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Previous Projects: Evolution of Sotmatal Funcation

This IRCSET funded research investigated changes in the function of land plant stomata over evolutionary time. Stomata control two of the most important physiological processes of vascular plants: uptake of carbon dioxide (CO2) for photosynthesis, and loss of water via transpiration. Stomatal control can also directly influence regional and global climate via feedbacks on the hydrological and carbon cycles. 

The project undertaken by Caroline Elliott entailed examining the stomatal complexes of many extant plants at species level. Sample plants were chosen from lycophytes, ferns, cycads, conifers, and angiosperms, spanning evolutionary histories of over 420 million years, and a wide range of ecological habitats.  Key morphological traits were mapped onto consensus molecular and morphological plant phylogenies to record changes over evolutionary time. The traits are: cellular (guard cell chloroplast number); functional (speed of opening and closing of stomata); anatomical (guard cell lignification); and developmental (stomatal density response to atmospheric CO2). Cryoscanning electron microscopy, epifluorescence and confocal microscopy will all be employed to collect data. 

The chloroplast-mutant plant Arabidopsis thaliana gigantea immutans were grown and tested to examine the role of guard cell chloroplasts in stomatal function. Preliminary studies at UCD have indicated that chloroplast number in guard cells is higher in basal plants than in derived plants; this research will confirm if this is accurate, and if chloroplast number affects function.

This research addressed the following questions:

  • Has there been a shift from a developmental response (loss/gain stomata) to a functional response (rapid, fine-tuned stomatal control) to changing atmospheric conditions?
  • What is the effect of chloroplast number on stomatal function?
The results of this innovative study, which combines cellular and evolutionary biology with ecology, will be vital in predicting future physiological and biodiversity responses of vegetation to rising atmospheric CO2 levels.

 

 



UCD Plant Palaeoecology and Palaeobiology Group Updated: July 2013
Professor J.C. McElwain