New sources of resistance to downy mildew in a collection of wild and cultivated brassicas
Brassica downy mildew (DM) is a foliar disease caused by the oomycete Hyaloperonospora brassicae (syn. Hyaloperonospora parasitica subs. brassica) that can affect plants at all stages including the nurseries and can limit the production of vegetable Brassica especially in temperate climates. Twenty-eight landraces and wild genotypes from different Brassica species, coming from Portuguese and Italian germplasm collections, were screened for DM resistance. Genotypes of B. oleracea (23 acc.), B. rupestris (3 acc.), B. incana (1 acc.), and B. villosa (1 acc.) were tested with four H. brassicae pathotypes from different geographical origin at the seedling stage. DM evaluation showed no differential responses to the four H. brassicae pathotypes but great differences in resistance were observed between accessions. Seven accessions including one B. villosa (UNICT3944), two B. oleracea var. acephala (BPGV4533 and UNICT4448), three B. oleracea var. costata (BPGV1773, BPGV1726, and BPGV1747), and one B. oleracea var. sabauda (UNICT4633) were resistant to DM infection at cotyledon stage. These accessions are potential sources of DM resistance to be genetically characterised and further exploited in breeding programmes.
Coelho, P.S., Monteiro, A.A., Lopes, V.R. and Branca, F. (2018). New sources of resistance to downy mildew in a collection of wild and cultivated brassicas. Acta Hortic. 1202, 93-100
Brassica sp., cotyledon resistance, germplasm collection, Hyaloperonospora brassicae