Research summary

To achieve successful long duration space exploration, a renewable food source for the astronauts must be available. Through the MULTIGEN experiment one will examine the possibility of sustainable plant growth for long duration space exploration by growing several generations of plants in orbit. A model plant, Arabidopsis thaliana will be used to study seed production and viability in microgravity. The MULTIGEN investigation will be split into three phases and spread over several ISS Increments.

Arabidopsis thaliana
©William S. Justice @ USDA-NRCS PLANTS Database

MULTIGEN-1

MULTIGEN-1 is a multi-generation seed-to-seed experiment. In addition to analysis of plant growth and development to mature seeds, the plant shoots will also be used for observations of circumnutations in Arabidopsis thaliana. Growth of the Arabidopsis plants will be performed in an Experiment Container (EC) in which a Plant Cultivation Chamber (PCC) i.e. a flower pot is located. The PCC is developed by EADS (Germany) and Prototech (Norway) as an Experiment Unique Equipment (EUE). Arabidopsis seeds will germinate and develop into mature seed-bearing plants after having been hydrated onboard the ISS. In order to harvest the newly developed seeds, the plants will be dehydrated. The seeds will be stowed onboard the ISS and eventually returned to Earth for further seed germination studies and morphological testing of the new plants.

Experiment Unique Equipment (EUE)

During MULTIGEN-1 seeds of Arabidopsis thaliana will be sown in a specialized plant cultivation chamber (PCC). The PCC is an advanced form of a flower pot which supplies the seeds with optimal support during micro-g conditions. The PCC consists of a chamber filled with zeolite enriched with controlled levels of nutrients. The zeolite is packed tightly into the pot, and a polypropylene felt is placed on top of it. A lid with holes in it is placed on top of the PCC, and Arabidopsis seeds are sown into these holes. The PCC supports the seedlings with optimal gas-flow and water-flow.

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PCC disassembled

PCC

PCC inside EC

MULTIGEN-2

MULTIGEN-2 involves DNA-microarray analysis of general expression of genes in the main metabolic pathways and specific gene expression quantification analysis of selected genes under micro-g conditions. Once the plants reach maturity on the ISS they will be fixated and stowed for return to Earth for such DNA analyses.

Experiment Unique Equipment (EUE)

Specialized collapsible cultivation chambers are designed for use during MULTIGEN-2. These chambers allow enough space for growth of Arabidopsis through 40 days, and can be compressed to half the size for fixations of the plants.

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Volume before compression and fixation (left) and after compression and fixation (right)

MULTIGEN-3

MULTIGEN-3 involves observation of plant circumnutations in roots. The scientific objective is to reveal the rotational movements around the plumb line (circumnutations) which the Arabidopsis plant-root performs during growth. The movements seem to be driven by inherent oscillatory processes but are also modified by the acceleration force (gravity or centripetal forces).

Experiment Unique Equipment (EUE):

The MULTIGEN-3 cultivation chamber (CC) contains a layer of agar on which Arabidopsis seeds will grow. The CC is tilted in a 45 ? angle and connected to a handler inside the EC. The handler contains an air waste bag, washing medium and fixative.

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EC with CC and handler

CC with internal handler for the seeds