Centre for Plant Success Webinar Series: Vanessa Tonet and Tom Fisher

Vanessa Tonet

What kills leaves: mechanisms and recovery

The last decades of climate warming are rapidly shaping our forests by causing canopy damage and tree mortality. However, the cause of leaf death in trees is unresolved and not explicitly linked to any physiological mechanism.

Tackling this question, we investigated the role of xylem failure in leaf death by comparing the timing of damage to the photosynthetic machinery with changes in plant hydration and cavitation during imposed water stress in a common Australian evergreen tree (Eucalyptus viminalis ). We found that the spread of cavitation into the distal part of the leaf vein system is the tipping agent determining tissue damage and leaf death.

At the same time, we also exposed saplings of the same species to cycles of drought and rewatering, seeking a link between the spread of xylem cavitation within the canopy and the degree of recovery post-drought. Leaves experiencing cavitation quickly desiccated and die but this did not translate to a rapid threshold in overall canopy damage. Rather, whole canopies showed a gradual decline in mean post-drought assimilation rates due to a significant variation in vulnerability of leaves.

Tom Fisher

Riccia, small plants, big genus

In the Bowman lab we’re known for our research on the liverwort, Marchantia polymorpha, and in collaboration with many others we’ve been somewhat successful in promoting Marchantia polymorpha as a useful genetic model. However, while Marchantia polymorpha is a good representative for liverworts, there is a broader diversity of liverworts out there in the world and a genus that beautifully demonstrates this diversity is Riccia. Riccia are tiny liverworts forming a genus with hundreds of species, many of which occur naturally within Australia, and thus we have been able to collect dozens of Riccia sp. and are currently cultivating them in our lab with the aim of systematically sequencing their genomes/transcriptomes. We believe that these data could have many potential applications in comparative and evolutionary genomics, such as sex chromosome evolution and adaptation to both aquatic and arid habitats. Although input from other Centre members would be much appreciated!

This event is open to Centre Members only. If you are a Centre Member who would like to attend, please contact admin@plantsuccess.org for the Zoom invitation.