The impact of growth at elevated [CO2] on stomatal anatomy and behavior differs between wheat species and cultivars

Abstract

The ability of plants to respond to changes in the environment is crucial to their survival and reproductive success. The impact of increasing atmospheric CO2 concentrations (a[CO2]), mediated by behavioral and developmental responses of stomata, on crop performance remains a concern under all climate change scenarios, with potential impacts on future food security. To identify possible beneficial traits that could be exploited for future breeding, phenotypic variation in morphological traits including stomatal size and density, as well as physiological responses and critically, the effect of growth [CO2] on these traits, was assessed in six wheat relative accessions (including Aegilops tauschii, Triticum turgidum ssp. Dicoccoides, T. turgidum ssp. dicoccon) and five elite bread wheat T. aestivum cultivars. Exploiting a range of different species and ploidy, we identified key differences in photosynthetic capacity between elite hexaploid wheat and wheat relatives (WR). We also report differences in the speed of stomatal responses which were found to be faster in WR than elite cultivars, a trait that could be useful for enhanced photosynthetic carbon gain and water use efficiency. Furthermore, these traits do not all appear to be influenced by elevated [CO2] and determining the underlying genetics will be critical for future breeding programmes.

Stomatal patterning is differently regulated in adaxial and abaxial epidermis in Arabidopsis

“…In conclusion, stomatal patterning in Arabidopsis is at least partly differently controlled in the adaxial and abaxial epidermis. In wheat, adaxial stomata are responsible for the majority of leaf gas-exchange, they are more responsive to light than abaxial stomata, and adaxial stomatal density is higher and more responsive to growth at elevated CO 2 levels (Wall et al, 2022(Wall et al, , 2023. These recent works show that adaxial stomata are critical for gas-exchange in cereals and, given the relatively large stomatal ratios in Arabidopsis (Figure 3), can potentially account for a large proportion of gas-exchange also in herbs.…”