Response Of Endophyte Diversity In Aquilaria Sinensis To The Process Of Agarwood Formation

As a kind of grafting tree species in Aquilaria sinensis,it is considered to be the best and most precious species.It is an endangered tree species in China.It also has important medicinal value,economic value and ecological benefit.In this study,the heartwood of Aquilaria sinensis in Maoming City,Guangzhou province was taken as the research object.The community structure and diversity of endophytic fungi and endophytic bacteria in heartwood of Aquilaria sinensis were studied by high-throughput sequencing technology.Combining with the physical and chemical properties of heartwood,the relationship between them was analyzed by variance analysis,and other methods to provide theoretical basis for artificial promotion of the study on the agarwood formation of Aquilaria sinensis.The main results are as follows:(1)The physicochemical properties of heartwood of Aquilaria sinensis in different periods of agarwood formation.The physicochemical properties of the heartwood were different in different degrees.With the prolongation of trauma period,the moisture content of heartwood decreased gradually,which were 35.48%,32.19%and 25.56%respectively.pH value and ash content also decreased gradually,which were 8.61,6.15,5.37 and 0.418%,0.320%and 0.271%respectively.The extractive contents of hot-water and benzene-alcohol extract of heartwood increased gradually,which were 2.890%,3.104%,3.450%and 2.974%,5.741%and 7.825%respectively.The content of K,Ca and Mg decreased significantly,with a decrease of 53.59%,26.20%and 73.14%respectively.The content of S increased significantly,with a growth of 27.55%.(2)Community structure and diversity of endophytic fungi in heartwood of Aquilaria sinensis in different periods.?After high-throughput sequencing,138,248 sequences were obtained.?204 OTUs were obtained.On the level of phylum,the dominant endophytes were ascomycetes and basidiomycetes.At genus level,Fusarium,Cladosporium and sarocladium are the dominant endophytic fungi in heartwood in the early stage of agarwood formation.The dominant fungi of heartwood in the middle stage of agarwood formation were Fusarium,ophiosphaerella,bulletibasidium,cystobasidium,tuber and Cladosporium.The dominant fungi of heartwood endophytes in the later stage of agarwood formation were Fusarium,Cladosporium,cystobasidium and tuber.At the seed level,the dominant fungi of heartwood in the early stage of agarwood formation were sarocladium zeae(8.84%),dicyma pulvinata and zasmidium cerophillum.In the middle stage of agarwood formation,Fusarium solani(17.18%),Rhodotorula glutinis(3.71%),rhynchogastroma complexa and parasagonospora nodorum were the dominant heartwood fungi.At the later stage of agarwood formation,the dominant fungi of heartwood were Fusarium solanacearum(17.34%),rhynchogasterema complexa,parasagonospora nodorum.?The endophytic fungi richness of heartwood in the middle stage is higher than that in the early stage and the later stage.Pielou's evenness index was lower in the early stage and higher in the middle and later stage.The comprehensive analysis of diversity index showed that the diversity of endophytic fungi was high in the middle stage of agarwood formation.(3)Community structure and diversity of endophytic bacteria in heartwood at different stages of agarwood formation.?After high-throughput sequencing optimization,191,092 sequences were obtained.?43 OTUs were obtained.At the door level,Proteobacteria is the dominant group of endophytic bacteria in the middle and late stage of the heartwood of agarwood formation,accounting for 92%and 96%respectively.At the genus level,the dominant endophytes in the heartwood at the initial stage of agarwood formation were Ralstonia,pelomonas,actinomyceteospora,Brachybacterium,Curtobacterium and mycoplasma.The dominant endophytic bacteria of heartwood in the middle stage of agarwood formation were as follows:Ralstonia,pelomonas,Pseudomonas,sphingobium,Sphingomonas,allorhizobium neorhizobium parrhizobium Rhizobium and Burkholderia caballeronia paraburkholderia.The dominant bacterial groups in the heartwood of the later stage of agarwood formation were as follows:Ralstonia,pelomonas,Pseudomonas,sphingobium,Sphingomonas,allorhizobium neorhizobium parrhizobium Rhizobium and hansschlegelia.At the seed level,the dominant bacteria of heartwood in the early stage of agarwood formation were Brachybacterium paraconsomeratum(3.33%)and Mycoplasma pulmonis.In the middle stage of agarwood formation,the dominant bacteria of heartwood were Rhizobium tropicalis,Mycoplasma pulmonis(3.66%),Pseudomonas aeruginosa(9.52%),methybacterium radioolerans,Boletus laboratories and Sphingomonas sp.CC-mhh0546.At the later stage of agarwood formation,the dominant bacteria of heartwood were Rhizobium tropicalis(11.59%),Mycoplasma pulmonis(3.26%),polyaromatic monospora Sphingomonas(9.43%)and methybacterium radioolerans.The abundance of other species is less than 2%.?The diversity of endophytic bacteria community structure in the middle and later stage of agarwood formation of A.sinensis was greater than that in the early stage of agarwood formation.The diversity index analysis showed that the endophytic bacteria species in heartwood in the middle stage of agarwood formation were rich,dominant and evenly distributed.