Expanding the Regulatory Network for Meristem Size in Plants

The remarkable plasticity of post-embryonic plant development is due to groups of stem-cell-containing structures called meristems. In the shoot, meristems continuously produce organs such as leaves, flowers, and stems. Nearly two decades ago the WUSCHEL/CLAVATA (WUS/CLV) negative feedback loop was established as being essential for regulating the size of shoot meristems by maintaining a delicate balance between stem cell proliferation and cell recruitment for the differentiation of lateral primordia. Recent research in various model species (Arabidopsis, tomato, maize, and rice) has led to discoveries of additional components that further refine and improve the current model of meristem regulation, adding new complexity to a vital network for plant growth and productivity.

TrendsRecent studies have uncovered the influence of post-translational regulation in controlling the movement of WUS from the OC to the CZ, and the trafficking of CLV1 from the plasma membrane to endosomal compartments, as well as the enzymes responsible for the arabinosylation of CLE peptides.The regulation of meristem size takes place by a conserved mechanistic framework among various plant species. However, the functions of orthologous members in this regulatory pathway differ between species.Recent studies have uncovered direct connections between plant hormones and the WUS/CLV pathway, and these help in understanding how environmental changes influence meristems.New genes and pathways discovered in various plant species have significantly improved our understanding of meristem size regulation. This highlights the importance of research in different species to dissect complex developmental pathways, and paves the way to modify the WUS/CLV pathway for enhanced crop productivity.