APPLICATION OF KNOWLEDGE ABOUT RESISTANCE GENE ORGANISATION IN ARABIDOPSIS THALIANA FOR GENETIC IMPROVEMENT OF BRASSICA OLERACEA
T WILKES1, D LECKIE1, N COGAN1, C RYDER1, S BREEDS1, P GORDON1, I PARKIN2, P BITTNER-EDDY1, K WILLIAMS3, J BEYNON1, I CRUTE1 and E HOLUB1
1Horticulture Research International, Wellesbourne, Warwick CV35 9EF, UK; 2Agriculture & AgriFood Canada, 107 Science Place, Saskatoon, Saskatchewan, Canada; 3Plant Research Centre, S. Aust. R & D Inst., Adelaide SA5001, Australia
Background and objectives
Two approaches have been taken to utilise the information available from A. thaliana to facilitate the identification, mapping and cloning of resistance genes from Brassica oleracea. Firstly, an investigation of the degree of synteny between a Major RPP gene complex (MRC-F) on the bottom of chromosome 3 of A. thaliana and corresponding regions in B. oleracea was carried out. Specific DNA sequences from the RPP1 gene family from the MRC-F region were used as heterologous probes to identify homologues in B. oleracea. The second approach was to identify functional resistance genes in B. oleracea and generate associated AFLP markers which could be placed on an A. thaliana map to enable the identification of further markers and candidate homologous genes from A. thaliana.
Results and conclusions
Eight sources of resistance to P. parasitica and seven sources of resistance to Albugo candida (the causal agent of white blister) have been identified from a large-scale screening of 410 accessions of B. oleracea. Selected resistant plants have been crossed with a susceptible rapid-cycling line of B. oleracea and F2 populations produced. Segregation analyses have been carried out and all the resistant responses appear to be under simple genetic control. DNA from F2 plants has been used to produce resistant and susceptible bulks from each cross for AFLP analysis. Markers are being generated for four of the sources of disease resistance.