Stopping Short


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Unlike animals, plants cannot run away from danger. They have therefore evolved various mechanisms to protect themselves against environmental stresses such as heat, cold, drought, mechanical pressure and lack of oxygen. One such protective measure is a slackening of their growth rate, which prevents them from reaching full size and may facilitate their survival in stressful situations.

One of the plant enzymes that rapidly swings into action in response to environmental stresses is glutamate decarboxylase (GAD), which stimulates the production of a substance known as gamma-aminobutyric acid (GABA).

Dr. Hillel Fromm of the Weizmann Institute's Plant Genetics Department was the first to clone the GAD gene from plants and to identify the mechanism that activates this enzyme in response to stress.

Now Fromm and colleagues have reproduced this growth-suppression phenomenon under lab conditions. They have genetically engineered a model tobacco plant lacking a protein segment that normally limits GABA production.

The mutant plants are thus forced to overproduce and accumulate GABA. As a result, cells in the plant stem fail to expand, and plant growth is stunted.

Fromm's next challenge is to determine whether and how the surplus GABA and the resultant curtailment of growth endow the plant with protection. This information might make it possible to genetically engineer crops with better resistance to environmental threats.

Certain aspects of this study were recently described in the EMBO Journal, while other aspects will soon be published in Molecular and General Genetics.


Dr. Fromm 's study in the EMBO Journal was co-authored by his graduate students Gideon Baum, Yael Fridmann, Tzahi Arazi, Hana Katsnelson and Moriyah Zik, as well as Dr. Simcha Lev-Yadun of the same department.

It was sponsored by the United States-Israel Binational Agricultural Research and Development Fund (BARD); the Wolfson Research Awards administered by the Israel Academy of Sciences and Humanities; and a fund sponsored jointly by the Israel Ministry of Science and the Gesellschaft Fuer Biotechnologische Forschung (GBF), Braunschweig, Germany.

The study described in Molecular and General Genetics was co-authored by Professor Moshe Feldman and graduate students Tianbao Yang, Gregorio Segal and Shahal Abbo, all of the Weizmann Institute's Plant Genetics Department.

It was sponsored by the Minerva Foundation, Munich,Germany, and the Charles & Tillie Lubin Center for Plant Biotechnology. Dr. Fromm holds the Abraham and Jenny Fialkow Career Development Chair in Biology, and Prof. Feldman, the Marshall and Edith Korshak Chair of Plant Cytogenetics.

The Weizmann Institute of Science is a major center of scientific research and graduate study located in Rehovot, Israel.