Soutenance de thèse : Fatima Diya

Research and study of A1b type entomotoxins: Application for the protection against the pest of tomato, Tuta absoluta

Doctorante :  Fatima Diya

Laboratoire INSA : BF2I

Ecole doctorale : ED 341 : Evolution, Ecosystèmes, Microbiologie, Modélisation

Pea albumin 1 subunit b, PA1b, is a plant cystine knot peptide, extracted from the seeds of peas Pisum sativum and is composed of 37 amino acids. It is a potential candidate for use to control economic pests such as cereal weevils, major pests of stored grains. The natural diversity of this peptide in the seeds of legumes native to the Middle East and belonging to the Faboideae subfamily was investigated. Additionally, the insecticidal activity of each of the seed flour from the selected seeds were evaluated against the susceptible and resistant strains of weevils. This has led to the identification of Vicia sativa ssp. sativa, a promising species containing potent A1b isoforms. The latter from different geographical regions of this species were biochemically characterized, and their biological activities were evaluated. A putative A1b sequence has been identified from Vicia sativa ssp sativa originating from Turkey. Previously, AG41, a 10-fold more toxic isoform was also identified from the roots of Medicago truncatula. In this study, we have identified the key residues responsible for the enhanced toxicity of this peptide using NMR. As a promising bio insecticide targeting the VATP-ase, a proton pump necessary for the absorption of nutrients, PA1b has been also tested on the major pest of tomato, Tuta absoluta. The peptide delivered through injection was lethal to the larval stage of the pest. This has raised interesting prospects about the potential targets of PA1b in insects.