Enhancement of tomato resistance to Tuta absoluta by the expression of two barley proteinase inhibitors

Abstract

Evolution has provided vast genetic diversity, enabling plants to surmount many biotic pressures. Plants have evolved various morphological and biochemical adaptations to cope with herbivores attacks. Despite that, yearly, around 40 % of worldwide crop production is lost due to pests and pathogens, with 13 % due to insects. Tuta absoluta has become a major pest threatening tomato crops worldwide and without the appropriated management it can cause production losses between 80 to 100 %. To cope with this threat, we need to strengthen plant defense arsenals. The incorporation to plants of defensive genes like proteinase inhibitors by means of genetic engineering is a promising alternative. In the first chapter of this work we investigated the inhibitory activity of two trypsin inhibitors from barley; BTI-CMe and BTI-CMc. Besides, we succeeded to increase the BTI-CMc in vitro inhibitory activity by introducing a single mutation in its putative reactive site. In the second chapter, we investigated the in vivo effect of (a serine proteinase inhibitor) BTI-CMe and a (cysteine proteinase inhibitor) Hv-CPI2 isolated from barley on Tuta absoluta and we examined the effect of their expression on the tomato defensive response. We found that larvae fed on the double transgenic plants showed a notable reduction in weight. Moreover, only 56% of the larvae reached the adult stage. The emerged adults showed wings deformities and reduced fertility. We also investigated the effect of proteinase inhibitors ingestion on the insect digestive enzymes. Our results showed a decrease in larval trypsin activity. Proteinase inhibitors had no harmful effect on Nesidiocoris tenuis; a predator of Tuta absoluta, despite transgenic tomato plants attracted the mirid. We investigated whether or not plant defensive mechanisms were activated in the transgenic tomato plants and found that, interestingly, the expression of the barley cysteine proteinase inhibitor promoted plant defense, inducing the tomato endogenous wound inducible proteinase inhibitor 2 (Pin2) gene. Moreover, glandular trichomes production was increased and the emission of volatile organic compounds was altered. Our results demonstrate the usefulness of the co-expression of different proteinase inhibitors for the enhancement of plant resistance to pests.; La evolucion ha proporcionado una gran diversidad genetica, permitiendo a las plantas superar muchas presiones bioticas. Las plantas han desarrollado diversas adaptaciones morfologicas y bioquimicas para hacer frente a los ataques de los herbivoros. A pesar de ello, anualmente, alrededor del 40 % de la produccion mundial de cultivos se pierde debido a plagas y patogenos, siendo un 13 % debido a insectos. Tuta absoluta se ha convertido en una de las principales plagas que amenazan los cultivos de tomate en todo el mundo y sin la gestion adecuada puede causar perdidas de produccion entre el 80 y el 100 %. Para hacer frente a esta amenaza, necesitamos fortalecer los arsenales de defensa de las plantas. La incorporacion a las plantas,…