Supervisor
Dr Johannes Kromdijk
Brief summary
Stomatal pores control gaseous exchange of CO2 and water vapour between plant leaves and the surrounding atmosphere. Transgenic perturbation of stomatal opening is typically expected to lead to a decline in carbon gain, however in many cases, mutant plants are observed to maintain photosynthetic rates at decreased stomatal opening, leading to enhanced water use efficiency. This project will study the mechanisms underpinning sustained carbon gain in plants with impaired stomatal opening and the implications for bioengineering strategies targeting plant water use efficiency (WUE) via altered stomatal regulation.
Importance of Research
All terrestrial plants suffer from the same contraption where in order to take up carbon, water must be lost to the atmosphere. As a result, insufficient water availability is a major limitation for plant growth both directly, but also indirectly due to its impact on carbon acquisition. Mechanistic definition of the relationship between carbon gain and water loss will improve our understanding of plant adaptation and acclimation potential to water limitation and may inspire water-conserving crop improvement strategies.
Project Summary
In the Kromdijk group we are interested in how plants achieve an effective balance between water loss and carbon gain, with particular focus on the regulation of stomatal movements in response to light. Our work has shown that perturbed stomatal opening can lead to increases in water use efficiency (Glowacka et al. 2018 Nature communications; Acevedo et al. 2022 Journal of Experimental Botany), yet curiously, CO2 assimilation rates are maintained in some of these lines. How plants maintain CO2 assimilation with decreased stomatal conductance and how and under which conditions this might affect crop performance is currently unclear. This project aims to address these questions by studying photosynthetic gene expression, gas exchange and productivity in transgenic lines with altered stomatal conductance under well-watered and water-limited conditions. The results will be instrumental in informing which stomatal engineering strategies have most potential to translate in enhanced crop performance under future climates with increasingly variable precipitation.
What will the successful applicant do?
The successful applicant will study adjustment of photosynthetic capacity in existing and new transgenic lines with altered stomatal movements to explain changes in water use efficiency. The project will assess protein abundance and photosynthetic gas exchange to probe photosynthetic capacity. Meanwhile, RNAseq analyses will be used to study the effects of transgenically decreased stomatal conductance on gene expression. Paired gas exchange observations and transcriptome profiles will be analysed under well-watered and water-limited conditions to look at phenotypic overlap or divergence between different transgenic strategies to decrease stomatal conductance in order to increase WUE.
References
Glowacka K, Kromdijk J, Katherine Kucera, Jiayang Xie, Cavanagh AP, Leonelli L, Leakey ADB, Ort DR, Niyogi KK, Long SP 2018. Photosystem II Subunit S overexpression increases the efficiency of water use in a field-grown crop. Nature communications 9 (1): 868. doi.org/10.1038/s41467-018-03231-x
Acevedo-Siaca LG, Glowacka K, Driever SM, Salesse-Smith CE, Lugassi N, Granot D, Long SP, Kromdijk J 2022. Guard-cell Targeted Overexpression of Arabidopsis Hexokinase 1 May Improve Water Use Efficiency in Field-Grown Tobacco Plants. Journal of Experimental Botany 73 (16): 5745-5757. doi.org/10.1093/jxb/erac218