| Casuarinas allelopathy have important effects on plant growth and forest,recent years, sources of Casuarina allelochemicals, Chemical pathway, and allelochemicals classification were researched. Study on allelochemicals sources are mostly on wood plants, soil microorganisms as an important component of Casuarina equisetifolia forest micro environment, not only has rich species, and its secondary metabolites are also abundant is an important and can not be ignored aspect. So we analyze the special bacterial and special fungal secondary metabolism product in different age of Casuarina woodland, through GC-MS to identify the substance in fermentation liquid, and analyze the species and content of these substances. Compared them with the substances identified in Casuarina equisetifolia root, litter and soil leaching extract. In order to explore the soil microbial allelopathic potential of Casuarina equisetifolia forest, We use different kinds of fermentation liquid to dispose trees native trees(Vatica mangachapoi, Calophyllum inophyllum L. and Thespesia lampas L.), to explore the seed germination rate differences and the effect of the same fermentation liquid on different native trees. Through real-time fluorescence quantitative PCR to explore main different enzymes expression in the synthetic process.In order to explore microflora community structure diversity in the Casuarina equisetifolia forest betterly, through PE250 sequencing platform to analyze Casuarina equisetifolia forest fungi community structure diversity to understand the soil micro environment, and provide more theoretical basis for Casuarina equisetifolia forest regeneration and protection.The main results of this paper are as follows:1. The GC-MS analysis results show that the secondary metabolites of the special bacteria and special fungi in different ages of Casuarina equisetifolia woodland are mainly acids, esters, alkanes, aldehydes, ketones, amide, phenols, ethers, pyran, pyridine and some other organic compounds, The secondary metabolites species and amount of the secondary metabolitesare are different between different strains. Using methanol as the extraction agent, more than 100 kinds of substances were extracted, is more abundant than using hexane as the extraction agent.The secondary metabolites of Casuarina equisetifolia forest soil special bacteria and Casuarina equisetifolia forest soil, root and litter total 5 kinds are the same, respectively 2,4-bis(1,1-dimethylethyl)-, Octadecanoic acid,methyl ester, 1,2,3,4- Butanetetrol, glycerol ether and Chromene and there are some special materials. There are also some same materials between soil special fungi and Casuarina equisetifolia forest soil, root and litter, respectively 2,4-bis(1,1-dimethylethyl)-, Octadecanoic acid,methyl ester, Methyl hexadecanoate, 2,4,7,9-Tetramethyl- 5-decyne-4,7- diol and a-Phenylacetamide, some kinds are the same with bacteria.2. Different sources of strains fermented liquid all have obvious inhibitory effect on Vatica mangachapoi, Calophyllum inophyllum L. and Thespesia lampas L., extended the germination time, and the germination rate, absolute germination rate, germination potential and response index are also inhibited.Among three native species Vatica mangachapoi seed has the strongest inhibition effect, Thespesia lampas L. is the second, and Calophyllum inophyllum L. is the weakest, it illustrate that different native tree species in the face of external environment tolerance is different, so the influence degree is different. Among bacteria fermented liquid Serratia ficaria has the strongest inhibition effect, and among fungi fermented liquid Aspergillus japonicus has the strongest inhibition effect, analysis the reason may be the two kinds of fermented liquid contained more different allelopathic potential materials so have stronger allelopathic inhibition.3. Serratia ficaria is the special bacteria of middle aged Casuarina equisetifolia woodland, and its secondary metabolite Octadecanoic acid,methyl ester contained both in fermentation liquid Casuarina equisetifolia forest soil, Therefore, it is inferred that the substance transformate into the soil from the bacteria metabolism.The key enzymes involved in the process of synthesis of octadecanoic acid,methyl ester real-time fluorescence quantitative PCR results showed that different enzymes the relative expression quantity are different, accA has the highest relative expression quantity among acetyl CoA enzymes; fabz has the highest relative expression quantity among acyltransferase.4. Through the PE250 sequencing sequencing platforms and classified at the level of 97% sequence similarity, the OTU number of CK is the richest, and it increased with the age of the forest. The analysis of sample clustering tree and histogram combination of samples in woodland of different stand ages show that CK has obvious difference between different ages samples so separate into a class, relative to the middle age forest, young forest and mature forest composition is more similar, and the dominant species are Ascomycota and Basidiomycota.The RDA/CCA analysis between samples in woodland of different stand ages and soli physical and chemical properties and soil enzyme activities showed that, effects of soil physical and chemical properties, soil Total-N and volume weight have obvious effect on the samples OTU numbers, among soil enzymes soil acid phosphatase and peroxidase have obvious effect on the samples OTU numbers. PCA and PCoA analysis showed that CK has obvious difference between different ages samples so separate into a class, relative to the middle age forest, young forest and mature forest composition is more similar.With the increase of forest age, there are obvious differences in woodland microbial community showed a trend of first decreased and then increased.Altogether, different ages Casuarina woodland soil special bacteria and special fungi secondary metabolism products are rich and part of the products have been identified has allelopathic potential. Different fermentation liquid all have inhibitory effect on Vatica mangachapoi, Calophyllum inophyllum L. and Thespesia lampas L., also a performance of its allelopathic potential. The common substance between bacteria fermentation liquid and soil Octadecanoic acid,methyl ester the relative expression of key enzymes in the synthesis process are different. From fungal community structure diversity to explore the soil micro environment we can know that soil fungi community structure diversity with increase of the forest age presents a trend of first decreased and then increased dynamic changes. |
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