Fungal effectors play important roles in inciting disease development on host plants. We identified an effector (Secreted in Xylem4, SIX4) in an Arabidopsis infecting isolate (Fo5176) of the root-infecting fungal pathogen Fusarium oxysporum and demonstrated this effector is required for full virulence. To explore the role of Fo5176_SIX4 we use whole transcriptome profiling of root tissues from plants overexpressing this effector (35sSIX4) versus wild-type (Col-0) plants after F. oxysporum infection. We grew both WT and 35sSIX4 plants for four weeks in soil. After four weeks the plants were infected with Fusarium oxyporum isolate Fo5176, trays covered with a plastic dome and incubated at 28C. There were four independent replicates of each treatment and each replicate contained root tissue from 20 plants. Each replicate (8 in total) was harvested 4 days post inoculation and the resulting RNA was used for hybridization to an Affymetrix ATH1 chip.