Genetic manipulation of stomatal density influences stomatal size, plant growth and tolerance to restricted water supply across a growth carbon dioxide gradient

Abstract

To investigate the impact of manipulating stomatal density, a collection of Arabidopsis epidermal patterning factor (EPF) mutants with an approximately 16-fold range of stomatal densities (approx. 20–325% of that of control plants) were grown at three atmospheric carbon dioxide (CO 2 ) concentrations (200, 450 and 1000 ppm), and 30 per cent or 70 per cent soil water content. A strong negative correlation between stomatal size ( S ) and stomatal density ( D ) was observed, suggesting that factors that control D also affect S . Under some but not all conditions, mutant plants exhibited abnormal stomatal density responses to CO 2 concentration, suggesting that the EPF signalling pathway may play a role in the environmental adjustment of D . In response to reduced water availability, maximal stomatal conductance was adjusted through reductions in S , rather than D . Plant size negatively correlated with D . For example, at 450 ppm CO 2 EPF2-overexpressing plants, with reduced D , had larger leaves and increased dry weight in comparison with controls. The growth of these plants was also less adversely affected by reduced water availability than plants with higher D , indicating that plants with low D may be well suited to growth under predicted future atmospheric CO 2 environments and/or water-scarce environments.

A morpho-physiological approach differentiates bread wheat cultivars of contrasting tolerance under cyclic water stress

“…3). An inverse correlation between size and density of stomata has been also noted by Doheny-Adams et al (2012) in Arabidopsis. In the same study, a less adverse effect of reduced water availability was observed on plants with lower stomatal density, which corresponds well with our results.…”

Stomatal Function across Temporal and Spatial Scales: Deep-Time Trends, Land-Atmosphere Coupling and Global Models

“…Changes in D appear to be inextricably linked to changes in S, and it is the combination of S and D that determines g c(max) and g w(max) . There is a consistent negative relationship between S and D at all scales, including leaves within a single species (Franks et al, 2009), across species in a population (Hetherington and Woodward, 2003;Russo et al, 2010), through the fossil record (Franks and Beerling, 2009b), and across mutants of a single species where D is induced to vary by genetic manipulation (Doheny-Adams et al, 2012;Dow et al, 2014;Franks et al, 2015). This negative logarithmic relationship (often represented as a negative linear log-log plot) fundamentally constrains the adaptation and evolution of stomata under forcing by any environmental variable affecting leaf gas exchange.…”

Stomatal Size, Speed, and Responsiveness Impact on Photosynthesis and Water Use Efficiency

“…As stomatal density has been correlated with g s (Franks and Beerling, 2009), the rationale behind manipulating stomata anatomical characteristics to increase or decrease stomatal density may be considered relatively straightforward, helped by studies that have illustrated that manipulation of a single gene can alter stomatal patterning (Doheny-Adams et al, 2012). However, the manipulation of stomatal functional responses is clearly more complicated.…”

“…It is noteworthy that the strong correlation between stomatal density and size was maintained within these plants: plants with lower stomatal densities also showed a greater mean stomatal size, whereas smaller stomata were found in leaves with greater stomatal densities. Interestingly, those plants with reduced density and larger stomata also showed reduced transpiration, greater growth rates, and a larger biomass (Doheny-Adams et al, 2012). The authors ascribed the improved growth rate to a combination of improved water status, higher metabolic temperatures, and lower metabolic costs associated with the development of guard cells.…”