Wolinska-Griese, Katarzyna Wiktoria (2021). Tryptophan metabolism and bacterial root commensals synergistically control fungal abundance in roots to promote Arabidopsis thaliana health. PhD thesis, Universität zu Köln.
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Wolinska-Griese_doctoral_dissertation_revised.pdf - Accepted Version Download (6MB) | Preview |
Abstract
The roots of healthy and asymptomatic plants are colonized by a staggering diversity of microbes, including bacteria, fungi, and oomycetes (i.e. the root microbiota), and yet plants have evolved a complex, multi-layer, immune system that detects microbial invasion and discriminate self from non-self. Although plant innate immunity has been extensively studied under laboratory settings between one specific microbe and one specific plant, our understanding of this complex machinery in a natural (i.e. community) context remains sparse, especially in plant roots. Recent studies indicate that certain sectors of plant immune system, namely phytohormones and tryptophan-derived (Trp-derived) secondary metabolites have an important role in the establishment of the plant microbiota. It is still unknown which pathways are required for a controlled accommodation of commensal microbes, which in return results in plant growth promotion. A major hypothesis is that colonization by both pathogenic and beneficial microbes acts as a selective force on the function of plant innate immunity, forcing task division among different immunity pathways. Using experiments in a natural soil, combined with microbiota reconstitution experiments in a gnotobiotic system with a multi-kingdom synthetic community and a set of immunocompromised plants, I tested the extent to which different plant immune sectors are needed for commensal-induced plant growth promotion. I provide novel evidence for the importance of interaction between bacterial commensals and Trp-derived secondary metabolites biosynthesis pathway and co-receptors BAK1 and BKK1 in beneficial plant-microbiota interactions, especially in mediating beneficial growth-promotion effect in Arabidopsis thaliana (A. thaliana). In this thesis I show that not only growth during vegetative stage is affected in Trp-metabolism and co-receptor mutants, but the mutations affect the plants during their reproductive stage. Particularly, I showed that bacterial commensals and host Trp-derived secondary metabolites act in concert to prevent fungal overgrowth in plant roots and promote host-microbial homeostasis. Additionally, I have developed a working gnotobiotic system which allows accommodation of A. thaliana plants in their reproductive stage, which has potential to highly facilitate future research on the effect of microbiota on plants fitness, giving higher biological relevance of obtained results.
Item Type: | Thesis (PhD thesis) | ||||||||
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URN: | urn:nbn:de:hbz:38-357450 | ||||||||
Date: | 18 February 2021 | ||||||||
Language: | English | ||||||||
Faculty: | Faculty of Mathematics and Natural Sciences | ||||||||
Divisions: | Außeruniversitäre Forschungseinrichtungen > MPI for Plant Breeding Research | ||||||||
Subjects: | Natural sciences and mathematics Life sciences Agriculture |
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Date of oral exam: | 18 February 2021 | ||||||||
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Refereed: | Yes | ||||||||
URI: | http://kups.ub.uni-koeln.de/id/eprint/35745 |
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