Jun Gu Lee

Comparison of Glucosinolate Profiles in Different Tissues of Nine Brassica Crops.

Glucosinolate (GSL) profiles and concentrations in various tissues (seeds, sprouts, mature root, and shoot) were determined and compared across nine Brassica species, including cauliflower, cabbage, broccoli, radish, baemuchae, pakchoi, Chinese cabbage, leaf mustard, and kale. The compositions and concentrations of individual GSLs varied among crops, tissues, and growth stages. Seeds had highest total GSL concentrations in most of crops, whereas shoots had the lowest GSL concentrations. Aliphatic GSL concentrations were the highest in seeds, followed by that in sprouts, shoots, and roots. Indole GSL concentration was the highest in the root or shoot tissues in most of the crops. In contrast, aromatic GSL concentrations were highest in roots. Of the nine crops examined, broccoli exhibited the highest total GSL concentration in seeds (110.76 µmol·g−1) and sprouts (162.19 µmol·g−1), whereas leaf mustard exhibited the highest total GSL concentration in shoots (61.76 µmol·g−1) and roots (73.61 µmol·g−1). The lowest GSL concentrations were observed in radish across all tissues examined.

Effects of Air Temperature and Air Flow Rate Control on the Tipburn Occurrence of Leaf Lettuce in a Closed-type Plant Factory System

This study aimed to establish a practical method to reduce tipburn symptoms on leaf lettuce cultivars in a closed plant factory system, focusing on air temperature conversion at specific plant growth stages and artificial air flow application strategies using pre-screened tipburn-sensitive cultivars. Inter-conversion effect of day temperature among 18, 22, and 25°C, 12 days after transplanting on tipburn occurrences, were compared with stable day temperature condition. Horizontal air flow rates were controlled at 0.28 (Low), 0.55 (Medium), and 1.04 m·s−1 (High). Tipburn occurrences were highly variable depending on the lettuce cultivars tested. Following the initial screening of 28 leaf lettuce cultivars under 3 different light intensity conditions (ranging from 150 to 250 mol·m−2·s−1), two cultivars exhibiting relatively higher percentages of tipburn were selected for the following air temperature and air flow treatments. None of the temperature treatments effectively reduced tipburn symptom, while adjusting the temperature to a lower day temperatures at 12 days after transplanting only had a minor effect on lettuce growth and tipburn occurrence. In contrast, stable horizontal 24-hour air flow rates above 0.28 m·s−1 effectively reduced tipburn symptom, with no significant differences being found among the tested air flow rates, while above 65% of tipburned plants were found in the control plot of 0.08 m·s−1 flow rate. When stable air flow was applied, compared to the control, there was an increase in the absolute calcium content and a decrease in the calcium content difference between the inner and outer lettuce leaves. This calcium balance change may have occurred due to the enhanced transpiration in the inner parts of plants. This study showed that stable horizontal air flow application along cultivation beds is more effective than air temperature control in decreasing tipburn symptoms in a closed plant factory system.

Comparative analysis of individual glucosinolates, phytochemicals, and antioxidant activities in broccoli breeding lines

The aim of this research was to evaluate the profile and concentration of individual glucosinolates (GSL), and the total phenol content (TPC), total flavonoid content (TFC), ascorbic acid content, and antioxidant activity of broccoli florets and flower stalks (10 commercial cultivars, 19 F1 hybrids, and 20 inbred lines). All broccoli heads were harvested at their marketable stage, and their flower stalks and florets were subjected to phytochemical analysis. GSL, TPC, TFC, and ascorbic acid content varied significantly depending on broccoli genotype. Altogether, nine GSLs were identified, four of which (glucoraphanin, progoitrin, glucoerucin, and glucobrassicin) were the most common in both broccoli flower stalks and florets. In florets, glucobrassicin was the most abundant GSL (4.46 μmol·g-1 DW), followed by glucoraphanin (1.93 μmol·g-1 DW), whereas glucoraphanin was the most abundant in flower stalks (1.47 μmol·g-1 DW). The concentrations of total GSLs, TPC, and TFC in florets were relatively higher than those in the flower stalks, whereas the concentration of ascorbic acid was higher in the flower stalks than the florets. Almost all F1 hybrids and inbred lines exhibited higher TPC, TFC, ascorbic acid concentration, and antioxidant activities than those in the commercial cultivars. Three F1 hybrids; 5075, 5078, and 5079, and one inbred line (5308) had the highest glucoraphanin and total GSL content. Three inbred lines, 5307, 5311, and 5409 had the higher concentration of glucobrassicin and total GSLs, superior antioxidant activity with low PRO+EPI content. These results suggest that these genotype selections had desirable compositions of individual GSLs and higher nutritional value for commercialization as functional vegetables.

