Iron is essential for plant growth, but soils can become toxic with too much
or excess iron. In the last two decades, plant scientists have attempted to
uncover the genes responsible for iron tolerance. However, they remained
elusive until recently when scientists from the Salk Institute for
Biological Studies found a gene called GSNOR, a major genetic regulator of
iron tolerance.



Elevated soil iron levels cause direct cellular damages in plants such as
rice. Excess iron harms fats and proteins and decreases the ability of roots
to grow. However, some plants have inherent tolerance to high iron levels.
The scientists tested a number of Arabidopsis strains, to observe if there
was natural variation in iron resistance. Some of the plants showed
tolerance to iron toxicity, so the researchers used genome-wide association
studies (GWAS) to locate the responsible gene. Their analyses identified the
gene GSNOR as the key to enabling plants and roots to grow in iron-heavy
environments.

The researchers also found that iron tolerance is related to the activities
of nitric oxide, a gaseous molecule which plays a role in plant response to
stress. High levels of nitric oxide induced cellular stress and impaired the
plant roots' tolerance for elevated iron levels. The researchers observed
this occurred when plants did not have a functional GSNOR gene and concluded
that GSNOR likely plays a central role in nitric oxide metabolism and
regulates the plants' ability to respond to cellular stress and damage.



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