Biology: Plant biology

Plant Biology and Physiology

57th ESA Parabolic Flight Campaign

23 October 2012

A. Mancuso ⁽¹⁾, E. Masi ⁽¹⁾, D. Comparini ⁽¹⁾, E. Monetti ⁽¹⁾

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This experiment was performed by the LINVforROS team within ESA's educational programme: "Fly Your Thesis! - An Astronaut Experience". The Fly Your Thesis! programme gives university students the possibility to fly their scientific experiment in microgravity, as part of their Masters thesis, PhD thesis or research programme, by participating in a series of parabolic flights. In total, three teams of postgraduate students were flying their experiments during the 2012 'Fly Your Thesis!' campaign.

OBJECTIVE
The objective of this project is the detection of coordinated variations in reactive oxygen species (ROS) production during the cyclic changes of gravity which occur during a parabolic flight. ROS control many different processes in plants and participate in responses to stress, such as gravity sudden changes.

In order to obtain more detailed and reliable information on ROS production during gravity changes, this Project aims to use different markers to detect ROS production in living cells derived from maize tissues.

On board, real-time measurement of ROS concentrations will be determined by a brand new approach, which will be used for the first time ever in the field of space plant biology. This technique, based on the oxidation of chemical compounds by ROS, will be used during the whole duration of the flight, in order to obtain a detailed profile of ROS production in each moment of each parabola. This will permit to explore the emerging complexity of the multiple roles that ROS play in cellular signalling in gravitystressed conditions, considering microgravity as a main source of stress for plants.

This Project is developed by an Italian team composed by two students and an endorsing professor from the University of Florence, Italy.

RELATED RESEARCH
Drop Tower Bremen - DYT2011
Falling Roots - Chemical signalling in roots under microgravity conditions

Reactive oxygen species (ROS) have been recently identified as new signaling molecules in plants or control and regulation of biological processes. They also actively participate in gravisensing and graviresponse of plants. On board, real-time measurement of total and specific ROS concentrations in plants tissues during gravity-changing conditions, collected into microplates, will be determined by a fast-multireader device. This device can control both a fluorimeter and a spectrophotometer for the measurement of Fluorescence and Absorbance of biological samples, respectively. Spectrophotometric analysis consists in the detection of the light radiation emitted by a sample to perform indirectly a chemical analysis; it can provide both qualitative and quantitative information. Every substance absorbs or emits light radiation at a determined wavelength. The analysis of the spectrum can individuate
the nature of the examined substance. The emitted/absorbed intensity of light radiation permits to understand the quantity of the analyzed substance.
Fluorescent dyes attached to biological target molecules enables the cellular distribution of the target molecule to be mapped by Fluorescence/Spectrophotometric analysis. When used at the right optimal dye-loading concentration, temperature, incubation, recovery, and retention time, any dye can work as an indicator of a target substance. By coupling targeting groups and fluorophores, the interaction dye-substance produces a specific change in the fluorescence intensity or spectra of the probe.
In details, ROS produced by plants tissues under gravitational stress (mainly hydrogen peroxide) bound with specific indicator dyes can form a stable colored and/or fluorogenic complex. Its content can be determined by a spectrophotometer using the absorbance at specific wavelenghts or through its fluorimetric emission spectrum by a fluorimeter. These analysis will be performed on a real-time schedule during the whole flight.

APPLICATIONS OF THE RESEARCH
This experiment will permit to study the emerging complexity of the multiple roles that ROS play in intra- and intercellular signalling and communication in both gravity-stressed and unstressed conditions, considering micro- and hypergravity as a main source of stress for plants. Plants are essential companion life forms especially for long-term space mission.
Astronauts could potentially sustain themselves with plants grown as food onboard space shuttles or in extraterrestrial habitats and exploit their ability to produce oxygen and recycle waste. Unfortunately plants growth in space presents several problems including absence of gravity. This is because plants are gravity-dependent as their growing organs need gravity in order to be guided for plant morphogenesis based on the negative gravitropism of shoots and the gravitropism of roots. Every change in direction and/or magnitude of the gravity vector are useful to study the response and the influence of micro or hyper-gravity condition on plant physiology. For this reason our Project offer a new supports in the field of space plant physiology that can elucidated plants behavior to different gravity levels focusing on micro-gravity.

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