Diversidade de fungos e vírus da endosfera foliar e caulinar de seringueiras (Hevea brasiliensis) nativas da Amazônia oriental

Abstract

Within vegetal tissues there are symbiotic microorganims that can interact and help in the protection of plants against pathogens, such as endophytic fungi. Endophytic fungi reside in living plant tissues without causing symptoms of disease in the host. The fungi diversity suggests that they may confer important characteristics to the host, for example, by increasing plant`s immunity against pathogens. Hevea brasiliensis is the best plant for natural latex production. The center of origin of the genus Hevea is the brazilian Amazon region. It is know that this genus is susceptible to various diseases caused by fungi and viruses, as South American Leaf Blight (SALB) and viral leaf disease. This illnesses are responsable for the reduction of latex production by H. brasiliensis and can lead to plant death. The objetive of this work were characterize the endophytic fungi community and detect phytopathogens associated with leaves and sapwood of H. brasiliensis in National Forest of Caxiuana (PA) and Nacional Park of Anavilhanas (AM). Five leaves were collected from nine plant individuals from the two conservation areas. A total of 335 fungal isolates were purified, preserved, deposited in collection and identified belonging to 23 genera distributed in 87 similarity groups (Operational Taxonomic Units – OTUs). The species were grouped and by ordination analysis it was possible to identify common and specific species for each collection site, indicating that the endophytic fungi community in each location is differet. One individual completely asymptomatic for any fungal or viral disease (C2) was sellected for small RNA sequencing (metatranscriptome of sRNA). At the end of the process, it was possible to set up contigs corresponding to the fungus Pseudocercospora ulei, SALB pathogen and a virus related to Tymoviridae family, probably a new species, never described infecting rubber trees. To confirm the presence of virus in the indvidual leaves, primers were designed with higly specific probes for detection by quantitative (qPCR) and digital (ddPCR) amplification. In both amplifications, it was possible to detect different parts of its genome, however ddPCR presented greater detection sensitivity and it was possibly to quantify absolutely the viral material. To confirm the presence of the fungus P. ulei, will be designed specific primers for detection in ddPCR. Further rubber tree individuals from other Brazilian Amazon region will be tested for the Tymoviridae family virus detection. This work allowed two phytopathogens detection and may be useful for the study of diseases that affect H. brasiliensis and for better understanding of these pathogens when they are living endophytically in asymptomatic host.