<P> Stomatal patterning is controlled by the interaction of many signal transduction components such as EPF (Epidermal Patterning Factor), ERL (ERecta Like) and YODA (a putative MAP kinase kinase kinase). Mutations in any one of the genes which encode these factors may alter the development of stomata in the epidermis . For example, a mutation in one gene causes more stomata that are clustered together, hence is called Too Many Mouths (TMM). Whereas, disruption of the SPCH (SPeecCHless) gene prevents stomatal development all together . Activation of stomatal production can occur by the activation of EPF1, which activates TMM / ERL, which together activate YODA . YODA inhibits SPCH, causing SPCH activity to decrease, allowing for asymmetrical cell division that initiates stomata formation . Stomatal development is also coordinated by the cellular peptide signal called stomagen, which signals the inhibition of the SPCH, resulting in increased number of stomata . </P> <P> Environmental and hormonal factors can affect stomatal development . Light increases stomatal development in plants; while, plants grown in the dark have a lower amount of stomata . Auxin represses stomatal development by affecting their development at the receptor level like the ERL and TMM receptors . However, a low concentration of auxin allows for equal division of a guard mother cell and increases the chance of producing guard cells . </P> <P> Different classifications of stoma types exist . One that is widely used is based on the types that Julien Joseph Vesque introduced in 1889, was further developed by Metcalfe and Chalk, and later complemented by other authors . It is based on the size, shape and arrangement of the subsidiary cells that surround the two guard cells . They distinguish for dicots: </P> <Ul> <Li> actinocytic (meaning star - celled) stomata have guard cells that are surrounded by at least five radiating cells forming a star - like circle . This is a rare type that can for instance be found in the Ebenaceae family . </Li> <Li> anisocytic (meaning unequal celled) stomata have guard cells between two larger subsidiary cells and one distinctly smaller one . This type of stomata can be found in more than thirty dichot families, including Brassicaceae, Solanaceae, and Crassulaceae . It is sometimes called cruciferous type . </Li> <Li> anomocytic (meaning irregular celled) stomata have guard cells that are surrounded by cells that have the same size, shape and arrangement as the rest of the epidermis cells . This type of stomata can be found in more than hundred dichot families such as Apocynaceae, Boraginaceae, Chenopodiaceae, and Cucurbitaceae . It is sometimes called ranunculaceous type . </Li> <Li> diacytic (meaning cross-celled) stomata have guard cells surrounded by two subsidiary cells, that each encircle one end of the opening and contact each other opposite to the middle of the opening . This type of stomata can be found in more than ten dichot families such as Caryophyllaceae and Acanthaceae . It is sometimes called caryophyllaceous type . </Li> <Li> hemiparacytic stomata are bordered by just one subsidiary cell that differs from the surrounding epidermis cells, its length parallel to the stoma opening . This type occurs for instance in the Molluginaceae and Aizoaceae . </Li> <Li> paracytic (meaning parallel celled) stomata have one or more subsidiary cells parallel to the opening between the guard cells . These subsidiary cells may reach beyond the guard cells or not . This type of stomata can be found in more than hundred dichot families such as Rubiaceae, Convolvulaceae and Fabaceae . It is sometimes called rubiaceous type . </Li> </Ul>

How is control of stomata utilized by different types of plants