Soils of southern South America, including Patagonia, have endured a high frequency of disturbances from volcanic eruptions, earthquakes, landslides, and erosion.
Left, small seedling (ca. 5 mo–old) collected in Reserva Nacional Cerro Castillo, Chile, with its noticeable cluster roots holding soil. Right, one young cluster root; notice that they are simple cluster roots (i.e., bottle-brush-like structures).
Credit: Left by Frida Piper; right by Mabel Delgado.
In addition, massive fires in the mid-20th century were set to forests in the region in an effort to promote colonization. In 2010, another 17,000 acres of Patagonia burned, fueling an international reforestation effort.
Although the young soils of southern South America may contain high phosphorus levels, the element is tightly bound to the soil, offering limited phosphorus available to plants.
So how can plants in this area take root and access that phosphorus?
According to a recent article published in the American Journal of Botany, scientists have identified a mechanism enabling a native tree species access to this limiting nutrient. As a result, the Chilean fire bush (Proteaceae, Embothrium coccineum), a tree endemic to Chile and Argentina, could have an important role in the reforestation of Patagonia.
In the wild, E. coccineum colonizes highly disturbed land where other tree species rarely occur. Proteaceae species, common in the southern hemisphere, are known for a root structure adaptation that increases phosphorus acquisition from weathered, phosphorus-poor soils. The greater surface area of cluster roots increases root exudates of organic acids and phosphatases. These exudates enhance plant phosphorus acquisition from unavailable forms in the soil.
"I was particularly curious of the ecological role of this root adaptation," explained Frida Piper, a terrestrial ecosystem ecologist at the remote research center Centro de Investigación en Ecosistemas de la Patagonia (CIEP) in Coyhaique, Chile. Piper designed a field study to better understand the role of cluster roots of E. coccineum across a natural precipitation and phosphorus gradient in its native habitat. How does the production of cluster roots in this Proteaceae enable successful establishment in young volcanic soils of South America?
Small and large E. coccineum seedlings and topsoil were collected at four sites in the Aysén Region of Patagonia, Chile, in 2010-2013. Seedlings were assessed for number and biomass of cluster roots, plant size and growth, and foliar phosphorus levels. Soil samples were analyzed for pH, total nitrogen (N), available phosphorus (P) and organic matter. Based on biomass and chemical analyses, four dominant factors were identified: soil P, soil N, foliar P, and seedling age. A suite of generalized linear mixed–effect model regressions were fitted to the data.
In contrast to previous studies of Proteaceae in Australia and South Africa, the best-fit model for predicting the number of cluster roots in this study did not contain any soil P factor; foliar P levels correlated with cluster root formation. The number of cluster roots was significantly higher in large seedlings, yet biomass investment in cluster roots was greater for small seedlings.
Piper found that cluster roots mediate a decoupling of foliar P from soil P concentrations for small seedlings. This enabled small seedlings to maintain adequate foliar P levels, critical to their ontogenetic growth. The relative investment in cluster roots was directly linked to both low soil N and leaf P. Seedlings from sites with lower total soil N had more cluster roots, regardless of other soil characteristics. The cluster root adaptation is very sensitive and highly expressed at low total soil N levels but rapidly disappears as soil N levels increase. The investment in cluster roots declines after seedling establishment, most likely as aerial growth is increasingly important for light competition.
Embothrium coccineum may have an important role in reforestation of Patagonia as an early successional species. Cluster roots have been identified in other plant species, including some agronomic crops in the Cucurbitaceae. "The biotechnology potential of these traits is being studied now," Piper says. Piper's research clarifying the mechanism of seedling establishment success for E. coccineum in conditions with limited availability of N and P may lead to advantageous root adaptation in other plants.
Piper is already exploring further research to understand how E. coccineum benefits neighbors by providing increased nutrient availability from root exudates or leaf litter decomposition. As a result of this study, nitrogen status of soil and plants, in addition to phosphorus, will always be included in Proteaceae studies by Piper. "Proteaceae can do something no other plant can do," Piper explains. "They are accessing nutrients that no other plants can access."
Piper, Frida I., Gabriela Baez, Alejandra Zúñiga-Feest, and Alex Fajardo. 2013. Soil nitrogen, and not phosphorus, promotes cluster-root formation in a South American Proteaceae, Embothrium coccineum. American Journal of Botany 100:2328-2338. doi:10.3732/ajb.1300163
The full article in the link mentioned is available for no charge for 30 days following the date of this summary at http://www.amjbot.org/content/100/12/2328.full.pdf+html. After this date, reporters may contact Richard Hund at email@example.com for a copy of the article.
The Botanical Society of America is a non-profit membership society with a mission to promote botany, the field of basic science dealing with the study and inquiry into the form, function, development, diversity, reproduction, evolution, and uses of plants and their interactions within the biosphere. It has published the American Journal of Botany for nearly 100 years. In 2009, the Special Libraries Association named the American Journal of Botany one of the Top 10 Most Influential Journals of the Century in the field of Biology and Medicine.
For further information, please contact the AJB staff at firstname.lastname@example.org.
Richard Hund | EurekAlert!
Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology
Scientists generate an atlas of the human genome using stem cells
24.04.2018 | The Hebrew University of Jerusalem
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
24.04.2018 | Life Sciences
24.04.2018 | Materials Sciences
24.04.2018 | Trade Fair News