A new paper has been released by scientists in China studying changes in gene expression in the model organism Arabidopsis Thaliana. This experiment used special biological hardware called SIMBOX (Science in Microgravity BOX) to fly plants aboard the Shenzhou 8 Spacecraft (November  of 2011).  It is understood that a spaceflight environment alters gene expression compared to earth and this study examined plant transcriptomes.  Microarray analysis was used to compare three treatments: microgravity (Shenzhou 8), 1g centrifugal force also onboard Shenzhou, and earth ground control.  The major takeaways from this study: genes involved in plant stress response, genes involved in microgravity response, and genes involved in oxidative stress response were all regulated by spaceflight.  This experiment is more confirmation that plants respond on a molecular level to the effects of space environments.  You can check out the paper here:

The impact of space environment on gene expression in Arabidopsis thaliana seedlings