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.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/652894 |
| Date | 05 1900 |
| Creators | Jalal, Rewaa S. |
| Contributors | Hirt, Heribert, Biological and Environmental Sciences and Engineering (BESE) Division, Arold, Stefan T., Blilou, Ikram, Wrzaczek, Michael, de-julien-de-Zelicourt, Axel |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2020-05-16, 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. |
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