Influence of air temperature on yield and phytochemical content of red chicory and garland chrysanthemum grown in plant factory

This study was conducted to improve the yield and quality of red chicory (Cichorium intybus L.) and garland chrysanthemum (Chrysanthemum coronarium L.) grown in a plant factory where fluorescent lamps were used as an artificial light source. Seeds of a chicory ‘Juck’ and garland chrysanthemum ‘Joongyupssuckgot’ were sown in a peat-lite germination mix. Twenty-day old seedlings with roots being washed off were anchored on a styrofoam board and were grown in hydroponics for 30 days. Plants were exposed to one of the three different air temperature regimes (20, 25, and 30°C during the day combined with 18°C during the night) which were being monitored with a sensor at 30 cm above the plant canopy. In all treatments, light intensity was maintained at 200 ± 20 μmol·m−2·s−1, day length was 12 hours, and relative humidity was 50–80%. Electrical conductivity (EC) and pH of the nutrient solution were 2.0 ± 0.2 dS·m−1 and 6.5–7.0, respectively, in all treatments. Increase in fresh weight was observed in chicory, but not in garland chrysanthemum, in both 25 and 30°C as compared to 20°C. Photosynthetic capacity and ascorbic acid content of chicory leaves were higher at 25°C than in other temperatures. In garland chrysanthemum, photosynthetic capacity was the greatest in both 20 and 25°C, while ascorbic acid content was the greatest in 25°C. Also plants grown at 25°C had the greatest contents of total phenol and flavonoid in both chicory and garland chrysanthemum. Hence, the optimum temperature appears to be 25°C for growing both chicory and garland chrysanthemum in the plant factory with fluorescent light as the sole souse of light.

Ripening-Dependent Changes in Antioxidants, Color Attributes, and Antioxidant Activity of Seven Tomato (Solanum lycopersicum L.) Cultivars

To evaluate the ripening-dependent changes in phytonutrients, seven commercial cultivars (two general and five cherry) of tomatoes were cultivated under greenhouse conditions. Fruits were harvested at breaker, turning, pink, light red, and red stages of each cultivar, and antioxidant contents, color attributes, and antioxidant activities were measured. During ripening process, lycopene content increased from the breaker to red stage, while lutein displayed the reverse accumulation pattern, with higher values during the breaker stage. In contrast, β-carotene showed the highest levels of synthesis in pink and light red stages. Furthermore, flavonoids (quercetin, rutin, naringenin, and luteolin) also showed similar ripening-dependent changes, with higher quantities in pink and light red stages. Ascorbic acid showed continuously increasing patterns throughout ripening until the red stage, while the accumulation of total phenolics was cultivar-dependent. These results indicate that each antioxidant compound has a unique pattern of accumulation and degradation during the ripening process. “Unicon” exhibited highest total carotenoid (110.27 mg/100 g), total phenol (297.88 mg GAE/100 g) and total flavonoid content (273.33 mg/100 g), and consequently highest antioxidant activity (2552.4 μmol TE/100 g) compared to other cultivars. Throughout the ripening processes, total phenolics showed the highest correlation with antioxidant activity, followed by β-carotene and total flavonoids. In conclusion, ripening in tomatoes is accompanied by incremental increases in various antioxidant compounds to some extent, as well as by concomitant increases in antioxidant activity.

