Learning the language of the chloroplast: how chloroplasts can sense oxidative stress and regulate stomatal function
Date
Tuesday 7th June 2016
Time
12:30-13:30
Venue
CSIRO Black Mountain B1 Lecture Theatre
Speaker
Dr. Kai Xun Chan (PEB, ANU, Canberra, Australia).
Synopsis
Perturbations in chloroplastic processes such as photosynthesis by environmental stimuli are communicated to the nucleus to invoke acclimation responses; this process is termed retrograde signaling. During drought and high light stress, 3′-phosphoadenosine 5′-phosphate (PAP) functions as a chloroplast retrograde signal and it regulates nuclear expression of many stress-responsive genes. However, the sensors of chloroplast oxidative stress and switches for activating the PAP pathway have remained unidentified until now. The broader function(s) of PAP beyond regulating gene expression, such as in physiological responses to drought stress, are also unknown. Our new findings using protein biochemistry, crystallography and in vivo studies reveal a biochemical and structural mechanism by which oxidative stress in chloroplasts is perceived for activation of PAP retrograde signaling. We further examined the role of PAP in guard cells and discovered that PAP can function in abscisic acid (ABA)-mediated regulation of stomatal closure. Thus, chloroplasts can utilise messenger molecules such as PAP to exert control over cellular function and plant physiology. Possible applications of our findings to engineering drought tolerant plants will be discussed.
Speaker bio
Kai Xun Chan completed his PhD (December 2015) in Professor Barry Pogson’s laboratory at the ARC Centre of Excellence in Plant Energy Biology (CPEB), ANU, elucidating the biochemical and structural regulation of the PAP-mediated chloroplast stress signaling pathway. He is currently a CPEB Postdoctoral Fellow. Kai’s research interests include chloroplast-to-nucleus signaling, plant secondary sulfur metabolism, and how these two processes can be coordinated during abiotic stress. His work has been published in various high impact journals including Annual Review of Plant Biology, PNAS and Trends in Plant Science. Kai has received several awards and grants including a Young Scientist Award at the 9th International Conference on Plant Sulfur Metabolism (2014) and an ANU-UC Discovery Translational Fund (2016).
This is a public seminar.
No visitor pass is required for non-CSIRO attendees going to Lecture Theatre Building 1.