Next Step to Drought-Resistant Plants?
SEPTEMBER 30, 2010
Environmentally-friendly sprays that help plants survive drought and other stresses in harsh environments could result from findings based on research carried out at the U.S. Department of Energy's Advanced Photon Source (APS) at Argonne National Laboratory. The study, which could help combat global food shortages, is a follow-up to findings published by Van Andel Research Institute (VARI) scientists in Nature‡ last year, results that were named among the top breakthroughs of 2009 by Science magazine.
"I think that the work established the methodologies and feasibilities of finding cheap and environmentally benign chemicals for agricultural application to improve the water use efficiency and drought tolerance of crops," said Jian-Kang Zhu, Professor of Botany and Presidential Chair of Botany & Plant Sciences at the University of California, Riverside. "The work also provides a better understanding of ABA receptor function, which will help efforts in the genetic engineering of hardier crops."
In the 2009 study published in Nature, VARI scientists determined precisely how the plant hormone abscisic acid (ABA) works at the molecular level to help plants respond to environmental stresses such as drought and cold. These findings could help engineer crops that thrive in harsh environments.
In that study, derived from work on two Life Sciences Collaborative Access Team (LS-CAT) x-ray beamlines at the APS, the researchers obtained the first three-dimensional structure of ABA bound to a so-called “receptor molecule.” The structures show a “gate-and-latch” mechanism, by which the receptor protein encloses itself around the hormone, and which appears to be widespread in the plant kingdom. The hormone is useless without a receptor to recognize it and transfer its message to the rest of the cell. The importance of this process is such that, of 14 ABA receptors isolated from the same species of plant, all of them share certain amino acids, which implies they all work in the same way in a highly redundant manner.
One of ABA's effects is to cause plant pores to close when plants are stressed so that they can retain water. In the new study, researchers identified several synthetic compounds that fit well with ABA's many receptors, or cellular "docking stations," to have the same effect. By finding compounds that can close these pores, researchers' findings could lead to sprays that use a plant's natural defenses to help it survive harsh environmental conditions.
"Sprays would allow plants to be much more adaptable than if we genetically engineered them," said Karsten Melcher, Ph.D., one of the lead authors of the study and research scientist in the VARI Laboratory of Structural Biology led by Distinguished Scientific Investigator H. Eric Xu. "You could spray plants to close the pores only when drought or other harsh conditions threaten the plant."
The lab originally began studying ABA because a proposed ABA receptor was reported to be a member of a group of proteins that the lab studies, which are targeted by more than 50% of all drugs on the market. It was later found that the receptor was not part of this group of proteins, but Xu's lab continued its' studies.
The new findings, also based on research at LS-CAT and the APS, appear in Nature Structural & Molecular Biology† alongside a companion paper from authors Francis C. Peterson (first author), Brian Volkman, Davin R. Jensen, and Joshua J. Weiner from the Medical College of Wisconsin, Sean Cutler, Sang-Youl Park and Chia-An Chang from University of California, Riverside (UCR), and Sethe Burgie, Craig A. Bingman, and George Phillips, Jr., from the University of Wisconsin-Madison. A third parallel study has also been reported by Dr. Nieng Yan's group in the Journal of Biological Chemistry.
"Last year Dr. Xu and his lab offered the plant community the long-awaited key to creating drought-resistant crops," said VARI President and Research Director Dr. Jeffrey Trent. "Only a few short months later, and they already have taken huge strides further toward the ultimate goal of helping combat world hunger."
†See: Francis C. Peterson1, E. Sethe Burgie2, Sang-Youl Park3, Davin R. Jensen1, Joshua J. Weiner1, Craig A. Bingman2, Chia-En A. Chang3, Sean R. Cutler3**, George N. Phillips, Jr.2***, and Brian F. Volkman1*, “Structural basis for selective activation of ABA receptors,” Nat. Struct. Mol. Biol. 17(9), 1109 (September 2010). DOI:10.1038/nsmb.1898
Author affiliations: 1Medical College of Wisconsin; 2University of Wisconsin-Madison; 3University of California-Riverside; 4University of California-Riverside
Correspondence: *firstname.lastname@example.org, **email@example.com, or ***firstname.lastname@example.org
This publication was made possible in part by Grant Numbers DK066202 (10%), and GM087413 (10%) from the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute of General Medical Sciences respectively. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institute of Diabetes and Digestive and Kidney Diseases or the National Heart Lung and Blood Institute.