Seong-Hyu Shin

Changes in anthocyanin and isoflavone concentrations in black seed-coated soybean at different planting locations.

This study assessed the altitudinal variations in the anthocyanin and isoflavone contents of six black seed coated soybean [Glycine max (L.) Merrill] cultivars. The black soybean cultivars Heugcheong, Seonheuk, Geomjeong 1, Geomjeong 2, Cheongja 2, and Cheongja 3 were planted at Milyang (12 m above mean sea level — low altitude) and Muju (600 m — high altitude), Korea on 10 June 2005 and 2006. The total anthocyanin and isoflavone contents and individual components were investigated by reverse-phase high performance liquid chromatography (HPLC). All black soybean cultivars cultivated in high altitude possessed significantly higher total anthocyanin (p < 0.01) and isoflavone (p < 0.01) contents than those grown in low altitude. For anthocyanin composition, cyanidin-3-O-glucoside, cyanidin-3-O-galactoside, and peonidin-3-O-glucoside contents were significantly higher while delphinidin-3-O-glucoside contents was significantly lower at high altitude. The composition of individual isoflavones, 6″-O-malonyldaidzin, and 6″-O-malonylgenistin contents significantly increased at high altitude.

Yield of maize ( Zea mays L.) logistically declined with increasing length of the consecutive visible wilting days during flowering

Under future climate conditions, the frequency and severity of drought are expected to increase. Maize (Zea mays L.) is susceptible to drought, especially at flowering. The objective of this study was to investigate the effect of consecutive days of visible wilting (DAW) during tassel emergence using two types of Korean maize hybrids, Gwangpyeongok (Gwp; normal) and Ilmichal (Ilmi; waxy). Traits related to plant growth and yield were measured at harvest. Drought stress during tassel emergence significantly reduced the number of green leaves per plant. Silking was delayed due to drought stress during the stage of tassel emergence, although anthesis was only slightly affected, which resulted in an increase in the anthesis-silking interval (ASI). For each DAW, ASI increased by 1.6 days and 0.8 days for Gwp and Ilmi, respectively. The number of green leaves and ASI showed strong correlation with DAW length and grain yield, which suggested that those factors may be selective traits for drought tolerance at flowering. The filled grain number per plant declined logistically with increasing DAW due to reductions in kernels per row and percentage of filled grains. The filled grain number per plant significantly declined starting at 5 and 10 DAW in Gwp and Ilmi, respectively, which indicated that drought stress effects are dependent on drought severity and the genetic characteristics of specific hybrids. Probit analysis revealed that DAW causing 50% reduction in maize grain yield was about 4.7 and 6.3 days in Gwp and Ilmi, respectively, which resulted in about 13.6% and 9.2% reduction in grain yield per day of DAW, respectively. These results indicate that Gwangpyeongok is more sensitive to drought stress during flowering than Ilmichal.

Physiological and Protein Profiling Response to Drought Stress in KS141, a Korean Maize Inbred Line

Understanding the complex response mechanism of a crop to drought is the major step in the developing of tolerant genotypes. In our study, to investigate physiological traits and proteome dynamics, an inbred maize (Zea mays L.) line (KS141) was subjected to 10 days of water-withholding at the V5 or V6 leaf stage. The subsequent analysis of their physiological parameters revealed a decreased relative leaf water content, Fv/Fm, stomatal conductance, net CO2 assimilation rate, leaf transpiration, and water use efficiency, resulting in severe growth retardation of leaf area, stem length and width, aerial part, and root dry matter at 3 and 10 days after withholding water. However, aerial part and root dry matter were little changed during drought stress for 3 days. To understand the proteome dynamics during the 10-day drought stress in maize leaves, comparative proteome analysis was carried out between the well-watered and drought-treated leaves. Proteins were extracted using phenol extraction method from leaves with/without drought stress, and then separated by 2-DE. After 2-DE gel analyses, 14 differentially expressed protein spots were identified by MALDITOF mass spectrometry. Out of 14, eleven and three protein spots were found to be up- or down-regulated, respectively. Interestingly, stress-related proteins such as glutathione S-transferase, abscisic stress-ripening proteins, and pathogenesis-related proteins were increased by drought stress. Our study may provide molecular mechanisms and selective markers for drought tolerant maize genotypes.

Impact of the consecutive days of visible wilting on growth and yield during tassel initiation in maize ( Zea Mays L.)

