The eucalyptus (Eucalyptus spp.) belongs to the Myrtaceae family and is the most widely planted species for wood, pulp and derivative production. Over the past 50 years, Austropuccinia psidii, the causal agent of myrtle rust, has posed a constant threat to eucalyptus production and the biodiversity of native forests, ranking among the top ten most feared fungi globally. While in Brazil A. psidii populations are structured by the host, the rest of the world experiences a predominance of a pandemic population pathogenic to hundreds of species within the Myrtaceae family. The most commonly used control strategies in commercial cultivation of eucalyptus are genetic resistance and chemical control. However, new public policies focused on agroecosystem sustainability have redirected the search for plant disease management strategies. Within these, one of the most promising tools in the long term is the plant microbiome. There still is a considerable gap between microbiome characterization and translating knowledge into field-applicable strategies. The strategy begins with the exploration of microbial communities with the potential to suppress the progression of the disease. Hence, host-microorganism co-evolution is a significant ally, leading to the emergence of disease-suppressive environments due to microbial communities present either in the soil or the phyllosphere. Thus, this project aims to (i) modulate the eucalyptus phyllosphere using field microbial communities, under selection pressure from distinct A. psidii isolates, to reduce rust severity; (ii) characterize changes in the developed phyllosphere microbial community over time; and (iii) identify similarities among the phyllosphere microbiomes identified in (ii) in the search for a core microbiome. The development of a suppressive phyllosphere and the analysis of modulated microbial communities are crucial for exploring innovative and sustainable approaches in controlling myrtle rust in eucalyptus and other Myrtaceae species. (AU) 

Eucalyptus (Eucalyptus spp.) is native to Oceania, but Brazil is one of the world's largest producers, with a productive area of 7.6 million hectares dedicated to the production of wood derivatives. Extensive cultivation outside its center of origin promotes the adaptation of fungal pathogens, notably Austropuccinia psidii, the causal agent of myrtle rust, the main pathogen of the crop and a threat to other native forest species. In commercial fields, disease management is carried out through the use of resistant clones and chemical products. However, there is a growing demand for alternative strategies for plant disease control. The plant microbiome is a promising long-term solution; however, it is still necessary to explore and characterize microbial communities present in the soil or phyllosphere that are capable of suppressing diseases. In this context, the present project aims to (i) modulate a suppressive phyllosphere in two eucalyptus species using the naturally occurring microbiome from cultivation fields under the selective pressure of different A. psidii isolates to reduce rust severity; (ii) characterize the changes in the phyllosphere microbial community developed in (i) over time; and (iii) determine whether similarities exist between the phyllosphere microbiomes identified in (ii) in the search for a core microbiome. It is expected that successive passages of the microbiome will lead to the modulation of a microbial community suppressive to the pathogen A. psidii in eucalyptus. The microbiome present in the cultivation field and the pathogen-suppressive community are expected to be characterized and quantified.

The eucalyptus (Eucalyptus spp.) belongs to the Myrtaceae family and is the most widely planted species for wood, pulp and derivative production. Over the past 50 years, Austropuccinia psidii, the causal agent of myrtle rust, has posed a constant threat to eucalyptus production and the biodiversity of native forests, ranking among the top ten most feared fungi globally. While in Brazil A. psidii populations are structured by the host, the rest of the world experiences a predominance of a pandemic population pathogenic to hundreds of species within the Myrtaceae family. The most commonly used control strategies in commercial cultivation of eucalyptus are genetic resistance and chemical control. However, new public policies focused on agroecosystem sustainability have redirected the search for plant disease management strategies. Within these, one of the most promising tools in the long term is the plant microbiome. There still is a considerable gap between microbiome characterization and translating knowledge into field-applicable strategies. The strategy begins with the exploration of microbial communities with the potential to suppress the progression of the disease. Hence, host-microorganism co-evolution is a significant ally, leading to the emergence of disease-suppressive environments due to microbial communities present either in the soil or the phyllosphere. Thus, this project aims to modulate the eucalyptus phyllosphere using field microbial communities, under selection pressure from distinct A. psidii isolates, to reduce rust severity. The present proposal is part of a larger research project aimed at developing the suppressive filosphere and analyzing modulated microbial communities in search of innovative and sustainable approaches to control myrtle rust in eucalyptus and other species.