Scientists at the University of Florida Institute of Food and
Agricultural Sciences (UF/IFAS) are now one step closer to developing
plants with the ability to harness nitrogen-fixing bacteria.

Nitrogen is essential to plants, but plants can only absorb it in some
of its chemical forms. Some of these forms are naturally found in soils,
but not in quantities needed to reach adequate crop yields. Nitrogen is
plentiful in the air, but in a form that plants cannot use. Some
bacteria that live in the soil convert atmospheric nitrogen in a form
that plants can use in a process called nitrogen fixation. Some legumes
have evolved root nodules that attract and host these bacteria. These
nodules allow the plant to absorb the nitrogen the bacteria fix, and in
exchange, the bacteria get sugars from the plant.

To understand the process when legumes come in contact with
nitrogen-fixing microbes, the research team used a technique that causes
fluorescence in the presence of cytokinin. This allowed them to the
hormone's every move, and they found that cytokinin activity happens in
two stages. During the first stage, cytokinin is produced in the outer
layer of the root and moves inward. In the second stage, that inner part
of the root pushes outward like a balloon, forming the nodule.

The researchers also found that the second stage of cytokinin activity
is controlled by a genecalled IPT3. This was confirmed through the
fluorescence technique and by observing plants without the IPT3 gene. In
the plants missing the gene, nodule formation did not occur, which tells
the researchers that this gene plays a key role in the process.

UF/IFAS scientists take next steps toward crops that make their own
nitrogen - UF/IFAS News (ufl.edu)
[blogs.ifas.ufl.edu]