Young-Hyun Hwang

Effects of light treatment on isoflavone content of germinated soybean seeds.

Our research objective was to increase isoflavone content in the germinated soybean seeds of four different varieties (Pungsannamulkong, Cheongjakong, Aga4, and Aga3) by optimizing light treatments (dark, greenhouse, fluorescent, incandescent, and ultraviolet lamps). The results demonstrated that the highest isoflavone content was produced from the Aga3 variety, which was developed by an interspecific cross between Eunhakong (Glycine max) and KLG10084 (G. soja) at the Plant Genetic Laboratory, Kyunpook National University. Aga3 is known to have one of the highest isoflavone content in the world at present. Our results recommend exposure of 7-day-old Aga3 sprouts to a combined light treatment of greenhouse lamps (12 h per day) and ultraviolet light (40 min per day) for maximum isoflavone production. Aga3 produced high levels of isoflavone because, in part, it contained very high isoflavone levels within the seed as compared with the other varieties. Under stress conditions, Aga3 could produce over 1.90 times more isoflavone than its seed content and 1.53 times more isoflavone than when grown under dark conditions.

Chrysosporium pseudomerdarium produces gibberellins and promotes plant growth.

We isolated 10 endophytic fungi from the roots of drought stressed soybean cultivar Hwangkeumkong and bioassyed on waito-c rice and soybean seedlings, in order to identify plant growth-promoting fungi. The fungal isolate D-2-1 provided the best result for plant height and biomass promotion as compared to wild type Gibberella fujikuroi. The D-2-1 culture filtrate (CF) was analyzed for the presence of gibberellins (GAs) and it was observed that all physiologically active GAs, especially gibberellic acid, were present in higher amounts (GA1, 0.24 ng/ml; GA3, 8.99 ng/ml; GA4, 2.58 ng/ml and GA7, 1.39 ng/ml) in conjunction with physiologically inactive GA5, GA9, GA15, GA19, and GA24. The fungal isolate D-2-1 was identified as a new strain of Chrysosporium pseudomerdarium through phylogenetic analysis of 18S rDNA sequence. Plant growth promotion and GAs production capacity of genus Chrysosporium have been reported for the first time in this study.

Fatty acid composition in each structural part of soybean seed and sprout

Fatty acid composition and C18:2:C18:3 of soybean seed and sprout is important for soy-industries to manufacture quality products. Six soybean varieties were analyzed by gas chromatography to determine fatty acid composition and linoleic to linolenic acid ratio (C18:2:C18:3) in seed, sprout, and their structural parts. In the case of whole seed and its structural parts, significant variation in fatty acid composition and C18:2:C18:3 were observed between varieties except palmitic acid (C16:0), while all the parameters were significantly different for seed parts. Significant interactions of variety with seed parts were observed for oleic acid (C18:1), C18:2 and C18:2:C18:3. The highest saturated fatty acid, C18:1 and polyunsaturated fatty acid were recorded in seed coat, cotyledon, and seed axis, respectively. The lowest C18:2:C18:3 was found in seed axis. In the case of sprout study, variety had significant effect on all the parameters observed for whole sprout, cotyledon, root, and except C18:3 for hypocotyl. Culture days had significant effect on C16:0, C18:2 and C18:3 in whole sprouts, while only on C18:3 and C18:2:C18:3 in cotyledon. For hypocotyl, culture days had significant effect on C18:1, C18:2 and C18:2:C18:3, however, C16:0, C18:1, C18:3, and C18:2:C18:3 were significantly different in root. In sprout, days and variety interacted significantly for C16:0, C18:3 and C18:2:C18:3, and C18:1, C18:2, C18:3, and C18:2:C18:3, respectively for whole, cotyledon, and root. The significantly lowest C18:2:C18:3 (1.1) was observed in hypocotyl and root of Hwangkeumkong in 5 days. Knowledge of fatty acid composition and C18:2:C18:3 of seed, sprout, and their parts could be applicable for oil and other soy-food industries to make quality products.