Expression of Bacterial Blight Resistance in Brassica Leafy Greens Under Field Conditions and Inheritance of Resistance in a Brassica juncea Source.

Abstract

Brassica leafy greens are one of the most economically important vegetable commodity groups grown in the southeastern United States, and more than 28,000 metric tons of these crops are harvested in the United States annually. Collard and kale (Brassica oleracea Acephala group), mustard green (B. juncea), and turnip green (B. rapa) are the most commonly planted members of the brassica leafy greens group. In the last 10 years, numerous occurrences of bacterial blight on these leafy vegetables have been reported in several states. One of the pathogens responsible for this blight is designated Pseudomonas cannabina pv. alisalensis. Two B. rapa (G30710 and G30499) and two B. juncea (PI418956 and G30988) plant introductions (PIs) that exhibited moderate to high levels of resistance to this pathogen in greenhouse studies were tested for field resistance in comparison with eight commercial cultivar representatives of turnip green, mustard green, collard, and kale. The two B. juncea PIs and one of the B. rapa PIs (G30499) were found to have significantly less disease than all tested cultivars except 'Southern Curled Giant' mustard green (B. juncea) and 'Blue Knight' kale (B. oleracea). Inheritance of resistance studies performed with populations derived from the resistant G30988 and two susceptible PIs provided some evidence that resistance may be controlled by a single recessive gene.