Institute of Biology II/Molecular Plant Physiology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany.
Ann Bot. 2013 Dec;112(9):1803-14. doi: 10.1093/aob/mct235. Epub 2013 Nov 7.
The Mob1 family includes a group of kinase regulators conserved throughout eukaryotes. In multicellular organisms, Mob1 is involved in cell proliferation and apoptosis, thus controlling appropriate cell number and organ size. These functions are also of great importance for plants, which employ co-ordinated growth processes to explore the surrounding environment and respond to changing external conditions. Therefore, this study set out to investigate the role of two Arabidopsis thaliana Mob1-like genes, namely Mob1A and Mob1B, in plant development.
A detailed spatio-temporal analysis of Mob1A and Mob1B gene expression was performed by means of bioinformatic tools, the generation of expression reporter lines and in situ hybridization of gene-specific probes. To explore the function of the two genes in plant development, knock-out and knock-down mutants were isolated and their phenotype quantitatively characterized.
Transcripts of the two genes were detected in specific sets of cells in all plant organs. Mob1A was upregulated by several stress conditions as well as by abscisic acid and salicylic acid. A knock-out mutation in Mob1B did not cause any visible defect in plant development, whereas suppression of Mob1A expression affected organ growth and reproduction. In the primary root, reduced levels of Mob1A expression brought about severe defects in tissue patterning of the stem cell niche and columella and led to a decrease in meristem size. Moreover, loss of Mob1A function resulted in a higher sensitivity of root growth to abscisic acid.
Taken together, the results indicate that arabidopsis Mob1A is involved in the co-ordination of tissue patterning and organ growth, similarly to its orthologues in other multicellular eukaryotes. In addition, Mob1A serves a plant-specific function by contributing to growth adjustments in response to stress conditions.
Mob1 家族包括一组在真核生物中保守的激酶调节剂。在多细胞生物中，Mob1 参与细胞增殖和凋亡，从而控制适当的细胞数量和器官大小。这些功能对于植物也非常重要，植物通过协调生长过程来探索周围环境并响应不断变化的外部条件。因此，本研究旨在研究拟南芥中两种类似 Mob1 的基因，即 Mob1A 和 Mob1B，在植物发育中的作用。
通过生物信息学工具、表达报告系的生成和基因特异性探针的原位杂交，对 Mob1A 和 Mob1B 基因表达的详细时空分析。为了探索这两个基因在植物发育中的功能，分离了敲除和敲低突变体，并对其表型进行了定量描述。
在所有植物器官的特定细胞中都检测到了这两个基因的转录本。Mob1A 被多种胁迫条件以及脱落酸和水杨酸上调。Mob1B 的敲除突变在植物发育中没有引起任何可见的缺陷，而 Mob1A 表达的抑制则影响了器官的生长和繁殖。在主根中，Mob1A 表达水平降低导致干细胞龛和中柱组织模式严重缺陷，并导致分生组织大小减小。此外，Mob1A 功能的丧失导致根生长对脱落酸的敏感性增加。
总之，结果表明，拟南芥 Mob1A 参与组织模式和器官生长的协调，类似于其他多细胞真核生物中的同源物。此外，Mob1A 通过促进对胁迫条件的生长调整，发挥植物特有的功能。
