Stomata are microscopic pores in the epidermis of plant leaves which allow gas and water vapour exchange between internal plant tissues and the atmosphere. Environmental signals influence both stomatal pore aperture and the number of stomata developed to ensure plants possess the necessary means to effectively manage photosynthesis, water status and leaf cooling. High temperature and ultraviolet-B (UV-B) light can occur simultaneously and have significant effects on stomatal aperture and development, but their combined effects on stomata have not been explored. Epidermal peels and whole leaves of Arabidopsis thaliana were used to elucidate the combined effect of these two major environmental signals on stomatal aperture and development and investigate potential signalling pathways. UV-B antagonised the high temperature-induced stomatal opening in wild-type (WT) Arabidopsis plants. No UV-B-induced stomatal closure was observed in mutants deficient in the UV-B photoreceptor, ULTRAVIOLET B RESISTANCE LOCUS 8 (UVR8). Nitric oxide (NO) levels increased in response to UV-B and correlated with stomatal closure, in WT plants, but not in uvr8 mutants. These results suggest that UV-B antagonises high temperature-induced stomatal opening in a UVR8- and NO-dependent manner. High temperature decreased stomatal density in both WT and uvr8 mutant plants. UV-B induced a significant reduction in stomatal density in the uvr8 mutant but not in WT controls at both temperatures tested. These results may suggest that stomatal density is increased by a UVR8-dependent mechanism in response to UV-B but decreased in a UVR8-independent manner. Limited high temperature and UV-B-mediated effects on stomatal index were observed in this study.
|Date of Award||23 Jan 2019|
- The University of Bristol
|Supervisor||Antony Dodd (Supervisor) & Keara A Franklin (Supervisor)|