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Exploring plant tolerance to biotic and abiotic stresses

Karim, Sazzad (2007). Exploring plant tolerance to biotic and abiotic stresses. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:58
ISBN 978-91-576-7357-2
[Doctoral thesis]

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Plants are exposed to many stress factors, such as drought, high salinity or pathogens, which reduce the yield of the cultivated plants or affect the quality of the harvested products. Arabidopsis thaliana was used as a model plant to study the responses of plants to different sources of stress. With Agrobacterium T-DNA mediated promoter tagging, a novel di-/tripeptide transporter gene AtPTR3 was identified as a wound-induced gene. This gene was found to be induced by mechanical wounding, high salt concentrations, bacterial infection and senescence, and also in response to several plant hormones and signalling compounds, such as salicylic acid, jasmonic acid, ethylene and abscisic acid. Atptr3 mutants of two Arabidopsis ecotypes, C24 and Col-0, were impaired in germination on media containing a high salt concentration, which indicates that AtPTR3 is involved in seed germination under salt stress. Wounding caused local expression of the AtPTR3 gene, whereas inoculation with the plant pathogenic bacterium Erwinia carotovora subsp. carotovora caused both local and systemic expression of the gene. Atptr3 mutants showed increased susceptibility to infection caused by bacterial phytopathogens, E carotovora and Pseudomonas syringae pv. tomato, and the P. syringae type III secretion system was shown to be involved in suppression of the AtPTR3 expression in inoculated plants. Moreover, the Atptr3 mutation was found to reduce the expression of the marker gene for systemic acquired resistance, PR1 and the mutants accumulated reactive oxygen species (ROS) following the treatment of the plants with ROS generating substances. Overall results and observations suggest that the AtPTR3 is a novel and versatile stress responsive gene needed for defence reactions against many stresses. In a second part of the study, the yeast (Saccharomyces cerevisiae) trehalose-6-phosphate synthase gene (ScTPS1) was utilized to improve the drought tolerance of Arabidopsis. This gene codes for the first enzyme in the trehalose biosynthesis pathway of yeast, and expression in plants leads to improved drought tolerance but also growth aberrations. In this study, the ScTps1 protein was expressed in Arabidopsis using the constructs containing chloroplast targeting transit peptide sequence that facilitated the import of the ScTps1 into the chloroplast. The drought tolerance and growth phenotypes of Arabidopsis transgenics transformed with ScTPS1 with or without transit peptide, were characterized. The plants with cytosolic localization of the ScTps1 protein showed aberrant root phenotype, but the plants with the chloroplast targeted ScTps1 protein caused no aberration in root morphology. Even though both the transgenic lines showed enhanced drought tolerance, the relative water content of the lines was found to be similar to the wild type control. Moreover, both the transgenic lines showed slightly better water holding capacity or reduced water loss over time compared to wild type plants. The overall results indicated that the growth aberrations caused by cytosolic localization of ScTps1 could be uncoupled from the enhanced drought tolerance in the transgenic plants when the ScTps1 was targeted to chloroplast.

Authors/Creators:Karim, Sazzad
Title:Exploring plant tolerance to biotic and abiotic stresses
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2007
Number of Pages:66
ALLI. Karim, S., Lundh, D., Holmström, K-O., Mandal, A. & Pirhonen, M. 2005. Structural and functional characterization of AtPTR3, a stress-induced peptide transporter of Arabidopsis. Journal of Molecular Modeling 11, 226-236. (DOI: 10.1007/s00894-005-0257-6). II. Karim, S., Holmström, K-O., Mandal, A., Dahl, P., Hohmann, S., Brader, G., Palva, ET. & Pirhonen, M. 2006. AtPTR3, a wound-induced peptide transporter needed for defence against virulent bacterial pathogens in Arabidopsis. Planta 2 December 2006, 1-15. (DOI: 10.1007/s00425-006-0451-5). III. Karim, S., Aronsson, H., Ericson, H., Pirhonen, M., Leyman, B., Welin, B., Mäntylä, E., Palva, ET., Van Dijck, P. & Holmström, K-O. 2007. Improved drought tolerance without undesired side effects in transgenic plants producing trehalose. Plant Molecular Biology 28 February 2007, 1-16. (DOI: 10.1007/s11103-007-9159-6).
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7357-2
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:arabidopsis thaliana, stress, drought resistance, peptides, pathogens, osmotic stress, gene expression, dna, genetic markers, trehalose
Keywords:Arabidopsis thaliana, abiotic stress, biotic stress, drought tolerance, peptide transporter, plant pathogen, promoter trapping, salt stress, T-DNA tagging, trehalose, trehalose-6-phosphate, trehalose-6-phosphate synthase
Permanent URL:
ID Code:1427
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: Sazzad Karim
Deposited On:26 Apr 2007 00:00
Metadata Last Modified:02 Dec 2014 10:12

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