Submitted to: International Conference on Pseudomonas syringae Pathovars
Publication Type: Proceedings
Publication Acceptance Date: September 20, 2002
Publication Date: June 20, 2003
Citation: Bull, C.T., Goldman, P.H., Cintas, N.A., Koike, S.T. Identification of pseudomonas species from a variety of hosts in the salinas valley of california. International Conference on Pseudomonas syringae Pathovars. 2003. p. 607-615. Technical Abstract: Since 1995 several new bacterial diseases on vegetables have emerged in the Salinas Valley of California, USA. Some of these diseases are becoming increasingly problematic to the vegetable production industry. Recently, a new pathogen, Pseudomonas syringae pv. Alisalensis was shown to cause both bacterial blight on broccoli (Brassica oleracea L. var italica/botrytis) and broccoli raab (Brassica rapa subsp. rapa), while P. syringae pv. maculicola was shown to cause bacterial spot on yet another crucifer, broccolini (Brassica oleracea L. var. botrytis X Brassica alboglabra). Additional bacterial diseases have occurred on crucifers in the Salinas Valley since 1999, particularly on swiss chard (Beta vulgaris ssp. vulgaris), Arugula (Eruca vesicaria ssp. Sativa), and brussel sprouts (Brassica oleracea var. gemmifera). Bacterial diseases on sugarbeet (Beta vulgaris ssp. vulgaris), and celery (Apium graveolens) have also emerged as problems during the last three years. We are interested in understanding the relationships among these bacterial pathogens and how their ability to infect multiple hosts influences disease development in the current vegetable production system. To this end we studied the etiology of these diseases. The phenotypes of the kale and swiss chard pathogens have been characterized. Isolated pathogens were gram negative, positive for levan production and the hypersensitive response on tobacco. The strains were negative for oxidase production, potato rot, and arginine dehydrolyase activity. The kale isolates were fluorescent on KMB but the swiss chard isolates were variable for fluorescence. Strains from kale were consistently identified as P. syringae by fatty acid analysis, but fatty acid analysis was not useful for the swiss chard isolates because the identity of the organism varied among the isolates. Isolates from all hosts mentioned have been evaluated by REP-PCR and banding patterns were compared to several pathotypes. Rep-PCR analysis indicated that the pathogen from brussel sprouts was very similar to P. syringae pv. maculicola strains isolated in this region. None of the other isolates showed similarity to the controls, P. syringae pv. maculicola, P. syringae pv. tomato, or P. syringae pv. alisalensis.