Tag Archives: A. Sampathkumar

Inside-out plants show researchers how cellulose forms

Strictly speaking this story of tricking cellulose into growing on the surface rather than the interior of a cell is not a nanotechnology topic but I imagine that the folks who research nanocellulose materials will find this work of great interest. An Oct. 8, 2015 news item on ScienceDaily describes the research,

Researchers have been able to watch the interior cells of a plant synthesize cellulose for the first time by tricking the cells into growing on the plant’s surface.

“The bulk of the world’s cellulose is produced within the thickened secondary cell walls of tissues hidden inside the plant body,” says University of British Columbia Botany PhD candidate Yoichiro Watanabe, lead author of the paper published this week in Science.

“So we’ve never been able to image the cells in high resolution as they produce this all-important biological material inside living plants.”

An Oct. 8, 2015 University of British Columbia (UBC) news release on EurekAlert, which originated the news item, explains the interest in cellulose,

Cellulose, the structural component of cell walls that enables plants to stay upright, is the most abundant biopolymer on earth. It’s a critical resource for pulp and paper, textiles, building materials, and renewable biofuels.

“In order to be structurally sound, plants have to lay down their secondary cell walls very quickly once the plant has stopped growing, like a layer of concrete with rebar,” says UBC botanist Lacey Samuels, one of the senior authors on the paper.

“Based on our study, it appears plant cells need both a high density of the enzymes that create cellulose, and their rapid movement across the cell surface, to make this happen so quickly.”

This work, the culmination of years of research by four UBC graduate students supervised by UBC Forestry researcher Shawn Mansfield and Samuels, was facilitated by a collaboration with the Nara Institute of Technology in Japan to create the special plant lines, and researchers at the Carnegie Institution for Science at Stanford University to conduct the live cell imaging.

“This is a major step forward in our understanding of how plants synthesize their walls, specifically cellulose,” says Mansfield. “It could have significant implications for the way plants are bred or selected for improved or altered cellulose ultrastructural traits – which could impact industries ranging from cellulose nanocrystals to toiletries to structural building products.”

The researchers used a modified line of Arabidopsis thaliana, a small flowering plant related to cabbage and mustard, to conduct the experiment. The resulting plants look exactly like their non-modified parents, until they are triggered to make secondary cell walls on their exterior.

One of the other partners in this research, Stanford University’s Carnegie Institution of Science published an Oct. 8, 2015 news release on EurekAlert focusing on other aspects of the research (Note: Some of this is repetitive),

Now scientists, including Carnegie’s David Ehrhardt and Heather Cartwright, have exploited a new way to watch the trafficking of the proteins that make cellulose in the formation cell walls in real time. They found that organization of this trafficking by structural proteins called microtubules, combined with the high density and rapid rate of these cellulose producing enzymes explains how thick and high strength secondary walls are built. This basic knowledge helps us understand plants can stand upright, which was essential for the move of plants from the sea to the land, and may useful for engineering plants with improved mechanical properties for to increase yields or to produce novel bio-materials. The research is published in Science.

The live-cell imaging was conducted at Carnegie with colleagues from the University of British Columbia (UBC) using customized high-end instrumentation. For the first time, it directly tracked cellulose production to observe how xylem cells, cells that transport water and some nutrients, make cellulose for their secondary cell walls. Strong walls are based on a high density of enzymes that catalyze the synthesis of cellulose (called cellulose synthase enzymes) and their rapid movement across the xylem cell surface.

Watching xylem cells lay down cellulose in real time has not been possible before, because the vascular tissues of plants are hidden inside the plant body. Lead author Yoichiro Watanabe of UBC applied a system developed by colleagues at the Nara Institute of Science and Technology to trick plants into making xylem cells on their surface. The researchers fluorescently tagged a cellulose synthase enzyme of the experimental plant Arabidopsis to track the activity using high-end microscopes.

“For me, one of the most exciting aspects of this study was being able to observe how the microtubule cytoskeleton was actively directing the synthesis of the new cell walls at the level of individual enzymes. We can guess how a complex cellular process works from static snapshots, which is what we usually have had to work from in biology, but you can’t really understand the process until you can see it in action. ” remarked Carnegie’s David Ehrhardt.

Here’s a link to and a citation for the paper,

Visualization of cellulose synthases in Arabidopsis secondary cell walls by Y. Watanabe, M. J. Meents, L. M. McDonnell, S. Barkwill, A. Sampathkumar, H. N. Cartwright, T. Demura, D. W. Ehrhardt, A.L. Samuels, & S. D. Mansfield. Science 9 October 2015: Vol. 350 no. 6257 pp. 198-203 DOI: 10.1126/science.aac7446

This paper is behind a paywall.

With all of this talk of visualization, it’s only right that the researchers have made an image from their work available,

 Caption: An image of artificially-produced cellulose in cells on the surface of a modified Arabidopsis thaliana plant. Credit: University of British Columbia.

Caption: An image of artificially-produced cellulose in cells on the surface of a modified Arabidopsis thaliana plant. Credit: University of British Columbia.