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Frontiers news briefs: August 20


Frontiers in Plant Science

Transgenic bacteria shed light on symbiotic exchanges within the soil

Adding light-producing bacteria to soil can be a powerful method for tracking in real time how plant roots provide soil bacteria with carbohydrates, according to a new study in Frontiers in Plant Science.

Soil bacteria rely for their growth on compounds released from plant roots in the form of excretions and sloughed-off cells, while bacteria often make scarce nutrients available to roots in exchange. For the first time, researchers from Woods Hole Marine Biological Laboratory and the University of Connecticut visualized the fueling of bacterial growth by roots in real time by inoculating soils with a light-producing strain of the harmless, widespread soil bacterium Pseudomonas putida. Since these bacteria only produce light when they are growing rapidly, the emitted light reveals when and where plants provide nourishment to soil bacteria.

The patterns were highly complex, and differed strongly across five plant species used in the study, which included economically-important tomato, maize, and poplar. With the new method, researchers can begin to disentangle the many ecologically important relationships that exist below ground between soil bacteria and their plant hosts.

A video of luminescence around a tomato root system is available. Please contact Gozde Zorlu:

Researcher contact:

Dr Zoe G. Cardon
The Ecosystems Center
Marine Biological Laboratory, USA

Article title: Better to light a candle than curse the darkness: illuminating spatial localization and temporal dynamics of rapid microbial growth in the rhizosphere
Journal: Frontiers in Plant Science
DOI: 10.3389/fpls.2013.00323


Frontiers in Human Neuroscience

A simple joystick task could reduce social stress

People who are socially anxious show a strange contradictory reaction to smiling faces: they say that these faces are pleasant, yet automatically avoid them. In a study in Frontiers in Human Neuroscience, researchers report that this avoidance of smiling faces is one of the reasons for the social fear that socially anxious individuals feel.

In the experiment, 32 socially anxious participants performed a simple, short joystick task 240 times. By pulling or pushing the joystick, they pulled images on the computer screen closer to themselves or pushed them away. Half of the participants pulled smiling faces closer all the time, and the other half pushed them away all the time. Afterwards, all participants were exposed to social stress: they had to record a 1-minute self-presentation video, believing that the video would later be watched and judged by others.

The researchers show that the socially anxious participants who had received approach-smiling-faces training felt less anxious after the self-presentation than those who had received avoid-smiling-faces training. These results open up new, simple and cheap possibilities to boost cognitive behavior therapy for patients.

Researcher contact:

Prof Mike Rinck
Clinical Psychology and Behavioural Science Institute
Radboud University Nijmegen, The Netherlands

Article title: Training Approach-Avoidance of Smiling Faces Affects Emotional Vulnerability in Socially Anxious Individuals
Journal: Frontiers in Human Neuroscience
DOI: 10.3389/fnhum.2013.00481


Frontiers in Plant Science

Flowers get their colors through predictable genetic changes

The amazing diversity of flower colors among species is often controlled by a predictable set of genes, suggesting that evolution may be repeatable. In a review of the published literature, researchers from the University of Oregon revealed that mutations in a single gene are responsible for much of this diversity. Although mutations in at least ten genes are capable of causing similar changes in color, mutations in only one of these genes are believed to be preferentially targeted by natural selection. This is thought to occur because this gene is only active in the flower, suggesting that its mutations have fewer detrimental side effects than other genes that affect the plant more broadly. This research further explores the mechanisms that drive this diversity of floral forms and finds that experimental predictions are upheld for comparisons involving multiple evolutionary scales and histories. These results demonstrate that the convergence of flower color evolution among distantly related species is frequently the result of mutations in the same gene, which provides insight into the processes that affect how novel traits are formed.

Color images are available. Please contact Gozde Zorlu:

Researcher contact:

Dr Matthew A. Streisfeld
Institute of Ecology and Evolution
University of Oregon, USA

Article title: Flower color as a model system for studies of plant evo-devo
Journal: Frontiers in Plant Science
DOI: 10.3389/fpls.2013.00321


Frontiers in Psychology

The role of scene context on object processing

Researchers from the University of Trento replicated 'scene-context' effect in two experiments by showing that participants identified pictures of objects more accurately when presented in a consistent scene background (a barbecue in a garden) compared to when presented in an inconsistent scene background (barbecue in a living room).

Current research shows that the human skill of rapidly and accurately identifying everyday objects is due in part to the context in which they are presented. This well-known scene-context effect was found to be independent of the focus of attention.

But in a third experiment, they addressed whether the consistency effect can occur without paying attention to the scene background. Results showed that the consistency effect occurred with a similar magnitude regardless of whether participants attended to the target object or the scene background.

These results indicate that a consistent context benefits object recognition independently of attentional focus. The researchers suggest that the consistency effect is driven by so-called "scene gist," (the meaning of what a scene represents), making it easier to identify objects that belong to that specific scene-type.

Color images are available. Please contact Gozde Zorlu:

Researcher contact:

Dr Jaap Munneke
Center for Mind/Brain Science
University of Trento, Italy

Article title: The influence of scene context on object recognition is independent of attentional focus
Journal: Frontiers in Psychology
DOI: 10.3389/fpsyg.2013.00552



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