Forschungszentrum für Umwelt und Gesundheit GmbH Wissenschaftliche Highlights in der Helmholtzgemeinschaft

H Wissenschaftlich-Technische Abteilung der GSF 2007

Abfrage Oktober 2007

Institut / Selbst. Abteilung / KKG / Nachwuchsgruppe:

AMP, AG Wurzel Mikrobiologie

FE-Nr.: 74610

Kontaktperson für Rückfragen: Prof. Dr. Anton Hartmann, [email protected], Tel.-Nr. 4109

Titel des Highlights: Plant growth promotion by in salt-stressed wheat plants

Keywords: Plant growth promotion, osmotolerance, bacterial phytohormone production, inoculation

Kernaussage des Highlights in einem Satz: A newly isolated halophilic rhizosphere bacterium ( brasilense NH) from salt affected agricultural soil in Algeria is able to promote the growth of wheat under salt stress conditions.

Darstellung des Highlights:

In wide areas of agricultural land - especially in the Mediterranean area and in subtropical, dry climate - crop growth is restricted due to salinity problems in the soil. To overcome this problem, halotolerant plant growth promoting rhizosphere bacteria were isolated from salt affected agricultural land. This investigation resulted in the isolation of a new bacterial isolate (isolate NH) from salt-affected soil of a wheat field in the Bejaïa area (Northern Algeria) which was identified as using phenotypic analyses and 16S rDNA-based phylogeny. This isolate showed resistance towards 3, 4-dehydroproline and optimal growth at 200 mmol/L NaCl. It tolerated salt stress by 300 mmol/L NaCl in the absence of osmoprotectants as well as by 400 and 600 mmol/L NaCl in the presence of glycine betaine and Ulva lactuca extract, respectively. It is able to produce the auxin indole acetic acid under saline conditions too. Both at 160 mmol/L and 200 mmol/L NaCl, normal wheat growth were restored after inoculation with A. brasilense NH. Its plant growth promoting effect of wheat under salinity conditions was significantly superior to that of A. brasilense Sp7 (less halotolerant type strain). A. brasilense NH restored wheat growth at elevated salt concentrations in pot and field experiments even better in the presence 1 osmoprotective Ulva lactuca extract. The combination of A. brasilense NH and Ulva lactuca extract may successfully improve agriculture in salt-affected soils. These results justify further attempts along these lines to improve salt-affected crop growth using these specific biostimulatory bacterial inoculants.

Original publication Nabti, E., Sahnoune, M., Adjrad, S., Van Dommelen, A., Ghoul, M., Schmid, M., Hartmann, A. (2007) A halophilic and osmotolerant Azospirillum brasilense strain from Algerian soil restores wheat growth under saline conditions. Engineering in Life Sciences 7, 354-360

Cooperation with: M. Ghoul1, H. Nabti2, M. Sahnoune2, S. Adjrad2, A. Vandommelen3 1University of Setif, Algeria, 2University of Bejaia, Targa Ouzemmour, Bejaia, Algeria, 3Kath. Univ. Leuven, Belgien

Bezug zur GSF-Strategie:

The results represent a contribution to the POF I Programme Biogeosystems, Topic 3.2, which highlight the interaction of soil microbes with plants and their effects on the growth and performance of plants and improve the agrobiotechnological know how about ways to improve crop growth using natural biological resources. In the light of climate change and generally expected climate challenges (e.g. lack of water and other soil related stress scenarios), the interaction of rhizosphere bacteria with root of crop plants to stimulate the stress resistance of plants are highly important.

GSF-interne Kooperationspartner, mit denen das Highlight ggf. erarbeitet wurde:

Keine

2 A halophilic and osmotolerant Azospirillum brasilense strain from Algerian soil restores wheat growth under saline conditions

E. Nabti1, M. Sahnoune1, S. Adjrad1, A. Van Dommelen2, M. Ghoul3, M. Schmid4, A. Hartmann4

1 University of Bejaïa, Targa Ouzemmour, Bejaïa, Algeria. 2 KU Leuven, Centre of Microbial and Plant Genetics, B-3001 Heverlee, Belgium. 3 University of Setif, Ecology, 19000 Setif, Algeria. 4 GSF-Department Microbial-Plant Interactions, Neuherberg / Munich, Germany.

