LRP7, a Gene Expressed in Lateral and Adventitious Root Primordia of Arabidopsis

We describe a gene that is expressed in lateral and adventitious root primordia of Arabidopsis. The gene was identified by expression of a transposon-borne promoterless P-glucuronidase gene in lateral root primordia. The gene, designated LRP7 for lateral root primordium 1, and its corresponding cDNA were cloned and sequenced. The expression pattern of the gene in lateral root primordia was confirmed by in situ hybridization wlth LRPl cDNA probes. The LRPl gene encodes a nove1 protein. LRP7 expression is activated during the early stages of root primordium development and is turned off prior to the emergence of lateral roots from the parent root. lnsertion of the transposon in the LRP7 gene disrupted its expression. To evaluate the homozygous insertion line for a mutant phenotype, severa1 aspects of wild-type lateral root development were analyzed. A mutant phenotype has not yet been identified in the insertion line; however, there is evidence that the gene belongs to a small gene family. LRPí provides a molecular marker to study the early stages of lateral and adventitious root primordium development.