Selección de bacterias bioestimulantes para trigo duro y maíz común, y búsqueda de nuevos agentes de biocontrol frente a fitopatógenos mediante el análisis del bacterioma del escarabajo de la corteza del abeto europeo (lps typographus)

Abstract

[EN]World population is growing at an unprecedented rate, reaching 8 billion people in 2023 and projected to surpass 9 billion by 2050. This situation implies an increasing number of resources needed to meet humanity's demand for food and other necessities, intensifying human impacts on natural ecosystems. In this context, wheat and maize play a crucial role in human nutrition as they are two major crops worldwide, accounting for 28% of the global agricultural yield. However, current agricultural practices heavily rely on inorganic fertilizers and pesticides to achieve high yields. This causes significant environmental degradation. Inorganic fertilizers production is largely based on fossil fuels, contributing to greenhouse gas emissions and local acidification. Moreover, the overuse of these products degrades soil quality and leads to nutrient accumulation in freshwater systems, causing eutrophication. On the other side, phytopathogens, if not treated, are predicted to reduce cereal yield in around 32%, mostly because of fungi-caused diseases. Chemical pesticides are non-specific, persistent in the environment, and can lead to the development of resistances, reducing their effectiveness. This situation necessitates a paradigm shift in agriculture to address these issues, leading to the development of more sustainable practices. Bacterial inoculants based on plant-growth promoting bacteria (PGPB) can benefit plant development and provide protection against pests and diseases. PGPB action mechanisms enhance nutrient availability, stimulate plant growth, induce plant resistances to biotic and abiotic stresses, and provide protection against phytopathogens by competition and/or antagonism. PGPB based biostimulants have the potential to increase crop yields and quality without relying on chemical additives or, at least, reducing the dependence on them. Similarly, bacterial biocontrol agents (BBCA) based on PGPB can protect plants against phytopathogens meanwhile reducing the use of chemical pesticides. Recent studies revealed that insects might harbour more bacterial strains with strong antagonistic capacities against microbial pathogens than other niches, such as soil or plants. The Ips typographus bark beetle ecological context and previous studies suggest that bacterial associates to this beetle may have biocontrol potential against pathogenic fungi, representing an almost unexplored niche for obtaining strains with BBCA capacities. In this thesis, different laboratory, field, and computational techniques were used to search for bacterial inoculants of interest for wheat and maize plants, promoting their growth and protecting them against phytopathogens. The work has been divided in two sections: Section I includes the work carried out in the search for bacteria with biostimulant potential for durum wheat and common corn. Meanwhile, Section II focused on the search for BBCA of interest for forestry and crops management, with special interest in durum wheat, in a novel niche for BBCA, the Ips typographus bark beetle.