Dynamics of regulatory protein complexes in a changing environment: using the example of plant glucosinolate biosynthesis

• Applicant: Privatdozentin Dr. Tamara Gigolashvili
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems ; Plant Genetics and Genomics ; Plant Cell and Developmental Biology
• Term: from 2016 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 322540466

• Final Report Year: 2021

Final Report Abstract

Plants of the order Brassicales produce glucosinolates (GSLs) as a biochemical defense against herbivores and pathogens. If the plant is attacked, these secondary metabolites are activated into toxic compounds such as thiocyanates, isothiocyanates and nitriles. Both intact GSLs and their degradation products influence plant-environment interactions in numerous ways. The regulation of GSL biosynthesis is known to be controlled by a complex consisting of MYB and bHLH transcription factors. In this project we studied the regulatory protein complexes controlling GSL biosynthesis by: (i) identifying MYB binding sites (MBS) and bHLH protein binding sites (G-boxes) in the promoters of GSL biosynthesis genes in Arabidopsis thaliana using in silico data, as well as CHIP-seq and DAP-seq data. Following the mapping of cis-regulatory elements, we have generated deletions in the promoters of the GSL biosynthesis gene CYP79B3 and have addressed the role of MBS and G-boxes in GSL biosynthesis via cell-based assays. (ii) identify new regulatory components, which relay signals into MYB-bHLH complex. We can show, that in addition to jasmonate, the MYB–bHLH complex integrates other environmental cues, including light and gibberellin, via the SPA–DELLA complex. (ii) characterizing of the role of EML proteins as novel components of MYB–bHLH complexes involved in the epigenetic regulation of GSL biosynthesis. We showed that EML proteins interact with all three bHLHs that regulate GSL biosynthesis. Arabidopsis eml knockout mutants are defective in GSL biosynthesis and coexpression studies showed that EML1 affects the production of these secondary compounds by affecting the activity of the MYB–bHLH complex in cultured Arabidopsis cells. (iv) Analysis of metabolite sensing in the regulation of GSL biosynthesis in Arabidopsis plants. We showed that GSL taken up from external medium, can switch the MYB–bHLH transcription complex “on” or “off” in cultured Arabidopsis cells. “On” and “off” switches cause changes in the expression of GSL biosynthesis genes and in the synthesis rate of GSL within the cell.

Publications

• (2017) The photosynthetic bacteria Rhodobacter capsulatus and Synechocystis sp. PCC 6803 as new hosts for cyclic plant triterpene biosynthesis. PLoS One. Dec 27;12(12):e0189816
  Loeschcke A., Dienst D., Wewer V., Hage-Hülsmann J., Dietsch M., Kranz-Finger S., Hüren V., Metzger S., Urlacher VB., Gigolashvili T., Kopriva S., Axmann IM., Drepper T., Jaeger K.-E.
  
• (2018) AP2 transcription factor CBX1 with a specific function in symbiotic exchange of nutrients in mycorrhizal Lotus japonicus. Proceedings of the National Academy of Sciences 115, E9239-E9246
  Xue L., Klinnawee L., Zhou Y., Saridis G., Vijayakumara V., Brands M., Dörmann P., Gigolashvili T., Turck F., and Bucher M.
  
• (2018) Tracking an ancestral role of MYBs regulating Glucosinolate biosynthesis. Book of abstracts. 11th International Plant Sulfur Workshop in Conegliano. Sep 16-20, 2018
  Mitreiter S Frerigmann H, Kopriva S, Gigolashvili T
  
• (2019) PAPST2 plays a critical role for PAP removal from the cytosol and subsequent degradation in plastids and mitochondria. The Plant Cell. 2019 Jan;31(1):231-249
  Ashykhmina N., Geier, M., Frerigmann H., Hofsetz E., Stührwohldt N., Flügge U.-I., Haferkamp I., Kopriva S. and Gigolashvili T.
  
• (2019). The role of EMSY-Like histone readers in regulation of glucosinolate biosynthesis in Arabidopsis thaliana; Book of abstracts. 6th European Workshop on Plant Chromatin, 13-14 June 2019
  Mitreiter S., Lee Y. S., Bahlmann A.K., Grotewold E., Brkljacic J, Gigolashvili T.
  
• (2021) Regulation of glucosinolate biosynthesis. J. of Exp. Bot. 72-1, Pages 70–91
  Mitreiter S. and Gigolashvili T.
  
• (2021). The COP1/SPA and DELLA proteins balance the gibberellin and jasmonate phytohormone network to regulate glucosinolate synthesis in Arabidopsis thaliana. Front. Plant Sci., 01 July 2021
  Frerigmann H., Höcker U., Gigolashvili T.