Auxin regulates shoot stem cells

Auxin and cytokinin play critical roles in determination of cell fate in the shoot apical meristem (SAM). Until now auxin’s role was thought to be confined to the peripheral zone (PZ), promoting cell differentiation and organogenesis, mediated by AR5/MP. However, studies using GC-MS have shown the presence of IAA in the central zone (CZ). MP also has been found to be present not only in the PZ but also in the CZ. In order to elucidate the possible function of MP in auxin signaling in stem cells, Luo and co-workers crossed the mp mutant with the stem cell overproliferating clv3. With this double mutant they were able to have enough stem cells to identify possible targets of MP. DRN was identified as a target and negatively regulated by MP. They also demonstrated that DRN positively regulates CLV3. The authors concluded that MP-DRN mediates negative auxin regulation of CLV3 to regulate the stem cell pool.  (Summary by Cecilia Vasquez-Robinet) Mol Plant 10.1016/j.molp.2018.04.006