Overexpression of CsMIXTA, a Transcription Factor from Cannabis sativa, Increases Glandular Trichome Density in Tobacco Leaves

Abstract

Cannabinoids are synthesized in glandular stalked trichomes on the female flowers of Cannabis sativa (cannabis). The regulation of glandular trichome development has not been characterized in cannabis. We recently identified an R2R3-MYB transcription factor, CsMIXTA, which could be involved in trichome morphogenesis in cannabis. Some homologous genes of CsMIXTA are known to function in glandular trichome initiation in other plant species. CsMIXTA is highly expressed in flower tissue compared to vegetative tissues. Interestingly, CsMIXTA is also highly expressed in trichomes isolated from female flower tissue. In addition, CsMIXTA is upregulated during the peak stages of female flower maturation in correlation with some cannabinoid biosynthetic genes. Transient expression in Nicotiana benthamiana showed that CsMIXTA is localized in the nucleus. Furthermore, yeast transcriptional activation assay demonstrated that CsMIXTA has transactivation activity. Overexpression of CsMIXTA in Nicotiana tabacum resulted in higher trichome density, larger trichome size, and more branching on stalked glandular trichomes. The results indicate that CsMIXTA not only promotes glandular trichome initiation in epidermal cells, but also regulates trichome development in tobacco leaves. In this report, we characterized the novel function of the first cannabis transcription factor that may be critical for glandular trichome morphogenesis.

Deep learning‐based quantification and transcriptomic profiling reveal a methyl jasmonate‐mediated glandular trichome formation pathway in Cannabis sativa

“…sativus ) (Dong et al., 2022), but our understanding of the regulatory network involved in cannabis GT development is still in its infancy. Recently, an R2R3‐MYB TF, CsMIXTA, was reported to positively regulate GT development in cannabis (Haiden et al., 2022). Several MIXTA homologs have been identified as key factors involved in GT formation, such as AaMIXTA1 which has been shown to be involved in the regulation of GT initiation and cuticle biosynthesis in A. annua (Shi et al., 2018).…”

“…Recent research in cannabis has led to the identification of an R2R3‐MYB TF, named CsMIXTA, that may play a positive regulatory role in cannabis GT development. This hypothesis is based on the observed high expression levels of CsMIXTA in cannabis GTs and the resulting increase in GT density when CsMIXTA is overexpressed in transgenic tobacco plants (Haiden et al., 2022). However, how TFs regulate GT development in cannabis remains poorly understood.…”

Applying quantitative spatial phenotypes analysis to the investigation of peltate glandular trichomes development pattern in Perilla frutescens

“…The number and density of GTs are crucial parameters for the quality evaluation of various crops that produce volatile oils as economic products [ 46 ]. Traditional studies have typically relied on manual counting of GTs in a random or entire area of the samples [ 46 – 48 ].…”

“…The number and density of GTs are crucial parameters for the quality evaluation of various crops that produce volatile oils as economic products [ 46 ]. Traditional studies have typically relied on manual counting of GTs in a random or entire area of the samples [ 46 – 48 ]. However, these experimental strategies often fail to ensure the effectiveness of the statistical procedure or the completeness of the information gathered.…”