Insights into the transcriptional cascade involved in the initial and early phases of glandular trichome development in Nicotiana tabacum [RNAseq_MIXTA]

Glandular trichomes play a pivotal role in plant defense against a wide range of biotic and abiotic stresses. This study aims to employ AmMIXTA as a transcriptional switch to explore the genetic network that triggers glandular trichome development by leveraging its known role in promoting glandular trichome development when heterologously expressed in Nicotiana tabacum. To this end, we conducted a comprehensive RNA-seq analysis on transgenic tobacco lines expressing AmMIXTA under the control of a ß-estradiol-inducible promoter across key time points. Our findings reveal a significant upregulation of a suite of genes, predominantly transcription factors, following the induction of AmMIXTA, providing insights into the transcriptional cascade involved in the initial and early phases of glandular trichome development. Moreover, through confocal live cell imaging of transcriptional reporter lines, interaction studies and DAP-seq assays, we confirmed the involvement of NtZFP8, a gene identified in our study, in glandular trichome development. Our data support a synergistic model where AmMIXTA and NtZFP8 co-regulate a network of genes critical for glandular trichome formation. Our study opens new lead to investigate the complex genetic network controlling glandular trichome formation in tobacco and related Solanaceae species of agronomical interest. Overall design: By employing AmMIXTA as a transcriptional switch under the regulation of a ß-estradiol inducible promoter, we aimed to dissect the molecular mechanisms governing glandular trichome initiation and development on the cotyledons of tobacco, which are naturally devoid of trichomes. Two timepoints were analyzed: 4h and 48h post-MIXTA induction. While the 4h time point post-AmMIXTA induction should capture genes involved in the initiation and early stages of glandular trichome development, the later time point (48 hrs post-induction) should capture the trans-differentiation of cells into glandular trichome cells.