Drought-tolerant crops have moved closer to becoming reality.
A collaborative team of scientists has made a significant advance on the discovery last year by the University of California, Riverside's Sean Cutler of pyrabactin, a synthetic chemical that mimics a naturally produced stress hormone in plants to help them cope with drought conditions.
Led by researchers at The Medical College of Wisconsin, the scientists report in Nature Structural & Molecular Biology (online) on Aug. 22 that by understanding how pyrabactin works, other more effective chemicals for bringing drought-resistance to plants can be developed more readily.
Abscisic acid versus pyrabactin
Plants naturally produced a stress hormone, abscisic acid (ABA), in modest amounts to help them survive drought by inhibiting growth. ABA has already been commercialized for agricultural use. But it has at least two disadvantages: it is light-sensitive and costly to make.
Pyrabactin, on the other hand, is relatively inexpensive, easy to make, and not sensitive to light. But its drawback is that, unlike ABA, it does not turn on all the "receptors" in the plant that need to be activated for drought-tolerance to fully take hold.
Lock and key
A receptor is a protein molecule in a cell to which mobile signaling molecules – such as ABA or pyrabactin, each of which turns on stress-signaling pathways in plants – may attach. Usually at the top of a signaling pathway, the receptor functions like a boss relaying orders to the team below that then proceeds to execute particular decisions in the cell.
Each receptor is equipped with a pocket, akin to a padlock, in which a chemical, like pyrabactin, can dock into, operating like a key. Even though the receptor pockets appear to be fairly similar in structure, subtle differences distinguish a pocket from its peers. The result is that while ABA, a product of evolution, can fit neatly in any of these pockets, pyrabactin is less successful. Still, pyrabactin, by being partially effective (it works better on seeds than on plant parts), serves as a leading molecule for devising new chemicals for controlling stress tolerance in plants.
Cutler explained that each receptor is equipped with a lid that operates like a gate. For the receptor to be activated, the lid must remain closed. Pyrabactin is effective at closing the gate on some receptors, turning them on, but cannot close the gate on others. The researchers have now cracked the molecular basis of this behavior.
"A key insight from the current work is that this difference is controlled by subtle differences between the receptors in their binding pockets," said Cutler, an associate professor of plant cell biology in the Department of Botany and Plant Sciences and one of the members of the research team.
He explained that in a receptor where the gate closes, pyrabactin fits in snugly to allow the gate to close. In a receptor not activated by pyrabactin, the chemical binds in a way that prevents the gate from closing and activating the receptor.
"These insights suggest new strategies for modifying pyrabactin and related compounds so that they fit properly into the pockets of other receptors," Cutler said.
Impact of pyrabactin
According to Cutler, pyrabactin has paved the way for manufacturing new molecules that activate or turn on receptors.
"For it to be a good agriculture chemical, however, it needs to turn on more receptors by fitting into their pockets," he said. "If a derivative of pyrabactin could be found that is capable of turning on all the receptors for drought tolerance, the implications for agriculture are enormous. The current research is an important step on the way to what is likely to be the next big result: an ABA-mimicking chemical that can be sprayed on corn, soy bean and other crops."
The discovery of pyrabactin by the Cutler lab was heralded as a breakthrough research of 2009 by Science magazine.
In the current research, Cutler collaborated with Brian Volkman and his research group at the Medical College of Wisconsin, and helped guide critical questions.
"Specifically, we performed genetic experiments that helped us pinpoint which amino acids in the receptors are critical for pyrabactin to either work or not work," Cutler said. "We also identified reasons for why one receptor is sensitive to pyrabactin while a neighboring receptor is not."
A grant from the National Science Foundation supported Cutler's contribution to the study.
Cutler and Volkman were joined in the study by Francis C. Peterson (first author of the research paper), Davin R. Jensen and Joshua J. Weiner of the Medical College of Wisconsin; Sethe Burgie, Craig A. Bingman and George N. Phillips, Jr. of the University of Wisconsin-Madison; and Sang-Youl Park and Chia-An Chang of UCR.
Cutler is a coauthor also on a companion paper, titled "Identification and Mechanism of ABA Receptor Antagonism," that appears online Aug. 22 in Nature Structural & Molecular Biology.
He joins the following researchers in that study: Karsten Melcher (first author), Yong Xu, Ley-Moy Ng, X. Edward Zhou, Fen-Fen Soon, Kelly M. Suino-Powell, Amanda Kovach, Jun Li and H. Eric Xu of the Van Andel Research Institute, Grand Rapids, Mich.; Eu-Leong Yong of the National University of Singapore; and Viswanathan Chinnusamy, Fook S. Tham, and Jian-Kang Zhu of UCR.
The University of California, Riverside (www.ucr.edu) is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of over 19,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion.
A broadcast studio with fiber cable to the AT&T Hollywood hub is available for live or taped interviews. To learn more, call (951) UCR-NEWS.
Iqbal Pittalwala | EurekAlert!
Cascading use is also beneficial for wood
11.12.2017 | Technische Universität München
The future of crop engineering
08.12.2017 | Max-Planck-Institut für Biochemie
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences