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Use of rhizobacteria for the alleviation of plant stress

Abd El-Daim, Islam Ahmed Moustafa (2015). Use of rhizobacteria for the alleviation of plant stress. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2015:48
ISBN 978-91-576-8294-9
eISBN 978-91-576-8295-6
[Doctoral thesis]

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Abstract

Plant growth promoting rhizobacteria are beneficial microbes able to induce plant stress tolerance and antagonise plant pathogens. The present study showed that wheat seedlings pre-treated with Bacillus thuringiensis AZP2 had better tolerance to severe drought stress and showed 78% greater plant biomass and five-fold higher survivorship compared to wheat seedlings not treated with the bacterium. The effect of B. thuringiensis AZP2 also resulted in improved net assimilation and reduced emission of stress volatiles.

The study investigated the effect of the inactivation of sfp-type phosphopantetheinyl transferase in plant growth promoting bacterium Paenibacillus polymyxa A26. The inactivation of the sfp gene resulted in loss of NRP/PK production such fusaricidins and polymyxins. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. Its biofilm promotion is directly mediated by NRP/PK, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Further, increased biofilm formation was connected with enhanced ability of the sfp inactivated strain to remarkably protect wheat seedlings by improving its survival and biomass under severe drought stress conditions compared to wild type.

Fusarium graminearum and F. culmorum are the causing agents of a destructive disease known as Fusarium head blight (FHB). The disease is the leading cause of contamination of grain with Fusarium mycotoxins that are severe threat to humans and animals. Biological control has been suggested as one of the integrated management strategies to control FHB causing agents. The present study showed that P. polymyxa A26 is a potent antagonistic agent against F. graminearum and F. culmorum. In order to optimize strain A26 production, formulation and application strategies traits important for its compatibility need to be revealed. Hence, a toolbox comprising of dual culture plate assays and wheat kernel assays including simultaneous monitoring of the FHB causing pathogens, A26 and mycotoxins produced was developed in the present study. Using this system results showed that, besides the involvement of lipopeptide antibiotic production by P. polymyxa in the antagonism process, biofilm formation ability may play a crucial role in the case of A26 F. culmorum antagonism.

Authors/Creators:Abd El-Daim, Islam Ahmed Moustafa
Title:Use of rhizobacteria for the alleviation of plant stress
Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :2015
Depositing date:2015
Volume:2015:48
Number of Pages:58
Papers/manuscripts:
NumberReferences
ITimmusk S, Abd El-Daim IA, Copolovici L, Tanilas T, Kannaste A, Behers L, Nevo E, Seisenbaeva G, Stenström E, Niinemets U (2014) Drought-tolerance of wheat improved by rhizosphere bacteria from harsh environments: enhanced biomass production and reduced emissions of stress volatiles. PloS One 9 (5):e96086. doi:10.1371/journal.pone.0096086
IITimmusk S, Kim S, Nevo E, Abd El-Daim IA, Ek B, Bergquist J, Behers L (2015) Sfp-type PPTase inactivation promotes bacterial biofilm formation and ability to enhance wheat drought tolerance. Frontiers in Microbiology; doi: 10.3389/fmicb.2015.00387
IIIAbd El-Daim IA, Häggblom P, Stenström E, Karlsson M, Timmusk S, (2015) Paenibacillus polymyxa A26 sfp-type phosphopantetheinyl transferase inactivation limits bacterial antagonism against Fusarium graminearum but not of F. culmorum (Manuscript submitted)
Place of Publication:Uppsala
Publisher:Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8294-9
ISBN for electronic version:978-91-576-8295-6
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F30 Plant genetics and breeding
F Plant production > F60 Plant physiology and biochemistry
H Protection of plants and stored products > H20 Plant diseases
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Microbiology (Microbiology in the medical area to be 30109)
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Agricultural Science
Agrovoc terms:rhizobacteria, plants, triticum aestivum, drought stress, drought tolerance, bacillus thuringiensis, fusarium, fungal diseases, biological control, genes
Keywords:Plant drought tolerance, Biocontrol, NRPS/PKS, Rhizobacterial biofilm, sfp-type PPTase, Stress volatiles, DON, ZEA
URN:NBN:urn:nbn:se:slu:epsilon-e-2641
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-2641
ID Code:12206
Faculty:S - Faculty of Forest Sciences
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: Islam A Abd El-Daim
Deposited On:11 May 2015 13:58
Metadata Last Modified:18 Dec 2015 00:15

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