33F-5


Isoflavone content in soybean seeds from different parts of plants grown under elevated atmospheric CO2 or O3

J. R. BORDIGNON, Food Science, University of Illinois at Urbana-Champaign / EMBRAPA Soybean, 259 ERML, 1201 W. Gregory Dr., Urbana, 61801-3838, S. P. Long, Crops Science, University of Illinois, 190 ERML 1201 W. Gregory Dr., Urbana, 61801-3838, and N. J. Engeseth, Dept. of Food Science & Human Nutrition, Univ. of Illinois, Urbana-Champaign, 259 ERML, 1201 W. Gregory Dr., Urbana, IL 61801.

Soybean plants are one of the most sensitive crops to changes in atmospheric O3 concentration, showing a yield reduction of 60% when grown under higher O3 concentration. Also, high concentration of CO2 leads to taller plants and increases in biomass. The atmosphere concentration of these two gases is increasing steadily and expected to double in the next 40-50 years.

The objective was to evaluate changes in isoflavone concentration of soybean seeds collected from different parts of plants grown under ambient conditions, high CO2 or high O3.

Eight soybean cultivars (Corsoy, Dwight, Loda, Mandarin, Pana, Pioneer, Richland and Williams) were grown in a FACE (Free Air gas Concentrated Enrichment) facility. Four rings 20 m diameter were set for each of the three gas conditions evaluated: 1- Control (normal CO2 and O3), 2- high CO2 and normal O3, and 3- normal CO2 and high O3. Samples were collected from the top canopy, medium and base part of plants (right before harvesting) and after harvesting. Isoflavones were extracted with 80% methanol for 24 hr, separated by HPLC and peak areas were used to estimate their concentration.

Cultivars Dwight, Mandarin, Pana and Williams grown under elevated CO2 experienced an increase (p<0.05) in total isoflavone content in seeds, while cultivars Corsoy, Dwight, Loda, Pioneer and Williams grown under elevated O3 experienced a decrease (p<0.05). Isoflavone concentration was higher in seeds obtained from the bottom part of the plants and lower in seeds from the top canopy.

In conclusion, high of CO2 or O3 can cause changes in isoflavone concentration of some cultivars but these changes are not accentuated by different position of the seeds in the plant. This research can shed light on future selection of cultivars for these potentially biologically active compounds in soy products.

Session 33F, Nutraceuticals & Functional Foods: Antioxidants and phytochemical analysis
2:00 PM - 5:30 PM, Tuesday PM Room Hall N-1

2004 IFT Annual Meeting, July 12-16 - Las Vegas, NV