Preliminary Study On The Diversity Of Endophytic Colletotrichum From Ageratina Adenophora And Its Growth Promotion To Arabidopsis Thaliana

Ageratina adenophora is a perennial herbaceous plant belonging to the Eupatorium,of Compositae family.It is a notorious alien invasive plant that has flooded in many countries such as New Zealand,Thaliand and China.Colletotrichum was listed as one of the top ten plant pathogens,which is widely distributed in healthy plants of A.adenophora,accounting for more than half of the total number of its endophytic fungi.Therefore,revealing the diversity of endophytic Colletotrichum from A.adenophora and testing the growth promotion to A.adenophora could lay foundation for explaining the invasion mechanism of A.adenophora from the perspective of endophytic fungi.In this study,combined six genes region(ITS,GAPDH,CHS-1,CAL,GS,TUB2)and morphological characteristics,86 representative endophytic Colletotrichum strains isolated from 14 invasive areas of A.adenophora in Yunnan Province were identified to species level.The growth promotion effects of 11 strains on Arabidopsis thaliana were tested.A strain with obvious growth promotion effect on A thaliana was screened out,which belongs to C.simuliocitri and numbered Y53.Through the analysis of A.thaliana transcriptome data,the growth promotion mechanism was preliminarily revealed,which laid a foundation for further exploration of the growth promotion of this strain on A.denophora in nature and the influence of population diffusion.The main results were as follows:1.Combined morphological characteristics and multi-locus analysis,a total of 26 species were identified among 86 Colletotrichum strains,including 11 known species:Colletotrichum boninense,Colletotrichum fioriniae,Colletotrichum fructicola,Colletotrichum gigasporum,Colletotrichum godetiae,Colletotrichum karstii,Colletotrichum magnum,Colletotrichum nymphaeae,Colletotrichum plurivorum,Colletotrichum siamense,Colletotrichum thailandicum,and 15 new species :Colletotrichum analogum,Colletotrichum dimorphum,Colletotrichum gracile,Colletotrichum labyrinthinum,Colletotrichum lancangensis,Colletotrichum latum,Colletotrichum nullisetosum,Colletotrichum oblongisporum,Colletotrichum parvisporum,Colletotrichum speciosum,Colletotrichum pulchellum,Colletotrichum robustum,Colletotrichum simile,Colletotrichum simuliocitri,Colletotrichum sublunatum.2.After testing the growth promotion effect of 11 strains on A.thaliana,a strain numbered Y53(C.simuliocitri)with obvious growth promotion was obtained.Transcriptome data of A.thaliana at three key time points in the fungus-A.thaliana co-culture system were compared to that of A.thaliana cultured alone.The results show:after 5 days of co-culture,the differentially expressed genes were significantly enriched in fatty acid metabolism,plant-pathogen interaction,biosynthesis and metabolism of various amino acids,phenylpropanoid biosynthesis,starch and sucrose metabolism,glutathione metabolism,flavonoid and anthocyanin biosynthesis,nitrogen metabolism,circadian rhythm-plant,plant hormone signal transduction,MAPK signaling pathway-plant;after 7 days of co-culture,the differentially expressed genes were significantly enriched in biosynthesis of ribosomes,biosynthesis and metabolism of various amino acids,metabolism of purines,biosynthesis of flavonoids and other compounds;after 9 days of co-culture,the differentially expressed genes were significantly enriched in sugar metabolism,VB6 metabolism,biosynthesis of various amino acids,biosynthesis of organic compounds,MAPK pathway and other processes.We speculated that the strain numbered Y53 can affect the growth and development of Arabidopsis thaliana,and make Arabidopsis thaliana respond to external stresses.3.The LCMS analysis of liquid fermentation products of of Y53 showed,compared to fermentation products for 5 days,among fermentation productsfor 10 days,flavonoids,ascorbic acid,etc.were significantly upregulated.These substance are known to promote plant growth.