Kyong-Hee Nam

Metabolomic changes in grains of well-watered and drought-stressed transgenic rice

BACKGROUND Drought induces a number of physiological and biochemical responses in cereals. This study was designed to examine the metabolite changes in grains of drought-tolerant transgenic rice (Oryza sativa L.) that overexpresses AtCYP78A7 encoding cytochrome P450 protein using proton nuclear magnetic resonance ((1)H-NMR) and gas chromatography/mass spectrometry. RESULTS Principal component analysis showed that the (1)H-NMR-based profile was clearly separated by soil water status of well-watered and water-deficit. A discrimination of metabolites between transgenic and non-transgenic grains appeared under both watering regimes. Variations in the levels of amino acids and sugars led to the discrimination of metabolites among genotypes. In particular, drought significantly enhanced the levels of γ-aminobutyric acid (GABA, 244.6%), fructose (155.7%), glucose (211.0%), glycerol (57.2%), glycine (65.8%) and aminoethanol (192.4%) in the transgenic grains compared with the non-transgenic control grains. CONCLUSION These changes in amounts of metabolites may assist in improving drought tolerance in transgenic rice by playing crucial roles in stress-responsive pathways including GABA biosynthesis, sucrose metabolism and antioxidant defenses.

Comparative analysis of key nutrient composition between drought-tolerant transgenic rice and its non-transgenic counterpart

Nutritional composition is the main consideration in the safety assessment of foods derived from genetically modified (GM) crops. In this study, the key nutrients in drought-tolerant rice that had been generated by the insertion of AtCYP78A7 encoding cytochrome P450 protein were analyzed. Results were compared with those obtained from its non-transgenic counterpart and other commercial rice. When transgenic rice lines 10B-5 and 18A-4 were compared with the non-transgenic counterpart, no significant differences were found in their contents of proximates, amino acids, fatty acids, minerals, and vitamins. Except for fiber contents and levels of vitamin B2, most of the measured values fit within the reference ranges established for other commercial rice. These results indicate that the key nutritional composition of drought-tolerant transgenic rice is substantially equivalent to its non-transgenic counterpart. Therefore, insertion of AtCYP78A7 to improve drought tolerance does not change the constitution and quality of key nutrients in brown rice.

Comparative analysis of chemical compositions between non-transgenic soybean seeds and those from plants over-expressing AtJMT, the gene for jasmonic acid carboxyl methyltransferase.

Transgenic overexpression of the Arabidopsis gene for jasmonic acid carboxyl methyltransferase (AtJMT) is involved in regulating jasmonate-related plant responses. To examine its role in the compositional profile of soybean (Glycine max), we compared the seeds from field-grown plants that over-express AtJMT with those of the non-transgenic, wild-type (WT) counterpart. Our analysis of chemical compositions included proximates, amino acids, fatty acids, isoflavones, and antinutrients. Overexpression of AtJMT in the seeds resulted in decreased amounts of tryptophan, palmitic acid, linolenic acid, and stachyose, but increased levels of gadoleic acid and genistein. In particular, seeds from the transgenic soybeans contained 120.0-130.5% more genistein and 60.5-82.1% less stachyose than the WT. A separate evaluation of ingredient values showed that all were within the reference ranges reported for commercially available soybeans, thereby demonstrating the substantial equivalence of these transgenic and non-transgenic seeds.

Effects of Bt Cabbage (Brassica oleracea) on the Host Preference and Performance of the Green Peach Aphid, Myzus persicae Sulzer (Hemiptera: Aphididae)

ABSTRACT: Transgenic crops that produce insecticidal toxins have a great potential for controlling target pest insects, but there is a growing concern about unintended influences on non-target species. In the present study, the preferences and performance of non -targetgreen peach aphid, Myzus persicae (Sulzer), on transgenic cabbages ( Brassica oleracea ) that produce Bt toxin (Cry1Ac1) and untransforme dcontrol plants were investigated as a part of risk assessment. In a free-choice situation, the number of nymphs larviposited by 10 winge dadults over 3 days was 21.9±1.8 and 22. 5±2.2 on transgenic and the control plants, respectively, indicating that the aphids did not discriminate between the two types of plants. In a performance assay, the development time (D) and intrinsic rate of increase (r m ) of wingless aphids reared on transgenic and control plants were also similar (D, 5.8±0.2 and 5.9±0.1 (days) and r m , 0.7±0.1 and 0.8±0.1,for transgenic and control plants, respectively). These results suggest that M. persicae is not significantly affected by transgenic Bt cabbage. Key words: Environmental risk assessment, Bt cabbage, Host preference, Myzus persicae, Transgenic crop초 록: 해충저항성 유전자변형 작물은 대상 해충에 대한 방제 효과를 증진시킬 수 있는 효과적인 수단이 될 수 있지만 , 생태계 내의 다른 비표적 생물에 부정적인 영향을 줄 가능성 또한 있기 때문에 상업적인 재배에 앞서 이에 대한 충분한 연구가 이루어져야 한다 . 본 연구에서는 배추좀나방 내성 유전자변형 Bt (Cry1Ac1)양배추가 비표적 곤충인 복숭아혹진딧물에 미치는 영향을 알아보기 위한 기초적인 실험으로서 기주선택실험 및 성장실험을 실시하였다. 기주선택실험에서, 두 개체씩의 Bt 양배추와 모본 양배추에 각각 10마리의 유시 성충(alate virginoparae)을 접종하고, 사흘간 생식(reproduction) 기회를 제공한 후 생산한 약충의 마리수를 측정한 결과, Bt 양배추와 모본 양배추에 낳은 약충의 수가 각각 21.9±1.8와 22.5±2.2로 비슷하였다. 성장실험에서, 갓 태어난 무시 약충(apterous virginoparae)을 Bt 양배추 및 모본 양배추를 기주로 하여 키웠을 때, 성충이 될 때까지 걸린 시간은 Bt 양배추와 모본 양배추에서 각각 5.8±0.2, 5.9±0.1 일(day)로 통계적으로 유의한 차이가 없었고, 개체군 생장률(r

Salinity affects metabolomic profiles of different trophic levels in a food chain

Salinization is one of the most important abiotic stressors in an ecosystem. To examine how exposing a host plant to excess salt affects the consequent performance and metabolism of insects in a food chain, we determined the life history traits and the metabolite profiles in rice (Oryza sativa), the herbivore Sitobion avenae, and its predator Harmonia axyridis. When compared with performance under normal (non-stressed) conditions, exposing plants to 50mM NaCl significantly delayed the timing of development for S. avenae fed on rice and H. axyridis and also reduced the body mass of the latter. Our GC-MS-based analysis revealed clear differences in metabolite profiles between trophic levels or treatment conditions. Salinity apparently increased the levels of main components in rice, but decreased levels of major components in S. avenae and H. axyridis. In addition, 16 metabolites showed salinity-related contrasts in this trophic interaction for our rice-S. avenae-H. axyridis system. Salinity impeded the accumulation of metabolites, especially several sugars, amino acids, organic acids, and fatty acids in both insects, a response that was possibly associated with the negative impacts on their growth and reproduction under stress conditions.