Spaceflight drives tomato into a salicylic-acid–deficient, biotic-defense-primed state

A cross-mission integration of two independent ISS tomato RNA-seq experiments — OSD-767 (VEG-05 chamber) and an Advanced Plant Habitat study manipulating salicylic-acid signalling — asking what is conserved about the plant response to space when individual genes are not.

MIT licensedFAIR NASA OSDRPlant PhysioSpace 2 ISS missionstomato
Read the manuscript → Figures Analysis code Code & data (GitHub)

Headline: leaf spaceflight responses do not replicate at the gene level (Spearman ρ = 0.05), yet the Plant PhysioSpace stress-pattern is conserved and matches the SA-deficient (NahG) state (r = 0.78) — SA signalling is the conserved causal buffer.

Abstract

Spaceflight reproducibly perturbs the plant transcriptome, yet individual differentially expressed genes rarely replicate across missions, hardware and cultivars — leaving open what, if anything, is conserved. We integrated two independent ISS tomato RNA-seq experiments: OSD-767 (VEG-05 chamber; red/blue light × spaceflight; leaf and root) and an Advanced Plant Habitat study manipulating salicylic-acid (SA) signalling (wild-type MoneyMaker vs SA-deficient NahG, ± exogenous SA × spaceflight). At the individual-gene level the two leaf spaceflight responses were uncorrelated (Spearman ρ = 0.05; 9 shared DEGs). However, projecting both studies into a shared Plant PhysioSpace revealed a strongly conserved stress-pattern response dominated by biotic/hormone, nitrogen and cold axes with light/UV suppression. Critically, the OSD-767 spaceflight signature matched the SA-deficient (NahG) state (Pearson r = 0.78, p = 0.001) far more than wild-type (r = −0.15), and similarity increased monotonically as SA tone fell (SA −0.20 → wild-type −0.15 → Mock +0.66 → NahG +0.78). In both studies the response localized to outer/epidermal cell types. We conclude that spaceflight pushes tomato into an SA-deficient–like, biotic-defense-primed transcriptional state, and that SA signalling is a conserved causal buffer — a pattern-level principle that is robust where gene-level signatures are not.

Highlights

Genes don't replicate

Leaf spaceflight responses uncorrelated across missions (ρ = 0.05; 9 shared DEGs) — the individual gene is not the reproducible unit.

Patterns do

Plant PhysioSpace stress-pattern conserved across both studies: biotic/hormone, nitrogen and cold up; light/UV down.

An SA-deficient state

Spaceflight signature matches SA-deficient NahG (r = 0.78) far more than wild-type (r = −0.15).

Monotonic SA gradient

Similarity rises as SA tone falls: SA −0.20 → MM −0.15 → Mock +0.66 → NahG +0.78. Response localizes to outer/epidermal cells.

Selected figures

Concept schematic: integrating OSD-767 and APH tomato studies via Plant PhysioSpace.
Fig 1 — Concept: integrating OSD-767 and the APH SA study through a shared Plant PhysioSpace.
Joint PhysioSpace heatmap showing the conserved stress-pattern response.
Fig 3 — Joint PhysioSpace heatmap: the conserved cross-mission stress-pattern response.
SA-status gradient; spaceflight similarity increases as SA tone falls toward NahG.
Fig 2 — SA-status gradient: similarity to the spaceflight signature rises as SA tone falls (peak at NahG, r = 0.78).

Data & code

Transcriptomic data derive from NASA OSDR (OSD-767) and the APH tomato SA study; cite the individual accessions. OSDR data remain subject to the NASA Open Data policy.