Epigenetic change in Arabidopsis thaliana in response to spaceflight - differential cytosine DNA methylation of plants on the ISS (APEX-04) - 06.13.18

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Science Objectives for Everyone
Spaceflight causes several changes to animals and plants, and those that take place on a molecular level can affect how the organism grows without altering its outward appearance. Epigenetic change in Arabidopsis thaliana in response to spaceflight - differential cytosine DNA methylation of plants (APEX-04) studies molecular changes in thale cress seedlings grown in microgravity. Results provide new insight into the molecular biology underlying how plants grow differently in space.
Science Results for Everyone
Information Pending

The following content was provided by Anna-Lisa Paul, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: APEX-04

Principal Investigator(s)
Anna-Lisa Paul, Ph.D., University of Florida, Gainesville, FL, United States

Robert J. Ferl, Ph.D., University of Florida, Gainesville, FL, United States

NASA Kennedy Space Center, Cape Canaveral, FL, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
NASA Research Office - Space Life and Physical Sciences (NASA Research-SLPS)

Research Benefits
Earth Benefits, Scientific Discovery

ISS Expedition Duration
September 2016 - September 2017

Expeditions Assigned

Previous Missions
APEX-04 builds upon the previously flown Plant Growth Investigations in Microgravity (PGIM) experiment which flew on STS-93, the Biological Research in Canisters (BRIC)-16 experiment which flew on STS-131, and the Transgenic Arabidopsis Gene Expression System (TAGES) experiment which operated in the Advanced Biological Research System (ABRS) on the International Space Station (ISS), and APEX-03-2 which operated in Veggie on the ISS.

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Experiment Description

Research Overview
Plants experiencing spaceflight are quite normal in appearance, but can exhibit growth habits distinctly different from plants on earth. This research explores the molecular biology guiding the altered growth of plants in spaceflight.


This project seeks to use an unbiased genome-wide approach to define the changes in DNA methylation that occur in Arabidopsis during spaceflight, in order to better understand the spectrum of responses that allow adaptation to the spaceflight environment. This project is one of both discovery on a genome-wide scale and application to specific hypotheses. The research team proposes replicated whole genome bisulfite sequencing in Arabidopsis roots and leaves to discover, and quantify, 5-methylCytosine (5mCyt) epigenetic modification coupled with RNASeq examination of the comparable transcriptomes, to both quantitatively and qualitatively assess spaceflight associated DNA methylation on transcript profiles. The research team then tests the hypothesis that methylation is involved in spaceflight adaptation by similarly examining methylation mutants.
Epigenetic features play a role in the regulation of gene expression and the subsequent response of an organism to its environment. DNA methylation is a major epigenetic modification that is not directly coded into the genome sequence and yet can modify expression and be inherited for at least one generation. Several groups, including this team, have shown that large numbers of plant genes are differentially expressed in response to spaceflight.
Extensive preliminary data shows significant genome-wide 5mCyt modification differences in spaceflight plants, as compared to ground controls.
The tactical objectives of this proposal are: 1) Bisulfite whole genome sequencing is used to generate maps of spaceflight-induced changes in 5mCyt at single base-pair resolution for roots and leaves. 2) RNASeq is used to digitally quantify and qualitatively assess transcriptome in the samples, as differential methylation has been functionally linked to changes in both promoter regulation and structural changes in RNAs. These data characterize functional impacts of spaceflight induced across the entire genome. 3) DNA methylation mutants are used to directly test the hypothesis that epigenetic modification of DNA is a key aspect of spaceflight adaptation.
Learning more about the spaceflight methylomes of plants contributes to the fundamental understanding of how biology responds and adapts to the spaceflight environment, and also provides insight in the adaptive strategies plants use in the face of novel stimuli outside of their evolutionary experience. The long term goal of this line of inquiry is to understand how the methylome contributes to the adaptive strategies of plants to novel environments.

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Space Applications
Previous research has demonstrated that large numbers of plant genes are expressed differently in space compared to plants on Earth, which can alter how plants grow. This investigation studies the entire genome of thale cress plants grown in space, creating maps of spaceflight-specific changes in certain groups of genes. Results give new insight into plants’ molecular responses to spaceflight, which benefits efforts to grow plants in space for food and oxygen.

Earth Applications
Understanding the basic growth and response mechanisms of plants has important implications for research on Earth, including biomass and agricultural production. Improved understanding of the genetic pathways affected by different environments yields new techniques for growing plants in challenging places, benefiting people on Earth.

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Operational Requirements and Protocols

Crew installs petri plates into Veggie Facility to start the experiment. During the growth phase, the crew removes plates to photograph and track any changes in growth. Crew harvests plants to KSC Fixation Tubes (KFTs). Crew transfers KFTs to cold stowage (-80°C or colder)  Note: 18 to 24 hours must elapse between harvest and insertion of KFTs into cold stowage. Crew transfers KFTs with frozen samples to Cold Bag for return.

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Decadal Survey Recommendations

Plant and Microbial Biology P2

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Results/More Information

Information Pending

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Related Websites

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Ten-day old Arabidopsis thaliana plants growing vertically on the surface of a 10 cm square nutrient gel Petri plate. This experiment form factor is routinely used in the PIs’ laboratory for ground-based studies, and will be used in the APEX04 flight experiment as well. Image courtesy Dr. Anna-Lisa Paul.

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