Plants acquire nutrients, including heavy metals, form soil. The in-depthunderstanding of the action mechanisms of heavy metal homoeostasis is essential forfuture materialization of phytoremediation and biofortification. A balanced heavy metalhomeostasis relies on seamless integration of uptake, transport andsequestration/detoxification. However, this line of research is still in its juvenile stage.In addition, physiological impacts under various metal conditions are largely unknown.To fill the gap in knowledge of heavy metal homeostasis, my lab started the study ofhyperaccumulators. In addition to revealing genes related to classical heavy metalhomeostasis, we have learned of the critical strategies Arabidopsis halleri, a heavymetal accumulator, uses for Zn tolerance and accumulation. We found that themaintenance of Fe homeostasis is most important for plants to survive in the heavymetal–rich habitat. The mechanisms include adjusted gene expression for Feacquisition and “protectant” secretion to protect against toxicity in an excess Znenvironment. Researches derived from this hypothesis will be discussed in theseminar. Nevertheless, we made additional efforts to study Fe homeostasis andfunctions to understand the importance of the metal in the defense against heavymetal stress. We hope that our discoveries made in the past few years could expandthe knowledge in key steps of heavy metal homeostasis, including the processes ofacquisition, detoxification and the physiological impacts of metals.

1. M. Tsednee, S.-C. Yang, D.-C. Lee and K.-C. Yeh* (2014) Root-secreted nicotianamine fromArabidopsis halleri facilitates zinc hypertolerance by regulating zinc bioavailability. Plant Physiology inpress: 2. L.-J. Shin, J.-C. Lo, G.-H. Chen, J. Callis, H. Fu and K.-C. Yeh* (2013) IRT1 DEGRADATIONFACTOR 1, a RING E3 ubiquitin ligase, regulates the degradation of IRON-REGULATED TRANSPORTER1 in Arabidopsis. Plant Cell 25: 3039-3051; 3. Y.-Y. Chen, Y Wang, L.-J. Shin, J.-F. Wu, V. Shanmugam,M. Tsednee, J.-C. Lo, C.-C. Chen, S.-H. Wu and K.-C. Yeh* (2013) Iron is involved in the maintenance ofcircadian period length in Arabidopsis. Plant Physiology 161: 1409-1420; 4. V. Shanmugam, M. Tsedneeand K.-C. Yeh* (2012) ZINC TOLERANCE INDUCED BY IRON 1 reveals the importance of glutathione inthe cross homeostasis between zinc and iron in Arabidopsis thaliana. Plant Journal 69 (6): 1006-1017

第111回 Plant Science Seminar

Heavy metal homeostasis in plants and application

日時 ： ９月８日 (月) １３：００〜１４：００場所 ： 農学部総合研究棟一階多目的室（Ｗ１０９）

Dr. Kuo-Chen YehAgricultural Biotechnology Research Center,

Academia Sinica,Taipei, Taiwan

Plant Science Seminar 北大内で植物科学を研究している（特に）若い人たちの交流促進の場を提供するためのセミナーです。Yeh氏は重金属輸送の研究で注目を集める気鋭の研究者です。9月8-9日にはDiscussionの時間も設けますので希望の方はご連絡ください。

世話人： 高野順平（内線：3888）