Dr. Joanne Bentley

Joanne Bentley

Position: Postdoctoral research fellow at the University of Cape Town

The research interests of Dr. Bentley are in exploring the evolutionary adaptations and responses of organisms, particularly plants, to their environment, whether at the molecular, physiological, or morphological level. In her MSc, she used phylogenetics and statistical modelling to estimate the evolutionary history of a large lineage of daisies across Africa and the Mediterranean. During her PhD, she utilized chemical ecology and metabolomics to unravel the metabolic response of a southern African desiccation-tolerant plant, collected from across a rainfall gradient, to its environment. She used her findings to assess whether plants occurring in more arid regions possessed chemical adaptations in comparison to those in more mesic regions. In her current work she explores aspects of phenotypic plasticity and evaluates the potential for evolution to rescue species from climate change. The main task during her RESIST secondment was to contrast the metabolomes of two closely-related desiccation-tolerant species, namely Xerophyta elegans and Xerophyta humilis, during dehydration in order to characterize their metabolic responses. The former species is homoiochlorophyllous, which means that it retains most of its photosynthetic apparatus and chlorophyll during dehydration, whereas the latter species is poikilochlorophyllous, which means it dismantles the photosynthetic machinery during dehydration. Thus, these two species are subject to variations in photodamage from the photosynthetic machinery during dehydration, particularly temporally, and thus their metabolic responses to the process are likely to differ. The obtained results demonstrate that X. elegans and X. humilis indeed exhibit distinct differences in their primary and secondary metabolite profiles, as well as in their hormone contents. The poikilochlorophyllous X. humilis favours an earlier response to desiccation, with most changes detected between 50% and 30% relative water content, whereas the homoiochlorophyllous X. elegans exhibits the most drastic metabolic changes at very low water contents (<30%). This was the first study to contrast the metabolomes of a closely-related poikilochlorophyllous and homoiochlorophyllous plant.