Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2009
Publication Date: 10/1/2009
Citation: Griffiths, P.D., Marke, L.F., Robertson, L.D. 2009. Identification of Crucifer Accessions from the NC-7 and NE-9 Plant Introduction Collections that are Resistant to Black Rot (Xanthomonas campestris pv. campestris) Races 1 and 4 . HortScience 44:284-288.
Interpretive Summary: Black rot is a serious disease of vegetable crucifer crops worldwide and the most efficient way to control it would be through use of black rot resistant varieties. This research was to find sources black rot resistant varieties in the oilseed Brassica and the vegetable Brassica germplasm collections of the North Central and Northeast Plant Introduction Stations. These germplasm accessions were evaluated to resistance to race 1 and race 4 of black rot. Resistance was found with a high frequency for Brassica juncea (353 of 389 accessions tested) and also in Brassica carinata and Brassica nigra. However, the most important finding was the discovery of five accessions of Brassica juncea (PI 633154, A9285, PI 340208, PI 597831, PI 173847) with resistance to Black rot. This finding was important because it provided new sources of resistance than that found before and this was in a species that is more easily crossable to the vegetable crucifers. These five accessions can more easily be used in breeding for resistance to black rot in vegetable crucifers.
Technical Abstract: Black rot, caused by Xanthomonas campestris pv. campestris (Pam.) Dawson (Xcc), is a serious disease of vegetable crucifers worldwide. The USDA NC-7 and NE-9 regional plant introduction stations maintain vegetable, mustard and oilseed crucifers, of which 4084 accessions were available for testing, representing 23 genera and 125 species. These accessions were evaluated for resistance to black rot following wound inoculation with race 1 of the pathogen. Accessions that exhibited resistance to race 1 of Xcc were re-planted and inoculated with race 4 of the pathogen. Resistance was identified in 362 accessions of the mustard species (Brassica juncea, Brassica carinata and Brassica nigra), in particular, B. juncea where 353 of the 389 accessions tested exhibited high levels of resistance to Xcc. Resistance was also identified in five accessions of B. carinata out of 63 evaluated (PI 193460, PI 193959, PI 194254, PI 280230, PI 633077), and four accessions of B. nigra from the 83 evaluated (PI 197401, A 25399, A 25401, PI 458981). Five accessions of Brassica rapa (PI 633154, A9285, PI 340208, PI 597831, PI 173847) were identified, which represent new sources of resistance to Xcc that may be more easily crossed to the vegetable crucifers. Moderate resistance was identified in an accession of Eruca sativa (PI 633207), an accession of Lepidium spp. (PI 633265), an accession of Sinapis arvensis (PI 296079) and two accessions of B. napus (PI 469733 and PI 469828). These identified accessions represent germplasm that can be used in breeding for resistance to Xcc in vegetable crucifers.