Mechanisms of Stomatal Development

Abstract

The main route for CO(2) and water vapor exchange between a plant and the environment is through small pores called stomata. The accessibility of stomata and predictable division series that characterize their development provides an excellent system to address fundamental questions in biology. Stomatal cell-state transition and specification are regulated by a suite of transcription factors controlled by positional signaling via peptide ligands and transmembrane receptors. Downstream effectors include several members of the core cell-cycle genes. Environmentally induced signals are integrated into this essential developmental program to modulate stomatal development or function in response to changes in the abiotic environment. In addition, the recent identification of premitotic polarly localized proteins from both Arabidopsis and maize has laid a foundation for the future understanding of intrinsic cell polarity in plants. This review highlights the mechanisms of stomatal development through characterization of genes controlling cell-fate specification, cell polarity, cell division, and cell-cell communication during stomatal development and discusses the genetic framework linking these molecular processes with the correct spacing, density, and differentiation of stomata.

Auxin transport and activity regulate stomatal patterning and development

“…Stomata are separated by at least one intervening cell 1,3 . To determine whether this spacing involves PIN protein-mediated auxin transport, loss-of-function mutants in each PIN gene were examined, but none showed any stomatal defects.…”

“…The larger sister cell of an unequal division, a stomatal lineage ground cell (SLGC), either differentiates into a generic epidermal cell or reacquires a stem cell fate and produces a 'satellite' M after unequal division. The M converts to a guard mother cell (GMC) that divides equally followed by a coordinated morphogenesis yielding the two guard cells (GCs) of the stoma [1][2][3] .…”

Arabidopsishomeodomain-leucine zipper IV proteins promote stomatal development and ectopically induce stomata beyond the epidermis

“…The shoot epidermis, which is derived from the L1 layer of the shoot apex, gives rise to specialized cell types -pavement cells, stomatal guard cells and trichomes -to optimize the balance between protection and gas exchange. The cuticulated pavement cells form a tightly sealed barrier that protects plants from desiccation, UV damage and pathogen entry, while the stomata act as valves for efficient gas exchange and transpiration (Dong and Bergmann, 2010;Javelle et al, 2011b;Pillitteri and Torii, 2012). Trichomes are appendages for herbivore protection, and, in some plants, accumulate and secrete defensive chemicals (Hülskamp, 2004;Serna and Martin, 2006).…”

“…In Arabidopsis, a subpopulation of protodermal cells adopts the identity of a meristemoid mother cell (MMC) and initiates an asymmetric entry division that creates a meristemoid, a transiently amplifying stomatal lineage cell. The meristemoid reiterates asymmetric amplifying divisions but eventually differentiates into a guard mother cell (GMC), which divides symmetrically to form paired guard cells (GCs) that constitute a stoma (Dong et al, 2010;Pillitteri et al, 2012). …”

Integrating cell biology, image analysis, and computational mechanical modeling to analyze the contributions of cellulose and xyloglucan to stomatal function

“…Stomatal dynamics are driven by changes in guard cell turgor, and are regulated via stomatal patterning 2 and the unique mechanical properties of guard cells and their walls. 3 However, despite the detection of certain wall components 4,5 and functional analyses of pectic arabinans 7,8 in guard cells, the question of how guard cell walls are constructed to be both sufficiently strong to withstand high turgor and flexible enough to allow repeated stomatal movements remains largely unexplored.…”