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K-State Today

April 17, 2019

Rebecca Roston presents today's Biochemistry and Molecular Biophysics Seminar

Submitted by Biochemistry and Molecular Biophysics

Rebecca Roston, assistant professor of biochemistry at the University of Nebraska, Lincoln, is the featured speaker for Biochemistry and Molecular Biophysics Seminar on Wednesday, April 17. She will present "Cold tolerance sensing in plants may be a continuum rather than a step" at 4 p.m. 120 Ackert Hall.

Roston earned her doctorate in biochemistry and molecular biology from University of California, Davis in 2009 under Kentaro Inoue in plant sciences. Her research was on understanding mechanisms of protein targeting to the chloroplast by studying the effects of removing targeting information. Following her degree, she served five years as a postdoctoral researcher with Christoph Benning in biochemistry at Michigan State University, studying plant lipid trafficking between the endoplasmic reticulum and chloroplast, and freezing responses. She had the opportunity to begin her independent investigations with the University of Nebraska, Lincoln in 2014. Her current research is on the role of membrane dynamics affecting plant health using a combination of genetics, molecular biology, protein biochemistry and biophysical approaches. She focuses on membrane response to freezing stress and understanding molecular mechanisms of photosynthetic membrane biogenesis.

Internal cellular membranes must have their lipid composition remodeled for plants to survive low temperatures. One mechanism necessary for freezing tolerance of the chloroplast envelope membranes is well defined. An enzyme named "Sensitive to Freezing 2" (SFR2) changes monogalactolipid into oligogalactolipids at temperatures below freezing. Interestingly, SFR2 activity does not respond to initial cool temperatures, it only responds to barely tolerable freezing temperatures. Here, we show that SFR2 is post-translationally regulated by modifications and changes to cytosolic acidification. We show that freezing increases cytosolic acidification and that proton pumps at both the plasma and vacuolar membranes participate in maintaining the acidification during low temperatures. Finally, quantitative measurements of SFR2 activation in a large number of plant species with diverse phylogenetic backgrounds shows that SFR2 is likely responding to membrane damage in some, if not all species. We conclude that plant low temperature sensing and response is likely a continuum rather than a switch, and that internal cellular membranes have systems set up to respond to damage in a diverse set of abiotic stresses.

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