Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Endurance of plants under quartz rocks possible model for life on early Earth, Mars

06.01.2004


Microscopic Mojave Desert plants growing on the underside of translucent quartz pebbles can endure both chilly and near-boiling temperatures, scavenge nitrogen from the air, and utilize the equivalent of nighttime moonlight levels for photosynthesis, a new study reports. The plants, which receive enough light through the pebbles to support photosynthesis, could offer a model for how plants first colonized land, as well as how they might have evolved on Mars, said the scientists who performed the study.



"Here you have a really bizarre habitat," said William Schlesinger, dean of Duke University’s Nicholas School of the Environment and principal author of a paper on the study that appears in the December, 2003 issue of the research journal Ecology, which was just published. "When I first went to the site in 1978 I thought: ’That’s weird, how do these plants photosynthesize?’ Then it dawned on me that they photosynthesized on the light coming through the rocks."

Years after he first noticed the primitive plants -- mostly species of blue-green algae -- growing under every quartz pebble he turned over at the site in California’s Joshua Tree National Park, Schlesinger assembled a scientific team to investigate the phenomenon. He said what the scientists learned suggests a possible way that land plants established their first toehold in the harsh conditions of the early Earth: by staying under cover.


Such habitats may also be "prime locations to search for extraterrestrial life" on other planets, wrote Schlesinger and his other team members in their paper. Other authors include Schlesinger’s technician Jeffrey Pippen and Duke graduate students Matthew Wallenstein and Kirsten Hofmockel; also Bruce Mahall of the University of California at Santa Barbara and Debra Klepeis, Mahall’s graduate student.

Under Schlesinger’s direction, Pippen counted 295 whitish, light transmitting quartz pebbles commingled with a much larger number of opaque black pebbles within a 1–by-50 meter desert test plot. The scientists found all quartz pebbles that were about one inch or less thick supported active plant colonies on their undersides. Quartz pebbles thicker than one inch still had rings of plant life around those parts of their bottom edges where sunlight could penetrate through the stone at an oblique angle.

By placing heat sensors above and below some of the pebbles in all four seasons, the scientists documented that living under the quartz pebbles kept the plants warmer in winter and cooler in summer compared to conditions underneath black pebbles. In fact, their Ecology paper suggested that sunlight transmitted through the translucent quartz might "confer a modest greenhouse effect" during the cooler months, in essence trapping some of the sun’s heat.

Comparatively moderate though they were, temperatures underneath the quartz pebbles still logged as low at 41 degrees Fahrenheit in January and almost 150 degrees Fahrenheit at midday in August under harsh desert conditions.

The researchers then brought some pebble samples back to their laboratory at Duke and heated them to 194 degrees for six hours. Despite that ordeal in the lab, when the baked rocks were then moistened, their resident plant colonies proved still able to photosynthesize. Photosynthesis is the process by which plants synthesize sugars using atmospheric carbon dioxide through the action of light on green chlorophyll molecules.

The algae’s demonstration of high temperature resilience presented a paradox, because chlorophyll molecules themselves normally begin to degrade at about 167 degrees, according to Schlesinger, who is a biogeochemist and ecologist. "Either they have some special kind of chlorophyll, or they were in a resting phase which bacterial groups can go into to get through really extreme conditions," Schlesinger said. Blue- green algae are more properly called cyanobacteria.

Wallenstein’s DNA identification of the algae species in plant colony samples revealed 26 different kinds of cyanobacteria. Of those, the Ecology paper suggested that five species may be previously unknown to science.

Cyanobacteria are suspected of being "one of the first colonizers of land" on Earth, Schlesinger noted -- a time when there was no atmospheric ozone shield to block harmful solar ultraviolet radiation and no nitrogen-rich topsoil covering the ground. The lack of soil nitrogen provided no obstacle for the plant colonies living under the quartz rocks. Hofmockel, another of Schlesinger’s graduate students, found those algae obtain the nitrogen they needed for growth directly from the air like some less primitive plants are also able to do.

The UC Santa Barbara researchers found that the pebbles did not filter out more ultraviolet rays than they did other wavelengths of sunlight, meaning that quartz did not provide an especially protective environment. On the other hand, analysis also showed that that only about .08 percent of the light of any wavelength that entered one-inch-thick pebbles could reach plants on the other end. "That’s pretty shady," Schlesinger added. "That’s like photosythesizing by moonlight on the bottom of the thickest rocks."

"The growth of hypolithic (beneath rocks) algae under diaphanous quartz pebbles in the Mojave Desert is another illustration of the successful microbial exploitation of a novel habitat in an otherwise harsh environment," the authors concluded in their Ecology paper. "Similar environments might harbor life on other planets," the paper added.

While the paper did not specify which other planets, Schlesinger singled out Mars, whose surface is known to harbor quartz rock, be extremely dry and cold, and receive larger doses of ultraviolet radiation than Earth’s surface does today "Right now Mars doesn’t look too good for life," Schlesinger said. "But if Mars had something alive two billion years ago, when it is believed to have been slightly wetter, this might have been where that something lived."

Monte Basgall | EurekAlert!
Further information:
http://www.duke.edu/

More articles from Life Sciences:

nachricht Tag it EASI – a new method for accurate protein analysis
19.06.2018 | Max-Planck-Institut für Biochemie

nachricht How to track and trace a protein: Nanosensors monitor intracellular deliveries
19.06.2018 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Carbon nanotube optics provide optical-based quantum cryptography and quantum computing

19.06.2018 | Physics and Astronomy

How to track and trace a protein: Nanosensors monitor intracellular deliveries

19.06.2018 | Life Sciences

New material for splitting water

19.06.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>