Dynamism of Auxin Efflux Facilitators, CsPINs, Responsible for Gravity-regulated Growth and Development in Cucumber (CsPINs) - 12.28.16

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
The Dynamism of Auxin Efflux Facilitators (CsPINs) Responsible for Gravity-regulated Growth and Development in Cucumber investigation uses cucumber seedlings to analyze gravity’s effect on plants. The investigation examines the formation of small horizontal “pegs” in cucumber plants, which develop near the transition between the plant’s root and stem. Gravity plays a role in where the peg forms. The investigation examines how plants sense gravity, and how gravity affects plant hormone transportation, plant growth and root development, all of which are important for plant cultivation in space.
 
Science Results for Everyone
The force is strong with this one. Plant hormones called auxins help young plants to properly grow in response to changes in the direction of gravitational force. Protein molecules in the Protein Interaction Networks, or PINs for short, carry auxins into and out of developing plant cells and redistribute these hormones where they are needed based on the plant’s sense of gravity. This investigation shows that changing direction of gravitational force causes changes in location of Cucumber PINs and that inner cell layers form canals to efficiently transport auxin. Growth orientation, or auxin chemical inhibitor, can change the normal auxin distribution inside the plant thus affecting its normal growth structure.

The following content was provided by Hideyuki Takahashi, Ph.D., and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Japan Aerospace and Exploration Agency (JAXA).
Experiment Details

OpNom:

Principal Investigator(s)
Hideyuki Takahashi, Ph.D., Tohoku University, Miyagi, Japan

Co-Investigator(s)/Collaborator(s)
Nobuharu Fujii, Ph.D., Tohoku University, Sendai, Japan
Akira Higashibata, Ph.D., Japan Aerospace and Exploration Agency, Tsukuba, Japan
Yutaka Miyazawa, Ph.D., Tohoku University, Sendai, Japan
Genji Kamata, AES, Japan
Hiroe Kobayashi, Ph.D., Tohoku University, Miyagi, Japan

Developer(s)
Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan

Sponsoring Space Agency
Japan Aerospace Exploration Agency (JAXA)

Sponsoring Organization
Japan Aerospace Exploration Agency

Research Benefits
Information Pending

ISS Expedition Duration
March 2011 - May 2012; March 2014 - September 2014

Expeditions Assigned
27/28,29/30,39/40

Previous Missions
Information Pending

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Experiment Description

Research Overview

  • Plants sense gravity as an environmental signal and, use it for governing their morphology and growth orientation. It has been found that the change in auxin efflux facilitators, CsPINs, play an important role in the regulation of gravity-dependent redistribution of auxin, and thereby controls gravimorphogenesis (peg formation) in cucumber (Cucumis sativus L.) seedlings. Moreover, it has been found that gravitropism interferes with hydrotropism in cucumber roots, in which also the change in auxin efflux facilitators may also play a role. In this space experiment, cucumber seedlings are used to analyze the effect of gravity on the expressions of CsPINs, and unravel their contributions to peg formation. At the same time, hydrotropism from gravitropism in roots is differentiated and compared the expression of CsPINs to figure out the interacting mechanism between the two tropisms. Dry cucumber seeds are launched, and imbibed and grown under either microgravity, or 1G conditions, in the Cell Biology Experiment Facility (CBEF) of ISS. Immediately after the experiment, seedlings are fixed using RNAlater, and refrigerated until recovery on earth. Investigations of morphology and the expressions of CsPINs are done as post-flight analyses.

  • Auxin efflux facilitators, CsPINs, play an important role in the regulation of gravity-dependent redistribution of auxin and thereby control gravimorphogenesis, or how gravity affects plant growth.

  • Investigators could analyze the effect of gravity on the expressions of CsPINs, and try to better understand their contributions to peg formation.

  • The investigation seeks to develop new techniques for controlling plant growth via regulation of auxin transport, morphogenesis, and root hydrotropism (new tools/methods for plant cultivation in space).

 

Description

The expression pattern of auxin efflux facilitator, CsPIN1, changes in response to gravity. This could be responsible for auxin reduction, and thereby suppression of peg formation on the upper side of the transition zone in cucumber seedlings.

The expression pattern of CsPIN5 changes in response to moisture gradient and gravity, which could be responsible for auxin redistribution in hydrotropically and gravitropically responding roots of cucumber seedlings.

Using microgravity environment, the investigation seeks to verify that gravity and moisture gradient induce the changes in expression patterns of CsPINs proteins.
 

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Applications

Space Applications
CsPINS enables new techniques for studying how plants sense gravity and determine which direction to grow. Auxin is a type of plant hormone involved in the formation of pegs in cucumber seedlings, which are a gravity-related physical trait, that develop between the plant’s roots and its stem. Understanding how plants sense gravity could enable new genetically modified variants that can grow in microgravity.
 

Earth Applications
CsPINS provides fundamental insight into the genetic expression and environmental sensing of plants. Improved understanding of plants’ environmental response could have implications for agriculture. The investigation also establishes a framework for a life-support system cultivating plants in space and on the ground.
 

