Burgos, E. | bioRxiv Science

bioRxiv2020

Genetic structure of Photosystem II functionality in rice unraveled by GWAS analysis

Rice production is a particularly important crop for the half-world population. Therefore, knowledge about which genes are implicated in the functionality of the Photosystem II, that are still poorly explored could collaborate in the assisted selection of rice improving. In the present study, we applied Genome wide Association Studies of PSII chlorophyll fluorescence under two contrasting environmental conditions in 283 rice accessions highly diverse. A total of 110 significant association SNP-phenotype were observed, and 69 quantitative trait loci identified with a total of 157 genes, of which 38 were highly significant, mapped spread out through rice genome. These underlying regions are enriched in genes related to biotic and abiotic stresses, transcription factors, Calvin cycle, senescence, and grain characters. The correlations analyses PSII chlorophyll fluorescence parameters and some panicle characteristics found here suggest the possibility of developing molecular markers to assist the breeding programs that improve photosynthesis and yield in rice. HighlightThe genetic structure of the Photosystem II functionality in rice was studied by using genome-wide association through chlorophyll fluorescence.

plant biology↗

bioRxiv2020

Bacterial gene essentiality under modeled microgravity

To support long-duration spaceflight, identifying genes that enable microbial survival and stability under space stressors is crucial, as these factors can affect both host health and in-space biomanufacturing efforts. Our objective was to determine what bacterial genes are required for growth in culture under modeled, or simulated, microgravity conditions compared to normal gravity controls. We focused on the marine bacterium Vibrio fischeri, which forms a monospecific symbiosis with the Hawaiian bobtail squid, Euprymna scolopes. The symbiosis has been studied during spaceflight and in ground-based modeled microgravity conditions. Using transposon insertion sequencing (INSeq), we identified dozens of genes that exhibited fitness defects under both conditions, yet we identified relatively few genes with differential effects under modeled microgravity or gravity specifically. We additionally compared RNA-seq and INSeq data and determined that expression under microgravity was not predictive of the essentiality of a given gene. In summary, empirical determination of conditional gene essentiality identifies few microgravity-specific genes for environmental growth of V. fischeri, suggesting that the condition of microgravity has a minimal impact on symbiont gene requirement during growth in media. These findings suggest that maintaining beneficial microbial communities during spaceflight, and enabling their use in biomanufacturing applications, may require minimal genetic adaptation, easing the challenges of supporting healthy symbiotic relationships on long-duration missions.

microbiology↗