Enhanced fungal resistance in transgenic potato expressing different antimicrobial proteins such as AP24 tobacco osmotin, chicken lysozyme and dermaseptine

RIVERO PÉREZ, M.M., MENCACCI, N., TOUM, L., PICCA, P., FURMAN, N., BRAVO-ALMONACID, F. AND MENTABERRY, A.

Viña del Mar, Chile

Congreso; VI Encuentro Latinoamericano y del Caribe del Biotecnología Agropecuaria; 2007

Red de Cooperación Técnica en Biotecnología Agropecuaria para América Latina y el Caribe (REDBIO-FAO)

Genetically engineered resistance to micro-organisms represents a promising approach for generating broad-spectrum pathogen-resistant potato plants. Solanum tuberosum (var. spunta) plants were transformed with genetic constructions constitutively expressing different antimicrobial genes products that are directly toxic to pathogens or reduce their growth. These include pathogenesis-related proteins (PR proteins) such as antifungal osmotin (AP24 osmotin-like protein), antimicrobial peptides as dermaseptine (Phyllomedusa sauvagii dermaseptine) and bacteriolytic proteins such as the chicken lysozyme (Gallus gallus lysozyme). The Ap24 is a basic 24-kDa protein that exhibits antifungal activity and belongs to the PR-5 family. The PR-5 proteins induce fungal cell leakiness through a specific interaction with the plasma membrane that results in the formation of transmembrane pores. The chicken lysozyme cleaves the â-(1–4) glycosidic bond of peptidoglycan in the bacterial cell wall and of chitin in the fungal cell wall. While the dermaseptine, a cationic antimicrobial peptide, exhibits a lytic activity and provides a rapid, non-specific defense against invading microorganisms. Transgenic potato lines bearing and expressing one, two or combinations of three antimicrobial sequences were assayed under controlled conditions for resistance to the phytopathogenic fungi Fusarium solani, Rhyzoctonia solani and Phytophtora infestans. Whole transgenic plants as well as detached leaves and tubers were inoculated with the different fungal microorganisms under statistically designed infection assays. Disease resistance was evaluated by arbitrary semi-quantitative scales, direct observation and measurement of disease symptoms development. All transgenic potato lines were characterized by PCR, qPCR, Western-blot, ELISA and/or Dot-blot. Best protective results against the fungal pathogens were obtained using combinations of two or three antimicrobial genes though substantial resistance levels to tested pathogens could be observed in all cases. Higher degrees of resistance were roughly correlated with higher expression of foreign genes. On the basis of these observations, pyramiding of antimicrobial coding sequences appears to be a promising tool to develop durable resistance to microbial pathogens. This biotechnological approach offers a promising tool in order to control important plant diseases that cause economical impact on agronomic-based economies.â-(1–4) glycosidic bond of peptidoglycan in the bacterial cell wall and of chitin in the fungal cell wall. While the dermaseptine, a cationic antimicrobial peptide, exhibits a lytic activity and provides a rapid, non-specific defense against invading microorganisms. Transgenic potato lines bearing and expressing one, two or combinations of three antimicrobial sequences were assayed under controlled conditions for resistance to the phytopathogenic fungi Fusarium solani, Rhyzoctonia solani and Phytophtora infestans. Whole transgenic plants as well as detached leaves and tubers were inoculated with the different fungal microorganisms under statistically designed infection assays. Disease resistance was evaluated by arbitrary semi-quantitative scales, direct observation and measurement of disease symptoms development. All transgenic potato lines were characterized by PCR, qPCR, Western-blot, ELISA and/or Dot-blot. Best protective results against the fungal pathogens were obtained using combinations of two or three antimicrobial genes though substantial resistance levels to tested pathogens could be observed in all cases. Higher degrees of resistance were roughly correlated with higher expression of foreign genes. On the basis of these observations, pyramiding of antimicrobial coding sequences appears to be a promising tool to develop durable resistance to microbial pathogens. This biotechnological approach offers a promising tool in order to control important plant diseases that cause economical impact on agronomic-based economies.