Inheritance of quantitative resistance to downy mildew (Plasmopara halstedii) in sunflower (Helianthus annuus L.)

Felicity F. Vear (1) , F. Serre (1) , Isabelle Jouan-Dufournel (2) , Pierre-François P.-F. Bert (3) , S. Roche (1) , P. Walser (1) , Denis D. Tourvieille de Labrouhe (1) , Patrick P. Vincourt (1)

1 Unité MIAJ - INRA - Mathématiques et Informatique Appliquées
2 LMGE - Laboratoire Microorganismes : Génome et Environnement
3 GDEC - Génétique Diversité et Ecophysiologie des Céréales

Quantitative resistance to sunflower downy mildew was studied on inbred lines and hybrids not carrying efficient major gene resistance, in field trials in one to four sites over 3 years. Hybrids from factorial crosses showed that inheritance is under additive control and comparison with reactions of parental inbred lines gave narrow sense heritabilities of 27-57%. Analysis of a polymorphic recombinant inbred line population without efficient major gene resistance indicated that two highly significant Quantitative Trait Loci (QTL) explained 42% of variation in field reaction to downy mildew. These QTL were mapped on linkage groups 8 and 10, and do not appear related to any of the known major resistance gene clusters. Possible bases of this type of resistance and its use in breeding are discussed.

Mots clés: Oil plant (vegetal); Plant pathogen; Spermatophyta; Angiospermae; Dicotyledones; Compositae; Stramenopila; Oomycota; Nonspecific resistance; Genetic improvement; Helianthus annuus; Plasmopara halstedii; Major gene; Quantitative trait loci; Marker; Hybrid; Pure line; Heritability; Sunflower; Fungus resistance; Genetic determinism

Felicity F. Vear, F. Serre, Isabelle Jouan-Dufournel, Pierre-François P.-F. Bert, S. Roche, et al.. Inheritance of quantitative resistance to downy mildew (Plasmopara halstedii) in sunflower (Helianthus annuus L.). Euphytica, 2008, 164 (2), pp.561-570. ⟨hal-00528103⟩