ISHS Acta Horticulturae 407: ISHS Brassica Symposium - IX Crucifer Genetics Workshop
SCREENING PORTUGUESE COLE LANDRACES FOR RESISTANCE TO WHITE RUST [ALBUGO CANDIDA (PERS.) KUNTZE] |
| Authors: | M.P. Santos, J.S. Dias, A.A. Monteiro |
| Keywords: | Brassica oleracea, disease resistance, Galega kale, Tronchuda cabbage |
| Abstract:
Thirty-one Brassica oleracea accessions including Portuguese cole landraces and two imported cabbage cultivars grown in Portugal for a long time were screened for resistance to two Portuguese isolates of A. candida. The two cotyledons of seven-day old seedlings were inoculated with a 1 x 105/ml suspension of zoospores after germination at 12°C. The host-pathogen interaction phenotype (IP) of sixty plants per accession and two controls was evaluated at 8 and 10 days after inoculation using a 0–9 scale of increasing susceptibility (Williams, 1987). Results are expressed as the mean score disease index (DI) and as the number of seedlings per IP class. No differential reaction was revealed in relation to the two isolates tested. The screening revealed highly variable reactions within Portuguese cole landraces ranging from IP=2.9 to IP=8.2. Most of the accessions were very susceptible although some expressed resistance to both isolates. ‘Couve Algarvia’ (DI=2.9), ‘Couve Glória de Portugal’ (DI=3.4) and ‘Couve Portuguesa’ (DI=3.5) were the most resistant landraces. This study confirmed the existence of resistance among Portuguese coles to white rust and the potential benefit of exploring the high genetic diversity among Portuguese cole landraces as a source of disease resistance. | |
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