Universität Tübingen, Zentrum für Molekularbiologie der Pflanzen (ZMBP) - Allgemeine Genetik, Auf der Morgenstelle 28, D-72076 Tübingen, Germany.
Mech Dev. 2013 Jan;130(1):54-60. doi: 10.1016/j.mod.2012.05.008. Epub 2012 Jun 5.
The functions of plant class B-heat shock factors (Hsfs) are not well understood. Hsfs belonging to this group differ from class A-Hsfs in structural features of the oligomerization domain and by the absence of a typical AHA motif for transcriptional activation. AtHsfB4 is expressed in different parts of the plants with highest levels in root tissue. Transgenic Arabidopsis plants overexpressing (OE) HsfB4 by CaMV-35S-promoter showed massively enhanced levels of Hsf mRNAs. The root surface of OE-plants was rough and cells became detached. Crossings with cell type specific root marker lines and confocal laser scanning microscopy provided clear evidence for a duplication of cells in the ground tissue and ectopic layers of lateral root cap (LRC) cells in HsfB4-OE plants. A duplication of endodermis cells occurs already during embryonic development, while the ectopic LRC cells are only detected during postembryonic growth. The mutant phenotypes of Hsf-OE plants are without precedence and indicate that class B-Hsfs may play an important role in root development.
植物 B 类热休克因子（Hsfs）的功能尚未得到很好的理解。该组中的 Hsfs 在寡聚化结构域的结构特征上与 A 类-Hsfs 不同，并且不存在用于转录激活的典型 AHA 基序。AtHsfB4 在植物的不同部位表达，在根组织中表达水平最高。通过 CaMV-35S-启动子过表达（OE）HsfB4 的拟南芥转基因植物显示 Hsf mRNAs 水平显著升高。OE-植物的根表面粗糙，细胞脱落。与细胞类型特异性根标记系的杂交和共焦激光扫描显微镜提供了明确的证据，表明 HsfB4-OE 植物中存在胚性组织和侧根帽（LRC）细胞异位层的细胞重复。内皮层细胞的重复发生在胚胎发育过程中，而异位 LRC 细胞仅在胚胎后生长期间检测到。Hsf-OE 植物的突变表型前所未有，表明 B 类 Hsfs 可能在根发育中发挥重要作用。
