OpNom: Seedling Growth-XExperiment Overview
Seedling Growth-2 Research Objectives: Seedling Growth-2 is the second part of the Seedling Growth Experiment series and uses the plant Arabidopsis thaliana to determine the effects of gravity on cellular signaling mechanisms of phototropism and to investigate cell growth and proliferation responses to light stimulation in microgravity conditions. The investigation will determine, (1) Is the red light effect on blue-light-based phototropism a direct or indirect effect?; (2) What are the alterations in red-light-based phototropism of plants defective in essential components of auxin transport or lacking essential factors of cell growth and proliferation?; (3) What are the effects of a red light photostimulation on cell growth and proliferation under conditions of gravitational stress? Seedling Growth 2 requires three EMCS runs to be performed to collect image data and frozen samples.Principal Investigator(s)
NASA Ames Research Center, Moffett Field, CA, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Science Mission Directorate (SMD)Research Benefits
Information PendingISS Expedition Duration
March 2014 - September 2014Expeditions Assigned
39/40Previous ISS Missions
TROPI-2; TROPI2; GENARA-A; Seedling Growth-1
This experiment builds on previous spaceflight experiments for both Principal Investigators (Dr. John Z. Kiss and Dr. F. Javier Medina) using the model plant Arabidopsis thaliana to study the combined effects of light and gravity on plant growth, development and proliferation.
The experiment is a collaboration between a NASA PI (Kiss) and an ESA PI (Medina) and is co-sponsored by NASA and ESA.
In previous experiments by the PIs in the EMCS on the ISS, data were obtained on the phytochrome photoreceptors responsible for the phototropic response of seedlings grown in microgravity. Growth, development, and phototropic curvature of plants in response to varying qualities of light were analyzed, as well as global gene expression changes using DNA microarrays.
In the ROOT experiment (Medina, ISS) and in the experiments GENARA and ROOT CELL PROLIFERATION (approached until now in ground-based facilities), results indicated that cell growth and proliferation in root meristems were altered by changing the effective gravity, including the expression of relevant cell cycle genes. Furthermore, the distribution of auxin was altered, resulting in modifications of the pattern of primary and secondary root growth.
Since previous research has already shown the perception phase of phototropism, this experiment focuses on the signal transduction phase and on the crosstalk between the red and blue light signaling pathways, by means of the use of different mutants in the transduction pathways. The contribution of light stimuli to the regulation of cell growth and proliferation will be evaluated by using morphometry and immunolocalization methods on the indicated mutants and using red-light treatments to auxin mutants, to ribosome biogenesis mutants as well as to transformed lines containing the GFP reporter gene coupled with auxin-responsive elements and with regulators of cell cycle and ribosome biogenesis. On these materials, microscopical and RT-PCR postflight analyses will be performed.
Since down mass is limited in the spaceflight opportunities, a part of these experiments will be accomplished with telescience and, during experimental runs, images of seedlings will be downlinked to Earth.
Significant to the success of this proposal is that the PI teams are already experienced with the European Modular Cultivation System (EMCS). The US group was the first group to successfully use this research facility on the ISS in a project termed as outlined in our recent publications (Kiss et al. 2011; Millar et al. 2010). The European groups have used the EMCS in the GENARA experiment. In addition, the PIs have done extensive ground-based testing at NASA facilities and have performed tests in Europe on the engineering and flight models.
In terms of long-term research goals, the flowering plant Arabidopsis is an excellent model for spaceflight experiments because of its small size and simple growth requirements. A number of US and international agencies have supported Arabidopsis research efforts, including the establishment major genome programs. Indeed, Arabidopsis has already proven to be a valuable experimental model during several spaceflight experiments by our group and others. Again, since the EMCS has a variable speed centrifuge, this project is also relevant to the emphasis to understand how plant growth and development occurs at fractional g-levels, such as those found on the Moon and Mars.
The major goals of this project are to determine how gravity and light responses influence each other in plants and to better understand the cellular signaling mechanisms involved in plant tropisms. This proposed project builds on previous spaceflight experiments on the ISS with the EMCS using the model plant Arabidopsis. This new experiment is designed to confirm and extend previous data from the recent ISS experiment of a novel red-light-based positive phototropic response in plant shoots. The hypothesis is that positive red-light-sensing, which was known in older plant lineages, is masked by normal 1-g conditions in more recently evolved lineages. The experiment also investigates fundamental interactions among red and blue light signaling pathways and the gravity sensing mechanisms. The ISS is the only laboratory facility where it is possible to reliably and simultaneously vary light and gravity stimuli for the proposed experiments. A significant advantage of this proposed project is the use of existing flight hardware that has been flown successfully and allowed for growth of Arabidopsis seedlings in the EMCS. This project is also relevant to the recent emphasis at NASA to study plant growth and development at fractional g-levels such as those found on the moon and Mars. Improved knowledge of the basic mechanistic processes that will be the focus of this project is vital to develop ways to use plants in extraterrestrial bioregenerative life support systems.Earth Applications
The proposed research is relevant to understanding plant requirements in space. Arabidopsis is an excellent model plant for spaceflight experiments because of its small size and simple growth requirements. A number of US and international agencies have supported Arabidopsis research efforts, including the establishment of major genome programs. Indeed, Arabidopsis has already proven to be a valuable experimental model during several spaceflight experiments by the PIs and others, and is one of the model systems targeted for research by NASA. Since the EMCS has a variable speed centrifuge, this project is also relevant to the emphasis at NASA to understand how plant growth and development occurs at fractional gravity levels, such as those found on the Moon and Mars. This project deals with light and gravity sensing, which are both key parameters for the growth and development of plants. Thus, understanding these factors will help to develop strategies to optimize light sensing, and, in turn, to better modify plant species by using biotechnological approaches to improve crop plants. In addition, from this type of research, improvements in agricultural biotechnology can be realized and can contribute to goals of increased production, lessened environmental impact, and sustainability of agricultural production. Therefore, in the long-term, the research also is relevant to improving the characteristics of crop plants to benefit human agriculture on Earth.
Kiss JZ, Millar KD, Edelmann RE. Phototropism of Arabidopsis thaliana in microgravity and fractional gravity on the International Space Station. Planta. 2012; 236(2): 635-645. DOI: 10.1007/s00425-012-1633-y. PMID: 22481136.
Millar KD, Kumar P, Correll MJ, Mullen JL, Hangarter RP, Edelmann RE, Kiss JZ. A novel phototropic response to red light is revealed in microgravity. New Phytologist. 2010; 186(3): 648-656. DOI: 10.1111/j.1469-8137.2010.03211.x.
Matia I, Gonzalez-Camacho F, Herranz R, Kiss JZ, van Loon JJ, Marco R, Medina F, Gasset G. Plant Cell Proliferation and Growth Are Altered by Microgravity Conditions in Spaceflight. Journal of Plant Physiology. 2010; 167(3): 184-193. DOI: 10.1016/j.jplph.2009.08.012. PMID: 19864040.
Kiss JZ, Kumar P, Millar KD, Edelmann RE, Correll MJ. Operations of a spaceflight experiment to investigate plant tropisms. Advances in Space Research. 2009; 44(8): 879-886. DOI: 10.1016/l.asr.2009.06.007.
Kiss JZ, Millar KD, Kumar P, Edelmann RE, Correll MJ. Improvements in the re-flight of spaceflight experiments on plant tropisms. Advances in Space Research. 2011; 47(3): 545-552. DOI: 10.1016/j.asr.2010.09.024.