BrrTCP4b interacts with BrrTTG1 to suppress the development of trichomes in Brassica rapa var. rapa.

The number of trichomes significantly increased in CRISPR/Cas9-edited BrrTCP4b turnip (Brassica rapa var. rapa) plants. However, the underlying molecular mechanism remains to be uncovered. In this study, we performed the Y2H screen using BrrTCP4b as the bait, which unveiled an interaction between BrrTCP4b and BrrTTG1, a pivotal WD40-repeat protein transcription factor in the MYB-bHLH-WD40 (MBW) complex. This physical interaction was further validated through bimolecular luciferase complementation and co-immunoprecipitation. Furthermore, it was found that the interaction between BrrTCP4b and BrrTTG1 could inhibit the activity of MBW complex, resulting in decreased expression of BrrGL2, a positive regulator of trichomes development. In contrast, AtTCP4 is known to regulate trichomes development by interacting with AtGL3 in Arabidopsis thaliana. Overall, this study revealed that BrrTCP4b is involved in trichome development by interacting with BrrTTG1 in turnip, indicating a divergence from the mechanisms observed in model plant A. thaliana. The findings contribute to our understanding of the regulatory mechanisms governing trichome development in the non-model plants turnip.

Genome-Wide Analysis of the WOX Transcription Factor Genes in Dendrobium catenatum Lindl.

The WUSCHEL-related homeobox (WOX) proteins are a class of transcription factors exclusive to plants. They can promote cell division or inhibit stem cell differentiation to regulate plant growth and development. However, the WOX transcription factor genes in the monocotyledon Dendrobium catenatum Lindl. remain relatively uncharacterized. Specifically, the effects of phytohormones on their expression levels are unclear. In this study, we identified and analyzed 10 candidate DcaWOX transcription factor genes in D. catenatum. The DcaWOX family was divided into the modern/WUS, intermediate, and ancient clades. The subcellular localization analysis detected DcaWOX-GFP fusion proteins in the tobacco epidermal leaf cell nucleus. In DcaWOX, members of the WUS clade with the WUS-box motif can significantly activate the expression of TPL in vivo, while members of the intermediate and ancient clades cannot. The expression of the DcaWOX genes varied among the examined tissues. Moreover, the DcaWOX expression patterns were differentially affected by the phytohormone treatments, with differences detected even between homologs of the same gene. Furthermore, the gene expression patterns were consistent with the predicted cis-acting elements in the promoters. The above results suggest that DcaWOX may have an important role in its growth and development and resistance to stress. The results of this comprehensive investigation of the DcaWOX gene family provide the basis for future studies on the roles of WOX genes in D. catenatum.