Stomatal development and orientation: a phylogenetic and ecophysiological perspective

Abstract

Background Oriented patterning of epidermal cells is achieved primarily by transverse protodermal cell divisions perpendicular to the organ axis, followed by axial cell elongation. In linear leaves with parallel venation, most stomata are regularly aligned with the veins. This longitudinal patterning operates under a strong developmental constraint and has demonstrable physiological benefits, especially in grasses. However, transversely oriented stomata characterise a few groups, both among living angiosperms and extinct Mesozoic seed plants. Scope This review examines comparative and developmental data on stomatal patterning in a broad phylogenetic context, focusing on the evolutionary and ecophysiological significance of guard-cell orientation. It draws from a diverse range of literature to explore the pivotal roles of the plant growth hormone auxin in establishing polarity and chemical gradients that enable cellular differentiation. Conclusions Transverse stomata evolved iteratively in a few seed-plant groups during the Mesozoic era, especially among parasitic or xerophytic taxa, such as the hemiparasitic mistletoe genus Viscum and the xerophytic shrub Casuarina, indicating a possible link with ecological factors such as the Cretaceous CO2 decline and changing water availability. The discovery of this feature in some extinct seed-plant taxa known only from fossils could represent a useful phylogenetic marker.

Parallel evolution of angiosperm‐like venation in Peltaspermales: a reinvestigation of Furcula

“…The absence of preferred orientation in stomatal apertures is a character that Furcula shares with various extinct seed plants, including medullosans, glossopterids, peltasperms, corystosperms, and Caytoniales (Barbacka & Bóka, 2000; Rudall et al ., 2013; Feng et al ., 2020; Unverfärth et al ., 2022; Xu et al ., 2023). The shift from longitudinal to transverse or oblique stomatal orientations appears to have arisen in multiple lineages during the course of seed plant evolution and was probably linked to localised variance in auxin levels at crucial stages of development during leaf expansion (Rudall, 2023).…”

Update on stomata development and action under abiotic stress

“…In dicotyledonous, it is also postulated that stomatal arrangement is associated with the structure of leaf venation, which is less organized, translating into a more chaotic pattern of stomatal arrangement ( Figure 1B ). One of the main principles of epidermal pattern formation in dicots is that there must be at least one-cell space between the stomata ( Hepworth et al., 2018 ; Conklin et al., 2019 ; Rudall, 2023 ).…”