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Characterization and insights into the molecular mechanism of cytokinin-induced priming of plant defenses

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dc.contributor.authorMcIntyre, Kathryn, author
dc.contributor.authorArgueso, Cristiana, advisor
dc.contributor.authorBush, Daniel, committee member
dc.contributor.authorLeach, Jan, committee member
dc.contributor.authorStewart, Jane, committee member
dc.contributor.authorReddy, Anireddy, committee member
dc.date.accessioned2024-01-01T11:25:24Z
dc.date.available2025-12-29
dc.date.issued2023
dc.description.abstractPlants have developed several mechanisms to cope with pathogenic challenges. One of these mechanisms, known as defense priming can be effective at reducing susceptibility to pathogens. Compared to unprimed plants, the immune response from primed plants, upon pathogen attack, is much stronger. This mechanism of induced disease resistance can be initiated by biological and chemical agents. The major benefit of priming is the induction of a high level of protection with considerably low fitness costs making it an attractive disease management strategy to preserve agricultural output. Recent research has demonstrated that the plant hormone cytokinin (CK) has a priming effect against biotrophic pathogens, a phenomenon referred to here as cytokinin-induced priming (CIP). This dissertation aims to gain further understanding of CIP against the hemibiotrophic bacterial pathogens Pseudomonas syringae pv. tomato (Pst) and Pseudomonas syringae pv. maculicola (Psm) in Arabidopsis thaliana (Arabidopsis) and Brassica napus, respectively as well as the necrotrophic fungal pathogen Botrytis cinerea in Arabidopsis. Chapter 2 focuses on characterizing CIP as a true priming agent by investigating the timeframe in which CIP is most effective at reducing susceptibility to Pst and Psm in both Arabidopsis and its closely related relative, B. napus and the impacts on plant growth due to CIP in these pathosystems. Moreover, we discovered that other known priming agents depend on endogenous CK signaling suggesting CK-mediated processes are involved in the priming of defense responses. The role of CK in primed defenses against B. cinerea is explored in chapter 3 where CIP is demonstrated to reduce necrotic lesion size caused by B. cinerea in a manner dependent on the JA-mediated defenses and partially on SA-mediated defenses. Transcriptome analysis revealed that during the priming stage, CK prepares the plants for pathogenic challenge through the accumulation of cellular components needed for translation and metabolites utilized for energy production and defense. Following B. cinerea inoculation, CIP suppresses defense while increasing photosynthetic-related processes. In the final chapter, molecular mechanisms are explored during CIP against Pst. Through transcriptome changes, priming by CK potentiates gene expression associated with systemic induction of defense, also known as systemic acquired resistance (SAR), following Pst challenge. Using this information, it is demonstrated that CK treatment can also induce SAR and that the known SAR inducer, L-pipecolic acid, is dependent on endogenous CK signaling. Due to the previously identified relationship between CK and source-sink relationships, amino acid transport was demonstrated to have a role in both CIP and CK-induced SAR. New agricultural practices that mitigate crop loss due to plant diseases are beneficial in terms of sustainability and economic costs. The use of CK as a priming agent offers an avenue for a new disease management strategy in that CIP protects plants against a broad range of pathogens with minimal effects on plant growth. The molecular mechanisms underlying CIP discovered here offers new insights into the relationship between plant metabolism and defense, where its exploitation could be used to create disease protection strategies.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierMcIntyre_colostate_0053A_18139.pdf
dc.identifier.urihttps://hdl.handle.net/10217/237466
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2020-
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.rights.accessEmbargo expires: 12/29/2025.
dc.subjectplant hormones
dc.subjectplant priming
dc.subjectplant pathology
dc.subjectplant diseases
dc.titleCharacterization and insights into the molecular mechanism of cytokinin-induced priming of plant defenses
dc.typeText
dcterms.embargo.expires2025-12-29
dcterms.embargo.terms2025-12-29
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineCell and Molecular Biology
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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