In a study of the molecular underpinnings of plants' pest resistance, Rice University biologists have shown that plants both anticipate daytime raids by hungry insects and make sophisticated preparations to fend them off.
"When you walk past plants, they don't look like they're doing anything," said Janet Braam, an investigator on the new study, which appears this week in the Proceedings of the National Academy of Sciences. "It's intriguing to see all of this activity down at the genetic level. It's like watching a besieged fortress go on full alert."
Braam, professor and chair of Rice's Department of Biochemistry and Cell Biology, said scientists have long known that plants have an internal clock that allows them to measure time regardless of light conditions. For example, some plants that track the sun with their leaves during the day are known to "reset" their leaves at night and move them back toward the east in anticipation of sunrise.
In recent years, scientists have begun to apply powerful genetic tools to the study of plant circadian rhythms. Researchers have found that as many as one-third of the genes in Arabidopsis thaliana -- a widely studied species in plant biology -- are activated by the circadian cycle. Rice biochemist Michael Covington found that some of these circadian-regulated genes were also connected to wounding responses.
"We wondered whether some of these circadian-regulated genes might allow plants to anticipate attacks from insects, in much the same way that they anticipate the sunrise," said Covington, now at the University of California, Davis.
Danielle Goodspeed, a graduate student in biochemistry and cell biology, designed a clever experiment to answer the question. She used 12-hour light cycles to entrain the circadian clocks of both Arabidopsis plants and cabbage loopers, a type of caterpillar that eats Arabidopsis. Half of the plants were placed with caterpillars on a regular day-night cycle, and the other half were placed with "out-of-phase" caterpillars whose internal clocks were set to daytime mode during the hours that the plants were in nighttime mode.
"We found that the plants whose clocks were in phase with the insects were relatively resistant, whereas the plants whose clocks were out of phase were decimated by the insects feeding on them," Goodspeed said.
Wassim Chehab, a Rice faculty fellow in biochemistry and cell biology, helped Goodspeed design a follow-up experiment to understand how plants used their internal clocks to resist insect attacks. Chehab and Goodspeed examined the accumulation of the hormone jasmonate, which plants use to regulate the production of metabolites that interfere with insect digestion.
They found that Arabidopsis uses its circadian clock to increase jasmonate production during the day, when insects like cabbage loopers feed the most. They also found that the plants used their internal clocks to regulate the production of other chemical defenses, including those that protect against bacterial infections.
"Jasmonate defenses are employed by virtually all plants, including tomatoes, rice and corn," Chehab said. "Understanding how plants regulate these hormones could be important for understanding why some pests are more damaging than others, and it could help suggest new strategies for insect resistance."
The research was supported by the National Science Foundation and Rice University. Additional co-authors include Rice undergraduate Amelia Min-Venditti.
VIDEO is available at: http://www.youtube.com/watch?v=b9IdZb3z7Jw
A copy of the PNAS paper is available at: http://www.pnas.org/content/early/2012/02/07/1116368109.abstract
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is known for its "unconventional wisdom." With 3,708 undergraduates and 2,374 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 4 for "best value" among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to www.rice.edu/nationalmedia/Rice.pdf.
Jade Boyd | EurekAlert!
Hunting pathogens at full force
22.03.2017 | Helmholtz-Zentrum für Infektionsforschung
A 155 carat diamond with 92 mm diameter
22.03.2017 | Universität Augsburg
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
22.03.2017 | Materials Sciences
22.03.2017 | Physics and Astronomy
22.03.2017 | Materials Sciences