Plant cell architecture: Growth toward a light source

Nov 07, 2013

Inside every plant cell, a cytoskeleton provides an interior scaffolding to direct construction of the cell's walls, and thus the growth of the organism as a whole. Environmental and hormonal signals that modulate cell growth cause reorganization of this scaffolding. New research led by Carnegie's David Ehrhardt provides surprising evidence as to how this reorganization process works, with important evidence as to how the direction of a light source influences a plant's growth pattern. It is published by Science Express.

The cytoskeleton undergirding each cell includes an array of tubule-shaped protein fibers called microtubules. By directing and development, this scaffold is crucial for supporting important plant functions such as photosynthesis, nutrient gathering, and reproduction.

The cytoskeleton does not appear to be remodeled by moving these microtubules around in the cell. Rather, it is altered by changes to the way these fiber arrays are assembled or disassembled. Ehrhardt's team—including lead author Jelmer Lindeboom, Masayoshi Nakamura, Ryan Gutierrez and Viktor Kirik, all from Carnegie—used advanced tools to watch the reorganization process of these arrays under different conditions.

These imaging data, combined with the results of genetic experiments, revealed a mechanism by which plants orient microtubule arrays. A protein called katanin drives this mechanism, which it achieves by redirecting microtubule growth in response to blue light. It does so by severing the microtubules where they intersect with each other, creating new ends that can regrow and themselves be severed, resulting in a rapid amplification of new microtubules lying in another, more desired, direction.

"Our genetic data, together with previous studies that tie microtubule organization to cell growth, indicate that this restructuring is required for the plant to bend toward a as it grows, a phenomenon called phototropism," Ehrhardt explained. "Our findings also have broader implications for the construction of cytoskeletons in other types of cells, including human cells, because katanin is conserved between animals and plants."

"This is exceptional work, which draws upon decades of pioneering discoveries made by Carnegie's Winslow Briggs on blue light perception. For the first time Ehrhhardt's group demonstrates how blue light drives changes in cytoskeleton organization, which underlies the architecture and mechanical properties of the cell walls. These properties are critical for the light-induced bending" says Wolf B. Frommer, Director of the department. He terms the study: "fantastic work, a milestone in the history of research."

Explore further: How calcium regulates mitochondrial carrier proteins

More information: "A Mechanism for Reorientation of Cortical Microtubule Arrays Driven by Microtubule Severing" Science Express, 2013.

Related Stories

Scientists watch cell-shape process for first time

Oct 10, 2010

Researchers at the Carnegie Institution for Science, with colleagues at the Nara Institute of Science and Technology, observed for the first time a fundamental process of cellular organization in living plant cells: the birth ...

Cell biology: new insights into the life of microtubules

Jul 02, 2012

Every second, around 25 million cell divisions take place in our bodies. This process is driven by microtubule filaments which continually grow and shrink. A new study shows how so-called motor proteins in the cytosol can ...

Advance in understanding cellulose synthesis

Jun 14, 2009

Cellulose is a fibrous molecule that makes up plant cell walls, gives plants shape and form and is a target of renewable, plant-based biofuels research. But how it forms, and thus how it can be modified to design energy-rich ...

Recommended for you

How calcium regulates mitochondrial carrier proteins

Nov 26, 2014

Mitochondrial carriers are a family of proteins that play the key role of transporting a chemically diverse range of molecules across the inner mitochondrial membrane. Mitochondrial aspartate/glutamate carriers are part of ...

Team conducts unprecedented analysis of microbial ecosystem

Nov 26, 2014

An international team of scientists from the Translational Genomics Research Institute (TGen) and The Luxembourg Centre for Systems Biomedicine (LCSB) have completed a first-of-its-kind microbial analysis of a biological ...

Students create microbe to weaken superbug

Nov 25, 2014

A team of undergraduate students from the University of Waterloo have designed a synthetic organism that may one day help doctors treat MRSA, an antibiotic-resistant superbug.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.