The fern Pteris vittata can tolerate 100 to 1,000 times more arsenic than other plants. Jody Banks, a professor of botany and plant pathology, and David Salt, a professor of horticulture, uncovered what may have been an evolutionary genetic event that creates an arsenic pump of sorts in the fern.
"It actually sucks the arsenic out of the soil and puts it in the fronds," Banks said. "It's the only multi-cellular organism that can do this."
Without a genome sequenced for Pteris vittata, Banks and Salt used a method of gene identification called yeast functional complementation. They combined thousands of different Pteris vittata genes into thousands of yeast cells that were missing a gene that makes them tolerant to arsenic.
The yeast was exposed to arsenic, with most of it dying. The yeast strains that lived had picked up the genes from Pteris vittata that convey arsenic resistance.
To confirm that this was the correct gene, its function was knocked down and the plant was exposed to arsenic. Without the gene functioning properly, the plant could not tolerate arsenic.
"It tells us that this gene is necessary for the plant to function on arsenic," said Banks, whose findings were published in the early online version of the journal Plant Cell. "We looked for a similar gene in the plant Arabidopsis. We couldn't find it. It can't be found in any flowering plant."
Banks and Salt found that the protein encoded by this gene ends up in the membrane of the plant cell's vacuole. Salt said the protein acts as a pump, moving arsenic into the cell's equivalent of a trashcan.
"It stores it away from the cytoplasm so that it can't have an effect on the plant," Salt said.
Banks said understanding how the Pteris vittata functions with arsenic could lead to ways to clean up arsenic-contaminated land.
"Potentially you could take these genes and put them in any organism that could suck the arsenic out of the soil," Banks said.
Salt said rice plants could be modified with the gene to store arsenic in the roots of plants - instead of rice grains - in contaminated paddies.
Banks and Salt found another gene in Pteris vittata that looks almost exactly the same as the one that controls arsenic tolerance. When the fern was exposed to arsenic, the confirmed arsenic-tolerance gene increased its expression while the similar gene did not.
Salt said the gene that regulates arsenic tolerance could be a duplicate of the other that has changed slightly to give itself a new function.
"The fact that it has these two genes could be a sign of evolution," Salt said. "One of the thoughts of gene evolution is that one copy could continue to do what it has always done, while the duplicate can develop another function."
The plant might have evolved to accumulate arsenic, Banks and Salt theorized, as a defense against animals or insects eating them.
Banks hopes findings such as this will lead to more research emphasis on non-flowering plants. She said there are characteristics in plants such as Pteris vittata that cannot be found in other organisms.
The next step in their research is to put the arsenic-tolerance gene from Pteris vittata into Arabidopsis to see whether it gives the new plant the same characteristics.
The National Science Foundation funded the research.
Abstract on the research in this release is available at: http://www.purdue.edu/newsroom/research/2010/100610BanksFern.html
Brian Wallheimer | EurekAlert!
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
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
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...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
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...
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...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy