Anja Geitmann thinks that if a Guinness book of records
existed for plants, pollen would be a record holder. In
spite of its small size—barely a few microns—pollen
is quite a performer: it is the fastest growing plant cell,
the only one that carries another cell inside it, and one
of the few cells that can pass through tissue. The professor
in the Plant Biology Research Institute at Université
de Montréal explains that these amazing characteristics
are what enable pollen to reach the ovule deep inside the
flower where it lies concealed and carry out plant fertilization.
The young German-born biologist notes that, when pollen
lands on the pistil of a flower, it is already carrying
a cell that will produce the male gametes. However, it is
not mobile. But within just a few hours, to get to the ovule
it forms a pollen tube—sometimes measuring several
centimetres in length—through which the gametes migrate.
The tube extends to the base of the pistil and pierces the
embryonic sac that contains the ovule, where it releases
the gametes to ensure fertilization and create the seed.
In collaboration with researchers in the Physics Department,
Anja Geitmann studies and models the mechanics of pollen
tube development in order to discover “how the pollen
makes its way through the pistil tissue, and what signals
enable it to reach the ovule.” She is one of the first
researchers to investigate plant cells with the micro-indenter,
a high-precision device that she obtained through a grant
from the Canadian Foundation for Innovation. Only a few
of these have ever been built.
The micro-indenter can move a micro-needle one ten thousandth
of a millimetre at a time; the biologist can thus distort
the pollen tube while it is growing and measure its reaction.
This will give her valuable information on the viscosity
and elasticity of the pollen tube. “We still know
very little about the mechanics of plant cells,” she
notes. “While we can measure the hardness of materials
such as wood, it is difficult to do this with an individual
cell. This is why we are so interested in pollen, which
is not part of any tissue and can be cultivated in vitro.”
With her results, Anja Geitmann hopes to clarify some of
the mysteries of plant fertilization. The researcher believes
that her basic research could have applications in the near
future. “A cell capable of passing through complex
tissue, finding a target cell, and releasing its content
there may have interesting uses. This impressive biological
mechanism could have applications in medicine, for example,
where it might provide a way to release drugs in a precise
part of the human body, avoiding the unwanted side effects
of the drug. Pollen could thus serve as a model for nanotechnology
specialists who are trying to create microscopic systems
from atoms and molecules.”
Researcher: Anja Geitmann
Telephone: (514) 872-8492
Email: anja.geitmann@umontreal.ca
Funding: Canada Foundation for Innovation
