Résumé
As a non-essential metal, cadmium (Cd) pollution poses severe threats to plant growth, environment, and human health. Phytoextraction using nursery stocks prior to their transplantation is a potential useful approach for bioremediation of Cd contaminated soil. A greenhouse pot experiment was performed to investigate the growth, Cd accumulation, profiles of transcriptome as well as root-associated microbiomes of Photinia frase in Cd-added soil, upon inoculation of two types of arbuscular mycorrhizal fungi (AMF) Sieverdingia tortuosa and Funneliformis mosseae. Compared with the control, inoculation of F. mosseae increased Cd concentrations in root, stem and leaf by 57.2%, 44.1% and 71.1%, respectively, contributing to a total Cd content of 182 μg/plant. KEGG pathway analysis revealed that hundreds of genes involved in 'Mitogen-activated protein kinase (MAPK) signaling pathway', 'plant hormone signal transduction', 'biosynthesis of secondary metabolites' and 'glycolysis/gluconeogenesis' were enriched upon inoculation of F. mosseae. The relative abundance of Acidobacteria was increased upon inoculation of S. tortuosa, while Chloroflexi and Patescibacteria were increased upon inoculation of F. mosseae, and the abundance of Glomerales increased from 23.0% to above 70%. Correlation analysis indicated that ethylene-responsive transcription factor, alpha-aminoadipic semialdehyde synthase, isoamylase and agmatine deiminase related genes were negatively associated with the relative abundance of Glomerales operational taxonomic units (OTUs) upon inoculation of F. mosseae. In addition, plant cysteine oxidase, heat shock protein, cinnamoyl-CoA reductase and abscisic acid receptor related genes were positively associated with the relative abundance of Patescibacteria OTUs upon inoculation of F. mosseae. These finding suggested that AMF can enhance P. frase Cd uptake by modulating plant gene expression and altering the structure of the soil microbial community. This study provides a theoretical basis for better understanding the relationship between root-associated microbiomes and root transcriptomes of P. frase, from which a cost-effective and environment-friendly strategy for phytoextraction of Cd in Cd-polluted soil might be developed.
Sujets)
Humains , Cadmium , Microbiote , Mycorhizes , Photinia , Polluants du sol , TranscriptomeRésumé
Objective:To clarify the effect of the arbuscular mycorrhizal （AM） fungi on the rhizosphere soil nutrient content，AM fungi infection rate and total rhizome saponins content of Paris polyphylla var. yunnanensis under symbiosis culture. Method:The changes in the root AM fungi infection rate，rhizosphere soil nutrient content，total rhizome saponins content of P. polyphylla var. yunnanensis and the relationship of the rhizosphere soil factors，the infection rate and the total rhizome saponins content after AM fungi inoculation were analyzed by the method of combining room temperature pot inoculation and data analysis. Result:As compared with the CK group，the root AM fungi infection rate of the AM inoculation group was significantly enhanced （P<0.05），the content of easily extractable glomalin，total glomalin，and total nitrogen increased significantly，while available potassium content and pH significantly decreased. After inoculation with AM fungi，the contents of total phosphorus，available phosphorus，available nitrogen，ammonium nitrogen，nitrate nitrogen，available potassium，and organic matter in the rhizosphere soil of P. polyphylla var. yunnanensis showed significant differences as compared with the CK group. The soil nutrient status was improved，and the total saponin content in the rhizome of P. polyphylla var. yunnanensis was increased. Conclusion:Inoculation with AM fungi can improve the rhizosphere soil nutrient status of P. polyphylla var. yunnanensis，promote the nutrient transformation in the rhizosphere soil，promote the growth of P. polyphylla var. yunnanensis，and improve the quality of medicinal herbs.
Résumé
Orchidaceae (Orchidaceae) is the second largest family of angiosperms. It’s the "flagship" group in plant protection. The existence of orchid plant is closely related to mycorrhizal fungi. The relationship between orchids and their symbiotic mycorrhizal fungi is a benefit to the protection and population restoration of orchids. Aims: The research was aimed to study molecular identification about 15 strains of mycorrhizal fungi from 6 plots by rDNA ITS technology in order to understand and utilise the mycorrhizal fungi of Liparis japonica (Miq.) Maxim. Study Design: The mycorrhizal fungi collected from different geographical locations were isolated and purified from the mycorrhizal fungi symbiotic with Liparis japonica in Northeast China, which were identified by rDNA ITS, meanwhile computed evolutionary distance and constructed the phylogenetic tree. Place and Duration of Study: In 2017, the root segments of Liparis japonica were collected separately from Qianshan, Changbaishan, Gaoguan, Guanmenshan, Dongling, Daqinggou. Methodology: Fifteen strains of mycorrhizal fungi collected from six plots were identified by rDNA ITS. Using DNAMAN software to analyse, the pairwise homology was compared by using the optimal global sequencing option. The evolutionary distances of fifteen strains were calculated by MEGA (Molecular Evolutionary Genetics Analysis) software package and their phylogenetic trees were constructed by neighbour-joining method. Results: With primers ITS1 and ITS4, the 15 mycorrhizal fungi strains of rDNA ITS got about 600 bp length. ITS length was about 582-613 bp, in which ITS1 length was about 177-190 bp, and ITS2 length was 246-273 bp. The mycorrhizal fungi strains were highly homology separated from one plot, mostly above 90%. The plots from the south to the north were as follows: Qianshan, Guanmenshan, Gaoguan, Dongling, Changbaishan, Daqinggou in China. Fifteen strains after separated and purified were identified to be the Epulorhiza of Orchid Rhizoctonia blasted with Genbank. The homology of the strains gradually decreased affected by the difference of the north and the south, namely there was an increasing trend of diversity from south to north. Conclusion: The homology of mycorrhizal fungi from one plot was higher because of the same soil environment and climate environment and so on, and strain type was single. Under the influence of microclimate in Northeast China, the homology of strains decreased gradually in the sample area, that is, the diversity gradually increased from the south to the north.
Résumé
OBJECTIVE: To screen differentially expressed genes on the roots of Dendrobium candidum induced by a symbiotic mycorrhizal fungus, the differential cDNA library was constructed. METHODS: The ds cDNAs were synthesized and enriched by SMARTer PCR cDNA synthesis kit using total RNA of D. candidum roots symbiotic with the fungus as templates. The differential cDNA library was constructed by using suppressive subtraction hybridization (SSH). RESULTS: The differential cDNA library, containing 1975 clones in the storage capacity, was constructed successfully. It was detected that above 90% clones could be amplified effective products. The lengths of the differential cDNA fragments cloned were 150 bp to 1 kb by electrophoresis detection to 20 randomly selected clones. Then, the 20 ESTs similarity analysis based on BLASTx software was carried on and most of the cloned genes were the defensive genes of plant responding to environmental stresses. CONCLUSION: Using this technology system could construct a fine differential cDNA library and be operated easily, especially suitable to the rare species.