Arabidopsis MYB47 and MYB95 transcription factors regulate jasmonate-inducible ER-body formation Jakub Bizan, Shayan Sarkar, Arpan Kumar Basak, Subhankar Bera, Shino Goto-Yamada, Kaichiro Endo, Katarzyna Tarnawska-Glatt, Rituraj Batth, Kritika Bhardwaj, Mohamadreza Mirzaei, Paweł Czerniawski, Paweł Bednarek, Kenji Yamada Communications Biology, 2025 Endoplasmic reticulum (ER)-derived subcellular structures, namely ER bodies, are involved in glucosinolate-based chemical defense against insect pests and pathogenic fungi in the Brassicaceae family. In Arabidopsis thaliana, treatment of rosette leaves with the wounding hormone jasmonate (JA) induces β-GLUCOSIDASE 18 (BGLU18) and TSK-ASSOCIATING PROTEIN 1 (TSA1) gene expression, whose products accumulate in JA-inducible ER bodies; however, the underlying transcriptional regulatory mechanisms remain unknown. Here, we show that two paralogous Arabidopsis MYBs, namely MYB47 and MYB95, regulate TSA1 and BGLU18 expression and ER-body formation in response to JA. MYB47 and MYB95 bind to and activate the TSA1 promoter. TSA1 and BGLU18 expression levels are reduced in the JA-treated rosette leaves of myb47,95 mutants, suggesting that these MYBs play a key role in the activation of these genes. Transcriptome analysis reveals that MYB47 and MYB95 regulate a subset of JA-responsive genes, including ER-body and defense-related genes. Phylogenetic analysis shows that MYB47 and MYB95 belong to a MYB subfamily unique to the Brassicales order. Together, our findings indicate that MYB47 and MYB95 have evolved to regulate unique downstream target genes in response to JA, which include JA-inducible ER body genes important for protecting plants from fungal and herbivore attacks in Brassicaceae.
Arabinogalactan Proteins Accumulate in the Cell Walls of Searching Hyphae of the Stem Parasitic Plants, Cuscuta campestris and Cuscuta japonica Akitaka Hozumi, Subhankar Bera, Daiki Fujiwara, Takeshi Obayashi, Ryusuke Yokoyama, Kazuhiko Nishitani, Koh Aoki Plant and Cell Physiology, 2017 Stem parasitic plants (Cuscuta spp.) develop a specialized organ called a haustorium to penetrate their hosts' stem tissues. To reach the vascular tissues of the host plant, the haustorium needs to overcome the physical barrier of the cell wall, and the parasite-host interaction via the cell wall is a critical process. However, the cell wall components responsible for the establishment of parasitic connections have not yet been identified. In this study, we investigated the spatial distribution patterns of cell wall components at a parasitic interface using parasite-host complexes of Cuscuta campestris-Arabidopsis thaliana and Cuscuta japonica-Glycine max. We focused on arabinogalactan proteins (AGPs), because AGPs accumulate in the cell walls of searching hyphae of both C. campestris and C. japonica. We found more AGPs in elongated haustoria than in pre haustoria, indicating that AGP accumulation is developmentally regulated. Using in situ hybridization, we identified five genes in C. campestris that encode hyphal-expressed AGPs that belong to the fasciclin-like AGP (FLA) family, which were named CcFLA genes. Three of the five CcFLA genes were expressed in the holdfast, which develops on the Cuscuta stem epidermis at the attachment site for the host's stem epidermis. Our results suggest that AGPs are involved in hyphal elongation and adhesion to host cells, and in the adhesion between the epidermal tissues of Cuscuta and its host.
