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.
Read more about this research at the MLU website.