Alterations in hormonal signals spatially coordinate distinct responses to DNA double-strand breaks in Arabidopsis roots.

Plants have a high ability to cope with changing environments and grow continuously throughout life. However, the mechanisms by which plants strike a balance between stress response and organ growth remain elusive. Here, we found that DNA double-strand breaks enhance the accumulation of cytokinin hormones through the DNA damage signaling pathway in the Arabidopsis root tip. Our data showed that activation of cytokinin signaling suppresses the expression of some of the PIN-FORMED genes that encode efflux carriers of another hormone, auxin, thereby decreasing the auxin signals in the root tip and causing cell cycle arrest at G2 phase and stem cell death. Elevated cytokinin signaling also promotes an early transition from cell division to endoreplication in the basal part of the root apex. We propose that plant hormones spatially coordinate differential DNA damage responses, thereby maintaining genome integrity and minimizing cell death to ensure continuous root growth.