Molecular Evolution of Grass Stomata

Evolutionary trajectories of land plants have led to structurally complex and functionally active stomata for terrestrial life. A likely scenario for the emergence of active stomatal control is ‘evolutionary capture’ of key stomatal development, membrane transport, and abscisic acid signaling proteins in the divergence from liverworts to mosses. The unique morphology, development, and molecular regulation of grass stomata enable their rapid environmental response. Evolution of the molecular mechanism behind stomatal development and membrane transport has clearly drawn on conserved and sophisticated signaling networks common to stomata of all vascular plants and some mosses. Understanding this evolutionary trend will inform predictive modeling and functional manipulation of plant productivity and water use at all scales, and will benefit future efforts towards food security and ecological diversity. Grasses began to diversify in the late Cretaceous Period and now dominate more than one third of global land area, including three-quarters of agricultural land. We hypothesize that their success is likely attributed to the evolution of highly responsive stomata capable of maximizing productivity in rapidly changing environments. Grass stomata harness the active turgor control mechanisms present in stomata of more ancient plant lineages, maximizing several morphological and developmental features to ensure rapid responses to environmental inputs. The evolutionary development of grass stomata appears to have been a gradual progression. Therefore, understanding the complex structures, developmental events, regulatory networks, and combinations of ion transporters necessary to drive rapid stomatal movement may inform future efforts towards breeding new crop varieties. Grasses began to diversify in the late Cretaceous Period and now dominate more than one third of global land area, including three-quarters of agricultural land. We hypothesize that their success is likely attributed to the evolution of highly responsive stomata capable of maximizing productivity in rapidly changing environments. Grass stomata harness the active turgor control mechanisms present in stomata of more ancient plant lineages, maximizing several morphological and developmental features to ensure rapid responses to environmental inputs. The evolutionary development of grass stomata appears to have been a gradual progression. Therefore, understanding the complex structures, developmental events, regulatory networks, and combinations of ion transporters necessary to drive rapid stomatal movement may inform future efforts towards breeding new crop varieties. stomatal opening and closure regulated by non-hydraulic mechanisms stimulated by light, CO2, and ABA. This is achieved via, for example, modulation of light and the ABA signaling pathway to drive membrane transport for solutes and water uptake or loss to achieve stomatal opening and closure, respectively. It requires metabolic energy. dimeric transcription factors found in almost all eukaryotes. In plants, SPCH, MUTE, and FAMA are positive regulators of three-step sequential stomatal development. The first asymmetric division of protodermal cells to initiate the stomatal lineage is controlled by SPCH, then MUTE is required for termination of meristemoid stem cell identity and the transition to guard mother-cell fate. The last stage of stomatal development is guard mother-cell symmetric differentiation into a guard cell pair regulated by FAMA. the theory of evolution by natural selection is that organisms change over time as a result of changes in heritable traits. In this context, evolutionary capture means that organisms gain or acquire particular heritable traits in response to the changing environment. a stomatal patterning rule for most dicot leaves, where two stomata are separated by at least one intervening nonstomatal epidermal cell. stomatal opening and closure achieved by non-metabolic processes, such as equilibration of guard cell water potential with external water potential. Relies heavily on hydraulic negative feedback whereby guard cells re-equilibrate with any change in water potential of the guard cell wall, which changes guard cell turgor and stomatal aperture in the same direction, and thereby counteracts the initial change. a proposed shuttle process of K+ and anions between subsidiary cells and guard cells for the speedy movement of stomata of grass species.