SOMBRERO, BEARSKIN1, and BEARSKIN2 Regulate Root Cap Maturation in Arabidopsis
SOMBRERO, BEARSKIN1, and BEARSKIN2 Regulate Root Cap Maturation in Arabidopsis
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DOI：
10.1105/tpc.109.072272
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发表时间：
2010-03-01
期刊：
影响因子：
11.6
通讯作者：
Scheres, Ben
中科院分区：
文献类型：
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作者：
Bennett, Tom;van den Toorn, Albert;Scheres, Ben
根冠在根的生长中起着核心作用，决定了根的生长轨迹，并促进了对土壤的渗透。根冠细胞具有特殊的功能和形态，边缘细胞通过特定的细胞壁修饰释放到根际。在这里，我们证明了根冠细胞的成熟是由三个基因冗余地调控的，它们是IIB类NAC转录因子家族成员Sombrero(SMB)、BEARSKIN1(BRN1)和Brn2，以及调节特定细胞类型的次生细胞壁合成的维管NAC结构域(VND)和NAC次生壁增厚促进因子(NST)基因。SMB-3突变体中的侧帽细胞继续分裂，无法从根中分离，其表型独立于SMB-3中FEZ的上调。在brn1-1brn2-1双突变体中，小柱细胞不能分离，而在三重突变体中，小柱细胞不能在帽子的所有部分成熟。这种复杂的遗传冗余涉及表达、蛋白质活性和靶标特异性的差异。这三个基因的过表达表型都与VND/NST基因非常相似，这表明该家族的成员在功能上基本相同。我们的结果表明，IIB类NAC蛋白在经历了强烈的细胞壁修饰的终末分化的细胞中调节细胞成熟。
The root cap has a central role in root growth, determining the growth trajectory and facilitating penetration into the soil. Root cap cells have specialized functions and morphologies, and border cells are released into the rhizosphere by specific cell wall modifications. Here, we demonstrate that the cellular maturation of root cap is redundantly regulated by three genes, SOMBRERO (SMB), BEARSKIN1 (BRN1), and BRN2, which are members of the Class IIB NAC transcription factor family, together with the VASCULAR NAC DOMAIN (VND) and NAC SECONDARY WALL THICKENING PROMOTING FACTOR (NST) genes that regulate secondary cell wall synthesis in specialized cell types. Lateral cap cells in smb-3 mutants continue to divide and fail to detach from the root, phenotypes that are independent of FEZ upregulation in smb-3. In brn1-1 brn2-1 double mutants, columella cells fail to detach, while in triple mutants, cells fail to mature in all parts of the cap. This complex genetic redundancy involves differences in expression, protein activity, and target specificity. All three genes have very similar overexpression phenotypes to the VND/NST genes, indicating that members of this family are largely functionally equivalent. Our results suggest that Class IIB NAC proteins regulate cell maturation in cells that undergo terminal differentiation with strong cell wall modifications.