Discovery of a -regulatory element involved in dynamic regulation of synergid-specific .

is a key regulator of the genetic network behind pollen tube attraction toward the female gametophyte. 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 achieves this specific expression pattern. In the current study, we have determined that a normal SC-specific expression of is dependent on a 16-bp-long -regulatory element, CATTTACACATTAAAA, freshly named as the " " (). An 84 bp fragment harboring 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 homologous genes in the Brassicaceae (s). Significance of such family-wide element conservation in exclusive SC-specific expression was confirmed by the Arabidopsis-like activation feature of derived and absence of such feature of derived from a non-Brassicaceae member . Additionally, the yeast-one-hybrid assay showed that the can be recognized by ANTHOCYANINLESS2 (ANL2) and DAP-seq data further suggested for additional three ANL2 homologs targeting the similar element. Overall, our study has concluded that plays a crucial role in driving exclusively SC-specific expression of and strongly suggests for the involvement of ANL2 and its homologs in its dynamic regulation . Future study on the transcription factors is expected to shed more light on the mechanism behind the process.