Reducing Stomatal Density by Expression of a Synthetic EPF Increases Leaf Intrinsic Water Use Efficiency and Reduces Plant Water Use in a C4 Crop

Ferguson, J.N., Schmuker, P., Dmitrieva, A., Quach, T., Zhang, T., Ge, Z., Nersesian, N., Sato, S.J., Clemente, T.E., Leakey, A.D.B. July 22, 2024. “Data for Reducing Stomatal Density by Expression of a Synthetic Epidermal Patterning Factor Increases Leaf Intrinsic Water Use Efficiency and Reduces Plant Water Use in a C₄ Crop.” University of Illinois Urbana-Champaign. DOI: 10.13012/B2IDB-4017279_V1.

Enhancing crop water use efficiency (WUE) is a key target trait for climatic resilience and expanding cultivation on marginal lands. Engineering lower stomatal density to reduce stomatal conductance (g_s) has improved WUE in multiple C₃ crop species. However, reducing g_s in C₃ species often reduces photosynthetic carbon gain. A different response is expected in C₄ plants because they possess specialized anatomy and biochemistry which concentrates CO₂ at the site of fixation. This modifies the photosynthesis (A_N) relationship with intracellular CO₂ concentration (c_i) so that photosynthesis is CO₂-saturated and reductions in g_s are unlikely to limit A_N. To test this hypothesis, genetic strategies were investigated to reduce stomatal density in the C₄ crop sorghum. Constitutive expression of a synthetic epidermal patterning factor (EPF) transgenic allele in sorghum, led to reduced stomatal densities, reduced g_s, reduced plant water use and avoidance of stress during a period of water deprivation. In addition, moderate reduction in stomatal density did not increase stomatal limitation to A_N. However, these positive outcomes were associated with negative pleiotropic effects on reproductive development and photosynthetic capacity. Avoiding pleiotropy by targeting expression of the transgene to specific tissues could provide a pathway to improved agronomic outcomes.

Illinois Data Bank – Optical tomography stomatal density, and phenotypic data