title: The power of chemical genomics to study the link between endomembrane system components and the gravitropic response.
abstract: Chemical genomics is a powerful approach to dissect processes that may be intractable using conventional genetics because of gene lethality or redundancy. Recently, a link has been established between endomembrane trafficking and gravitropism. To understand this link, we screened a library of 10,000 diverse chemicals for compounds that affected the gravitropism of Arabidopsis seedlings positively or negatively. Sixty-nine of 219 compounds from the primary screen were retested, and 34 of these were confirmed to inhibit or enhance gravitropism. Four of the 34 compounds were found to cause aberrant endomembrane morphologies. The chemicals affected gravitropism and vacuole morphology in concert in a tissue-specific manner, underscoring the link between endomembranes and gravitropism. One of the chemicals (5403629) was structurally similar to the synthetic auxin 2,4-dichlorophenoxy acetate, whereas the other three chemicals were unique in their structures. An in vivo functional assay using the reporter beta-glucuronidase under the auxin-inducible DR5 promoter confirmed that the unique compounds were not auxins. Interestingly, one of the unique chemicals (5850247) appeared to decrease the responsiveness to auxin in roots, whereas another (5271050) was similar to pyocyanin, a bacterial metabolite that has been suggested to target the endomembranes of yeast. These reagents will be valuable for dissecting endomembrane trafficking and gravitropism and for cognate target identification.
authors.affiliation: Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA 92521,USA.
authors.forename: Marci
authors.initials: M
authors.lastname: Surpin
authors.forename: Marcela
authors.initials: M
authors.lastname: Rojas-Pierce
authors.forename: Clay
authors.initials: C
authors.lastname: Carter
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Hicks
authors.forename: Jacob
authors.initials: J
authors.lastname: Vasquez
authors.forename: Natasha V
authors.initials: NV
authors.lastname: Raikhel
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D001692:Biological Transport / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015698:Genomic Library; D023281:Genomics / Q000379:methods*; D018522:Gravitropism / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D007210:Indoleacetic Acids / Q000494:pharmacology; D007425:Intracellular Membranes / Q000502:physiology* / Q000648:ultrastructure; D018613:Microscopy, Confocal; D010940:Plant Proteins / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D007210:Indoleacetic Acids; D010940:Plant Proteins