Functional characterisation of NtML1 and NtRAX2-like, two transcription factors involved in the development of trichomes in Nicotiana tabacum
(2025)
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- Authors
- Supervisors
- Hachez, Charles
- Abstract
- Trichomes are specialised epidermal structures found on aerial parts of plants, playing a vital role in defence and environmental adaptation. They occur in various forms and are generally classified as glandular or non-glandular. Glandular trichomes are particularly notable for producing and secreting specialised metabolites that protect against herbivores and pathogens. Due to this high secretory capacity, they are prime candidates for metabolic engineering. Their post-embryonic multicellular development also makes them valuable models for studying cell differentiation. To explore the regulation of trichome development, two transcription factors in Nicotiana tabacum were investigated: NtML1 (a HD-Zip IV protein) and NtRAX2-like (a R2R3-MYB protein). NtML1 resembles SlWOOLLY from tomato, a key regulator of trichome initiation. RT-qPCR and transcriptional reporter lines showed broad NtML1 expression in epidermal cells of leaf primordia and floral organs, while NtRAX2-like expression was more restricted, appearing mainly in trichome stalks. These overlapping patterns suggested an interaction, later confirmed in vivo. DNA-protein interaction study identified target genes and conserved cis-regulatory motifs specifically bound by NtML1, validated through in vivo and in vitro assays. Mutant lines revealed that NtML1 promotes the formation of both long glandular and non-glandular trichomes, while also affecting secondary metabolite production and floral organ integrity. Conversely, NtRAX2-like role remains less defined, although its overexpression induced a dwarf phenotype. Finally, RNA-seq analysis of ntml1 lines revealed a set of novel genes not previously associated with trichome development, expanding our understanding of the molecular pathways involved. These findings highlight NtML1 as a key regulator of trichome development and identify NtRAX2-like as a novel interactor, offering new insights into the genetic networks underlying plant defence and metabolic engineering.
- Affiliations
UCLouvain SST/LIBST - Louvain Institute of Biomolecular Science and Technology
Citations
Gueuning, L. (2025). Functional characterisation of NtML1 and NtRAX2-like, two transcription factors involved in the development of trichomes in Nicotiana tabacum. https://hdl.handle.net/2078.5/248701