Plant growth strategies are remodeled by spaceflight

Abstract

BackgroundArabidopsis plants were grown on the International Space Station within specialized hardware that combined a plant growth habitat with a camera system that can capture images at regular intervals of growth. The Imaging hardware delivers telemetric data from the ISS, specifically images received in real-time from experiments on orbit, providing science without sample return. Comparable Ground Controls were grown in a sister unit that is maintained in the Orbital Environment Simulator at Kennedy Space Center. One of many types of biological data that can be analyzed in this fashion is root morphology. Arabidopsis seeds were geminated on orbit on nutrient gel Petri plates in a configuration that encouraged growth along the surface of the gel. Photos were taken every six hours for the 15 days of the experiment.ResultsIn the absence of gravity, but the presence of directional light, spaceflight roots remained strongly negatively phototropic and grew in the opposite direction of the shoot growth; however, cultivars WS and Col-0 displayed two distinct, marked differences in their growth patterns. First, cultivar WS skewed strongly to the right on orbit, while cultivar Col-0 grew with little deviation away from the light source. Second, the Spaceflight environment also impacted the rate of growth in Arabidopsis. The size of the Flight plants (as measured by primary root and hypocotyl length) was uniformly smaller than comparably aged Ground Control plants in both cultivars.ConclusionsSkewing and waving, thought to be gravity dependent phenomena, occur in spaceflight plants. In the presence of an orienting light source, phenotypic trends in skewing are gravity independent, and the general patterns of directional root growth typified by a given genotype in unit gravity are recapitulated on orbit, although overall growth patterns on orbit are less uniform. Skewing appears independent of axial orientation on the ISS – suggesting that other tropisms (such as for oxygen and temperature) do not influence skewing. An aspect of the spaceflight environment also retards the rate of early Arabidopsis growth.

To branch or not to branch: the role of pre-patterning in lateral root formation

“…However, roots that are agravitropic due to defects in auxin signaling or transport, or due to removal of gravity-sensing tissues, still form LRs on the outside of curves, suggesting that the gravity response is not specifically required (Ditengou et al, 2008;Lucas et al, 2008;Richter et al, 2009). Recent observations of roots grown during spaceflight further indicate that the pattern of LRs and gravitropic responses of the primary root are separable; in the micro-g environment, roots grow more slowly than those of control plants on Earth (at 1 g), but root waving persists and LRs are observed on the outside of curves (Paul et al, 2012). Thus, root waving and the coincidence of LRP with curves occur independently of gravity.…”

Analyses of a Gravistimulation-Specific Ca2+ Signature in Arabidopsis using Parabolic Flights

“…S4). Long-term (hours to days) morphological responses of plants under hypergravity or mg conditions have been described using plants grown in a centrifuge (Fitzelle and Kiss, 2001;Matsumoto et al, 2010) or aboard the space shuttle/station (Kiss et al, 1999(Kiss et al, , 2012Paul et al, 2012;Roux, 2012), respectively. Such reports indicate that plants can respond with alterations in growth and development to a variety of gravitational accelerations.…”

Flexible imaging payload for real-time fluorescent biological imaging in parabolic, suborbital and space analog environments

“…Systems have been incorporated into both temporarily and permanently installed ISS plant growth hardware such as Advanced Astroculture (Link et al, 2003;Zhou, 2005), Biomass Production System (BPS) (Morrow and Crabb, 2000;Stutte et al, 2005), Plant Generic Bioprocessing Apparatus (PGBA) (Hoehn et al, 1996;Evans et al, 2009), Lada (Sychev et al, 2007;Bingham et al, 2003), European Modular Cultivation System (EMCS) (Brinckmann, 2005;Johnsson et al, 2009), Biolab (Brinckmann, 2005) and the Green Fluorescent Protein (GFP) Imaging System (GIS) within the Advanced Biological Research System (ABRS) (Paul et al, 2012;Levine et al, 2009). Visible light imaging has been implemented in the bulk of these plant growth chambers, but monitoring has also been conducted through infrared and fluorescent means.…”

“…These systems were each designed to meet the specific criteria relevant to their particular application or deployment environment (Table 1). These imagers have been deployed in one or more of the following environments; laboratory (Paul et al, 2003(Paul et al, , 2008(Paul et al, , 2012(Paul et al, , 2013Abboud et al, 2013aAbboud et al, , 2013b, autonomous greenhouse in a remote environment (Paul et al, 2008;Abboud et al, 2013b), hypobaric plant growth chamber (Abboud et al, 2013a), parabolic flights, and aboard the Space Shuttle and ISS (Paul et al, 2012(Paul et al, , 2013Levine et al, 2009).…”

“…Proper imaging systems can provide real-time, macroscopic-level data on the response of biology to the spaceflight environment. These systems are also capable of delving deeper into spaceflight effects by providing information on responses at the gene expression level (Paul et al, 2013(Paul et al, , 2012. This information serves to improve our fundamental understanding of http://dx.doi.org/10.1016/j.lssr.2014.09.002 2214-5524/© 2014 The Committee on Space Research (COSPAR).…”