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Transgénesis Vegetal. Aplicaciones a la mejora agrícola. 1ª generación de productos vegetales transgénicos • Modificaciones genéticas dirigidas a incrementar la productividad agraria • Dirigidos fundamentalmente al productor • Mercado tradicional de variedades vegetales • Resistencias a plagas, patógenos, herbicidas,... Herbicide tolerance Glifosato (N-(phosphonomethyl) glycine) Acción del glifosato El glifosato inhibe a la enzima EPSPS (5enolpiruvilshikimato-3-fosfato sintetasa), que cataliza la reacción de S3P (shikimato3-fosfato y el fosfoenol-piruvato para formar el ESP (5-enolpiruvil-shikimato-3fosfato ). Corismato , precursor esencial en plantas de los aa aromáticos Glyphosate-tolerant transgenic plants Some micro-organisms have a version of (EPSPS) that is resistant to glyphosate inhibition. The version used in genetically modified crops was isolated from Agrobacterium strain CP4 (CP4 EPSPS) that was resistant to glyphosate. The CP4 EPSPS gene was engineered for plant expression by fusing the 5' end of the gene to a chloroplast transit peptide derived from the petunia EPSPS. This transit peptide was used because it had shown previously an ability to deliver bacterial EPSPS to the chloroplasts of other plants . The chloroplasts of higher plants synthesize amino acids phenylalanine, tyrosine and tryptophan. Insect resistance Las toxinas Cry de Bacillus thuringiensis Las toxinas Cry de Bacillus thuringiensis • Bt produces insecticidal proteins (d-endotoxins) during sporulation as parasporal crystals. These crystals are predominantly comprised of one or more proteins, called Cry and Cyt toxins These toxins are highly specific to their target insect, are innocuous to humans, vertebrates and plants, and are completely biodegradable. . • Different Bt strains show activity towards lepidopteran, dipteran or coleopteran insects. Bt strains active against Hymenoptera, Homoptera, Orthoptera and Mallophaga insect orders and to other non-insect organisms like nematodes, mites and protozoa have been isolated. More than 200 different cry genes have been isolated. This constitutes an important arsenal for the control of a wide variety of insect pests. Taladro del maíz (European corn borer, Sesamia nonagrioides) Bt corn effect Pathogen-derived resistance RESISTENCIA TRANSGÉNICA A TMV RESISTENCIA TRANSGÉNICA A PRSV RESISTENCIA TRANSGÉNICA A PRSV Healthy Puna papaya fields in 1992. RESISTENCIA TRANSGÉNICA A PRSV Severely PRSV-infected papaya fields in 1994 that were abandoned. RESISTENCIA TRANSGÉNICA A PRSV Kapoho field trial started in 1995, showing a solid block of PRSV-resistant Rainbow growing well while the surrounding susceptible non-transgenic Sunrise is severely infected with PRSV. Picture taken 19 months after start of the field trial. RESISTENCIA TRANSGÉNICA A PRSV Comparative infection of transgenic and nontransgenic papaya in the 1995 field trial in Kapoho . RESISTENCIA TRANSGÉNICA A PRSV PRSV infected papaya that were cut down in the foreground and healthy transgenic Rainbow papaya in the background. Resistance of Rainbow held up even under strong inoculum pressure of PRSV. Picture taken in 1999. RESISTENCIA TRANSGÉNICA A PRSV Green healthy transgenic Rainbow papaya growing among PRSV-infected trees in an abandoned papaya field. Picture taken in 1999. RESISTENCIA TRANSGÉNICA A PRSV By 1999 healthy fields of transgenic papaya were commonly seen as opposed to the period of 1994-1998 where it was very difficult to find healthy papaya fields in Puna. Picture taken in 1999. RESISTENCIA TRANSGÉNICA A PRSV PRSV is still in Puna, and more infections are occurring among the non-transgenic Kapoho. This site shows the dramatic difference between a block of nontransgenic papaya (foreground) adjacent to a block of transgenic Rainbow (background). Nontransgenic trees that became infected were cut down as seen in foreground. Plants were established at the same time. Picture taken in 2004.