjects. The bacterial (16s rRNA) and fungal internal transcribed spacer regions community structures were obtained using a denaturing gradient gel electrophoresis and substrate utilization patterns were determined using Biolog EcoPlates. In this research, the results showed that the 4-hydroxybenzoic acid caused a shift in the soil bacterial and fungal community structures and changed the soil microbial functional diversity. The results also showed that the diversity of the microbial community structure and function differed between the two designated groups. The application of 4-hydroxybenzoic acid (1 and 2 mg/g) to the soil resulted in a greater decrease in the average diversity of the bacterial community structure in Group 2, compared to Group 1. Moreover, the average diversity of the fungal community structure in Group 2 became higher than that in Group 1. However, the bacterial and fungal community structural diversities increased with the application of 0.5 mg/g of 4-hydroxybenzoic acid. Thus, we concluded that both soil microbes and root exudates might be the recipients of 4-hydroxybenzoic acid.

Soil mulching is a useful agronomic practice that promotes early fruit maturation and affects fruit quality. However, the regulatory mechanism of fruit metabolites under soil-mulching treatments remains unknown. In this study, variations in the gene sets and metabolites of grape berries after mulching (rice straw + felt + plastic film) using transcriptome and metagenomic sequencing were investigated. The results of the cluster analysis and orthogonal projection to latent structures discriminant analysis of the metabolites showed a difference between the mulching and control groups, as did the principal component analysis results for the transcriptome. In total, 36 differentially expressed metabolites were identified, of which 10 (resveratrol, ampelopsin F, piceid, 3,4′-dihydroxy-5-methoxystilbene, ε-viniferin, trans resveratrol, epsilon-viniferin, 3′-hydroxypterostilbene, 1-methyl-resveratrol, and pterostil-bene) were stilbenes. Their content increased after mulching, indicating that stilbene synthase activity increased after mulching. The weighted gene co-expression network analysis revealed that the turquoise and blue modules were positively and negatively related to stilbene compounds. The network analysis identified two seed genes (VIT_09s0054g00610, VIT_13s0156g00260) and two transcription factors (VIT_13s0156g00260, VIT_02s0025g04590). Overall, soil mulching promoted the accumulation of stilbene compounds in grapes, and the results provided key genetic information for further studies.

Although mulching is a widely used agronomic practice, its effects on the rhizosphere remain poorly understood. Here, we employed amplicon and transcriptomic sequencing to investigate variations in a grapevine rhizosphere system under mulch treatment (rice straw + felt + plastic film). Analyzing 16S and intergenic spacer (ITS) rRNA sequences indicated that the Shannon and Simpson indices of the bacterial and fungal communities increased markedly under mulch treatment. The bacterial and fungal compositions varied significantly between the control and mulch treatments. Mulching enriched for potentially beneficial microbes that confer disease resistance to plants or participate in nitrogen metabolism (Kaistobacter, Ammoniphilus, Lysobacter, Ammoniphilus, Alicyclobacillus, Aquicella, Nitrospira, Chaetomium, and Microascus), whereas more potentially pathogenic microbes (Fusarium and Gibberella) were detected in the control. Moreover, certain bacteria and fungi exhibited different correlations with the root transcriptome functions of the MEBlue module. The complexity of the bacterial and fungal co-occurrence networks increased with higher node numbers, positive and negative links after mulching. Following mulching, the rhizosphere showed elevated pH, organic matter, and catalase activities, and decreased sucrase and cellulase and β-glucosidase activities. Our results provide comprehensive data showing how a grapevine rhizosphere system responded to mulching treatment and shed important insight into mulching practices for fruit trees.

Aluminum (Al) toxicity is a major limitation to crop production in countries where acidic soil is abundant. In China, soybean production is constrained by Al stress-induced toxicity. As such, there is growing interest to develop Al-resistant varieties. In the present study, we sought to determine potential genes, functions and pathways for screening and breeding of Al-resistant varieties of soybean. First, we mined the E-GEOD-18517 dataset and identified 729 differentially expressed genes (DEGs) between untreated and Al-treated groups. Next, we performed Gene Ontology and Kyoto Encyclopedia of Genes and Genome pathways enrichment analysis and observed that most of the screened genes were mainly enriched in defense response, plasma membrane and molecular transducer activity. They were also enriched in three important pathways, the phenylpropanoid biosynthesis, plant-pathogen interaction, and cutin, suberine and wax biosynthesis. Utilizing weighted gene co-expression network analysis of 815 DEGs screened by Venn diagram, we identified DEGs that were the most disparate between treated and untreated groups. LOC100793667 (probable protein phosphatase 2C 60, GLYMA_17G223800), LOC100780576 (ethylene-responsive transcription factor 1B, GLYMA_02G006200), and LOC100785578 (protein ESKIMO 1, GLYMA_02G258000) were the most differentially expressed, which were consistent with the qRT-PCR results. As these genes are known to participate in essential functions, such as cell junction and phenylpropanoid biosynthesis, these genes may be important for breeding Al-resistant varieties.

Identification and Analysis of PGM and SUS Gene Families in Leymus Chinensis Seed Transcriptome