Chang-Gi Kim

Expression of the Arabidopsis AtMYB44 gene confers drought/salt-stress tolerance in transgenic soybean

AtMYB44, a member of the subgroup 22 R2R3 MYB transcription factors, positively regulates abscisic acid signaling to induce stomatal closure, thus conferring drought/salt-stress tolerance in Arabidopsis thaliana. In this study, AtMYB44 was transformed into soybean [Glycine max (L.) Merrill] using the cotyledonary-node method. The resulting homozygous lines were shorter than the non-transgenic controls (Bert) throughout the growth period when grown in a greenhouse. The transgenic soybeans exhibited significantly enhanced drought/salt-stress tolerance, as observed in Arabidopsis. In field cultivation studies, the transgenic soybean plants showed reduced growth, but much higher yields upon seed harvest, demonstrating improved environmental stress tolerance. The amino acid and fatty acid compositions were not significantly altered in seeds harvested from the transgenic lines. These results suggest that the interaction of AtMYB44 with specific sequences in target gene promoters and/or specific proteins activates a tolerance mechanism that is conserved in Arabidopsis and soybean.

Improved production of teicoplanin using adsorbent resin in fermentations

Aims: To use adsorbent resins in fermentations to eliminate toxic effects on growth, reduce feedback repression of production and assist in recovery of teicoplanin.

A bleaching herbicidal activity of methoxyhygromycin (MHM) produced by an actinomycete strain Streptomyces sp. 8E-12.

Aims: To screen bioherbicidal isolates and evaluate herbicidal activity of methoxyhygromycin (MHM) produced by Streptomyces sp. 8E‐12.

Effects of soil conservation measures in a partially vegetated area after forest fires

After forest fires on the east coast of Korea in 2000, some burnt areas were left untreated. Although 80% of the area was reasonably revegetated within 3 months, about 20% of the area was partially vegetated, mainly due to a low density of sprouters and poor growing conditions (eroded soil and steep slopes). Three years after the fires, the effect of soil conservation measures, such as mulching with wood chips, seeding with native plant species and log erosion barriers (LEBs), on runoff and soil erosion were examined using runoff plots. Wood chip mulching greatly reduced runoff and sediment yields and these effects were consistent regardless of the volume of rainfall. Neither seeding nor LEBs reduced runoff and sediment yields. No positive or negative effects of mulching, seeding or LEBs on ground vegetation cover were observed. The ineffectiveness of seeding and LEBs may have been due to the steep slope, the failure of germination and establishment of seeded plants, and the small diameter of logs. Treating hill slopes with mulch should be considered where post-fire regeneration is slow and there is an absence of organic material such as litter.

Arbuscular Mycorrhizal Fungi Community Structure, Abundance and Species Richness Changes in Soil by Different Levels of Heavy Metal and Metalloid Concentration

Arbuscular Mycorrhizal Fungi (AMF) play major roles in ecosystem functioning such as carbon sequestration, nutrient cycling, and plant growth promotion. It is important to know how this ecologically important soil microbial player is affected by soil abiotic factors particularly heavy metal and metalloid (HMM). The objective of this study was to understand the impact of soil HMM concentration on AMF abundance and community structure in the contaminated sites of South Korea. Soil samples were collected from the vicinity of an abandoned smelter and the samples were subjected to three complementary methods such as spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE) for diversity analysis. Spore density was found to be significantly higher in highly contaminated soil compared to less contaminated soil. Spore morphological study revealed that Glomeraceae family was more abundant followed by Acaulosporaceae and Gigasporaceae in the vicinity of the smelter. T-RFLP and DGGE analysis confirmed the dominance of Funneliformis mosseae and Rhizophagus intraradices in all the study sites. Claroideoglomus claroideum, Funneliformis caledonium, Rhizophagus clarus and Funneliformis constrictum were found to be sensitive to high concentration of soil HMM. Richness and diversity of Glomeraceae family increased with significant increase in soil arsenic, cadmium and zinc concentrations. Our results revealed that the soil HMM has a vital impact on AMF community structure, especially with Glomeraceae family abundance, richness and diversity.

Monitoring the occurrence of genetically modified soybean and maize around cultivated fields and at a grain receiving port in Korea

Increased imports of genetically modified (CM) soybean and maize might cause genetic contamination of those crops that are conventionally bred, as well as wild soybeans within Korea. Leaves of maize and both cultivated and wild soybeans were sampled in and near rural fields to detect the presence of transgenes. Roadsides around a major grain port in Incheon were also surveyed to monitor the occurrence of incoming CM soybean and maize. The amplificability of DNA extracted from the collected samples was determined by PCR using soybean- or maize-specific primers: lectin and zein genes, respectively. The presence or absence of transgenes was detected by primer sets for the 35S and nos genes. Transgenes were not found in the cultivated or wild soybean or in the maize collected from cultivated fields. However, we obtained one GM maize plant among seven along the roadsides around Incheon Port. Although the effect of a single GM maize plant would be negligible and would not pose any threat to natural environments, an increase in the import of GM plants might lead to future, unapproved cultivation of GM crops. Therefore, appropriate monitoring is necessary to detect the occurrence of GM plants in areas around grain receiving ports and within agroecosystems.

