LRP1, a gene expressed in lateral and adventitious root primordia of arabidopsis.

Abstract

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.

Mechanisms of primordium formation during adventitious root development from walnut cotyledon explants

“…These 530-bp regions of CHS1 and CHS4 showed 67% identity (El Euch 1997). The template for heterologous LRP1 probe was a PCR-ampli®ed 250-bp fragment corresponding to the 3¢ exon of the Arabidopsis thaliana LRP1 genomic clone (Smith and Fedoro 1995; GenBank accession number U24702).…”

“…The walnut CHS1, CHS4 (El Euch 1997;El Euch et al 1998) and TONOPLAST INTRINSIC PROTEIN (c-TIP) genes were used to detect the levels of root-related (El Euch 1997) and elongation-related (Ludevid et al 1992) transcripts, respectively. The comparison of histological and molecular data thus allowed us to determine dierent stages of development that were, at least in part, similar to those of lateral and adventitious root formation in other angiosperms (Laskowski et al 1995;Smith and Fedoro 1995). This adventitious process is discussed in terms of coherence with current models of adventitious root development (Lund et al 1997).…”

“…Furthermore, there is little molecular information about lateral, or adventitious, root development in any plant (Smith and Fedoro 1995;Malamy and Benfey 1997;Lorbiecke and Sauter 1999), although the key developmental stages of lateral root formation in Arabidopsis are slowly emerging from recent studies (Laskowski et al 1995;Malamy and Benfey 1997).…”

“…Expression of the tobacco HYDROX-YPROLINE-RICH GLYCOPROTEIN (HRGPnt3) gene (Vera et al 1994) was also determined by histolocalization of GUS activity in early lateral and adventitious root primordia in transgenic plants containing an HRGPnt3-GUS gene fusion. Smith and Fedoro (1995) showed by histolocalization of GUS activity in an enhancer trap line of Arabidopsis thaliana that a LAT-ERAL ROOT PRIMORDIUM-1 (LRP1) gene was speci®cally expressed in lateral and adventitious root primordia. Finally, screening and characterization of Arabidopsis mutants have also revealed genes which are speci®c to lateral root development such as ABERRANT LATERAL ROOT FORMATION genes (Celenza et al 1995).…”

“…Complementary molecular characterization was carried out with expression studies of potential molecular markers of primordium formation and root dierentiation. The Arabidopsis LRP1 gene (Smith and Fedoro 1995) was used to detect LRP1-like transcripts in relation to primordium formation. The walnut CHS1, CHS4 (El Euch 1997;El Euch et al 1998) and TONOPLAST INTRINSIC PROTEIN (c-TIP) genes were used to detect the levels of root-related (El Euch 1997) and elongation-related (Ludevid et al 1992) transcripts, respectively.…”