The wild type Col-0 plants and the Sku-6 mutant plants of the Col-0 background were germinated on ISS or on the ground and the gene expression profiles in roots at 4 days or 8 days were established. The Sku6 gene (At2g03680) codes for a protein that localizes to microtubule within the cortical array and putatively acting as an intramolecular linker. The development of Col-0 and Sku-6 plants on orbit differs from that on the ground as demonstrated by the comparison of the gene expression profiles between 4 days old to 8 days old plant in the two environments. However the development of Sku-6 mutant plants also differs from Col-0 at either age and in either environment, suggesting the role of the genetic background in these developmental decisions. The 4 days old Sku-6 roots in orbit engaged more genes than the 4 days old Col-0 roots in orbit but also more than the 4 days old Sku-6 roots on the ground. Overall the 4 days old roots differentially expressed more genes in spaceflight relative to ground than the 8 days old roots of either genotype. Overall design: APEX03-2 (Advanced Plant Experiment 03-2) also identified as TAGES-Isa (Transgenic Arabidopsis Gene Expression Systemâ€”Intracellular Signaling Architecture) was launched on SpaceX mission CRS-5 on 10 January 2015. Dry, sterilized Arabidopsis seeds were planted aseptically on the surface of 10-cm2 solid media plates and remained dormant until removed from cold stowage and exposed to light at the initiation of the experiment on the ISS (International Space Station). The plates were grown in the Vegetable Production System (VPS/Veggie) hardware on the Columbus Module of the ISS with the overhead LED lighting of the VPS. At four or for the second experimental set at eight days, seedlings were harvested by an astronaut into KFT (Kennedy Fixation Tube) containing RNAlater solutions. Upon return to Earth, the harvested material was used to compare the transcriptomes of each genotype and each age using RNAseq technology. The patterns of gene expression was compared between treatments (spaceflight versus ground control) within each genotype of same age or between two ages within same genotype and within same treatment. For 4 day old roots 5-8 roots were combined to serve as one biological replica. For 8 day old roots 2-3 roots were used to form one biological replica. In each case the four biological replicas were used for the transcriptomic analysis.