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REGULATION OF EXPRESSION OF GENES INVOLVED IN BIOLOGICAL NITROGEN FIXATION

Objective

A LONG TERM SCIENTIFIC OBJECTIVE OF THE CONTRACT IS TO DEVELOP A REPRODUCTIBLE TRANSFORMATION AND REGENERATION SYSTEM FOR LEGUMES, SUCH THAT THE TRANSFORMED ROOTS WILL FORM EFFECTIVE NODULES AFTER INFECTION WITH RHIZOBIA.

A MORE EFFICIENT ASSOCIATION BETWEEN LEGUMES AND RHIZOBIA WOULD LOWER THE NEED FOR NITROGEN FERTILIZERS. THE EFFECT OF MORE EFFICIENT NITROGEN FIXATION WOULD THEREFORE HAVE IMPORTANT ECONOMICAL CONSEQUENCES, AND WOULD AS WELL REDUCE THE EFFECT ON THE ENVIRONMENT PRESENTLY EXPERIENCED FROM THE HEAVY APPLICATION OF NITRATES INTO THE CULTIVATED SOILS.
The nodules formed on the roots of legumes are the result of a cooperative effort by both the plant and the bacteria. Thus specific bacterial and plant genes are involved in the formation and function of nodules. Research was carried out in order to identify and characterize the specific plant genes involved in nodule formation and function, using the methods of modern molecular biology.

Several of the specific plant genes involved in symbiotic nitrogen fixation were isolated and characterized, including genes from Soybean, Sesbania rostrata and Vicia faba. In order to study the regulation of these genes, a gene transformation system allowing the transfer of genes from one legume species to another was developed. The main result of the gene transfer studies is that the molecular mechanisms responsible for activation of the specific plant genes are conserved among the various legume Rhizobium associations existing in nature. Finally, the development of efficient gene transfer systems for legumes enabled a detailed analysis of regulatory regions involved in the activation of the specific plant genes from Soybean and Sesbania rostrata.
IT IS THE PURPOSE OF THIS CONTRACT TO STUDY THE REGULATION OF BOTH PLANT AND BACTERIAL GENES INVOLVED IN THE FORMATION OF EFFECTIVE ROOT NODULES UPON THE ESTABLISHMENT OF SYMBIOSIS WITH RHIZOBIA. THE GENES INVOLVED WILL HAVE TO BE ISOLATED AND CHARATERIZED. IN SOYBEAN, THE GROUP OF AARHUS IS ACTIVE IN STUDYING LEGHEMOGLOBIN GENES, AS WELL AS 14 OTHER NODULE-SPECIFIC PLANT GENES ISOLATED TO DATE. THE GROUP OF BIELEFELD INVESTIGATES ON CORRESPONDING GENES IN VICIA FABA. LEGUME TRANSFORMATION WITH CHIMERIC GENES COMBINING NODULE-SPECIFIC PLANT PROMOTORS AND MARKER SEQUENCES WILL BE THE CONTRIBUTION OF THE GENT LABORATORY, USING MODIFIED TI PLASMIDS AS VECTORS.
PARTICULAR ATTENTION SHALL BE GIVEN TO COMMON DNA SEQUENCES IN DIFFERENT LEGUME SPECIES, WHICH MAY BE INVOLVED IN THE COORDINATED EXPRESSION OF SYMBIOTIC GENES.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

AARHUS UNIVERSITY
Address
Ndr. Ringgade 1
8000 Arhus
Denmark

Participants (5)

MAX-PLANCK-GESELLSCHAFT ZUR FOERDERUNG DER WISSENSCHAFTEN E.V.
Germany
Address
Carl-von-linné-weg 10
50829 Koeln
RIJKSUNIVERSITEIT GENT
Belgium
Address

Gent
THIS CONTRACT IS A MULTI PARTY ONE WITH :
UNIVERSITAET BIELEFELD
Germany
Address

33501 Bielefeld
WITH THE COLLABORATIO OF :