植物ホルモンによる維管束幹細胞維持機構

抄録

Vascular system is essential for transporting water and nutrients throughout the plant body. During secondary growth, vascular stem cells located in the cambium undergo cell proliferation to give rise to xylem and phloem cells. For ensuring the permanent secondary growth, robust regulation of vascular stem cell maintenance is required. A peptide hormone tracheary element differentiation inhibitory factor (TDIF) and its receptor TDIF RECEPTOR (TDR) play central roles in controlling vascular stem cell maitenance. Further studies have uncovered the downstream cascade of the TDIF-TDR signaling. Based on these findings, Vascular cell Induction culture System Using Arabidopsis Leaves (VISUAL) was developed for molecular genetic studies of vascular cell differentiation. By utilizing VISUAL system, it is found that TDIF competes with a plant hormone brassinosteroid to regulate xylem cell differentiation by controlling their common downstream transcription factor BRI1-EMS-SUPPRESSOR (BES1). Moreover, molecular studies reveal the competitive relationship among BES family members in the regulation of vascular cell differentiation, suggesting the existence of signaling cross-talks at various signaling processes. Here I summarize the importance of cross-talk among various plant hormones including TDIF in the robust regulation of vascular stem cell maintenance.