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Sources and Origin of Resistance to Xanthomonas campestris pv. campestris in Brassica Genomes

January 2002 , Volume 92 , Number  1
Pages  105 - 111

J. D. Taylor , J. Conway , S. J. Roberts , D. Astley , and J. G. Vicente

Horticulture Research International, Wellesbourne, Warwick CV35 9EF, UK

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Accepted for publication 19 September 2001.

Two hundred and seventy-six accessions of mainly Brassica spp. were screened for resistance to Xanthomonas campestris pv. campestris races. In Brassica oleracea (C genome), the majority of accessions were susceptible to all races, but 43% showed resistance to one or more of the rare races (2, 3, 5, and 6) and a single accession showed partial resistance to races 1, 3, 5, and 6. Further searches for resistance to races 1 and 4, currently the most important races worldwide, and race 6, the race with the widest host range, were made in accessions representing the A and B genomes. Strong resistance to race 4 was frequent in B. rapa (A genome) and B. napus (AC genome), indicating an A genome origin. Resistance to races 1 and 4 was present in a high proportion of B. nigra (B genome) and B. carinata (BC genome) accessions, indicating a B genome origin. B. juncea (AB genome) was the most resistant species, showing either strong resistance to races 1 and 4 or quantitative resistance to all races. Potentially race-nonspecific resistance was also found, but at a lower frequency, in B. rapa, B. nigra, and B. carinata. The combination of race-specific and race-nonspecific resistance could provide durable control of black rot of crucifers.

Additional keywords: black rot of crucifers, disease resistance, pathogen variants.

© 2002 The American Phytopathological Society