A QTL detected in an interspecific pear population confers stable fire blight resistance across different environments and genetic backgrounds

Sara Montanari (1) , Laure Perchepied (1) , Déborah Renault (1) , Linda Frijters (2) , Riccardo Velasco (3) , Mary Horner (2) , Susan E. Gardiner (4) , David Chagne (4) , Vincent G. M. Bus (2) , Charles Eric Durel (1) , Mickael Malnoy (3)

1 IRHS - Institut de Recherche en Horticulture et Semences
2 V. G. M. Bus PFR
3 Research and Innovation Centre
4 Palmerston North Research Centre

Fire blight, caused by the bacterium Erwinia amylovora (Burrill) Winslow et al., is one of the most serious diseases of pear. The development of pear cultivars with a durable resistance is extremely important for effective control of fire blight and is a key objective of most pear breeding programs throughout the world. We phenotyped seedlings from the interspecific pear population PEAR3 (PremP003, P. x bretschneideri x P. communis) x 'Moonglow' (P. communis) for fire blight resistance at two different geographic locations, in France and New Zealand, respectively, employing two local E. amylovora isolates. Using a genetic map constructed with single nucleotide polymorphism (SNP) and microsatellite (SSR) markers previously developed for this segregating population, we detected a major quantitative trait locus (QTL) on linkage group (LG)2 of 'Moonglow' (R-2 = 12.9-34.4 %), which was stable in both environments. We demonstrated that this QTL co-localizes with another major QTL for fire blight resistance previously detected in 'Harrow Sweet' and that the two favorable (i.e., resistant) alleles were not identical by descent. We also identified some smaller effect (R-2 = 8.1-14.8 %) QTLs derived from the susceptible parent PEAR3. We propose SNP and SSR markers linked to the large effect QTL on LG2 as candidates for marker-assisted breeding for fire blight resistance in pear.

Mots clés: Erwinia amylovora; Pyrus communis; Pyrus x bretschneideri; Marker-assisted breeding

Domaines: Sciences du Vivant [q-bio]

Sara Montanari, Laure Perchepied, Déborah Renault, Linda Frijters, Riccardo Velasco, et al.. A QTL detected in an interspecific pear population confers stable fire blight resistance across different environments and genetic backgrounds. Molecular Breeding, 2016, 36 (4), pp.1-16. ⟨10.1007/s11032-016-0473-z⟩. ⟨hal-01456003⟩