(Press-News.org) MADISON — In a world full of hungry predators, prey animals must be constantly vigilant to avoid getting eaten. But plants face a particular challenge when it comes to defending themselves.
"One of the things that makes plants so ecologically interesting is that they can't run away," says John Orrock, a zoology professor at the University of Wisconsin–Madison. "You can't run, you can't necessarily hide, so what can you do? Some plants make themselves less tasty."
Some do this either by boosting their production of toxic or unpleasant-tasting chemicals (think cyanide, sulfurous compounds, or acids) or through building physical defenses such as thorns or tougher leaves.
But, he adds, "Defense is thought to come at a cost. If you're investing in chemical defenses, that's energy that you could be putting into growth or reproduction instead."
To balance those costs with survival, it may behoove a plant to be able to assess when danger is nigh and defenses are truly necessary. Previous research has shown that plants can induce defenses against herbivores in response to airborne signals from wounded neighbors.
But cues from damaged neighbors may not always be useful, especially for the first plant to be attacked, Orrock says. Instead he asked whether plants — here, black mustard, a common roadside weed — can use other types of cues to anticipate a threat.
In a presentation Aug. 6 at the 2013 Ecological Society of America Annual Meeting in Minneapolis, he and co-author Simon Gilroy, a UW–Madison botany professor, reported that the plants can eavesdrop on herbivore cues to mount a defensive response even before any plant is attacked.
Slugs and snails are generalist herbivores that love to munch on mustard plants and can't help but leave evidence of their presence — a trail of slime, or mucus. Where there's slime, there's a snail. So Orrock treated black mustard seeds or new seedlings with snail mucus, then tested how appealing the resulting plants were to hungry snails.
The result? Getting slimed made the plants become less palatable. "That shows that plants are paying attention to generalist herbivore cues and that they turn on their defenses before they even get attacked," says Orrock.
What's more, they used the information in a time-sensitive way. Plants exposed only as seeds were eaten more — evidence of lower defenses — than those exposed as seedlings.
"The more recently they receive the information about impending attack, the more likely they are to use the information to defend themselves," he says. "Not only do they eavesdrop, they eavesdrop in a sophisticated way."
With Gilroy, Orrock is now exploring the genetics — and possibly evolution — of induced defenses. "If selection is strong enough from generalist snail herbivores to drive the evolution of eavesdropping by plants, then it might be far more common than we think," he says.
###
-- Jill Sakai, 608-262-9772, jasakai@wisc.edu
Sidebar:
How did they do that? Collecting snail slime
"It's not easy to get mucus out of a snail," says John Orrock. For one thing, "they make three different kinds."
The UW–Madison zoology professor used snail slime to show that black mustard plants can use cues of predator proximity to trigger defense mechanisms against the hungry snails.
But his first challenge was collecting enough slime to treat the plants. Initially he turned the snails upside down and tapped them, but what bubbled up was just defensive mucus, not the locomotion mucus (or "slime trail") he sought.
Ultimately he devised a low-tech but effective solution: let the snails crawl around overnight on a piece of filter paper lining the bottom of a small plastic deli container, then wash the filter paper and use the resulting slime water to treat the seeds and plants.
"One thing that's so cool about ecology is that you can do really enlightening experiments very simply. Clearly, if you're interested in the molecular or chemical aspects of the question, this isn't going to cut it. But if you want to know if a plant gets paranoid with slime? This," Orrock says, shaking the container, "plus snails equals results."
END
VIDEO:
Botswana's Okavango Delta and the Makgadikgadi Salt Pans are two ends of a 360-mile round trip zebra migration, the second longest on Earth. In this animation, shades of red show...
Click here for more information.
One of the world's longest migrations of zebras occurs in the African nation of Botswana, but predicting when and where zebras will move has not been possible until now. Using NASA rain and vegetation data, researchers can track when and where arid lands ...
SALT LAKE CITY—When a child is diagnosed with cancer, one of the first questions the parents ask is "Will my other children get cancer?" A new study from Huntsman Cancer Institute (HCI) at the University of Utah suggests the answer to that question depends on whether a family history of cancer exists. The research results were published online in the International Journal of Cancer and will appear in the November 15 print issue.
