The Scarlet Ibis: Investigation Of Brother’s Guilt In William Armstrong’s Death
On the stems and leaves, land plants are covered with a waxy layer that prevents loss of water while also interfering with gas exchange. To deal with the problem, plants evolved stomata in their epidermis. The stoma is made up of two cells, guard cells and the pore-closing cells. These pores remove water and absorb CO2 in order to perform photosynthesis. Stomata movement and density are controlled by various hormones. In Arabidopsis Thaliana, the formation of stomata involves both asymmetric and symmetric divisions in a lineage of epidermal cells (Daszkowska and Le, 2009; Le et.al., 2014).
The one-celled rule states that stomata are separated by one cell at least. This process has been implicated by a number of signaling components (Table1) (Rychel, Serna, and Shimada, 2010). These transcription factors include the small secreted peptides; subtilisin, transmembrane kinase, a receptor-like family of proteins and a subfamily of receptors-like kinases. (Lai et al., 2005; Ohashi-Ito and Bergmann, 2006; MacAlister et al., 2007; Pillitteri et al., 2007; Wang et al., 2007).
In the absence of some of these components, stomatal numbers increase and patterns of epidermal cell divisions are lost. This leads to a breakdown in the one-cell rule and adjacent stomata. If stomata grow adjacently, it is thought that they will not be able to function effectively. The opposite is also true: Overexpression or gain of functionality in certain components results in a reduction of stomatal formation, indicating the presence of signaling molecules that inhibit the entry to the stomatal phenotype. The identification of several mutants that showed patterning revealed a core of signaling molecules, including a proteinase and a leucine repeat receptor-like kinase.
The stomatal density in young leaves can vary depending on the environment, but controls for this development are not well understood. In recent years, molecular methods have been employed to identify the genes responsible for stomatal regulation in Arabidopsis. Mitogen-activated Protein Kinase (MAPK), a cell cascade, is activated once the extracellular signaling receptors are detected (Shimada; al., 2011,). This review summarizes current research work on hormonal regulation, crosstalk and stomatal event development.
