EVALUATION OF FIELD PEPPERWEED (LEPIDIUM CAMPESTRE L.) AS A SOURCE FOR GLUCORAPHANIN PRODUCTION

Broccoli inflorescences have been recently shown to contain high levels of glucoraphanin (GLU), the precursor of the chemoprotective isothiocyanate, sulforaphanin. Field pepperweed (Lepidium campestre L.) leaves also contain a significant level of GLU. Eight field pepperweed accessions were evaluated in a greenhouse for higher aboveground biomass productivity and GLU yield. Results indicated that aboveground biomass production of the accessions varied from 5.2 to 35.6 g/plant, with the accession Ames 13,180 producing the highest. The GLU content of the accessions varied from 3.1 to 180.8 μg/FW g, with the accession Ames 15718 having the highest GLU content; whereas, Ames 13179 had the highest GLU yield/plant, mainly due to its higher biomass production. Ames 13179, 15718, and 13180 were the most promising accessions for GLU production under greenhouse conditions. A separate growth cabinet study was conducted to determine the impact of growing conditions (12/12 h day/night, 24/6°C; 12/12 h day/night, 24/12°C; 16/8 h day/night, 24/6°C; and 16/8 h day/night, 24/12°C) on plant growth and GLU content of the three most promising accessions. On average, under short day conditions, field pepperweed produced a significantly lower aboveground biomass when plants were grown in warmer nights than those grown in cooler nights. Under long day conditions, night temperatures had no impact on the total aboveground biomass production. On average, plants growing under short day conditions had a significantly higher GLU content when grown in cooler nights than those grown in warmer nights. However, under long day conditions, night temperatures had no impact on GLU content. On average, Ames 15718 produced significantly higher GLU content (> 2-fold) than that of the other two accessions, Ames 13179 and Ames 13180. For the highest GLU production, Ames 15718 should be grown under short day conditions with cooler nights.