Maize (Zea mays L.) is a major crop with different uses but shows significant susceptibility to drought stress. Recent climate change has caused prolonged drought stress, but in most countries maize production relies on rain-fed cultivation. This study was to investigate the impact of the consecutive days of visible wilting (DAW) during tassel initiation (V6) using two types of Korean maize hybrids, Gwangpyeongok (GWP) and Ilmichal (Ilmi). The traits related to plant growth and yield were measured at harvest. Drought stress during tassel initiation linearly reduced plant elongation and dry matter accumulation with the length of DAW increasing but did not affect the leaf number per plant. Our results from the simple linear regression analysis indicated that silking of GWP and Ilmi would be delayed by 0.78 and 0.61 days per DAW, respectively, which was similar to anthesis. Still, little change was observed for interval between anthesis and silking under the same condition. The kernels per row were very dependent on the length of DAW but the rows per ear were not. The percentage of filled grains and the 100- grain weight were significantly reduced only at 15- or 20-DAW and more markedly so in Gwangpyeongok at 20-DAW. The filled grain number per plant showed a gradual logistical decline mainly due to decreases in the kernels per row. All these reductions may be because initiation and growth of tassel, ear, and kernels and internode elongation beginning around V6 are sensitive to water deficits. Probit analysis revealed that the DAW to cause 50% reduction in plant grain yield was about 12 and 20 days in GWP and Ilmi, resulting in about 4.5 and 2.7% reduction a day of DAW, respectively. These results indicate that Gwangpyeongok may be more sensitive to drought stress during tassel initiation than Ilmichal.

Evaluation of waterlogging tolerance with the degree of foliar senescence at early vegetative stage of maize ( Zea mays L.)

Maize is highly susceptible to waterlogging, which is becoming one of worldwide abiotic threats in many agricultural areas. This study was evaluated to establish the screening method and to find tolerant maize genotypes. Six Korean maize inbred lines were subjected to waterlogging at V3 for 15 days using a big size pot with single maize plant (big pot method) and a box containing 31 maize plants at a time (box method). The degree of foliar senescence and the number of senescent leaves were better indicators for selecting waterlogging tolerant maize genotypes than SPAD value and plant height. The degree of foliar senescence revealed that KS124, KS140, and KS141 are tolerant, and KS85 is susceptible to waterlogging at the early growth stage. These responses of foliar senescence were in clear accordance with those of plant grain yield, which was supported by stress tolerance index for grain yield. The box method also showed the similar response of foliar senescence to the big pot method. Therefore, this box method based on foliar senescence may be simple and efficient for large-scale screening of maize germplasm against waterlogging stress. It was concluded that foliar senescence can be a good indicator for selecting tolerant maize genotypes against waterlogging at the early growth stage.

Crossbreeding of cry1Ac/bar Transgenic Progeny with a Non-transgenic Elite Rice Cultivar for Minimizing the Underlying Grain Cost of Bt Transgenic Rice

Most Bt transgenic rice events have an underlying grain cost depending on the insect pressure in the field. This study was conducted (1) to determine if the cry1Ac/bar genetically modified (GM) rice (designated Agb0101) based on a Korean japonica rice cultivar has any underlying grain cost and (2) to develop cry1Ac/bar GM rice lines with yield performance similar to those of Korean elite cultivars via crossbreeding. A three-year field experiment showed that Agb0101 had a high underlying grain cost equivalent to 18% grain yield loss, and this cost was mainly due to the grain number per panicle. Moreover, it was found that the cry1Ac/bar transgene was inherited as a single dominant gene. BC1F4―F5 crossbred progeny derived from an anther culture of Agb0101―showed phenotypic resemblance to non-transgenic Korean elite cultivars, resulting in a decrease in the grain yield cost of Agb0101 from 27% to 10%. These results suggest that Bt-GM rice-oriented cross-fertilization with a non-GM elite cultivar followed by two- or threefold selection is a feasible method to minimize or remove the underlying grain cost of the Bt transgenic insect-resistant rice line.

Effect of plant density on growth and yield of extremely late-planted korean sweet corn hybrids ( Zea mays L.) for fresh market

Sweet corn has a short growing period of 80 to 90 days in Korea, which allows famers to grow this crop using various cropping systems. This objective of this study was to find the optimum plant density for Korean sweet corn (se) hybrids ‘Godangok’ and ‘Guseulok’ when they were grown as the second crop. Plant densities were 5,710, 6,670, and 8,000 plants 10a-1 and planting dates were 20 July and 30 July, 2013. There was no interactive effect between plant density and hybrid for all the analyzed parameters in this study. Increasing plant density up to 8,000 plants 10a-1 led to no significant gain in marketable ear yield. Although the total number of ears was increased about 21 ç 33% at the highest plant density than at lower densities, e.g., 6,670 or 5,710 plants 10a-1, the percentage of marketable ear number and individual ear weight decreased with increasing plant density. Individual ear weight of marketable ears was significantly greater, e.g., by 8 ç 13%, at 5,710 plants 10a-1 and 6,670 plants 10a-1 than at 8,000 plants 10a-1. Similar results were obtained for ear length and width and filled length under the given plant densities, which indicated that increasing plant density may decrease individual ear fresh weight and ear size with good tip fill. Increasing plant density up to 8,000 plants 10a-1 caused the lowest harvest index, which resulted in little gain in fresh ear yield compared to the lower plant densities of 5,710 and 6,670 plants 10a-1. These results indicated that the optimum plant density for those sweet corn hybrids planted in July would be between 5,700 and 6,700 plants 10a-1 in terms of marketable ear yield and quality of marketable ears.