Forest Pathology (2021) 51 (2 - e12679)

Rosiane F. Almeida, Patrícia S. Machado, Michelle B. Damacena, Samuel A. Santos, Lúcio M.S. Guimarães, Ned B. Klopfenstein and Acelino C. Alfenas (2021)
A new, highly aggressive race of Austropuccinia psidii infects a widely planted, myrtle rust-resistant, eucalypt genotype in Brazil
Forest Pathology 51 (2 - e12679)
Abstract: Myrtle rust (MR) caused by Austropuccinia psidii is one of the most important diseases affecting eucalypt (Eucalyptus) plantations in Brazil. Over the years, selection and planting of MR-resistant clones has been the primary strategy for MR management. In May 2013, young trees of the GG100 hybrid (E. grandis × E. urophylla) clone—widely planted in Brazil and previously classified as resistant to MR—were infected by A. psidii in Minas Gerais, Brazil. In this study, artificial inoculations of a eucalypt clone set with differential reactions to A. psidii races were used to discover a new race of A. psidii (race 5) that was highly aggressive on the majority of eucalypt clones tested. In addition, only this new race successfully infected eucalypt G26 and 847 genotypes, which were formerly classified as resistant to the four previously known races of A. psidii. Since G26 genotype is homozygous for Ppr1 (a major resistance gene against A. psidii), this is the first report of MR resistance breakdown in a eucalypt genotype homozygous for Ppr1. Our findings demonstrate that this new A. psidii race is highly aggressive and capable of infecting a larger number of eucalypt genotypes compared with the previously known A. psidii races 1, 2, 3, and 4.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Ned B. Klopfenstein, Acelino C. Alfenas

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Austropuccinia psidii	Eucalypt (Eucalyptus)	Brazil (south)