Global warming has affected not only plant biodiversity, but also altered
the way plants grow. A team of researchers at Martin Luther University
Halle-Wittenberg (MLU) joined forces with the Leibniz Institute for Plant
Biochemistry (IPB) to discover which molecular processes are involved in
plant growth at high temperatures. This could help breed plants that adapt
to global warming.

Professor Marcel Quint, an agricultural scientist at MLU, explains that the
correlation between temperature and plant growth at the macrolevel is
relatively well understood, but there are still many open questions at the
molecular level. Previous studies showed that the protein PIF4 directly
controls plant growth, but this protein is also dependent on temperature.
PIF4 is less active when it's cold, but at higher temperatures, PIF4
activates growth-promoting genes and the plant grows taller. Though this
information is known to scientists, it had been unclear how the plant knows
when to activate PIF4 and how much should be released.

This is precisely what the research group in Halle has now discovered. They
investigated the growth behavior of Arabidopsis seedlings which normally
form short stems at 20 degrees Celsius. In the lab, the scientists
identified plants with a gene defect which still only formed short stems at
28 degrees. Then they searched for possible reasons for this lack in growth
and discovered a hormone that activates the PIF4 gene at high temperatures,
thus producing the protein. This reaction did not occur in the mutated
plants. "We have now discovered the role of this special hormone in the
signalling pathway and have found a mechanism through which the growth
process is positively regulated at higher temperatures," Quint explains.

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