The study, led by Joshua Schiffman, M.D., medical director of HCI's High Risk Pediatric Cancer Clinic and a pediatric hematologist/oncologist ...
HOUSTON -- A program that pushes immature cells to grow up and fulfill their destiny as useful, dedicated cells is short-circuited in the most common and deadly form of brain tumor, scientists at The University of Texas MD Anderson Cancer Center report this week in the Early Edition of the Proceedings of the National Academy of Sciences (PNAS).
Stuck in what amounts to cellular adolescence, these precursor cells accumulate, contributing to the variability among glioblastoma multiforme (GBM) cells that make it so difficult to treat, said first author Jian Hu, Ph.D., instructor ...
Every hourly increase in daily television watching at 29 months of age is associated with diminished vocabulary and math skills, classroom engagement (which is largely determined by attention skills), victimization by classmates, and physical prowess at kindergarten, according to Professor Linda Pagani of the University of Montreal and the CHU Sainte-Justine children's hospital. "This is the first time ever that a stringently controlled associational birth cohort study has looked at and found a relationship between too much toddler screen time and kindergarten risks for ...
Cincinnati, OH, August 8, 2013 -- Concussions have become a major public health issue, with both short- and long-term side effects. In sports, cheerleading has the highest rate of catastrophic injury, with some studies reporting approximately 6% of total injuries as concussions. Return-to-play guidelines have relied on athletes' self-reports; however, this has led to concerns about the ability of athletes to truly recognize their own symptoms and recovery. In a new study scheduled for publication in The Journal of Pediatrics, researchers evaluate the accuracy of neurocognitive ...
Results from a clinical trial of eteplirsen, a drug designed to treat Duchenne muscular dystrophy, suggest that the therapy allows participants to walk farther than people treated with placebo and dramatically increases production of a protein vital to muscle growth and health. The study, led by a team in The Research Institute at Nationwide Children's Hospital, is the first of its kind to show these results from an exon-skipping drug—a class of therapeutics that allows cells to skip over missing parts of the gene and produce protein naturally.
"I've been doing this ...
A Penn State-led research team has found that changes to proteins called histones, which are associated with DNA, can control whether or not a gene is allowed to function. The changes may be important in maintaining the genes' "expression potential" so that future cells behave as their parent cells did. The discovery, which may have implications for the study of diseases such as cancer, will be published in a print edition of the journal Proceedings of the National Academy of Sciences. The research was led by Lu Bai, an assistant professor of biochemistry, molecular biology, ...
Women living in large urban areas are at a significantly higher risk of postpartum depression after five to 14 months of giving birth compared to those living in rural areas, according to a new Canadian study led by Women's College Hospital's Dr. Simone Vigod.
The study, published today in the Canadian Medical Association Journal, strongly links geographic location and postpartum depression. The researchers suggest differences in risk factors, including place of birth, social support and history of depression, in combination with geography, may contribute to postpartum ...
Forests have a limited capacity to soak up atmospheric carbon dioxide, according to a new study from Northern Arizona University.
The study, available online in the journal New Phytologist, aimed to explore how rising atmospheric carbon dioxide could alter the carbon and nitrogen content of ecosystems.
By performing tests on subtropical woodland plots over an 11-year period, the researchers found that ecosystem carbon uptake was not significantly increased by the high CO2 treatment—in contrast to expectations. While plants did contain more carbon when CO2 levels were ...
The global study was led by University of Melbourne and the Peter MacCallum Cancer Centre and published in the Journal of Clinical Oncology today.
The study involved about 2,500 women from Europe, North America and Australia who have inherited mutations in BRCA1 or BRCA2, the breast cancer susceptibility genes, and who had been diagnosed with breast cancer. About one-third of these women were placed on tamoxifen.
Tamoxifen has been used for decades to treat breast cancer and has recently been shown to prevent breast cancers in many women.
Until now, there has been ...