Séminaires scientifiques ISA

Ana Cristina Miranda Brasileiro : "Espèces sauvages d'arachide: de l'exploitation à la valorisation des ressources génétiques"

Cultivated peanut (Arachis hypogaea) is subjected to several biotic and abiotic constraints which hamper its development and productivity. Conversely, wild Arachis species are genetically diverse and harbor resistance/tolerance to several stresses, being therefore important sources of new alleles of agronomic value for breeding peanut programs. In particular, A. duranensis and A. stenosperma display high adaptability to water-limited conditions and resistance to root-knot nematode, respectively. In the last few years, the transcriptome of these wild species has been exploited for the discovery of genes involved with resistance/tolerance to biotic and abiotic stresses and pointed to several differentially expressed candidates. The functional characterization of some candidate genes was further carried out using Agrobacterium rhizogenes-derived hairy roots of peanut and soybean susceptible genotypes and also in stable transformed model plants as Arabidopsis thaliana and Nicotiana tabacum. Analysis of the overexpression effects of these candidates in the response to RKN attack or drought imposition showed significant reduction in the stress symptoms when compared to the non-transformed controls. The discovery and characterization of candidate genes involved in the response to stresses will facilitate the understanding of the molecular mechanisms of resistance/tolerance abiotic and biotic constraints in wild Arachis species. Therefore, the use of wild genetic resources constitutes a valuable strategy for the identification and further introgression, through either interspecific hybridization or transgenic approaches, of agronomically important traits into high-yielding peanut genotypes.

Maria Fatima Grossi de Sa : "Crop-pest functional genomics and Brazilian opportunities in Biotechnology"

Brazil is a remarkable world leader in the agro-industrial production and, nowadays, agribusiness contributes with around 30% of Gross Domestic Product (GDP), with 37% of Brazil exports and, is responsible for 35% of employments. Biotic and abiotic forms of stress are responsible for significant yield losses worldwide. Thus, the challenge for biotechnology is to reverse this decline in yield and increase crop tolerance/resistance to stress in a sustainable and cost-effective way that is also compatible with IPM. Currently, biotechnological products are mainly held by agricultural biotechnology multi-transnational corporations, which have high innovative capacity in developing new cultivars. Plant pests as the root-knot nematodes (Meloidogyne spp) and the insect pest Anthonomus grandis (cotton boll weevil) cause severe damage to several crop commodities, especially soybean and cotton, reaching losses of billions of dollars annually. Embrapa Genetic Resources and Biotechnology have focused on functional genomics to identify biotech-assets with potential insecticide/nematicide activity, to be applied in the development of Brazilian crop plants resistant to insect-pests and nematodes. Our research has focused on gene silencing strategy, via RNA interference (RNAi), to knock-down potential target genes, essential to the metabolism and development, as a manner to control the parasite and the insect pest. Data for different classes of genes will be presented, and opportunities for collaborative research in Brazil will be discussed.