Comparison of avirulent pathogen Pseudomonas syringae and beneficial Enterobacter sp SA187 for enhancing salt stress tolerance in Arabidopsis thaliana
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PhD Dissertation
Type
DissertationAuthors
Jalal, Rewaa S.
Advisors
Hirt, Heribert
Committee members
Arold, Stefan T.
Blilou, Ikram

Wrzaczek, Michael
de-julien-de-Zelicourt, Axel
Program
BioscienceDate
2019-05Embargo End Date
2020-05-16Permanent link to this record
http://hdl.handle.net/10754/652894
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At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2020-05-16.Abstract
Abiotic stresses such as salt stress are the major limiting factors for agricultural productivity, and cause global food insecurity. It is well known that plant associated beneficial microorganisms can stimulate plant growth and enhance resistance to abiotic stresses. In this context, bacterial endophytes are a group of bacteria that colonize the host plant and play a fundamental role in plant growth enhancement under stress condition. Recently, our group reported that the beneficial bacteria Enterobacter sp.SA187 induces plant growth in Arabidopsis under salt stress conditions by manipulation of the plant ethylene signaling pathway. We therefore compared inoculation of plants by SA187 with virulent and non-virulent strains Pst DC3000. Although both strains inhibit plant growth at ambient conditions, Pst DC3000 hrcC-, but not Pst DC3000, induced salt stress tolerance, suggesting that Pst DC3000 hrcC- also contains plant growth promoting activity under stress conditions. Our results indicate that Pst DC3000 hrcC- shares features with beneficial bacteria by inducing salt tolerance through reduction of the shoot and root Na+/K+ ratio. To further elucidate the underlying mechanisms of this interaction with Arabidopsis, RNAseq, hormone and biochemical analyses were performed. Genetic studies also show that Pst DC3000 hrcC- induced salt stress tolerance involving several phytohormone pathways, including auxin, ethylene and salicylic acid. Transcriptome and genetic analyses indicate that glucosinolates play an important role in this beneficial interaction. We found that indolic and alkyl glucosinolates act as negative factors on Pst DC3000 hrcC-, alkyl glucosinolates are positive and indolic glucosinolates negative regulators in SA187 interaction with Arabidopsis. These results reveal that besides a repertoire of effectors, Pst DC3000 hrcC- also produces factors that can be beneficial for plant growth under certain stress conditions, as observed with Enterobacter sp. SA187.Citation
Jalal, R. S. (2019). Comparison of avirulent pathogen Pseudomonas syringae and beneficial Enterobacter sp SA187 for enhancing salt stress tolerance in Arabidopsis thaliana. KAUST Research Repository. https://doi.org/10.25781/KAUST-T44D3ae974a485f413a2113503eed53cd6c53
10.25781/KAUST-T44D3