Seed-to-Seed-to-Seed Growth and Development of Arabidopsis in Microgravity

Abstract

Arabidopsis thaliana was grown from seed to seed wholly in microgravity on the International Space Station. Arabidopsis plants were germinated, grown, and maintained inside a growth chamber prior to returning to Earth. Some of these seeds were used in a subsequent experiment to successfully produce a second (back-toback) generation of microgravity-grown Arabidopsis. In general, plant growth and development in microgravity proceeded similarly to those of the ground controls, which were grown in an identical chamber. Morphologically, the most striking feature of space-grown Arabidopsis was that the secondary inflorescence branches and siliques formed nearly perpendicular angles to the inflorescence stems. The branches grew out perpendicularly to the main inflorescence stem, indicating that gravity was the key determinant of branch and silique angle and that light had either no role or a secondary role in Arabidopsis branch and silique orientation. Seed protein bodies were 55% smaller in space seed than in controls, but protein assays showed only a 9% reduction in seed protein content. Germination rates for space-produced seed were 92%, indicating that the seeds developed in microgravity were healthy and viable. Gravity is not necessary for seed-to-seed growth of plants, though it plays a direct role in plant form and may influence seed reserves.

Functional alterations of root meristematic cells of Arabidopsis thaliana induced by a simulated microgravity environment

“…Other morphological alterations of the root, such as a skewed growth and an abnormal number of adventitious roots were also reported to occur in space-grown seedlings (Millar et al, 2011). Interestingly, a "seed-to-seed" experiment in space has shown that, even though the entire life cycle of plants can be achieved in real microgravity without serious apparent damages to the health and viability of daughter plants, noticeable changes in the shape of plant organs were identified (Link et al, 2014).…”

Effect of simulated microgravity on gene expression during embryogenesis ofArabidopsis thaliana

“…Based on previous studies, plants are able to grow and reproduce in outer space conditions Nevertheless, some abnormalities were observed, including chromosomal breakage, failures in seed production, nonviable embryos, and changes in gene expression (Link et al ., 2014).…”

“…A RPM is a version of 3D clinostat, which continuously realizes random changes in the orientation relative to the gravity vector in a biological experiment (Borst et al ., 2009). The first experiment of Arabidopsis thaliana in microgravity was performed by Merkys and Laurinavicius (1983), they obtained some viable seeds, on the other hand several of seed contained nonviable embryos (reviewed in Link et al ., 2014). Simulated (micro)gravity is stressful for plants, and has an influence on plant growth, as well as on cellular and molecular responses such as cell cycle, embryogenesis, seeds, photosynthesis, gravitropic sensing/response, cell wall composition/properties, and changes of gene expression (Link et al ., 2014).…”

“…The first experiment of Arabidopsis thaliana in microgravity was performed by Merkys and Laurinavicius (1983), they obtained some viable seeds, on the other hand several of seed contained nonviable embryos (reviewed in Link et al ., 2014). Simulated (micro)gravity is stressful for plants, and has an influence on plant growth, as well as on cellular and molecular responses such as cell cycle, embryogenesis, seeds, photosynthesis, gravitropic sensing/response, cell wall composition/properties, and changes of gene expression (Link et al ., 2014). The growth and development of plants is highly influenced by various external factors including abiotic and biotic stresses.…”

Expanded benefits for humanity from the International Space Station

“…Plant research in a space greenhouse [ Figure 7] has allowed the study of root zone substrates in space allowing scientists to improve predictions of how artificial soils will behave when irrigated both in space and on Earth in experimental forests [18].…”