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Isolation of the LEMMI9 Gene and Promoter Analysis During a Compatible Plant-Nematode Interaction

¹Departamento de Biología, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; ²Laboratorium voor Genetica, Department of Genetics, VIB, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium; ³Vakgroep Plantaardige Productie, Faculteit Landbouwkundige en Toegepaste Biologishe Wetenschappen, Universiteit Gent, Coupure links 653, B-9000 Gent, Belgium; ⁴Laboratorio de Bioquímica y Biología Molecular, CIF. Santa Fe de Bogotá, Colombia; ⁵Plant Genetic Systems n.v., Jozef Plateaustraat 22, B-9000 Gent, Belgium

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-β 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.

Additional keywords: DNA-binding protein(s), promoter elements.