Characterization of a NtODORANT1-like isoform and NtHAIR, transcription factors potentially involved in early steps of N. tabacum glandular trichome development

Details

Supervisors

Hachez, Charles ; Berhin, Alice

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

Nicotiana tabacum is a model plant from the Solanaceae family. This plant has on the surface of its aerial tissues epidermal outgrowths, called trichomes, allowing production and secretion of secondary metabolites that can be used in agricultural, pharmacological, and bio-technological sectors. N. tabacum trichomes include long non-glandular, long glandular, and short glandular trichomes. In contrast to non-glandular unicellular trichomes of A. thaliana, the development of multicellular glandular trichomes is poorly understood. To understand how N. tabacum multicellular glandular trichomes develop by modelling a transcription factor interaction network, this master’s thesis characterizes two genes: Nt-ODORANT1 (NtODO) and NtHAIR. The former is coding a MYB transcription factor homologous to AmMIXTA (Payne et al., 1999). It has been characterized as being involved in the initiation of trichome development. The latter is coding a zinc finger transcription factor homologous to SlHAIR, characterized in tomato to induce the formation of glandular trichomes (Chang et al., 2018). This analysis has two goals; to identify the gene expression localization and the function of these genes by reverse genetics. RT-qPCR was performed on different tissues of wild type plants. The experiments has revealed that NtODO is mainly expressed in leaf primordia while NtHAIR seems to be more expressed in young leaves. pODO:nlsGFP-GUS reporter lines were generated and showed expression in different cellular localization in leaf primordium including pavement cells, trichomes, stomata, veins and leaf edges. The results suggest that NtODO is involved in several developmental processes within leaf primordia. The analysis of few overexpressing NtHAIR plants has revealed a trend towards a lower trichome density and in some cases an absence of cuticle. These preliminary results imply that NtHAIR could be a negative regulator of both processes. Some plants with a reduced expression of NtODO (RNA-silencing phenomenon) showed a lower trichome density and an absence of cuticle. This suggests a role of NtODO as a positive regulator in trichome development initiation and in cuticle establishment. Finally, CRISPR Cas9 plants of the NtODO gene were generated. Different promoters were tested for Cas9 expression in order to determine future cell-specific and constitutive promoter preference.