Universität zu Köln

Chen, Li (2023). Alterations of Plant and Bacterial Sulfate Assimilation Pathway Affect Immunity and Pathogenicity. PhD thesis, Universität zu Köln.

PDF (Doctor thesis of Li Chen from the University of Cologne, MNF) Li Chen-Doctor dissertation-MNF, 2023 April.pdf - Published Version Download (3MB)

Abstract

Sulfur is an essential component for the biosynthesis of primary and secondary metabolites for all organisms. Camalexin and glucosinolates that share a common precursor Indole-3-acetaldoxime (IOAx), are important sulfur-containing secondary metabolites and play a crucial role in mediating sulfur-induced resistance against pathogens in Arabidopsis. It has been reported that pathogens deficient in cysteine biosynthesis have decreased virulence. However, it is still unclear how changes in the sulfur assimilation pathway and modulation of overall sulfur metabolism affect bacterial virulence and plant susceptibility. In this study, we used the rice pathogen Burkholderia glumae PG1 strain (wild type) and the model plant Arabidopsis thaliana (Col-0) to bilaterally investigate the effects of regulation of the sulfate assimilation pathway. We examined not only its influence on the pathogenicity of B. glumae, but also the effects of changes in plant sulfur metabolism on susceptibility and immune response to pathogens. As a non-host pathogen of Arabidopsis, B. glumae is able to colonize Arabidopsis and induce high camalexin accumulation. Its mutants cysH and cysM, are deficient in reducing 3′-phosphoadenosine 5′-phosphosulfate (PAPS) to SO32- and in converting thiosulfate to S-sulfocysteine respectively. Mutants cysH and cysM were less virulent than PG1 because they had attenuated pathogenic properties such as less plant growth inhibitory effect, less camalexin induction and triggering weaker hypersensitive response in Arabidopsis. The colonization result indicates that the ability of the pathogen to proliferate inside plants and acquire nutrients from the host plant are reduced when its sulfate assimilation pathway is impaired. Various Arabidopsis sulfur metabolisms mutants were investigated as well. Different camalexin accumulation patterns elicited by PG1, cysH and cysM at Col-0, myb28 myb29 and slim1-1 indicate that the regulation of sulfur metabolism in Arabidopsis has an impact on its response to pathogens, highlighting the complex sulfur flux between camalexin and glucosinolates in different Arabidopsis genotypes. Furthermore, it was found that SLIM1, a well studied transcription factor related to sulfur deficient response, is involved in the regulation of plant defense response because PG1 and bacterial mutants induced camalexin in slim1-1 at the same level, and SA accumulation in slim1-1 was significantly lower than in Col-0. This is the first research attempt that combines both bacterial and plant mutants to manipulate levels of sulfur metabolites and ability to use sulfur compounds to investigate effectsII of sulfur metabolism on plant-pathogen interactions and shed light on the comprehensive regulation of sulfur metabolism under pathogen attack.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Chen, Li chenli315@mails.ucas.ac.cn UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-655389
Date:	27 April 2023
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Botanical Institute
Subjects:	Natural sciences and mathematics
Uncontrolled Keywords:	Keywords Language Sulfate assimilation pathway English Pathogenicity English Plant immune response English
Date of oral exam:	19 April 2023
Referee:	Name Academic Title Kopriva, Stanislav Professor
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/65538