Occurrence of Rust in Myrcianthes pungens (O. BERG) D. Legrand Caused by Austropuccinia psidii in The State of Rio Grande do Sul

• Published in: Revista Brasileira de Fruticultura 2022-01, Vol.44 (5)
• Main Authors: Santos, Rodrigo Areze da Silva, Schwarz, Sergio Francisco, Silva, Magnólia Aparecida Silva da, Bertolini, Edson, Andrade, Camila Cristina Lage de, Pacini, Bruna Alana Haupt
• Format: Article
• Language: English
• Subjects: Genetic Resources; Guabiju; HORTICULTURE; Myrtaceae; Native Fruits of Brazil; Phytopathogen
• ISSN: 0100-2945; 1806-9967; 1806-9967
• DOI: 10.1590/0100-29452022073

Abstract Guabiju tree (Myrcianthes pungens) belongs to the Myrtaceae family, with wide occurrence in Rio Grande do Sul (RS), southern Brazil, demonstrates great commercial potential regarding the consumption of its fresh fruit, which has a sweet taste and can be used in drinks, jellies and ice creams, in addition to its nutraceutical properties. As their main characteristic, rusts present the formation of orange pustules containing urediniospores of the pathogen on affected organs. The action of the pathogen causes deformation of stems, leaves, flowers and fruits, thus interfer-ing with the physiological processes of the plant. Thus, the present work aimed at presenting information on the occurrence and confirmation of the causal agent of guabiju rust, in addition to reporting the accessions most susceptible and resistant to Austropuccinia in the guabiju working collection of Eldorado do Sul, RS, Brazil. The diagnosis of the disease was based on symptoms, observation of fungal structures by light microscopy and molecular analyses. From microscopy, ellipsoid to ovoid and slightly equinulate urediniospores were observed, characteristic of Austropuccinia sp. The sequence of the internal transcribed spacer (ITS) region of the isolate showed 99.06% similarity with sequences from the same region of A. psidii deposited on the nucleotide database - GenBank (NCBI). This is the first report of rust associated with guabiju in the state of Rio Grande do Sul, Brazil. From the diagrammatic scale developed, it was possible to identify different levels of susceptibility to A. psidii in guabiju accessions under study. Resumo Guabiju (Myrcianthes pungens), pertencente à família Myrtaceae, com ampla ocorrência no Rio Grande do Sul (RS), apresenta grande potencial para exploração de seus frutos no consumo in natura, com sabor adocicado, podendo compor bebidas, geleias e sorvetes, além de possuir propriedades nutracêuticas. As ferrugens, como característica principal, apresentam a formação de pústulas alaranjadas contendo urediniósporos do patógeno sobre os órgãos afetados. A ação do patógeno causa deformação dos órgãos: caules, folhas, flores e frutos, interferindo, assim, nos processos fisiológicos da planta. Assim, o presente trabalho teve como objetivo apresentar informações sobre a ocorrência, confirmação do agente causal da ferrugem do guabijuzeiro, além de relatar os acessos mais suscetíveis e resistentes a Austropuccinia na coleção de trabalho de guabijuzeiros em Eldor