Researchers discover key mechanism that regulates shape and growth of plants

August 16, 2011

UBC researchers have discovered a key mechanism that -- much like a construction site foreperson -- controls the direction of plant growth as well as the physical properties of the biopolymers that plants produce.

The finding is a major clue in a 50-year-long quest to explain how coordinate the behaviour of millions of cells as they grow upward to compete for light, penetrate soil to obtain nutrients and water, and even open petals to flower.

"We've known for decades that structures in plants called microtubules act as scaffolding to define the direction of ," says Professor Geoffrey Wasteneys, a UBC botanist and Canada Research Chair in .

"These are tiny multipurpose cylinders that grow, shrink and self-organize to transport cargo, capture and position large structures such as chromosomes, and establish the shape of cells. But we haven't been able to determine how these tiny microtubules are organized into scaffolds in the first place."

An interdisciplinary team of plant and mathematicians led by Wasteneys discovered that the inherent geometry of the cell itself plays an important role in the self-organization of microtubules into parallel arrays that guide cell growth and division. They also identified that a protein called CLASP plays a key role as a foreperson, modulating the geometric constraints of the cell.

Their findings will be published in the August 16 issue of the journal Nature Communications.

The research team used a specialized microscope that collects 3D images of plant components genetically engineered to fluoresce when irradiated with specially filtered light. They observed a striking difference in the way microtubules were arranged in normal plants compared to those of a dwarf mutant that fails to produce CLASP.

"Paradoxically, the microtubules appeared to be better organized in the severely stunted mutant plants than they were in the non-mutant plants," says Chris Ambrose, the post-doctoral fellow in Wasteneys' lab whose observations led to the discovery. "By examining how microtubules behave at the sharp edges between adjacent cell faces, we noticed that in the mutant, microtubules would grow into the edges and then undergo catastrophic disassembly. In the non-mutant plants containing the CLASP protein, microtubules would easily bend through 90 degrees and continue growing on the adjacent cell face upon encountering an edge."

Ambrose and Wasteneys then joined forces with UBC mathematicians Eric Cytrynbaum and Jun Allard to run three-dimensional computer simulations to test the ideas that emerged from imaging the living plant cells.

The researchers found that the simulations, which typically take about a day to run on a super computer, closely recapitulated the microtubule patterns observed in living cells.

"Simulation after simulation showed us that microtubules would form parallel arrays in the same patterns seen in living cells," says Allard, now a post-doctoral researcher at the University of California, Davis. "We confirmed that the self-organization depends on the extrinsic cues from the cellular geometry, and that the presence of the CLASP protein along select edges modified the pattern dramatically."

The finding may also be relevant to the burgeoning interest in stem cell biology in the biomedical research field. "Microtubules and the CLASP protein are common to all cell types in plants animals, fungi and many unicellular organisms," says Wasteneys. "So what we find out about their behaviour in plant cells is relevant to understanding their function in cells types as diverse as neurons and disease-causing protozoans."

Explore further: Formation of cellulose fibers tracked for the first time

Related Stories

Formation of cellulose fibers tracked for the first time

April 20, 2006

Cellulose--a fibrous molecule found in all plants--is the most abundant biological material on Earth. It is also a favored target of renewable, plant-based biofuels research. Despite overwhelming interest, scientists know ...

One-dimensional Diffusion Accelerates Molecular Motors

May 12, 2006

Max Planck scientists have identified a new strategy which motor proteins use to move. The research was carried out by Prof. Jonathon Howard and Stefan Diez at the Max Planck Institute of Molecular Cell Biology and Genetics ...

Advance in understanding cellulose synthesis

June 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 ...

The plant cell's corset

September 2, 2009

We still have a lot to discover about the mechanism in plants that ensures cell growth in a specific direction. However it is clear that a structure of parallel protein tubes plays an important role. Simon Tindemans investigated ...

Scientists watch cell-shape process for first time

October 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 ...

Recommended for you

Orangutan females prefer dominant, cheek-padded males

September 1, 2015

Unlike most mammals, mature male orangutans exhibit different facial characteristics: some develop large "cheek pads" on their faces; other males do not. A team of researchers studied the difference in reproductive success ...

Plastic in 99 percent of seabirds by 2050

August 31, 2015

Researchers from CSIRO and Imperial College London have assessed how widespread the threat of plastic is for the world's seabirds, including albatrosses, shearwaters and penguins, and found the majority of seabird species ...

Researchers unveil DNA-guided 3-D printing of human tissue

August 31, 2015

A UCSF-led team has developed a technique to build tiny models of human tissues, called organoids, more precisely than ever before using a process that turns human cells into a biological equivalent of LEGO bricks. These ...

Study shows female frogs susceptible to 'decoy effect'

August 28, 2015

(Phys.org)—A pair of researchers has found that female túngaras, frogs that live in parts of Mexico and Central and South America, appear to be susceptible to the "decoy effect." In their paper published in the journal ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Ortzmet
not rated yet Aug 21, 2011
How much more of what determines the supramolecular structures and functions of living systems remains hidden in geometric inevitability?

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.