Testing photosynthetic regulatory paradigms using natural variations and massive field measurements

Note different date and time than usual seminars.

Date

Friday 01 December 2017

Time

11:00 AEDT – Canberra, Armidale; 10:30 ACDT – Adelaide; 10:00 AEST – Brisbane

Venues

CSIRO: Black Mountain – Discovery Theatre; Adelaide Waite – B101-FG-SmallWICWest; Brisbane QBP – Level 3 South telepresence room (3.323); Armidale – B55-FG-R00-Small; Perth Floreat – B1b Boardroom; Werribee (Melbourne) – Peacock Room.

Speaker

Professor David M. Kramer, Biochemistry and Molecular Biology and the MSU-DOE Plant Research Lab, Michigan State University / PhotosynQ.org

Synopsis

Photosynthetic organisms must tightly regulate their (often competing) needs for efficient collection of solar energy with the avoidance of toxic side products that can be produced by the photosynthetic machinery when energy input and use is unbalanced. Our aim is to test the applicability, diversity and effectiveness of these proposed modes of regulation under real world conditions. To do this, we developed a series of phenotyping platforms that aim to bring the lab to the field (PhotosynQ.org) and the field to the lab (Dynamic Environmental Phenotype Imagers). For example, it was recently proposed that photosynthetic efficiency is limited by the slow rate of onset and decay of photoprotective nonphotochemical quenching (NPQ).  Combining results from over 1M PhotosynQ experiments and over 5M DEPI data sets led us to a similar conclusion but for very different reasons. We found that photosynthesis is often strongly limited by the effects of the thylakoid electric field (Dψ) that is generated during the initial events of photosynthesis, particularly under rapidly fluctuating light conditions, and results in a process that we call Field Recombination Induced Photodamage (FRIP), where large “spikes” in Dψ induce photosystem II recombination reactions that produce damaging singlet oxygen (¹O₂). Our results suggest that FRIP is likely a major producer of photodamage, and thus likely limits photosynthetic productivity in many organisms. We also show that FRIP is directly linked to the thylakoid proton motive force (pmf), and in particular the slow kinetics of partitioning pmf into its DpH and Dψ components that in turn are controlled by very slow ion movements. We then explore the possibilities and pitfalls of efforts to improve plant productivity by modifying this process. Finally, I will describe how community-based platforms, such as PhotosynQ.org can enable scientific data gathering and analyses to assess the limitations and modes of regulation of photosynthesis in different species and environments.

Bio

TBA

Prof. Kramer’s visit is jointly sponsored by ARC Centres of Excellence in Plant Energy Biology and Translational Photosynthesis.