Theoretical and Applied Genetics (2003) 108, 175-180

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D.T. Junghans, A.C. Alfenas, S.H. Brommonschenkel, S. Oda, E.J. Mello and D. Grattapaglia (2003)
Resistance to rust (Puccinia psidii Winter) in Eucalyptus: mode of inheritance and mapping of a major gene with RAPD markers
Theoretical and Applied Genetics 108 (1), 175-180
Abstract: Rust is one of the most-damaging eucalypt diseases in Brazil and is considered a potential threat to eucalypt plantations worldwide. To determine the mode of inheritance of resistance in the Eucalyptus grandis - Puccinia psidii pathosystem, ten full-sib families, generated from crosses between susceptible and resistant trees, were inoculated with a single-pustule isolate of the pathogen and rust severity was scored. The observed segregation ratios in segregating families suggested major gene control of rust resistance, although clearly incomplete penetrance, variable expressivity and minor genes are also involved in the global rust-resistance response. To identify markers linked to the resistance locus, screening of RAPD polymorphisms was conducted using bulked segregant analysis in a large full-sib family. A linkage group was built around the Ppr1 gene (P. psidii resistance gene 1) encompassing six RAPD markers, with a genetic window spanning 5 cM with the two most-closely linked flanking markers. Besides these two flanking markers, RAPD marker AT9/917 co-segregated with Ppr1 without a single recombinant in 994 meioses. This tightly linked marker should prove useful for marker-assisted introgression and will provide an initial lead for a positional cloning effort of this resistance allele. This is the first report of a disease resistance gene identified in Eucalyptus, and one of the few examples of the involvement of a major gene in a non-coevolved pathosystem.
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Link to article at publishers website
Database assignments for author(s): Acelino C. Alfenas

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Austropuccinia psidii Eucalypt (Eucalyptus)