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Operations

Operational Requirements and Protocols

Run3: Cucumber seeds are incubated 18 hours +/- 1 hour under micro gravity condition, then incubated 4 hours, or 8 hours under micro gravity, or 1G artificial condition . After  incubation, samples are videotaped using a G1 camcorder, and chemically fixed  using RNAlater, and placed in Chemical Fixation Chambers. The Chemical Fixation Chambers containing the samples are stored at +2 oC in MELFI, and recovered on earth at +4 oC.

Run3: 5 chambers which contains 7 cucumber seeds each incubate 18 hours +/- 1 hour under micro gravity, 1 chamber is removed and fixed, and the 4 other chambers are incubated under micro gravity . After  incubation, the samples are videotaped using a G1 camcorder, and chemically fixed by RNAlater. After fixation of the samples, the Chemical Fixation Chambers, containing the samples, are kept at +2 oC in MELFI and recovered at +4 oC on earth.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Charles Darwin proposed, over a hundred years ago, that plant growth could be directed by a stimulus such as light (phototropism) or gravity (gravitropism), and his work eventually lead to the discovery of the first plant hormone, auxin. It is now known that plants respond to changes in the direction of gravity by changing their growth orientation and body structure, and auxins are vital plant hormones which help regulate these processes. Auxins are transported into and out of plant cells by protein carriers, or “PINs” for short, of the Protein Interaction Network (PIN). Gravity affects where PINs distribute auxins in developing plants, thus affecting growth pattern, organ formation and positioning. In young cucumber seedlings, the “peg” is an out-growth tissue nub which functions to snag the hard seed coat from the soft developing body inside allowing the plant to freely grow. Cucumber (Cucumis sativus) seedlings grown in a horizontal position develop a curvature (a hook) and their peg on the lower side of the transition zone between the stalk and the root so the seed coat can be detached successfully in this unusual orientation. This is accomplished by suppressing upper stalk peg formation, had the plant been grown straight up, by decreasing auxin in this region. These results reveal that the localization of Cucumis sativus PIN (CsPIN) in plant cells changes in response to the direction of force. Furthermore, results suggest that the endodermal (inner) cell layer of the stalk develop canals by which auxin is laterally transported from the upper to the lower flank in response to gravity. In ground studies, 48-hour cucumber seedlings were treated with auxin transport and action (response) inhibitors to observe effects of treatments on gravitropism and elongation of cucumber seedlings. At low concentrations of inhibitors, growth curvature was affected more than body elongation. However, higher dosage inhibited both curving and lengthening, as well as, peg formation. When chemical treatment concentrations increased, the production of plant growth hormones decreased, with a corresponding increase in growth inhibiting factors in the lower part of the transition zone (germinating stalk below the first leaves and the root) of the peg. All results indicate that auxin interference inhibits peg formation in the transition zone of the cucumber seedlings.

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Results Publications

    Yamazaki C, Fujii N, Miyazawa Y, Kamada M, Kasahara H, Osada I, Shimazu T, Fusejima Y, Higashibata A, Yamazaki TQ, Ishioka N, Takahashi H.  The gravity-induced re-localization of auxin efflux carrier CsPIN1 in cucumber seedlings: spaceflight experiments for immunohistochemical microscopy. npj Microgravity. 2016 September 15; 2: 16030. DOI: 10.1038/npjmgrav.2016.30.

    Shimizu M, Miyazawa Y, Fujii N, Takahashi H.  p-Chlorophenoxyisobutyric Acid Impairs Auxin Response for Gravity-regulated Peg Formation in Cucumber (Cucumis Sativus) Seedlings. Journal of Plant Research. 2008; 121(1): 107-114. DOI: 10.1007/s10265-007-0121-0.

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites

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Imagery

image Peg formation in cucumber seedlings, image courtesy of JAXA.
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image Gravity-regulated Growth and Development in Cucumber (CsPINs). Image courtesy of JAXA.
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image NASA Image: ISS027E017840 - NASA astronaut Ron Garan, Expedition 27 flight engineer, supports the Dynamism of Auxin Efflux Facilitators responsible for Gravity-regulated Growth and Development in Cucumber (CsPINs) experiment in the Kibo laboratory of the International Space Station.
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image A, D, G: Photos of seedlings grown in 1-g, horizontally B, E, H: Photos of seedlings grown in 1-g, vertically C, F, I: Photos of seedlings grown in microgravity. Significant nutational movement (wobbling) in ΒΌ g. Image courtesy of JAXA.
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image Photo A: Seedling grown in 1-g, horizontally. Peg developed one side. Photo B: Seedling grown in 1-g, vertically. Peg developed both sides. Photo C: Seedlings grown in microgravity. Peg developed both sides. Images courtesy of JAXA.
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image NASA Image: ISS039E019667 - JAXA astronaut Koichi Wakata poses for a photo with CsPINs Chamber.
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image NASA Image: ISS039E019668 - Documentation of CsPINs Measurement Experiment in the Cell Biology Experiment Facility (CBEF) Incubator Unit.
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