INRA-UMR APBV
Amélioration des plantes et biotechnologies végétales,
Domaine de la Motte, BP35327,
35653 Le Rheu Cedex,
France
Mini-biographyMarie-Laure Pilet-Nayel is a research scientist at INRA, Department of Genetics and Plant Breeding, working on disease resistance in the Plant Genetics and Biotechnology unit of INRA Rennes. She received her PhD from INA-PG, Paris, France, in 1999, studying genetics of resistance to Leptosphaeria maculans in rapeseed. In 2000, she worked as a post-doc in Dr Coyne’s laboratory at USDA-ARS Pullman, WA, USA, on identifying QTL for Aphanomyces partial resistance in pea and was then appointed at INRA Rennes for developing a research program on genetics of resistance to this root disease in pea. Her current work focuses on analysis of Aphanomyces resistance QTL diversity in pea and comparative genetics of the resistance between pea and Medicago truncatula, in the aim of validating and pyramiding QTL for improving pea partial resistance and identifying genes underlying the resistance.
Improving resistance to Aphanomyces root rot in pea by validating and cumulating resistance QTLs in breeding linesMarie-Laure Pilet-Nayel, Clarice J Coyne C, Robert Esnault, Rebecca J McGee, Angélique Lesné, Martine Roux-Duparque, Pierre Mangin, Kevin E McPhee and Alain Baranger.
INRA, UMR INRA-Agrocampus Rennes APBV, Domaine de la Motte, BP35327, 35653 LeRheu Cedex, France
Marie-Laure.Pilet@rennes.inra.fr Aphanomyces root rot, due to
Aphanomyces euteiches, is an economically important disease that consistently affects large areas of pea production in many countries in the world. Apart from avoidance of pea cropping in infested fields, the development of resistant varieties is the only promising method of disease management. Resistance currently available in pea germplasm is partial and has not yet been sufficient to be integrated into commercial cultivars. The main objective for Aphanomyces resistance breeding is thus to improve levels of partial resistance by cumulating resistance genetic factors from different partially resistant germplasm.
In this objective, research programs have been developed aiming at i)- exploring genetic variability in Pisum for Aphanomyces resistance and identifying new sources of resistance and ii)- stuying the diversity of resistance genetic factors in various resistant germplasm and their stability towards environment, pathogen variability and genetic backgrounds. These programs mainly resulted in the identification of partially resistant pea germplasm from different origins and of stable resistance QTLs detected from two pea segregating mapping populations. From the RIL population Puget (susceptible) x 90-2079 (partially resistant), three main QTLs, namely Aph1, Aph2 and Aph3, were associated with resistance to
A. euteiches in US fields and in controlled conditions using two isolates from the US and France, respectively. From the RIL population DSP (susceptible) x 90-2131 (partially resistant), additional consistent QTLs were associated with resistance in French and US fields and in controlled conditions using isolates from different pathotypes and geographical origins. One of them expressed a major effect, explaining individually up to 60% of the phenotypic variation for resistance to a French reference isolate.
In order to cumulate resistance alleles at stable QTLs in elite pea cultivars, future plans will consist in i)- increasing marker density, precising genomic positions associated with resistance and estimating allelic diversity in target QTL regions, ii)- validating and cumulating resistance QTLs into elite cultivars through the creation of QTL-NILs by back-cross assisted selection and iii)- detecting and introgressing new resistance alleles from new sources of resistance into the same elite cultivars using advanced backcross selection.
For these prospects, the model legume, Medicago truncatula, will be particularly helpful to generate synteny-based markers in pea QTL regions or to identify genes associated with resistance in pea trough comparative genetics and genomics studies of Aphanomyces resistance in the model and crop legume.
