Caractérisation de gènes potentiellement impliqués dans le développement de trichomes glandulaires longs chez Nicotiana tabacum : création de lignées rapportrices et modulation de l’expression par RNA silencing ou surexpression

Details

Supervisors

Hachez, Charles

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries

Abstract

enTrichomes are uni or multicellular structures derived from the protoderm and developing on the aerial vegetative and reproductive parts of plants. These structures are non-essential to the survival of the plant but fulfill different roles in plant adapataion to its environment. The multicellular trichomes are often separated into two groups, the glandular trichomes and the non-glandular trichomes. Glandular trichomes include trichomes with one or more small glandular heads at the top of a stem, possibly branched (capitate), and trichomes forming a large gland with subcutaneous storage space(peltate). The peculiarity of glandular trichomes is their ability to synthesize a large amount of secondary metabolites also called specialized metabolites. Nicotiana tabacum has both glandular trichomes of capitate and peltate type. Our understanding of the initiation and development processes of glandular multicellular trichomes remains deficient for many species including N. tabacum. This, unlike unicellular (non-glandular) trichomes, such as those of Arabidopsis thaliana, where the cytological and molecular aspects of development are already well characterized. For N. tabacum, the initiation and development of trichomes seems to be ordered by a transcriptional network different from that operating in A. thaliana. In order to discover potential stakeholders, various genetic constructs on genes that are supposed to intervene in the initiation and development of trichomes of this plant have been carried out with a view to the creation of stable transgenic tobacco lines. First, the creation of reporter lines for PDF1 and HEC2 whose promoter sequences were placed upstream of a GUS-Venus reporter gene in order to be able to determine the activity profile of these promoters. Secondly, the creation of lines overexpressing the PDF1, HEC2 and CNR13 genes with a β-estradiol inducible promoter in order to observe the impact of the overexpression of these genes on the phenotype of tobacco trichomes. And finally, the creation of a line resulting in a silencing of the CNR13 gene by amiRNA technique with a β-estradiol inducible promoter in order to observe the impact of the silencing of this gene on the tobacco trichome phenotype.