Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plants have little wiggle room to survive drought, UCLA life scientists report

14.11.2014

Plants all over the world are more sensitive to drought than many experts realized, according to a new study by scientists at UCLA and China's Xishuangbanna Tropical Botanical Garden.

The research will improve predictions of which plant species will survive the increasingly intense droughts associated with global climate change.


Researchers measured leaves' drought tolerance at the "turgor loss point" -- the level of dehydration that causes them to wilt.

Credit: Lawren Sack

The research is reported online by Ecology Letters, the most prestigious journal in the field of ecology, and will be published in an upcoming print edition.

Predicting how plants will respond to climate change is crucial for their conservation. But good predictions require an understanding of plants' ability to acclimate to environmental changes, or their "plasticity." All organisms show some degree of plasticity, but because they're stationary, plants are especially dependent on this ability.

"Plants are masters of plasticity, changing their size, branching patterns, leaf colors and even their internal biochemistry to adjust to changes in climate," said Lawren Sack, a professor of ecology and evolutionary biology in the UCLA College and the study's senior author.

Little has been known about the degree to which plastic changes might allow plants to endure worsening droughts.

"Plants have evolved this amazing ability to sync with their environment, but they are facing their limits," said Megan Bartlett, a UCLA doctoral student in ecology and evolutionary biology and the study's lead author.

Compiling and analyzing data for numerous species from various ecosystems around the world, Bartlett found that most species accumulate salts in their cell sap to fine-tune their tolerance to seasonal changes in rainfall. But that adjustment only provides a relatively narrow degree of additional drought tolerance.

Saltier cell sap gives plants the ability to continue to grow as soil dries during drought. Unlike animal cells, plant cells are enclosed by cell walls. To hold up the cell walls, plants depend on "turgor pressure" -- the pressure produced by internal water pushing against the inside of the cell wall. As the cells dehydrate, the turgor pressure declines until the cell walls collapse, and the leaf becomes limp and wilted.

The team of biologists collected data on the "turgor loss point" -- the level of dehydration that causes leaves to wilt. Plants that have a lower turgor loss point can lose more water before wilting, and can keep open their pores, or stomata, to take up carbon dioxide for photosynthesis in drier soils.

"During a drought, plants have to choose between closing their stomata and risking starvation, and continuing to photosynthesize and risking cell damage from wilting," Sack said.

Previous research by the UCLA team revealed the key mechanism plants use to adjust their turgor loss point during drought. Plants load their cells with salts, which attract water molecules and limit turgor loss. In wet conditions, plants invest fewer resources in producing and accumulating these solutes and reduce the saltiness of their cell sap.

Drawing on both new data they produced and previously reported data for hundreds of species, the scientists determined the overall picture of how much plant species adjust their cell sap saltiness to maintain turgor and continue to grow during drought.

"For most plants, these adjustments were small," Sack said. "This means they have only limited wiggle room as droughts become more serious. On the plus side, this discovery means we can estimate species' drought tolerance relatively simply. We can make a reasonable drought tolerance measurement for most species regardless of time of year or whether we are sampling during wet or dry conditions."

Bartlett said the finding is good news for plant biologists. "It means that predicting how a species will respond to climate change from one season of drought tolerance measurements is a reasonable place to start," she said. "Our predictions will be more accurate when we take plasticity into account, but sampling in one season is a reasonable simplification for really diverse ecosystems, like tropical rainforests."

All ecosystems potentially vulnerable

The researchers expected plants' plasticity to be very different based on whether they live in deserts, which may get less than an inch of rainfall per year, or rainforests, which may receive more than 10 feet. Instead, they found relatively small differences across ecosystems, meaning that plants are potentially vulnerable no matter where they live, the scientists said.

The researchers also compared plasticity for crops. They found a strikingly contrasting result: Whereas differences in plasticity among wild species were relatively small and unimportant, among the varieties of certain crop species -- such as coffee and corn -- greater plasticity resulted in improved drought tolerance.

"It's been suspected for a long time that plasticity in cell saltiness might improve crop drought tolerance, so it makes sense that we found impressive differences among crop cultivars and that these differences translate into drought tolerance," Bartlett said. "Our study points to plasticity in turgor loss point as an especially important focus for breeding and selecting drought tolerant cultivars."

The research was funded by the National Science Foundation's Graduate Research Fellowship Program and East Asia and Pacific Summer Institute, the Smithsonian Institution's Center for Tropical Forest Science - Forest Global Earth Observatory, the Vavra Research Fellowship and UCLA's department of ecology and evolutionary biology.

Stuart Wolpert | EurekAlert!
Further information:
http://www.newsroom.ucla.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>