Biotechnologies et résistance variétale du sorgho aux insectes

Ratnadass Alain. 2001. Biotechnologies et résistance variétale du sorgho aux insectes. In : Les insectes ravageurs du sorgho en Afrique de l'Ouest et du Centre : actes = Insects pests of sorghum in West and Central Africa : proceedings. Ratnadass Alain (ed.), Ajayi Olupomi (ed.), Marley Paul S. (ed.), Akintayo Inussa (ed.). CIRAD, ROCARS, ICRISAT. Montpellier : CIRAD, 142-143. ISBN 2-87614-446-8 Atelier de formation sur les insectes ravageurs du sorgho, Samanko, Mali, 14 Octobre 1996/23 Octobre 1996.

Titre anglais : Biotechnologies

Résumé : Genetic transformation is the technology of transferring specific genes (DNA fragments conferring for instance pest resistance) to sorghum cells. Seeds integrating these useful genes must then be produced by whole fertile plants regenerated from these cells. The so-called " transgenic " varieties thus obtained can then be used either directly, or as sources of resistance. The resistance gene is generally coupled with a marker gene. Three methods have been investigated to obtain transgenic sorghums: (i) use of Agrobacterium; (ii) use of a particle-gun; (iii) direct transfer to protoplasts. Progress of genetic transformation has been slowed down by the problems of fertile plant regeneration from protoplasts. This technique is being abandoned now, to the benefit of particle bombardment using gene-guns on immature embryos, which produce calli easier to regenerate. Using insect resistance genes present in the crop plant itself or related species poses problem, as these are difficult to isolate, and probably do not confer high resistance levels. On the other hand, protease inhibitor genes are more promising (including against the sorghum midge). However, genes encoding toxins of Bacillus thuringiensis (Bt) are the most valuable candidates. There are various Bt strains, releasing crystals comprising proteins acting as insect group-specific endotoxins. For instance, CryII and CryIV are toxic to Diptera. A couple of decades ago, molecular biologists thought that achieving crop plant resistance by incorporating Bt genes would be the panacea for herbivorous caterpillar control. However, they probably overlooked the capacity of these pests to develop resistance to Bt toxins. However, progress is being made on sorghum transformation for resistance to the sorghum shoot fly and the spotted stem borer by ICRISAT in India.

Mots-clés Agrovoc : biotechnologie animale, Sorghum, transformation génétique, Agrobacterium, transfert de gène, protoplaste, Bacillus thuringiensis, résistance aux organismes nuisibles

Classification Agris : F30 - Génétique et amélioration des plantes

Auteurs et affiliations

• Ratnadass Alain, CIRAD-CA-CEREALES (MLI) ORCID: 0000-0002-8873-5671

Source : Cirad - Agritrop (https://agritrop.cirad.fr/478744/)

Métriques

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