Pea Albumin 1 Subunit b (PA1b), a Promising Bioinsecticide of Plant Origin

PA1b (Pea Albumin 1, subunit b) is a peptide extract from pea seeds showing significant insecticidal activity against certain insects, such as cereal weevils (genus Sitophilus), the mosquitoes Culex pipiens and Aedes aegyptii, and certain species of aphids. PA1b has great potential for use on an industrial scale and for use in organic farming: it is extracted from a common plant; it is a peptide (and therefore suitable for transgenic applications); it can withstand many steps of extraction and purification without losing its activity; and it is present in a seed regularly consumed by humans and mammals without any known toxicity or allergenicity. The potential of this peptide to limit pest damage has stimulated research concerning its host range, its mechanism of action, its three-dimensional structure, the natural diversity of PA1b and its structure-function relationships

High toxicity and specificity of the saponin 3-GlcA-28-AraRhaxyl-medicagenate, from Medicago truncatula seeds, for Sitophilus oryzae

<p>Abstract</p> <p>Background</p> <p>Because of the increasingly concern of consumers and public policy about problems for environment and for public health due to chemical pesticides, the search for molecules more safe is currently of great importance. Particularly, plants are able to fight the pathogens as insects, bacteria or fungi; so that plants could represent a valuable source of new molecules.</p> <p>Results</p> <p>It was observed that <it>Medicago truncatul</it>a seed flour displayed a strong toxic activity towards the adults of the rice weevil <it>Sitophilus oryzae</it> (Coleoptera), a major pest of stored cereals. The molecule responsible for toxicity was purified, by solvent extraction and HPLC, and identified as a saponin, namely 3-GlcA-28-AraRhaxyl-medicagenate. Saponins are detergents, and the CMC of this molecule was found to be 0.65 mg per mL. Neither the worm <it>Caenorhabditis elegans</it> nor the bacteria <it>E. coli</it> were found to be sensitive to this saponin, but growth of the yeast <it>Saccharomyces cerevisiae</it> was inhibited at concentrations higher than 100 μg per mL. The purified molecule is toxic for the adults of the rice weevils at concentrations down to 100 μg per g of food, but this does not apply to the others insects tested, including the coleopteran <it>Tribolium castaneum</it> and the Sf9 insect cultured cells.</p> <p>Conclusions</p> <p>This specificity for the weevil led us to investigate this saponin potential for pest control and to propose the hypothesis that this saponin has a specific mode of action, rather than acting <it>via</it> its non-specific detergent properties.</p

Effets biologiques précoces et perception des facteurs Nod au cours de la symbiose Rhizobium-Légumineuses.

National audienc

Perception of lipo-chitooligosaccharidic Nod factors in the legume-Rhizobia symbiosis : studies on Medicago Nod factor binding sites.

International audienc

Biochemical characterization and efficacy of <em>Pleurotus</em>, <em>Lentinus</em> and <em>Ganoderma</em> parent and hybrid mushroom strains as biofertilizers of attapulgite for wheat and tomato growth

International audiencePleurotus, Lentinus and Ganoderma are mushrooms which have various properties and should be explored as bioresources for various uses such as biofertilizers for sustainable intensification of agriculture. Pleurotus, Lentinus and Ganoderma species and intra- and inter-specific/generic hybrids produced with the dual culture technique were evaluated for chitinase and esterase activities, phosphate solubilization ability, siderophore production, mycelia growth, and efficacy as biofertilizers using semi-quantitative assays. All parent and selected hybrid strains were assessed as biofertilizers in attapulgite for wheat and tomato cultivation. Correlations between biochemical characteristics, plant root and shoot biomass, and microbial loads and ergosterol content of tomato cultivation substrate post-harvest were determined. Biochemical characteristics studied were mushroom strain-specific, independent on mycelia growth rate and were altered in hybrids. Esterase production was strain-dependent and precipitates produced differed in size. This is the first report of siderophore production by P. tuber-regium, L. squarrosulus and Ganoderma sp. from Ghana as well as alteration of siderophore production by intra-species/generic and inter-generic hybrid strains. Biofertilizer efficacy of parent strains and intra- and inter-specific/generic hybrids was mushroom strain- and plant species-specific. L. squarrosulus strain SqW and P. sajor-caju strain PScW were most efficacious strains for wheat and tomato cultivation respectively. Fungal (3.65-5.40 cfu g(-1)) and bacterial (0-6.43 cfu g(-1)) colony counts after tomato cultivation varied among treatments. Ergosterol concentration in all treatments (0.07-0.96 mu g g(-1)) were higher than in control treatment (0.05 mu g g(-1)). Chitinase activity and siderophore production of mushroom strains positively correlated with both wheat and tomato growth. Utilization of mushrooms as biofertilizers will enhance food security

Nod Factor Binding Sites : Receptors or Acceptors.

International audienceNod factors are the rhizobial determinants of nodulation and host specificity in the legume-rhizobia symbiosis. These lipochitooligosacccharides (LCOs) are capable of eliciting various responses on the roots of legumes at pico-micromolar concentrations, suggesting that they are perceived by specific receptors in legumes. By using radiolabelled Nod factors we have been able to characterise different types of binding sites in legumes. The relevance of these Nod factors binding proteins as putative receptors will be discussed

Nod factor perception and transduction in the legume-rhizobium symbiosis

International audienc

Utilisation d’une albumine PA1a de légumineuse comme insecticide

The present invention relates to the construction of transgenic plants, in particular of cereals, expressing a lagume albumin PA1a. This expression confers thereon an increased resistance to pests, in particular grains pestsLa présente invention concerne la construction des plantes transgéniques, notamment de céréales, exprimant une albumine PA1a de légumineuse. Cette expression leur confère une résistance accrue aux insectes ravageurs, en particulier aux ravageurs de grain