GLABRA3 (GL3) encodes a bHLH protein that interacts with the WD repeat protein, TTG1. GL3 overexpression suppresses the trichome defect of the pleiotropic ttg1 mutations. However, single gl3mutations only affect the trichome pathway with a modest trichome number reduction. A novel unlinked bHLH-encoding locus is described here, ENHANCER OF GLABRA3 (EGL3). When mutated, egl3gives totally glabrous plants only in the gl3 mutant background. The double bHLH mutant, gl3 egl3, has a pleiotropic phenotype like ttg1 having defective anthocyanin production, seed coat mucilage production, and position-dependent root hair spacing. Furthermore, the triple bHLH mutant, gl3 egl3 tt8, phenocopies the ttg1 mutation. Yeast two-hybrid and plant overexpression studies show that EGL3, like GL3,interacts with TTG1, the myb proteins GL1, PAP1 and 2, CPC and TRY, and it will form heterodimers with GL3. These results suggest a combinatorial model for TTG1-dependent pathway regulation by this trio of partially functionally redundant bHLH proteins.
A network of redundant bHLH proteins functions in all TTG1-dependent pathways of Arabidopsis
These authors contributed equally to this work
Present address: Departments of Medicine, Microbiology and Immunology,University of California at San Francisco, San Francisco, CA 94143, USA
Present address: CSIRO Horticulture Unit, Hartley Grove, Urrbrae, SA 5064,Australia
Fan Zhang, Antonio Gonzalez, Mingzhe Zhao, C. Thomas Payne, Alan Lloyd; A network of redundant bHLH proteins functions in all TTG1-dependent pathways of Arabidopsis. Development 15 October 2003; 130 (20): 4859–4869. doi: https://doi.org/10.1242/dev.00681
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