Isolation of theLEMMI9Gene and Promoter Analysis During a Compatible Plant-Nematode Interaction

Abstract

Plant-endoparasitic root-knot nematodes feed on specialized giant cells that they induce in the vascular cylinder of susceptible plants. Although it has been established that a number of plant genes change their expression pattern during giant cell differentiation, virtually no data are available about the mechanisms involved in that change. One possibility is differential promoter recognition by the transcription factor(s) responsible for the expression of specific genes. We have isolated and characterized a genomic clone from tomato containing the promoter region of LEMMI9, one of the few plant genes that have been reported to be highly expressed in galls (predominantly in giant cells). The analysis of transgenic potato plants carrying a LEMMI9 promoter-beta glucuronidase (GUS) fusion has demonstrated that the tomato promoter was activated in Meloidogyne incognita-induced galls in a heterologous system. We have located putative regulatory sequences in the promoter and have found that nuclear proteins from the galls formed specific DNA-protein complexes with the proximal region of the LEMMI9 promoter. The nuclear protein-binding sequence mapped to a region of 111 bp immediately upstream from the TATA box. This region contains a 12-bp repeat possibly involved in the formation of DNA-protein complexes, which might be related to the LEMMI9 transcriptional activation in the giant cells.

Distinct heat-shock element arrangements that mediate the heat shock, but not the late-embryogenesis induction of small heat-shock proteins, correlate with promoter activation in root-knot nematode feeding cells

“…Expression studies of genes with common regulation during late-embryogenesis, drought stress and nematode infection (Van der Eycken et al 1996;Escobar et al 1999Escobar et al , 2003de Meutter et al 2005 and this study) have revealed their complex regulation in nematode-feeding sites. Some genes are syncytia-specific (ABI3 and CDeT-27-45;de Meutter et al 2005), whereas others are specific for GCs (Hahsp17.7G4; Escobar et al 2003).…”

SAR induction in tomato plants is not effective against root-knot nematode infection

“…This same PR-5 response has been observed during the analysis of several Arabidopsis mutants. The function of the PR-5 protein might be related to water stress, which is induced during establishment of the nematode infestation (Van der Eycken et al 1996;Escobar et al 1999 Expression of the other genes studied (calmodulin, PR1-a and PR-3) was not modified by the elicitors. The lack of induction of the PR-1a gene could be explained by its greater association with developmental processes than pathogen defence (Tornero et al 1997).…”

Nematode Infection Triggers the de Novo Formation of Unloading Phloem That Allows Macromolecular Trafficking of Green Fluorescent Protein into Syncytia

“…Among these genes are a Gln-rich domain protein, cyclin-dependent kinases, mitotic cyclins, and a disaccharide transporter (Niebel et al, 1996;de Almeida Engler et al, 1999;Puzio et al, 2000;Jü rgensen et al, 2003). In the Lemmi9 promoter of tomato (Lycopersicon esculentum), a cis-regulatory element involved in nematode-induced gene expression has been identified (Escobar et al, 1999). This 12-bp element resembles a CANNTG motif also found in stress-regulated genes and is recognized by a nuclear protein identified in root galls of tomato.…”