SCREENING OF PORTUGUESE COLE LANDRACES (BRASSICA-OLERACEA L) WITH PERONOSPORA-PARASITICA AND PLASMODIOPHORA-BRASSICAE

Forty-four landraces of Portuguese coles (Brassica oleracea L.), repre senting different morphotypes, were screened at the cotyledon stage fo r downy mildew resistance, caused by Peronospora parasitica. Two isola tes of the pathogen, PHW 630 and PHW 828, were used in the experiment. The mean disease interaction phenotype varied among the landraces. Ov erall, the Portuguese coles have shown resistance to both isolates, pa rticularly to isolate PHW 828. Some landraces were identified with dif ferential reaction to the two P parasitica isolates. Some of the Portu guese coles are, therefore, good sources of resistance genes to P para sitica, and could be used in breeding programs or in the development o f a downy mildew host differential set. Among the morphotypes tested, Couve Algarvia (ISA 207), Couve Galega (ISA 243 and 187) and Couve Glo ria de Portugal (ISA 84) have presented the highest resistance interac tion. For the development of host differential sets, the landraces ISA 2 (Penca de Mirandela), ISA 35 (Couve de Valhascos) and ISA 600 (Penc a Espanhola) could be further selected for the differentiation of P pa rasitica isolates. They are resistant to PHW 828 and susceptible to PH W 643. The same morphotypes and landraces were also screened at the se edling stage for resistance to clubroot, caused by Plasmodiophora bras sicae Woron.. Although some variation for resistance could be noticed in some the landraces tested, mainly Galega kale types, none of them p resented a sufficient level of resistance as to be directly be useful in breeding for resistance to race 6 of P brassicae.