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Morphological and pathogenic variability of Austropuccinia psidii from guava and rose apple

Grant number: 21/06683-9
Support Opportunities:Scholarships in Brazil - Scientific Initiation
Effective date (Start): September 01, 2021
Effective date (End): December 26, 2022
Field of knowledge:Agronomical Sciences - Agronomy - Plant Health
Principal Investigator:Lilian Amorim
Grantee:João Vitor Pelizzaro Morales
Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
Associated research grant:19/13191-5 - Epidemiological components, damage characterization and control of tropical and temperate rusts at a global climate change scenario, AP.TEM
Associated scholarship(s):21/11421-3 - Pathogenic specificity of Austropuccinia psidii to guava plants, BE.EP.IC


Myrtle rust (Austropuccinia psidii) is an important disease on guava (Psidium guajava) and other species of the Myrtaceae family. There are several studies carried out with this pathogen in eucalyptus, but very little information is available about this disease in other hosts of the Myrtaceae family. Intraspecific diversity has already been observed in A. psidii, but most studies provide only qualitative data. The intensity of the disease, assessed by the lesion density or by disease severity, which are important variables to define the degree of specificity of an isolate, has not been reported in studies evaluating the diversity of the pathogen. This project, which aims to investigate the morphological and pathogenic variability of A. psidii from different hosts, belong to the thematic project 20109/13191 and intends to continue the activities of the grant "2020 / 10117-6 - Morphological and pathogenic variability of concession of A. psidii from diverse hosts". The morphological and pathogenic characterization of A. psidii will be performed for a higher number of isolates. Quantitative and qualitative analysis of reproductive structures of A. psidii, such as: shape, color and dimensions (length, width, and thickness of the cell wall) of urediniospores and teliospores will be used for morphological characterization of A. psidii. The pathogenic characterization of A. psidii will be investigated through cross inoculations. Components of the disease monocycle in young and mature leaves of the hosts will be assessed. Incubation and latent periods, lesion density, disease severity, lesion growth and number of uredinia per lesion will be estimated. Population growth models, routinely used in epidemiological analyzes will be fitted to lesion density and disease severity curves, by non-linear regression. Comparison of models parameters will be made by t test. Furthermore resistance reactions, either in mature leaves (ontogenic resistance) or in hosts in which the disease does not develop will be analyzed.(AU)

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