| Ginkgo biloba is one of the most important economic trees in China.It has been planted in the Ginkgo ecological garden in Cewu Town,Changting County,Longyan City,Fujian Province for 20 years,the surface soil is porous and loose,the erosion resistance is poor,the soil erosion is serious.Rhodomyrtus tomentosa is a pioneer species for afforestation and water and soil conservation in barren hills.In order to improve the status of water and soil erosion,it has been interplanted under the Ginkgo forest and has achieved better soil and water loss control effect.However,weather the relationship between Ginkgo and Rhodomyrtus interspecific coordination,has no relevant research been conducted.In this research,the experiments of potted plants were used to test the growth of Rhodomyrtus,chlorophyll fluorescence,soil enzyme activity and the effects of soil microbial communities and soil metagenomics after irrigating Rhodomyrtus for 3 months with fresh Gingko leaves and fresh root water extracts,ferulic acid solution and distilled water(CK)at different concentrations.The results of the study evaluated the biochemical relationship between Ginkgo and Rhodomyrtus from chemical ecology perspective and provided theoretical reference for construction of the soil erosion area between biochemical coordination in multi storied Ginkgo forest,improving soil and water conservation effect of Ginkgo forest.The main results of the study are as follows:(1)Identification of phenolic acids in Ginkgo leaves and rootsA liquid chromatography-mass spectrometer was used to analyze the phenolic acids in fresh leaves,fallen leaves and fresh roots of Ginkgo.In the positive ion mode,there were 8 phenolic acids detected in fresh leaves,8 in fallen leaves and 11 in fresh roots has been found.In the negative ion mode,there were 9 phenolic acids detected in fresh leaves,8 in fallen leaves and 9 in fresh roots has been found;there are 9 kinds of phenolic acids detected in Ginkgo leaves and roots,there are syringic acid,(C17:2),(C15:1),(C13:0),(C17:1),(C15:0),catechin,ferulic acid,quinic acid.The differences in the types and contents of phenolic acids in the fresh leaves and fallen leaves of Ginkgo were smaller,the roots of Ginkgo were significantly different from the leaves.(2)Effects of water extract of Ginkgo on chlorophyll fluorescence parameters of Rhodomyrtus leavesWith the increase of the concentration of water extracts of fresh leaves and fresh roots of Ginkgo,the three indicators of the minimum fluorescence variable Fo,the maximum fluorescence variable Fm and the variable fluorescence Fv of Rhodomyrtus leaves showed a phenomenon of"low promotion and high suppression".The leaves of Rhodomyrtus about Fo,the maximum light energy conversion efficiency Fv/Fm,the potential activity of PSII Fv/Fo were significantly different in the treatments.(3)Effects of water extract of Ginkgo on soil enzyme activity in the rhizosphere soil of RhodomyrtusWith the increase of the concentration of water extracts of fresh leaves and fresh roots of Ginkgo,the activities of cellulase and invertase in the rhizosphere soil of Rhodomyrtus increased.The activities of protease and urease decreased first and then increased.The activity of phenol oxidase and peroxidase gradually decreased,the activity of acid phosphatase showed a "W" curve.Compared with the treatment of fresh leaves of Ginkgo,the extract of Ginkgo root has a great influence on the activity of the enzymes.(4)Effects of water extract of Ginkgo on bacterial community structure in Rhodomyrtus rhizosphere soilThe Hi Seq2500 high-throughput sequencing platform was used to sequence the fresh leaves and fresh roots of Ginkgo with the 0.10 g·ML-1 concentration and distilled water-treated soil samples.The amplicon 341F-806R was sequenced.The bacterial sequences identified by different treatments belong to 10 gates,46 classes,73 orders,104 families,98 genera and 27 species.They are mainly distributed in Proteobacteria and there are 6 dominant bacteria,namely Burkholderia,Planctomyces,Bradyrhizobium,Acidibacter,Streptomyces,Pseudomonas.(5)Effects of water extract of Ginkgo on fungal community structure in Rhodomyrtus rhizosphere soilThe HiSeq2500 high-throughput sequencing platform was used to sequence the ITS2 region of the amplicons.The fungal sequences identified by different treatments belonged to 4 gates,17 classes,39 orders,65 families,86 genera and 49 species.They were mainly distributed in Ascomycota and Basidiomycota.There were 10 dominant fungi,they are Dipodascus,Geotrichum candidum,Saitozyma,Coprinus,Cladosporium,Serendipita,Fusarium,Pestalotiopsis,Lophodermium.(6)Effects of ferulic acid solution on soil microbial community structureA total of 3 boundaries were detected in the soil of ferulic acid solution and distilled water,which were bacteria(more than 90%of the test results),fungi and archaea.At the time of ferulic acid treatment,46 gates,87 classes and 209 orders were identified.46 gates,85 classes and 206 orders were identified in the treatment of distilled water.The sequencing results of the bacterial phylum showed that the dominant phylums were Proteobacteria,Actinomyces and Cyanobacteria.The sequencing results of genus bacteria showed that the dominant genus were Bradyrhizobium,Arthrobacter,Pseudomonas,Streptomyces,Burkholderia.(7)Effects of ferulic acid solution on functional annotation of eggNOGThe eggNOG functional annotation results showed that the number of defense mechanisms,replication-recombination-repair,energy conversion and transport metabolism genes in soil treated with ferulic acid solution increased,indicating that the soil cells were disturbed by the external environment and the cell's own defense and repair mechanisms were more active.The number of genes annotated with chromatin structure and kinetics,signal transduction mechanisms,cell motility,and cytoskeletal function was reduced,indicated that under ferulic acid treatment,soil cells were destroyed to a certain extent,cell movement was slowed,cellular activity was reduced.(8)Effects of ferulic acid solution on KEGG annotated differential genesThe results of the KEGG annotation differential genes showed that the number of genes was mainly enriched in metabolism,genetic information processing and environmental information processing.In the six major categories of bio-metabolism pathways in the A-class classification,the ferulic acid solution treated soils had higher numbers of genes than the distilled water group.That is,the ferulic acid solution increased the soil biogenic data and the life activity process changed;at the B level Twenty-five kinds of 43 seed functions were detected,of which 23 seed function in soil the number of genes of ferulic acid solution is higher than that of the distilled water group.(9)Effects of ferulic acid solution on CAZy carbohydrate enzymeThe results of CAZy carbohydrate enzyme database showed that glucoside hydrolase,glycosyltransferase,polysaccharide lyase and auxiliary oxidoreductase in ferulic acid-treated soil increased by 4.83%,3.05%,3.51%,7.57%,respectively.The carbohydrate esterase and carbohydrate binding modules of the soil treated by distilled water were increased by 1.22%and 20.18%,respectively.In the small family classification,the glycoside hydrolase family(14 species),the glycosyltransferase family(6 species),the carbohydrate esterase family(5 species)and the carbohydrate binding moiety(10 species)were predicted to be present in the 2 groups of trials.Polysaccharide lyase and auxiliary oxidoreductase families weren't detected. |
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