Discovery of a cis-regulatory element SaeM involved in dynamic regulation of synergid-specific MYB98

Prakash Babu Adhikari; Shaowei Zhu; Xiaoyan Liu; Chen Huang; Liyang Xie; Xiaoyan Wu; Jiale He; Nobutaka Mitsuda; Benjamin Peters; Lynette Brownfield; Shingo Nagawa; Ryushiro Dora Kasahara

doi:10.3389/fpls.2023.1177058

Discovery of a cis-regulatory element SaeM involved in dynamic regulation of synergid-specific MYB98

Front Plant Sci. 2023 May 8:14:1177058. doi: 10.3389/fpls.2023.1177058. eCollection 2023.

Authors

Prakash Babu Adhikari^{1

2

3}, Shaowei Zhu², Xiaoyan Liu², Chen Huang², Liyang Xie³, Xiaoyan Wu², Jiale He², Nobutaka Mitsuda⁴, Benjamin Peters⁵, Lynette Brownfield⁵, Shingo Nagawa^{2

3}, Ryushiro Dora Kasahara^{2

3

6}

Affiliations

¹ Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China.
² College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
³ Horticultural Plant Biology and Metabolomics Center (HBMC), Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
⁴ Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
⁵ Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
⁶ International Research Organization for Advanced Science and Technology (IROAST), Kumamoto University, Kumamoto, Japan.

Abstract

MYB98 is a key regulator of the genetic network behind pollen tube attraction toward the female gametophyte. MYB98 is specifically expressed in the synergid cells (SCs), a female gametophyte component cells specialized for pollen tube attraction. However, it had not been clear how exactly MYB98 achieves this specific expression pattern. In the current study, we have determined that a normal SC-specific expression of MYB98 is dependent on a 16-bp-long cis-regulatory element, CATTTACACATTAAAA, freshly named as the "S ynergid-specific A ctivation E lement of M YB98" (SaeM). An 84 bp fragment harboring SaeM in the middle was sufficient to drive exclusively SC-specific expression. The element was present in a significantly large proportion of SC-specific gene promoters and in the promoter of MYB98 homologous genes in the Brassicaceae (pMYB98s). Significance of such family-wide SaeM-like element conservation in exclusive SC-specific expression was confirmed by the Arabidopsis-like activation feature of Brassica oleracea-derived pMYB98 and absence of such feature of pMYB98 derived from a non-Brassicaceae member Prunus persica. Additionally, the yeast-one-hybrid assay showed that the SaeM can be recognized by ANTHOCYANINLESS2 (ANL2) and DAP-seq data further suggested for additional three ANL2 homologs targeting the similar cis-element. Overall, our study has concluded that SaeM plays a crucial role in driving exclusively SC-specific expression of MYB98 and strongly suggests for the involvement of ANL2 and its homologs in its dynamic regulation in planta. Future study on the transcription factors is expected to shed more light on the mechanism behind the process.

Keywords: MYB98 promoter; SaeM; cis-element; dynamic regulation; synergid cell.

Grants and funding

The work was supported by start-up funds from the School of Life Sciences, Fujian Agriculture and Forestry University (Grant #: 114-712018008 to RK) and the FAFU-UCR Joint Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University (Grant #: 102-118990010 to RK). This work was also supported by the Chinese NSFC fund (Grant #: 31970809 to RK). This work was also supported by a grant-in-aid(22K21366 to R.D.K.) from the Japanese Society for the Promotion of Science (JSPS).