Figure 8.

The regulatory network composed of DlXTH23.5/25 and its related transcription factors may be involved in the regulatory pathway of longan under heat stress via cell wall repair through the action of xyloglucan endotransglucosylase (XET), and increased XET activity inhibits somatic embryogenesis (SE). Left: Secretory pathway of the DlXTH23.5/25 proteins in cells. The DlXTH23.5/25 proteins were cotranslationally translocated into the endoplasmic reticulum and subsequently modified in the Golgi. They were transferred via a conventional secretory pathway to the plasma membrane and eventually to the cell wall. Right: A model in which transcription factor-mediated regulation of DlXTH23.5/25 enhances XET activity for participation in cell wall modification during early longan SE and the response to heat stress. Red and blue arrows represent upregulation and downregulation of XET activity, respectively. The yellow arrow represents the upregulation of TF and DlXTH23.5/25 expression during early longan SE and under heat stress. The dotted line represents possible regulatory mechanisms.