The Arabidopsis thaliana Mob1A gene is required for organ growth and correct tissue patterning of the root tip
07.11.2013
Pinosa F, Begheldo M, Pasternak T, Zermiani M, Paponov IA, Dovzhenko A, Barcaccia G, Ruperti B, Palme K.
Ann Bot. 2013;112(9):1803-14.
† Background and Aims 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,whichemploy co-ordinated growth processes to explore the surrounding environment and respondto changing external conditions. Therefore, this studysetout to investigate the role of two Arabidopsis thalianaMob1-like genes, namelyMob1A andMob1B, in plant development.
† Methods 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.
† Key Results Transcripts of the two geneswere detected in specific sets of cells in all plant organs. Mob1Awas upregulated by several stress conditions aswell as by abscisic acid and salicylic acid.Aknock-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.
†Conclusions 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 multicellulareukaryotes. In addition,Mob1Aserves a plant-specific function by contributing to growth adjustments in response to stress conditions.