Using T-RFLP to Assess the Impact on Soil Microbial Communities by Transgenic Lines of Watermelon Rootstock Resistant to Cucumber Green Mottle Mosaic Virus (CGMMV)

To establish quantitative methods for ecological risk assessment, we assessed the impacts of transgenic watermelon rootstock (Citrullus lanatus (Twinser) cv. Gongdae) that was resistant to cucumber green mottle mosaic virus. The diversity of soil bacteria and fungi was monitored from May to July of 2005. Terminal restriction fragment length polymorphism (T-RFLP) was used with 16S ribosomal RNA (rRNA) coding genes for bacterial communities and with internal transcribed spacer (ITS) regions of rRNA coding genes for fungal communities. Multivariate analysis of variance (MANOVA) on the principal component analysis (PCA) scores of T-RF profiles detected no significant difference between microbial communities with transgenic or non-transgenic watermelon. Likewise, the results of our multi-response permutation procedure (MRPP) tests on non-metric multidimensional scaling (NMS) showed no significant difference between plant types. However, both MANOVA on PCA and MRPP on NMS revealed significant changes in the microbial community during the growing season. We used loading values of PCA to rank the abundances of bacterial species and found increases of some species in June and July.

Two-year field study shows little evidence that PPO-transgenic rice affects the structure of soil microbial communities

There is global concern about the environmental consequences associated with transgenic crops. Their effects on the soil ecosystem are of special interest when assessing ecological safety and integrity. Although many efforts have been made to develop crops genetically modified to have resistance to protoporphyrin oxidase (PPO)-inhibiting herbicides, little is known about their influence on soil microbial communities. We conducted a 2-year field study and an analysis via terminal restriction fragment length polymorphism (T-RFLP) to assess the impacts of PPO-transgenic rice on bacterial and fungal communities. In the first year we sampled the rhizosphere and surrounding bulk soil, while in the second year we sampled rhizosphere soil only. No differences were observed in the diversity indices and community composition of microbial communities between transgenic rice and its parental non-transgenic counterpart (cultivar Dongjin). Instead, community variation was strongly dependent on growth stage and year. Therefore, we observed no adverse effects by these crops of modified rice on the microbial community composition in paddy soils.

Effects of the ignition timing retard and the compression ratio on the full-load performance and the emissions characteristics of a heavy-duty engine fuelled by hydrogen–natural-gas blends

Heavy-duty natural-gas vehicles contribute towards environmental improvement in the air quality of downtown areas because the particulate matter emissions are quite low and lean combustion facilitates improvement in the efficiency and reduction in the harmful emissions. However, because stronger emission regulations such as Euro VI cannot be satisfied using the current technology, new technology is required. Hydrogen–natural-gas blend engines have been investigated as an alternative in preparation for the hydrogen era. Such engines make further emission reductions and efficiency improvements possible by extending the lean-combustion limit. However, they do have some disadvantages such as the degradation in the full-load performance, which can limit the reduction in the nitrogen oxide emissions or the operation range because the extension of the lean-burn limit requires a larger amount of intake air even under a wide-open throttle operating condition. In the present study, the full-load performance and emissions characteristics of a hydrogen–compressed-natural-gas engine were evaluated using hydrogen–compressed-natural-gas fuel with a hydrogen content of 30 vol %. In order to achieve performance improvement, a spark timing retard strategy was employed, together with a change in the compression ratio. After examining the full-load performance for each parameter change, the emission characteristics were assessed to analyse the commercialization potential and feasibility of this hydrogen–compressed-natural-gas engine. For a higher compression ratio, the specified torque value could be achieved with spark timing retard; an excess air ratio of 1.8 was found to be preferable, and the nitrogen oxide emissions standard of Euro VI was satisfied.

Appearance / Instance of Genetically Modified Maize at Grain Receiving Harbors and Along Transportation Routes in Korea

Genetically modified (GM) crops are not permitted to be cultivated in Korea, but can only be imported as food or feed purposes. The import of GM crops has sharply increased in recent years, thus raising concerns with regard to the unintentional escape of these crops during transport and manufacturing as well as the subsequent contamination of local, non-GM plants. Hence, monitoring of GM crops was studied in or outside of grain receiving ports as well as from feed-processing plants in Korea during July 2008. We observed spilled maize grains and established plants primarily in storage facilities that are exposed around the harbors and near transportation routes of the feed-processing areas. Based on the PCR analyses, a total of 17 GM maize plants and 11 seeds were found among the samples. In most cases, the established maize plants found in this study were at the vegetative stage and thus failed to reach the reproductive stage. This study concludes that, in order to prevent a genetic admixture in the local environment for GM crops or seeds, frequent monitoring work and proper action should be taken.