Structural and functional aspects of stomata

Abstract

Differential cell wall thickening in developing guard cells of Polypodium vulgare L. has been studied with particular reference to guard cell protoplast deformation and the eventual formation of the stomatal pore. Concomitant studies on the development of guard cell chloroplasts and their starch inclusions during ontogeny of the stomatal complex have provided data which have been incorporated into a model to account for the formation of the pore. Guard cell starch inclusions reach a maximum density per unit volume at the same time as the guard cell walls achieve maximum differential thickening. These events coincide with the development of the pore. It is suggested that, whilst pore formation is initiated enzymatically, the mechanical forces required to bring about the separation of the two guard cells are of an osmotic nature derived from starch hydrolysis. The development of the mesophyll in relation to the epidermis is examined in respect of the formation of substomatal chambers.

The EPIP Peptide of INFLORESCENCE DEFICIENT IN ABSCISSION Is Sufficient to Induce Abscission inArabidopsisthrough the Receptor-Like Kinases HAESA and HAESA-LIKE2

“…In plant species displaying such abscission, it can be hypothesized that an IDA or IDL ortholog induces the pedicel separation event. Sloughing (i.e., detachment of the rootcap from the remaining root), release of the seed body from the funiculus, and disruption of adhesion at the junction between two adjacent cells during the formation of stomata are also cell-cell separation processes (Stevens and Martin, 1978;Zhao and Sack, 1999;Roberts et al, 2002;del Campillo et al, 2004). During the maturation of continuous tubes of tracheary elements, the middle lamella between two neighboring tracheary elements is digested completely by cell wall-degrading enzymes (Fukuda, 2004).…”

COBL7 is required for stomatal formation via regulation of cellulose deposition in Arabidopsis

“…Consistently, fluorescent protein‐tagged COBL7/8 are concentrated in a region at the mid‐length of the ventral wall corresponding to the well‐documented lens‐shaped thickening area before the initiation of pore formation (Figs 3c, S3f). This thickening has been assumed to provide a structural basis for the mechanically induced separation of GCs to initiate the pore formation (Stevens & Martin, 1978; Rui et al ., 2019). Equally important is the restricted distribution yet abundant accumulation of COBL7/8 proteins in the cell walls surrounding the expanding pore (Figs 3c, S3f), implicating their function in tuning the mechanical properties of cell walls lining the developing pore.…”

“…Stomata formation is tightly regulated by a coordinated series of cell divisions and cell state transitions (Bergmann & Sack, 2007; Pillitteri & Torii, 2012; Torii, 2021). After the cytokinesis of the guard mother cell (GMC), the newly formed ventral walls of the two daughter guard cells (GC) are progressively modified, and eventually form a pore at the middle region (Stevens & Martin, 1978; Zhao & Sack, 1999; Nadeau & Sack, 2002). It has been assumed that the differentially thickened ventral wall is essential for stomatal morphology and function (Aylor et al ., 1973; Cooke et al ., 1976; Carter et al ., 2017; Chen et al ., 2021; Dauphin et al ., 2022).…”

Stomatal Opening: The Role of Cell-Wall Mechanical Anisotropy and Its Analytical Relations to the Bio-composite Characteristics

“…Over the years, vast experimental efforts have been invested in characterizing stomatal guard cell structural properties, including geometric parameters (Copeland, 1902 ; Meckel et al, 2007 ), material-level composition and micro-structural organization (Palevitz and Hepler, 1976 ; Zeiger and Hepler, 1976 ; Stevens, 1977 ; Mishkind et al, 1981 ; Jones et al, 2003 , 2005 ; Shtein et al, 2017 ). In addition, stomatal functionality, i.e., the effects of water pressure on stomatal opening characteristics such as the aperture and the pore opening, have also been extensively studied (Franks et al, 1998 , 2001 ; Franks, 2003 ; Franks and Farquhar, 2007 ).…”