REPOSITORY > RESULTS

Abstract

Rising demands for food, instigated by population growth and urbanization, are calling for advanced agricultural approaches to increase crop yields. However, the expansion of food production should not come with an unmanageable environmental cost. Plant science is therefore challenged to provide sustainable innovations for combating the detrimental effects of unfavourable abiotic and biotic environmental factors on crop plants. In this thesis, we aimed to contribute to the development of biotechnological production of sustainable insect pest control compounds and to develop molecular tools for studying interactions between plants and viral pathogens.
Advances in synthetic biology and biotechnology can provide valuable solutions for sustainable insect pest control. One approach is the biotechnological production of alternative insecticides with less adverse effects, such as insect sex pheromones. To this end, transgenic Nicotiana benthamiana lines with constitutive production of moth pheromones were developed. However, high pheromone production resulted in stunted growth and development of the plant chassis. We have investigated the observed growth penalty with gene expression and network analyses and discovered a transcriptional reprogramming towards the stress response, with upregulated jasmonic acid and downregulated gibberellic acid signalling. Genetic manipulation of hardwired growth retardation in response to perceived stress could therefore improve the growth of plants with high insect sex pheromone biosynthesis. This would improve the suitability of such plants for biotechnological production in a greenhouse setting or even as living biodispensers in the field.
Additionally, we searched for coding sequences of enzymes catalysing the biosynthesis of mealybug sex pheromones. Focusing on the citrus mealybug, Planococcus citri, we generated long- and short-read transcriptomic data and found several candidate genes that could be involved in the biosynthesis of the rare cyclobutane structure in the P. citri sex pheromone. Their identification presents the groundwork for the future implementation of plant-based biotechnological production of mealybug sex pheromones.
To protect crops from the devastating effects of pathogenic infections, breeding or engineering resistant crop cultivars is essential. Therefore, it is necessary to understand the molecular mechanisms underlying successful plant immune response to infection. For this, efficient molecular tools, tailored to the pathosystem of interest are needed, such as plant virus infectious clones, which could enable functional studies of plant and viral genes. We have developed a robust protocol for mutagenesis of the monopartite infectious clone of the potato virus Y, thereby constructing a clone tagged with green fluorescent protein. The clone was able to infect potato plants and establish systemic infection, and expressed green fluorescent protein enabled microscopic evaluation of viral replication and spread in planta. As such it will contribute to the identification of important targets for genetic improvement of potato resistance to potato virus Y.