Dr. Erik Hanschen
LANL

Topic: The genetics of diploid algae and how they respond to the stress of spaceflight

Academic host: Carl Simpson

Abstract: Algae are increasingly being used as a feedstock for food, fuel, and other sustainable commodities, but improvements to cultivation efficiency are needed. Whole genome duplication (WGD), the process where the entire DNA content of a cell is doubled, played a critical role in the ancient domestication and commoditization of other species, namely all plant crops. While most algal species are haploid (one copy of each chromosome), plants are either diploid (two copies of each chromosome) or polyploid (three or more copies of each chromosome). However, current efforts to improve algal crop strains have not utilized whole genome duplication. This project pursued two goals to understand the prevalence of diploid algae and improve algal crop strains through WGD. First, we identify several diploid algal species and demonstrate improved methods for assembling phased, diploid, genome assemblies. Second, this project developed methods to artificially induce WGD causing diploidy. Preliminary data suggests algae with artificial WGDs have a higher growth rate, suggesting that artificially induced diploidy supports increased biomass production, and ultimately may support increased biofuel production. In a separate project, we utilize NASA’s Advanced Plant Habitat (APH) to provide a unique and valuable perspective into plant physiology response to microgravitational environments during spaceflight. We utilize NASA’s Advanced Plant Habitat (APH) to grow Arabidopsis thaliana in both microgravity (aboard the International Space Station) and under usual gravitational regimes (1G, Kennedy Space Center). We investigate the differential expression and alternative splicing differences between ground control and flight treatments. Using PacBio Hi-Fi RNA sequencing, we demonstrate systemic changes in alternative splicing in response to spaceflight, resulting in protein and functional differences including stress response and intracellular transport. Additionally, a substantial number of genes are both differentially expressed and alternatively spliced, which indicates specific gene pathways are being modified in response to spaceflight, using both differential expression and alternate splicing. Our results suggest that alternative splicing is an under-appreciated mechanism of plant response to microgravity and spaceflight.