A Novel Stomatal Mutant Implicates Clathrin Mediated Endocytosis as a Factor in Arabidopsis Carbon Dioxide Signalling

  • Alex Lamb

Student thesis: Master's ThesisMaster of Science (MSc)

Abstract

Screening of a mutant population of Arabidopsis thaliana identified a mutant, EO2, that was insensitive to elevated atmospheric Carbon dioxide and further study found that the mutant had a wild type response to Abscisic Acid. These results indicated that the mutant was impaired in CO2 perception upstream of the point of convergence with ABA signalling pathways at OST1/SnRK2. DRP1E was identified as the causative gene of the EO2 mutant stomatal phenotype and corresponding phenotypes were found in 2 independent drp1e lines. EO2 and drp1e mutants were found to have decreased transpiration rate, but increased carbon assimilation rate and water use efficiency compared to Col-0.

Based on an assessment of the collected results against the relevant literature, the role of DRP1E in clathrin mediated endocytosis (CME) was selected for further research in stomatal CO2 responses. Inhibition of CME was found to strongly inhibit stomatal responses to elevated CO2 but had only a moderate effect on responses to ABA. Confocal vesicle assays found that EO2 exhibited similar vesicle formation rates to Col-0 in response to ABA and CO2, indicating that rates of endocytosis were not the source of the CO2 insensitivity displayed by EO2 and in CME-inhibited Col-0. These results imply that targeted endocytosis of specific carbon dioxide signalling proteins at the cell membrane may act to regulate stomatal closure in response to elevated CO2.
Date of Award25 Jun 2019
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorAlistair M Hetherington (Supervisor) & Keith J Edwards (Supervisor)

Keywords

  • Arabidopsis
  • Guard Cell
  • Stomata
  • Carbon Dioxide
  • Clathrin
  • Endocytosis

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