Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Plant Cell Physiol. 2011 Jan;52(1):59-69. doi: 10.1093/pcp/pcq138. Epub 2010 Sep 8.
Molecular genetics has been successful in identifying leaf- size regulators such as transcription factors, phytohormones, and signal molecules. Among them, a ROTUNDIFOLIA4-LIKE/DEVIL (RTFL/DVL) family of Arabidopsis, genes encoding peptides with no secretion-signal sequence, is unique in that their overexpressors have a reduced number of leaf cells specifically along the proximodistal axis. However, because the RTFL/DVL lack any obvious homology with functionally identified domains, and because of genetic redundancy among RTFL/DVL, their molecular and developmental roles are unclear. In this study we focused on one member in the family, ROTUNDIFOLIA4 (ROT4), and identified the core functional region within it and we found no proteolytic processing in planta. Developmental analysis of leaf primordia revealed that ROT4 overexpression reduces the meristematic zone size within the leaf blade. Moreover, induced local overexpression demonstrated that ROT4 acts as a regulator of the leaf shape via a change in positional cue along the longitudinal axis. Similarly, ROT4 overexpression results in a protrusion of the main inflorescence stem, again indicating a change in positional cue along the longitudinal axis. These results suggest that ROT4 affects the positional cue and cell proliferation along the body axis.
分子遗传学已经成功地鉴定出叶片大小的调节剂，如转录因子、植物激素和信号分子。在这些调节剂中，拟南芥的 ROTUNDIFOLIA4-LIKE/DEVIL（RTFL/DVL）家族的基因编码没有分泌信号序列的肽，其特点是过表达的基因在沿近-远轴的特定位置叶片细胞数量减少。然而，由于 RTFL/DVL 与功能已确定的结构域没有明显的同源性，并且由于 RTFL/DVL 之间存在遗传冗余，它们的分子和发育作用尚不清楚。在本研究中，我们专注于该家族的一个成员 ROTUNDIFOLIA4（ROT4），并确定了其核心功能区域，我们发现植物体内没有蛋白水解加工。叶片原基的发育分析表明，ROT4 过表达会减小叶片内分生组织区的大小。此外，诱导局部过表达表明 ROT4 通过改变沿长轴的位置线索来调节叶片形状。同样，ROT4 过表达导致主花序茎的突起，再次表明沿长轴的位置线索发生变化。这些结果表明 ROT4 影响沿体轴的位置线索和细胞增殖。
