Chimeric gene for the transformation of plants

Abstract

Chimeric gene for conferring to plants an increased tolerance to a herbicide having as its target EPSPS comprises, in the direction of transcription, a promoter region, a transit peptide region, a coding sequence for glyphosate tolerance and a polyandenylation signal region, wherein the transit peptide region comprises, in the direction of translation, at least one transit peptide of a plant gene encoding a plastid-localized enzyme and then a second transit peptide of a plant gene encoding, a plastid-localized enzyme. Production of glyphosate-tolerant plants is disclosed.

Description

BACKGROUND OF THE INVENTIONThe present invention relates to novel transit peptide DNA sequences, to novel chimeric genes and to their use in plants for conferring to them an increased tolerance to herbicides in general especially to those of the phosphonomethylglycine family. It also relates to the plant cells transformed by means of these genes, to the transformed plants regenerated from these cells as well as to the plants derived from crossbreedings using these transformed plants.Glyphosate, sulfosate or fosametine are broad-spectrum systemic herbicides of the phosphonomethyl-glycine family. They act essentially as competitive inhibitors of 5-(enolpyruvyl)shikimate-3-phosphate synthase (EC 2.5.1.19) or EPSPS in relation to PEP (phosphoenolpyruvate). After their application to the plant, they are translocated inside the plant where they accumulate in the rapidly growing parts, in particular the caulinary and root apexes, causing the deterioration and even the destruction of sensit...

AI Technical Summary

Benefits of technology

Construction of the entire transit region may be carded out in a manner known per se, in particular by fusion or any other suitable means. The role of this characteristic region is to enable the release of a mature, native protein with a maximum efficiency.

The coding sequence for herbicide tolerance which may be used in the chimeric gene according to the invention encodes a mutant EPSPS having a degree of glyphosate tolerance. This sequence, obtained in particular by mutation of the EPSPS gene, may be of bacterial origin, for example derived from Salmonella typhymurium (and called in the text which follows "AroA gene"), or of plant origin, for example from petunia or from tomatoes. This sequence may comprise one or more mutations, for example the Pro 101 to Ser mutation or alternatively the Gly 96 to Ala mutations.

The promoter region of the chimeric gene according to the invention may consist advantageously of at least one promoter on a fragment thereof of a gene which is expressed naturally in plants, that is to say promoters of vital origin such as that of 35S RNA of the cauliflower mosaic virus (CaMV35S) or of plant origin such as the small subunit of the ribulose 1,5-diphosphate carboxylase (RuBisCO) gene of a crop such as maize or sunflower.

The untranslated polyadenylation signal region in 3' of the chimeric gene according to the invention may be of any origin, for example bacterial, such as the nopaline synthase gene, or of plant origin, such as the small subunit of the maize or sunflower RuBisCO.

Problems solved by technology

After their application to the plant, they are translocated inside the plant where they accumulate in the rapidly growing parts, in particular the caulinary and root apexes, causing the deterioration and even the destruction of sensitive plants.