Gravitropism of Root Tip Growth in Arabidopsis thaliana

Carly Schafer ’23

Student: Carly Schafer ’23
Research Mentor: Chris Wolverton (OWU Department of Biological Sciences)

Gravity is a downward force with which everything on Earth is influenced by, including plants. The shape and internal processes of plants are highly affected by the Earth’s gravitational pull. This begs the question of how plants, and potentially agriculture as a whole, would be affected by a gravitational pull of a different magnitude, say on a different planet. By altering the genetic make-up of seedlings of a plant called Arabidopsis thaliana, and rotating the plants to change the direction of gravity, it can be determined exactly what segments of plant DNA are most affected by gravity, and how changes to those segments ultimately affect plant growth and development.

Essential for the development of agriculture in space is an understanding of how plants grow in microgravity environments. Rather than inducing growth responses in space directly, gravitropism can be analyzed more accessibly on Earth via rotating surfaces that alter the direction of gravity. By altering the direction of gravity, starch-filled amyloplasts within root tip cells sediment to the bottom of cells, inducing signaling that leads to the downward growth of roots via the intracellular movement of auxin. Phenotyping of twenty-five mutants of Arabidopsis thaliana previously found to have altered genetic profiles after exposure to simulated microgravity environments was conducted using continuous rotation experiments, free rotation experiments, phototropism experiments, and RT-PCR. The goal of this study is to determine if any of the rotation experiments produce significantly altered root tip growth responses in the mutants with relation to wild-type strains. Those mutants with significantly altered responses would indicate genes that are responsible for some aspect of growth response to gravity. Additionally, closer examination of one mutant in particular, whose wild-type variant produces a protein containing an SPla/RYanodine receptor (SPRY) domain, will aim to predict, prior to further experimentation, the molecular basis of how this gene influences growth response. The results of this study have implications related to cultivating plants in space, which could ultimately expand on humanity’s access to land and other agricultural resources, and a deeper knowledge of how the physiology and morphology of plants is impacted by gravity on Earth.