ARS | Publication request: New consistent QTL in pea associated with partial resistance to Aphanomyces euteiches in multiple field and controlled environments from France and the United States

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 14, 2011
Publication Date: April 10, 2011
Citation: Hamon, C., Baranger, A., Coyne, C.J., Mcgee, R.J., Le Goff, I., L Anthoene, V., Esnault, R., Riviere, J., Klein, A., Mangin, P., Mcphee, K.E., Roux-Duparque, M., Porter, L., Miteul, H., Lesne, A., Morin, G., Onfroy, C., Moussart, A., Tivoli, B., Delourme, R., Pilet Nayel, M. 2011. New consistent QTL in pea associated with partial resistance to Aphanomyces euteiches in multiple field and controlled environments from France and the United States. Theoretical and Applied Genetics. 123:261-281.

Interpretive Summary: Partial polygenic resistance to plant diseases has been recently shown of high interest for a more durable genetic control of plant pathogens, especially for increasing the durability of major resistance genes, which were widely reported in the past years to be overcome by virulent isolates appearing in pathogen populations. However, classical phenotypic breeding for partial resistance in major crop plants has often been difficult due to the polygenic inheritance of resistance. The increasing amount of data about quantitative trait loci controlling disease resistance in major crops would have greatly contributed to facilitate breeding for partial polygenic resistance through the development of Marker-Assisted Selection (MAS) strategies. Several examples of gene pyramiding combining resistance QTL and major genes using MAS have thus been published in legumes. For optimizing success probabilities in MAS, extensive genetic dissection of complex traits, including stability study of QTL effects and genomic positions towards multiple environments and genetic backgrounds and analysis of genetic effects of loci controlling complex traits, has become indispensable in initial QTL studies. These results confirm the complexity of inheritance of partial resistance to A. euteiches and provide good base for the choice of consistent QTL to use in successful marker assisted selection (MAS) schemes to increase current levels of resistance to A. euteiches in pea.

Technical Abstract: Partial resistances, often controlled by QTL (Quantitative Trait Loci), are considered to be more durable than monogenic resistances. Prior to develop efficient breeding programs for polygenic resistance to pathogens, a higher understanding of genetic diversity and stability of resistance QTL in plants is required. In this study, we deciphered the diversity and stability of resistance QTL to Aphanomyces euteiches in pea towards pathogen variability, environments and scoring criteria, from two new pea sources of resistance efficient in France (PI180693 and 552). Two mapping populations of 178 recombinant inbred lines each, derived from crosses between 552 or PI180693 (partially resistant) and Baccara (susceptible), were used to identify quantitative trait loci for Aphanomyces root rot resistance in multiple French and American field and controlled conditions using several resistance criteria. We identified a total of 136 additive effect QTL corresponding to 23 genomic regions and 13 significant epistatic interactions associated with partial resistance to A. euteiches in pea. Among the 23 additive effect genomic regions identified, five of them were highly consistently detected and a high stability of QTL effects was observed toward the A. euteiches strains, environments, resistance criteria, test conditions and RIL populations studied. These results confirm the complexity of inheritance of partial resistance to A. euteiches and provide good base for the choice of consistent QTL to use in successful marker assisted selection (MAS) schemes to increase current levels of resistance to A. euteiches in pea.