🚀 NASA OSDR OSD-375 (APEX-06) Spaceflight Study

📸 Hardware and Seedlings (Su et al. 2023)

Seedlings. Representative 5-day-old Bd21, Bd21-3 and Gaz8 seedlings grown on the ISS and as ground controls, with root, shoot and root-hair lengths. Reproduced from Su et al. (2023) Life 13(3):626, Fig. 2, CC BY 4.0.

APEX Growth Unit. The Oasis Hortcube foam block that supports the seeds, and the assembled growth unit. Reproduced from Su et al. (2023) Life 13(3):626, Fig. 1, CC BY 4.0.

View Study OSD-375 on NASA OSDR →

OSD-375 Sample Design

Figure 1. The 48 OSD-375 RNA-seq samples by accession, organ and condition, counted from the OSDR ISA sample table: four APEX Growth Units per accession and condition, each giving one root and one shoot sample.

What Su et al. (2023) Reported

• Roots of all three accessions grew more slowly and had longer root hairs in microgravity than in the ground control; Bd21 shoots also grew more slowly.
• Differentially expressed genes (DEGs), flight versus ground, in the abstract: Gaz8 4,527, Bd21 1,353, Bd21-3 570, with only 47 shoot DEGs and six root DEGs shared between accessions. Their supplementary tables list slightly different numbers per organ (Figure 3).
• Bd21 was sequenced at the University of Wisconsin–Madison (2 × 150 bp) and Bd21-3 and Gaz8 by NASA GeneLab (2 × 100 bp), both on NovaSeq 6000. Differences between accessions are therefore confounded with sequencing batch.

Figure 3. DEGs per accession, organ and direction, counted from Su et al.'s Supplemental Tables S2–S4: Bd21 325 root and 1,027 shoot, Bd21-3 224 and 345, Gaz8 475 and 4,186. Every listed gene has DESeq padj and edgeR q below 0.05; direction is the sign of the DESeq log₂ fold change.

Source: Su, Levine & Masson (2023) Life 13(3):626, doi:10.3390/life13030626, CC BY 4.0. No new analysis of OSD-375 has been run in this repository; OSDR holds the raw FASTQ files for this study. The gene-level fold changes shown here before 14 October 2026 were typed-in values and were withdrawn.

Gravitropism Candidate Genes in the DEG Lists

Figure 4. Brachypodium genes of the 29 gravitropism candidates that Su et al. list as spaceflight DEGs, with their DESeq log₂ fold changes (ISS / ground). Genes are Ensembl Compara orthologs of the candidate's Arabidopsis anchor; * marks a match only through Su et al.'s best-hit Arabidopsis ortholog. Thirteen candidates have at least one DEG call, seven of them through a Compara ortholog; no gene matched to LAZY1 or CPK28 is listed.

Blank cells mean "not listed as a DEG", which may mean unexpressed or below significance, not a measured zero. Being a spaceflight DEG does not by itself link a gene to gravitropism. Full values per gene are in the AstroGrass database and in candidate_spaceflight_degs.csv.

Mission Hardware, Timeline and Growth Conditions (Fig S1)

Supplementary Figure S1. APEX Growth Unit and seedlings (Su et al. 2023, CC BY 4.0); the APEX-06 timeline from launch to return; and growth conditions from the OSD-375 metadata (22 °C, continuous light at 40–55 µmol m⁻² s⁻¹, 1.397 mGy absorbed dose in flight).