Soybean (Glycine max) is susceptible to root rot when subjected to continuous cropping, and this disease can seriously diminish the crop yield. Proteomics analyses can show the difference of protein expression in different treatment samples. Herein, isobaric tag for relative and absolute quantitation (iTRAQ) labeling and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were employed for proteomic analysis of continuously cropped soybean inoculated with the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae. The AMF can reduce the incidence of root rot and increase plant height, biomass index in 1, 2 and 4 year of continuous cropping. Differential expression of proteins in soybean roots was determined following 1 year of continuous cropping. A total of 131 differentially expressed proteins (DEPs) were identified in F. mosseae-treated samples, of which 49 and 82 were up- and down-regulated, respectively. The DEPs were annotated with 117 Gene Ontology (GO) terms, with 48 involved in biological processes, 31 linked to molecular functions, and 39 associated with cell components. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis mapped the DEPs to 113 mainly metabolic pathways including oxidative phosphorylation, glycolysis and amino acid metabolism. Expression of glucan 1,3-beta-glucosidase, chalcone isomerase, calcium-dependent phospholipid binding and other defense-related proteins was up-regulated by F. mosseae, suggesting inoculation promotes the growth and development of soybean and increases disease resistance. The findings provide an experimental basis for further research on the molecular mechanisms of AMF in resolving problems associated with continuous soybean cropping.
Glycine max is easily infected with root rot in continuous cropping systems, which can severely affect crop yield. Arbuscular mycorrhizal fungi (AMF) can reduce the incidence of root rot and increase plant height and biomass indices. However, the molecular changes that occur during soybean symbiosis with AMF remain largely unknown. To better understand the molecular mechanism underlying soybean symbiosis with AMF, we performed transcriptomic and proteomic analyses to explore the changes in protein expression during a high-incidence period (79 days) in asymbiotic and symbiotic plants and to identify the key proteins that regulate the mechanism of soybean symbiosis with AMF. A total of 10 104 genes were identified in the CK-vs-F comparison, and 11 562 genes were significantly differentially expressed in the AF group compared with the F group. A total of 9488 proteins were identified, with 256 differentially expressed proteins (DEPs) in the CK-vs-F comparison and 651 DEPs in the F-vs-AF comparison. Key pathways and DEPs were found to be involved in processes associated with "phenylalanine metabolism", "plant hormone signal transduction", "plant-pathogen interaction", and "metabolic pathways". The expression of phenylalanine ammonia-lyase (PAL), calcium-dependent protein kinase (CPK), and other defense-related proteins was upregulated by Funneliformis mosseae, indicating that inoculation promotes the development of soybean and increases disease resistance. Our results suggest that symbiosis promotes the growth and development of soybean and increases disease resistance. This study provides new insight into the molecular basis of the mechanism by which AMF affect plant disease resistance.
Continuous cropping in soybean is increasingly practiced in Heilongjiang Province, leading to substantial yield reductions and quality degradation. Arbuscular mycorrhizal fungi (AMF) are soil microorganisms that form mutualistic interactions with plant roots and can restore the plant rhizosphere microenvironment. In this study, two soybean lines (HN48 and HN66) were chosen as experimental materials, which were planted in different years of continuous cropping soybean soils and were inoculated or not with Funneliformis mosseae in potted-experiments. Ultimately, analysis of root tissue metabolome and root exudates, soil physicochemical properties, plant biomass, as well as rhizosphere soil properties in different experimental treatments, inoculated or not with F. mosseae, was performed. Experimental results showed that: (a) The disease index of soybean root rot was significantly lower in the treatment group than in the control group, and there were differences in disease index and the resistance effect of F. mosseae between the two cultivars; (b) compared with the control, the root tissue metabolome and root exudates remained unchanged, but there were changes in the relative amounts in the treatment group, and the abundant metabolites differed by soybean cultivar; (c) soybean biomass was significantly higher in the treatment group than in the control group, and the effect of F. mosseae on biomass differed with respect to the soybean cultivar; and (d) there were differences in the physiochemical indexes of soybean rhizosphere soil between the treatment and control groups, and the repairing effect of F. mosseae differed between the two cultivars. Therefore, F. mosseae can increase the biomass of continuously cropped soybean, improve the physicochemical properties of the rhizosphere soil, regulate the root metabolite profiles, and alleviate barriers to continuous cropping in potted-experiments of soybean.
ABSTRACT Soybean is a sulfur-loving oilseed crop, and continuous cropping can lead to soil sulfur deficiency, which can inhibit the growth and quality of soybean. This experiment used transcriptomic and proteomic sequencing techniques to analyse the changes in the expression of functional genes and related proteins in the root system of continuously cropped soybean and to reveal the molecular mechanism of F. mosseae inoculation on the soybean root system in response to sulfur nutrient supply at the molecular level. It was thus demonstrated that F. mosseae could enhance the uptake and transport of soil sulfur in continuously cropped soybean. This study, therefore, provides a theoretical basis for the application of F. mosseae as a biofertilizer in soybean production on sulfur-deficient soils. One-sentence summary F. mosseae affects soybean genes and proteins at the transcriptome and proteome levels.
Soybean root rot is a major disease of soybean (Glycine max [L.] Merr.) under continuous cropping, which leads to dramatic variations in the rhizosphere microflora. Soybean was sown in a different field after year zero, and continuous cropping was applied for 1 or 2 yr. The objectives were to investigate the variation in fungal populations present or inhabiting soybean roots during 3 yr of monocropping using next-generation sequencing to compare the three sets of root samples and provide a theoretical basis for the following inoculation study of the different pathogens involved in root rot disease in soybean, variation in fungal populations, and incidence of root rot. Results showed that operational taxonomic units (OTUs) of the three samples were divided into 19 phyla, 169 families, and 235 genera. Ascomycota and Basidiomycota were the dominant phyla in the continuous cropping root samples. Continuous cropping could increase the relative abundance of some fungi, namely Fusarium, Rhizoctonia, and Thelebolus, which are associated with soybean root rot for 2 and 3 yr of cropping. Continuous cropping could also increase the abundance of Gymnoascus, Chrysosporium, Ctenomyces, Aphanoascus, and Aspergillus, which are soil pathogenic fungi that can cause other plant diseases
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