Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA.
Proc Natl Acad Sci U S A. 2012 Jul 17;109(29):11723-8. doi: 10.1073/pnas.1204566109. Epub 2012 Jun 11.
Plants exhibit various kinds of movements that have fascinated scientists and the public for centuries. Physiological studies in plants with the so-called motor organ or pulvinus suggest that cells at opposite sides of the pulvinus mediate leaf or leaflet movements by swelling and shrinking. How motor organ identity is determined is unknown. Using a genetic approach, we isolated a mutant designated elongated petiolule1 (elp1) from Medicago truncatula that fails to fold its leaflets in the dark due to loss of motor organs. Map-based cloning indicated that ELP1 encodes a putative plant-specific LOB domain transcription factor. RNA in situ analysis revealed that ELP1 is expressed in primordial cells that give rise to the motor organ. Ectopic expression of ELP1 resulted in dwarf plants with petioles and rachises reduced in length, and the epidermal cells gained characteristics of motor organ epidermal cells. By identifying ELP1 orthologs from other legume species, namely pea (Pisum sativum) and Lotus japonicus, we show that this motor organ identity is regulated by a conserved molecular mechanism.
植物表现出各种运动，这些运动让科学家和公众着迷了几个世纪。对具有所谓运动器官或叶枕的植物进行的生理学研究表明，叶枕相对两侧的细胞通过膨胀和收缩来介导叶片或小叶的运动。运动器官身份是如何确定的尚不清楚。我们使用遗传方法从小叶榕中分离出一个突变体，命名为伸长叶柄 1（elp1），由于运动器官的丧失，该突变体无法在黑暗中折叠其小叶。基于图谱的克隆表明，ELP1 编码一个假定的植物特异性 LOB 结构域转录因子。RNA 原位分析表明，ELP1 在产生运动器官的原基细胞中表达。ELP1 的异位表达导致植株矮小，叶柄和轴缩短，表皮细胞获得运动器官表皮细胞的特征。通过鉴定来自其他豆科植物物种的 ELP1 同源物，即豌豆（Pisum sativum）和百脉根（Lotus japonicus），我们表明这种运动器官身份受保守的分子机制调控。
