Temporal And Spatial Dynamics Of The Fungi In Leaf Tissues And Canopy Air Of Ageratina Adenophora And Its Seed Endophytic Fungi

Studying the interaction between invasive plants and their microorganisms is of great significance for understanding the mechanism of plant invasion.At present,studies have been performed on the diversity and structure of fungal communities in fresh leaf tissue,dead leaf tissue,and canopy air of invasive plant Ageratina adenophora,but the dynamic changes in the diversity and structure of these fungal communities under climate factors have not been carried out on a time scale.In addition,it is also not known whether there is horizontal and vertical transmission of leaf endophytic fungi in A.adenophora.Based on the above background,we collected monthly the canopy air and leaf tissue(fresh and dead leaves)of A.adenophora in Xishan Park in Kunming,Yunnan Province and explored and analyzed the diversity and structural dynamics of the fungal community in these samples by the culture method and high throughput sequencing method.In addition,combined with the species composition of the endophytic fungi in the seeds of A.adenophora,we deduced whether the foliar endophytic fungi of A.adenophora occur a vertical transmission.This research has the following conclusions:1.The fungi in the canopy air,fresh leaves and dead leaf of A.adenophora are abundant and diverse.Totally 5142 strains of fungi were obtained through and the culture method.After colony morphological classification and merging,DNA was extracted from the representative strains and their ITS sequences were divided into operational taxonomic units(OTUs)at the unique level.A total of 132 OTUs were obtained in the canopy air,and classified into 2 phyla,5 classes,12 orders,26 families and 41 genera;118 OTUs was obtained from fresh leaves,and classified into 2 phyla,4 classes,and 12 orders,21 families and 31 genera;46 OTUs were obtained from dead leaves,which were classified into 2phyla,3 classes,8 orders,15 families and 22 genera.By the high throughput sequencing method 375 OTUs were obtained in the canopy air,and classified into 5 phyla,31 classes,97 orders,270 families and 660 genera;1026 OTUs were obtained in fresh leaves,and classified into 5 phyla,25 classes,66 orders,146 families and 256 genera;1263 OTUs were obtained from dead leaves,which were classified into 5 phyla,23 classes,60 orders,117 families and 221 genera.There is a great difference between the fungal community structure obtained by the traditional culture method and by the high throughput sequencing method.2.Seasons had a significant impact on the diversity and community structure of fungi in the canopy air,in the fresh leaf tissues and in the dead leaf tissues.The principal coordinate analysis of the single-sample type community structure showed that seasons had a significant impact on the community structure,of which the impact on the canopy air is the most significant.Then linear regression analysis showed that temperature and humidity had a significant impact on the fungal diversity of canopy air and fresh leaf tissue.According to variance analysis of displacement,seasonal changes and sample types had significant effects on community structure of fungi.3.The transmission mode of endophytic fungi in A.adenophora leaves was complicated.Analysis of the distribution of endophytic fungi in fresh leaf tissue and canopy air,dead leaf tissue and seed fungi community structure showed that there were multiple transmission modes of endophytic fungi in A.adenophora leaves,including horizontal transmission through spores in leaf tissues into the air,the way that fungi in dead leaf tissues entering into the soil,as well as the way transmitted vertically through seeds.All of these transmission modes were related to the season.For example,there are fungi that can spread through multiple transmission modes,but the horizontal transmission was most significant in summer and autumn,without the horizontal transmission in winter;however,the way of spreading with dead leaves could occur in all three seasons.This study combined traditional culture and high throughput sequencing technology to characterize the seasonal dynamics of the fungi in the canopy air,fresh leaves and dead leaves of the invasive plant A.adenophora.Our results greatly contribute to understanding the interaction between invasive plants and fungi in the invaded range and also lay a theoretical foundation for evaluating the potential disease transmission risk in local ecosystem.