Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

M.S. in Biological Science



First Advisor

Jason Hoeksema

Second Advisor

Erik Hom

Third Advisor

John Z. Kiss

Relational Format



Simulated microgravity has been a useful tool to help understand plant development in altered gravity conditions. Thirty-one genotypes of the legume plant Medicago truncatula were grown in either simulated microgravity on a rotating clinostat, or a static, vertical environment. Twenty morphological features were measured and compared between these two gravity treatments. Within-species genotypic variation was a significant predictor of the phenotypic response to gravity treatment in 100% of the measured morphological and growth features. In addition, there was a genotype–environment interaction (G×E) for 45% of the response variables, including shoot relative growth rate (p < 0.0005), median number of roots (p ∼ 0.02), and root dry mass (p < 0.005). These findings are discussed in the context of improving future studies in plants space biology by controlling for genotypic differences, and by connecting traits to their underlying genetic causes by using genome-wide association (GWA) mapping. In the long-term, manipulation of genotype effects, in combination with M. truncatula’s symbiotic relationships with rhizobacteria and arbuscular mycorrhizal fungi, will be important for optimizing legumes for cultivation on long-term space missions.

Included in

Biology Commons



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