What can mechanistic models tell us about guard cells, photosynthesis, and water use efficiency?

Quantitative System Modeling Bridges the Gap between Macro‐ and Microscopic Stomatal Model

“…The stomatal pore open and close is driven by the guard cell turgor changes with the osmotic contents including K + , Cl − , and Mal. [10,11,18] The changes in osmotic contents are obvious in guard cells during stomatal open and close: in Vicia for example, the closed guard cell has 53-93 × 10 −3 m K + in cytosol and 38-92 × 10 −3 m in vacuole, but when stomatal fully opened, these values are raised to 150-247 × 10 −3 m in cytosol and 181-454 × 10 −3 m in vacuole. [10] The coordinate activities of various transporters and channels to facilitate these solutes across plasma membrane and tonoplast.…”

“…However, the lack of essential “macro‐micro” connections hinders the insightful understanding of stomatal regulation mechanisms at the molecular level and the broader applications in the study of agriculture, ecology, and environment. [ 15,18 ]…”

“…However, the lack of essential "macro-micro" connections hinders the insightful understanding of stomatal regulation mechanisms at the molecular level and the broader applications in the study of agriculture, ecology, and environment. [15,18] In the last half-century, a wealth of knowledge at the cellular and molecular level on guard cell transport, signaling, and homeostasis has been generated, [10,11,19,20] which provided more details about how stomata operate. Such information can be used as a "Bottom-up" approach to establishing a novel quantitative systems model that connects individual genes at the microscopic level and the macroscopic physiological traits of photosynthesis and transpiration in plants.…”

“…The system modeling approach has already yielded a series of important predictions to guide molecular physiological studies in stomatal biology. [10,18,[21][22][23] It also exhibits great potential in breeding practice, which represents a key step toward "Breeding by design" of improving plant carbon-water use efficiency. In the following text, we discuss the development of stomatal models, and emphasize the effort to establish a quantitative system model that will provide us with novel insights into the underlying mechanisms of stomatal behavior.…”

Leaf starch metabolism sets the phase of stomatal rhythm

“…However, neither bam1 nor amy3 bam1 had a discernible transpiration phenotype in our study, suggesting cell-autonomous starch breakdown is dispensable to maintain sugar homeostasis and endogenous rhythm in the guard cells of more mature plants. Overall, spatiotemporal uncoupling between sugar metabolism and stomatal movements may arise from different mechanisms, making it hard to predict the transpiration phenotype of a given mutant based on its starch turnover or sugar content in the absence of a quantitative, mechanistic model (Blatt et al, 2022).…”