Abstract
The regulation of the root growth pattern is an important control mechanism during plant growth and propagation. To understand how root growth direction is altered in response to environmental stimuli, we characterized an Arabidopsis thaliana mutant, wavy growth 3 (wav3), whose roots show a shorter-pitch wavy growth pattern on inclined agar medium. The wav3 mutant shows larger angles of root bending in response to gravity, but smaller angles in response to light. WAV3 encodes a novel protein with a RING-finger domain in the N-terminal region and a vWA domain in the middle, both of which are involved in protein–protein interactions. The WAV3 protein shows an ubiqutin E3 ligase activity and binding activities to all members of SINAT family proteins, which belong to the other RING-finger-type E3 ligase family, in vitro. There are three WAV3-homologus genes, WAVH1, WAVH2, and WAVH3, in Arabidopsis genome, and the wav3 wavh1 wavh2 wavh3 quadruple mutants show remarkable abnormalities on root gravitropism. Our results suggest that the WAV3 family is a novel E3 ligase family required for root gravitropism in Arabidopsis.
