BRC Science Highlight WRINKLED1, a key regulator of oil biosynthesis, also affects hormone homeostasis Objective WRINKLED1 (WRI1) is a key transcriptional regulator of fatty acid biosynthesis genes in diverse oil-containing tissues; the Arabidopsis wri1-1 loss-of-function mutant displays reduced seed oil content and impaired seedling establishment. Here we further characterize the wri1-1 mutant, identify a primary root growth defect, and confirm altered auxin homeostasis. Approach Observe root morphology of the wri1-1 loss-of-function mutant, AtWRI1 overexpression lines, and wild-type (WT) Arabidopsis; examine proton efflux in roots In WT and wri1-1 plants, quantify auxin (indole-3-acetic acid (IAA)) metabolites, shown to be associated with Arabidopsis root growth, by mass spectrometry; investigate auxin sensitivity and transport in these plants Identify genes altered in expression in the wri1-1 mutant Conduct DNA binding assays of AtWRI1 protein and AtWRI1 promoter regions of genes identified with altered expression in wri1-1; identify putative AtWRI1 binding sites Results/Impacts wri1-1 displays a primary root growth defect and altered auxin-conjugate content Results presented here are consistent with AtWRI1 playing a role in mediating auxin homeostasis by binding to the promoter of the auxin-responsive gene GH3.3, providing a mechanism for how AtWRI1 might affect auxin homeostasis. AtWRI1 also binds to the promoter regions of some of the PIN genes, which encode IAA carrier proteins Some GH3 and PIN genes (e.g, GH3.3, PIN1, PIN3, PIN5, and PIN6) have altered expression in wri1-1, providing further evidence that AtWRI1 affects auxin homeostasis The knowledge that WRI1 affects hormone homeostasis is of importance for engineering crops for increased oil content Notes: text Title again: Text 1-2 sentence summary? Kong, Q. et al. “The Arabidopsis WRINKLED1 transcription factor affects auxin homeostasis in roots.” Journal of Experimental Botany (2017) [DOI: 10.1093/jxb/erx275]. Expression profiles of AtWRI1 in Arabidopsis root. GLBRC August 2017