The ubiquitin ligase XBAT32 regulates lateral root development in Arabidopsis.

Ubiquitin-mediated protein modification plays a key role in many cellular signal transduction pathways. The Arabidopsis geneXBAT32encodes a protein containing an ankyrin repeat domain at the N-terminal half and a RING finger motif. The XBAT32 protein is capable of ubiquitinating itself. Mutation inXBAT32causes a number of phenotypes including severe defects in lateral root production and in the expression of the cell division markerCYCB1;1::GUS. TheXBAT32gene is expressed abundantly in the vascular system of the primary root, but not in newly formed lateral root primordia. Treatment with auxin increases the expression ofXBAT32in the primary root and partially rescues the lateral root defect inxbat32-1mutant plants. Thus, XBAT32 is a novel ubiquitin ligase required for lateral root initiation. [ABSTRACT FROM AUTHOR]