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HAIRY ROOT TRANSFORMATION NEW STRATEGY FOR PLANT BREEDING

Objective

THE HAIRY ROOT SYNDROME INDUCED BY THE RI PLASMIDS OF AGROBACTERIUM RHIZOGENES IS A CROWN GALL-RELATED DISEASE OF DICOTYLEDONOUS PLANTS. IN THE PAST FEW YEARS SEVERAL FEATURES OF THIS SYSTEM HAVE BEEN EVIDENCED THE PROPOSING LABORATORY THAT EMPHASIZE ITS UNIQUE POTENTIALITIES BOTH FOR PLANT GENETIC ENGINEERING AND FOR THE COMPREHENSION OF FUNDAMENTAL ASPECTS OF HIGHER PLANT PHYSIOLOGY AND PLANT CELL GROWTH, DIFFERENTIATION AND HORMONAL RESPONSE. SIGNIFICANT ADVANCES IN THE GENETIC ENGINEERING OF CROP PLANTS AND IN THE UNDERSTANDING OF THEIR ESSENTIAL FUNCTIONS (PHYSIOLOGY, GROWTH, DIFFERENTIATION AND HORMONAL RESPONSE) COULD RESULT, IN THE LONG TERM, FROM THE RESEARCH WHICH THE CONTRACTANT ENVISAGES TO UNDERTAKE.
The hairy root disease is a neoplastic syndrome of dicotyledonous plants due to infection by the soil bacterium Agrobacterium rhizogenes and characterized by abundant proliferation of roots at the site of bacterial infection. Root growth is due to transfer and expression of a fragment of bacterial deoxyribonucleic acid (DNA) (the T-DNA) in infected plant cells.

The main interest in studying this biological system is in the unique tools and the advantageous standpoint it provides for investigating the molecular basis of higher plant (root) differentiation. Also, novel strategies of plant transformation and selection of transformants could be developed based on some unique characteristics of hairy roots.

A major change in the ideas concerning neoplastic growth in plants arosefrom the demonstration of the relative role of auxin and of (previously unsuspected) T-DNA genes conferring auxin responsiveness to plant cells. These genes were cloned and their effects characterized. The (auxin) regulated expressed of the most relevant of these genes (rolB) was demonstrated.
The effectiveness of a hairy root based plant transformation strategy and the increased sensitivity of plant cells transformed by T-DNA genes was also demonstrated. This work led to the concept that the cause or at least an early sign of cell commitment to root morphogenesis is a dramatic increase in auxin sensitivity.
THE RESEARCH WILL BE CARRIED OUT AS PART OF A JOINT EFFORT BETWEEN THE UNIVERSITY OF PARIS AND THE UNIVERSITY OF ROME.

THE CONTRIBUTION OF THE CONTRACTANT TO THIS JOINT EFFORT WILL CONCENTRATE ON :

- CONSTRUCTION OF DELETIONS IN THE T-DNA OF RI PLASMIDS AND THE USE OF THESE DELETIONS FOR ANALYSING THE FUNCTIONS OF RI PLASMID T-DNA.
- DEFINITION OF THE ROLE OF PLANT HORMONES IN THE INSURGENCE OF HAIRY ROOTS.
- COMPARATIVE ANALYSIS OF THE TRANSCRIPTION PRODUCTS OF T-DNA IN TRANSFORMED TISSUES AND BACTERIA.
- DETAILED SOUTHERN BLOT COMPARATIVE ANALYSIS OF DIFFERENT T-DNAS.
- DEVELOPMENT OF IN VITRO TRANSFORMATION SYSTEMS WITH ENGINEERED STRAINS OF A. RHIZOGENES AND OF BINARY VECTORS DERIVED FROM RI PLASMIDS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITY OF ROME "LA SAPIENZA"
Address
Piazzale Aldo Moro 5
00185 Roma
Italy

Participants (1)

UNIVERSITE DE PARIS-SUD XI
France
Address
Rue Georges Clemenceau 15
91405 Orsay