Black Rot of Broccoli Caused by Xanthomonas campestris pv. Campestris

Lee, Seung Don; Lee, Jung Hee; Kim, Sun Yee; Kim, Yong Ki; Lee, Yong Hoon; Heu, Sung Gi; Ra, Dong Soo

Research in Plant Disease 2006;12(2):134-138.
Published online August 30, 2006.

Xanthomonas campestris pv. campestris에 의한 브로콜리의 검은썩음병

이승돈, 이정희, 김선이, 김용기, 이용훈, 허성기, 나동수

Black Rot of Broccoli Caused by Xanthomonas campestris pv. Campestris

Seung Don Lee, Jung Hee Lee, Sun Yee Kim, Yong Ki Kim, Yong Hoon Lee, Sung Gi Heu, Dong Soo Ra

Abstract

A new bacterial disease of broccoli (Brassica oleracea var. italica) was observed on field-grown plants in Pyungchang during 2003 and 2004. Seedling infections first appeared as a blackening along the margins of the cotyledon. Cotyledon shriveled and dropped off. Infected seedlings were stunted and yellowed and eventually died. The disease was easily recognized by the presence of yellow, V-shaped, or U-shaped areas extending inward from margin of the leaf. As the disease progressed, the yellow lesions turned brown and the tissues died. Isolations made from diseased leaves on yeast extract dextrose calcium carbonate agar yielded nearly pure cultures of a yellow-pigmented bacterium typical of a xanthomonad. Two bacterial strains were purified and used for further tests. Pathogenicity of strains was confirmed on 3-week-old crucifer (cabbage, Chinese cabbage, kale, radish and broccoli) plants cut by scissors with bacterial suspensions containing 108 cfu/ml of phosphate buffered saline. The Biolog and fatty acid analyses and 16S rDNA sequencing of two strains (SL4797 and SL4800) from broccoli black rot showed that they could be identified as X. campestris pv. campestris because of their high similarity to the tester strain (X. campestris pv. campestris NCPPB528) with a match probability of 100%. This is the first report of black rot of broccoli in Korea.

Key Words: Black rot, Brassica oleracea var. italica, Xanthomonas campestris pv. campestris