AMP A halophilic and osmotolerant Azospirillum brasilense strain restores wheat growth under saline conditions

In wide areas of agricultural land - especially in subtropical, dry regions - crop growth is restricted due to salinity problems. To overcome this problem, halotolerant plant growth promoting rhizosphere bacteria were isolated from salt affected agricultural land. This investigation resulted in the isolation of a new halophilic and osmotolerant bacterial isolate NH from salt-affected soil of a wheat field in the Bejaïa area (Northern Algeria). As control, the salt-sensitive strain A. brasilense Sp7 was used in the investigation.

Effect of osmoprotectants glycine Salt inhibition of growth (A560nm) Salt inhibition of bacterial betain (GB) and algal extract on phytohormone (IAA) production growth of strain NH 2,5 0,8 60 0,7 2 0,6 50 0,5 40 1,5 0,4 0,3 30 A nm 560 1 0,2 20 nm 560 A IAA (µg/ml) 0,1 10 0 0,5 0 1,72 200 250 300 1,72 200 250 300 NaCl mmol/l 0 NaCl mmol/l 200 250 300 350 400 450 500 550 600 650 Sp7 NH Sp7 NH mmol l -1 NaCl

no osmoprotectant + G B + Algal extracts AMP A halophilic and osmotolerant Azospirillum brasilense strain restores wheat growth under saline conditions

The halophilic bacterial isolate NH was identified by sequencing the 16S rDNA and molecular phylogenetic analysis as member of the Azospirillum brasilense, which usuallyRoseomonas does not containlacus, AJ786000 halotolerant strains. Further work is needed to characterize thisRoseomonas interesting bacterium gilardii, in more detail. massiliae, AF531769 RoseomonasAY220740 mucosa, AF538712 Roseomonas aquatica, AM231587 16S rDNA phyogeneticRoseomonas tree with thegenomospecies new Azospirillum 5, AY150049 brasilense NH strain Roseomonas cervicalis, AF533353 Roseomonas genomospecies 4, AY150048 Azospirillum irakense, Z29583 Rhodocista pekingensis, AF523824 Rhodocista xerospirillum, AM072288 Azospirillum amazonense, Z29616 Skermanella parooensis, X90760 Azospirillum doebereinerae, AJ238567 Azospirillum oryzae, AB185396 Azospirillum largimobile, X90759 Azospirillum melinis TMCY, DQ022958 Azospirillum halopraeferens, X79731 Azospirillum canadense, DQ393891 Azospirillum brasilense NH Azospirillum brasilense, DQ288687 Azospirillum brasilense, DQ288690 Roseomonas genomospecies 6, AY150050 Azospirillum brasilense, Z29617 Azospirillum brasilense, AY958234 Azospirillum brasilense, X79734 Azospirillum brasilense, AY324110 Roseomonas fauriae, AF533354 Roseomonas fauriae, AY150046 0.10 Azospirillum brasilense Sp7, X79739 A halophilic and osmotolerant Azospirillum brasilense strain restores wheat growth under saline conditions - Inoculation of wheat roots with strain at 200 mM NaCl restores wheat growth (stem height and spike length) almost completely, while other salt sensitive bacteria had no effect. - The combined treatment with strain NH and extracts of the marine algae Ulva lactuca (containing effective osmolytes to further support osmoprotection of plants). - Under osmotic stress conditions (200mM NaCl), the inoculant strain A. brasilense NH is effectively colonising the apoplast of roots (yellow dots) and the root central cylinder (not shown). Conclusion: The halophilic and osmotolerant rhizosphere bacterium Azospirillum brasilense NH is able to promote growth of wheat under salt stress conditions. Further translational experiments are warranted to develop and test it as a agrobiotechnological inoculum. Endophytic localization of strain NH (FISH analysis)

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