[Plant Cell Division]
Effects of space environments on cell division in plants

RESEARCH OVERVIEW

• One of the differences between the Earth and Space environment is the magnitude of gravity. In order to produce crops on the Moon and Mars in the future, it is necessary to understand the effect of gravity on the body plan of plants. The basic elements of plant morphogenesis are cell elongation and division. Many studies have been conducted on the effect of microgravity on cell elongation, but there are few experimental examples of the effects on cell division. In addition, structures consisting of microtubules play an important role in the cell division process, but the formation process of these structures in the microgravity environment has not been clarified.
• In the Effects of the Space Environment on Cell Division in Plants (Plant Cell Division) investigation, the green algae plant Coleochaete scutata Bréb. and the tobacco (Nicotiana tabacum L.) BY-2 cells are used as plant specimens to try to clarify the effects of microgravity, and images of the plants are to be acquired using the newly installed JAXA Confocal Microscope (COSMIC) in the Japanese Experiment Module (JEM). The Plant Cell Division investigation seeks to provide a better understanding of the effects of microgravity on the cell division of plant cells, and the formation of microtubule structures formed during the cell division process. Samples are collected, chemically fixated, and frozen for analysis of the microstructure, microtubules, proteome, and transcriptome.

SPACE APPLICATIONS

Cell elongation and division are basic elements of plant formation. Many studies have looked at microgravity’s effects on cell elongation, but few have examined effects on cell division before this. In addition, the availability of a confocal microscope on the space station makes it possible to clarify the formation process of microtubules in microgravity. Understanding these processes supports development of better methods for growing plants in space and on the Moon and Mars.

EARTH APPLICATIONS

This investigation could help identify the relationship between cell elongation and division and gravity and lead to development of more efficient plant production systems on Earth.

OPERATIONAL REQUIREMENTS AND PROTOCOLS

The science operations of Plan Cell Division consists of two different runs:

Run-1 is the Recovery experiment:

• The Coleochaete scutata Bréb.(4 chambers) and tobacco BY-2 cells (4 chambers) are launched to the International Space Station (ISS) at a temperature of +4°C.
• Upon arrival at the space station, the plant samples are incubated using the Cell Biology Experiment Unit (CBEF) in the Japanese Experiment Module (JEM) for 12 days (Coleochaete scutata Bréb.) and 10±2 days (tobacco BY-2 cells) respectively.
• After the incubation process is complete, the plant samples are returned to Earth under either chemical fixation or frozen conditions.

Run-2 is the Observation experiment:

• The Coleochaete scutata Bréb. (2 chambers) and tobacco BY-2 cells (2 chambers) are launched to the ISS at +4°C.
• The plant samples are observed using the JAXA COSMIC for 12 days (Coleochaete scutata Bréb.) and 2 days (tobacco BY-2 cells) respectively.
• Image data from COSMIC is downlinked to Earth.

TAMAOKI Daisuke [University of Toyama]