Roots grow deeper in the heat.
Scientists of MLU in a team with partners from IPB, Cologne and Switzerland have found out that not only the above-ground plant parts but also the roots react to elevated temperatures. According to the study, seedlings of Arabidopsis respond to moderate increases in soil temperature with enhanced growth of primary roots. They do this in order to reach deeper soil regions with better water saturation, the scientists from Halle assume. While the temperature-responsive cell elongation of the shoot has been well studied, little is known about the heat effect on the roots. In their study, the scientists show that the root system is also capable of sensing elevated temperatures and responding to this stressor - independently of signals from the shoot. This stress response is mediated by a yet unknown root thermosensor that uses auxin as a messenger to transmit the temperature signals. In the root, however, this growth process does not rely on cell elongation as in the shoot, but by increased cell division. Thus, the response to elevated temperature is similar in shoot and root, but is achieved by different processes, which in turn are both mediated and regulated by the phytohormone auxin.