ISHS Acta Horticulturae 663: XI Eucarpia Symposium on Fruit Breeding and Genetics
ESTIMATION OF FIRE BLIGHT RESISTANCE HERITABILITY IN THE FRENCH PEAR BREEDING PROGRAM USING A PEDIGREE-BASED APPROACH |
| Authors: | C.E. Durel, P. Guérif, A. Belouin, M. Le Lezec |
| Keywords: | Pyrus communis, Erwinia amylovora, genetic parameter, relationships, best linear unbiased predictor |
| Abstract:
A breeding program for fire blight resistance in pear was initiated 23 years ago at INRA Angers-Beaucouzé by Thibault (1990). Numerous crosses have been made using resistant parental cultivars such as ‘Harrow Sweet’, US309, or ‘Michigan 437’ and high fruit quality parental cultivars such as ‘William’s’ or ‘Pierre Corneille’. The parents were crossed according to a very wide crossing design similar to an incomplete diallel design. Some of the parents were also related to each other resulting in an even more complex relationship network. To evaluate fire blight resistance, seedlings 20-30 cm tall were inoculated with a reference strain of Erwinia amylovora. Three weeks after inoculation, seedlings were scored for progression of the disease in the stem. Using the software REML VCE developed by Groeneveld (1996) for animal breeding, we estimated the narrow-sense heritability of fire blight resistance in this breeding population, using more than 17000 seedling data and 123 parental/ancestor pedigree information. The mathematical method used in this software is based on the ‘individual genetic model’ (maximum-likelihood procedure). The estimated heritability value was 0.40 (± 0.04). Best linear unbiased predictors of the additive genetic values of the parents and higher ancestors were also estimated. The applicability of the methodology and the results are discussed. | |
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