Genotypic variation in carotenoid, ascorbic acid, total phenolic, and flavonoid contents, and antioxidant activity in selected tomato breeding lines

Genotypic diversity of antioxidants is important for the development of tomato cultivars with high antioxidant contents. The contents and antioxidant activities of major antioxidant phytochemicals (carotenoids, ascorbic acid, total phenolics, and flavonoids) of 119 cherry and non-cherry tomato genotypes (16 commercial cultivars and 103 germplasm lines) were analyzed. Antioxidant activity was evaluated using FRAP, ABTS, and DPPH aßsays. Significant genotypic differences were observed in the content and antioxidant activity of all of the studied antioxidant phytochemicals. Relatively higher genotypic variation was found in carotenoid, ascorbic acid, and flavonoid content than in total phenolic content and antioxidant activities. Most variation in total carotenoid content of tomato fruits was caused by lycopene, followed by ß-carotene and lutein. One cherry tomato line, TG-110, and 3 non-cherry tomato germplasm lines, IT237605, IT237703, and IT237706, had much higher lycopene contents (> 1930 mg·kg -1), and thus higher total carotenoid contents, than did the other lines. The highest ascorbic acid and total flavonoid contents were found in TG-106 (388 mg·kg -1) and TC-053 (2353.0 mg·kg -1), respectively. Two cherry tomato lines, TC-019 and TC-053, and 3 non-cherry tomato lines, TG-107, TG-112, and TG-113, had significantly higher total phenolic contents and antioxidant activities than did the commercial cultivars. The genotypes selected on the basis of their phytochemical content could be used to develop new tomato cultivars with high antioxidant contents and activities.

Rapid monitoring of proline accumulation in paprika leaf sap relative to leaf position and water stress

The present study evaluated the pattern of proline accumulation in paprika leaf sap using a modified high-performance liquid chromatography (HPLC) method. Leaf sap samples were extracted using five different solvents and two extraction procedures, and were analyzed using modified HPLC analytical conditions. Enhanced extraction and HPLC analytical conditions were applied to analyze paprika leaf sap obtained from different plant parts (petiole and lamina sap) under different environmental conditions. The results showed that pure water extraction without heating or organic solvent performed best. This newly developed HPLC method was validated and confirmed suitable for analyzing proline content in leaf sap. The proline concentration in both the petiole and lamina sap showed a similar accumulation pattern, exhibiting the lowest proline concentration in the arbitrary node group I (1–5 nodes) and the highest concentration in the VI node group (21–30 nodes). In addition, sap from both the petiole and lamina of side stem leaves showed statistically higher proline content than the main stem leaves. The proline concentration also increased with increasing water stress during both the fruit enlargement and coloring stages, but primarily during the fruit coloring stage. The overall results suggest that the proline concentration in paprika leaves differentially accumulates throughout the plant and can be analyzed by water extraction using a modified HPLC method.

Yearly Variation in Glucosinolate Content in Inflorescences of Broccoli Breeding Lines

This study aimed to evaluate yearly variation in individual glucosinolate (GSL) profiles and content in inflorescences of 42 broccoli genotypes (9 commercial cultivars, 16 F1 hybrids, and 17 inbred lines) grown at the same location for two consecutive years (2014 and 2015). Broccoli heads were harvested at the marketable stage, and individual GSLs were analyzed using high performance liquid chromatography (HPLC). Eight GSLs, namely glucoiberin (IBE), progoitrin (PRO), epiprogoitrin (EPI), glucoraphanin (GRA), sinigrin (SIN), gluconapin (NAP), glucoerucin (ERU), and glucobrassicin (BRA) were identified in broccoli breeding lines grown in both 2014 and 2015. BRA was the most dominant GSL, followed by GRA and ERU, in both 2014 and 2015. The GSL content and profiles were dependent on both the genotype and the growing year. In total, five F1 hybrids (A311, 5022, 5036, 5075, and 5078) and three inbred lines (5401, 5402, and 5409) showed similar levels of BRA in both years. In addition, the levels of GRA in genotypes 5078, 5079, 5075, and 5308, and levels of IBE in 5078, 5079, and 5312 were stable between 2014 and 2015. Total GSL content varied from 3.32-16.92 μmol·g-1 in 2014 and 3.83-14.20 μmol·g-1 in 2014. The average total GSL content was higher in 2015 (8.18 μmol·g-1 DW) than in 2014 (7.66 μmol·g-1 DW). This trend was positively correlated to climatic factors such as relative humidity, temperature, and radiation, which were also higher in 2015 than in 2014. The genotypes 5035, 5402, and 5409 had the highest total GSL content among all genotypes in both years. Altogether, two F1 hybrids (5078 and 5079) and two inbred lines (5308 and 5409) showed stable and high GSL contents under two different climatic conditions. Therefore, these genotypes could be used for breeding functional materials for commercialization in the future. Additional key words: environmental variation, F1 hybrid, glucobrassicin, glucoraphanin, inbred line