1. Department of Crop Science, College of Sanghuh Life Science, Konkuk University, Seoul 05029, Republic of Korea
2. Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 406-772, Republic of Korea
3. UC Davis Stable Isotope Facility, University of California, Davis, 1 Shields Avenue, Davis, California 95616, United States