ET biosynthesis is rapidly induced by Nod factors and negatively regulated by ET in a feedback loop. A, Differential expression of several ACS genes in the RNA-seq data set. B, Specificity of symbiotic induction observed in roots for ACS4, ACS7, and ACS8 was verified in the double mutant dmi1 skl using qPCR. Detailed expression of A17, dmi1, and dmi1 skl is shown on the right. C, Expression of ACO in the RNA-seq data set. Heat maps represent relative expression values (average TMM counts normalized to cv Jemalong A17 at 0 hpi) in the four genotypes across time. In A and C, the vertical axis dendrogram organizes genes according to coexpression. The horizontal axis is a genotype-specific time course.