Plant cell proliferation and growth are altered by microgravity conditions in spaceflight.

This research paper explores how plants grow in the unique conditions of outer space or under artificial gravity. The study focuses on a common plant called Arabidopsis thaliana (Col-0), which is often used to understand more about other plants too, including crops that we eat every day! Researchers found out what changes happen inside these little green buddies when they're in space or simulated microgravity conditions. In simple terms, the scientists looked at how different levels of gravity affect plant growth by examining their genes and proteins - think of it as checking which parts are switched on (or off) under various gravitational forces. They discovered that plants have specific responses to these changes in gravity: some increase or decrease gene activity depending on whether the force is stronger or weaker, others show a peak response at an intermediate level, while yet another group responds only when they reach a certain threshold of this space-like condition.

In the study by Kruse et al. (2020), published in iScience on August 19, 2022, researchers investigated plant growth responses during spaceflight and simulated microgravity conditions to enhance our understanding of how plants adapt biologically under such extreme environments. The study focused primarily on Arabidopsis thaliana (Col-0) seedlings with a compromised unfolded protein response (UPR), which is crucial for cellular homeostasis, particularly in stressful situations like spaceflight or microgravity exposure. The methodology employed involved the use of RNA sequencing and gene expression profiling to examine transcriptional responses at different gravitational levels during a SpaceX CRS-12 mission launched on August 14, 2017. The researchers observed three distinct patterns in plant response: dose-dependent linear reactions where the expression of genes increased or decreased with increasing gravity; peak up/peak down responses at intermediate gravitational levels leading to either a gene's maximum induction or repression; and threshold responses, which were induced only beyond certain gravity thresholds.