Domain-specific expression of meristematic genes is defined by the LITTLE ZIPPER protein DTM in tomato.

Shoot meristems, which harbor a small population of stem cells, are responsible for generating new above-ground organs in plants. The proliferation and differentiation of these stem cells is regulated by a genetic pathway involving two key meristematic genes: CLAVATA3 ( CLV3 ) and WUSCHEL ( WUS ). However, it is not well understood how CLV3 and WUS expression domains in the shoot meristems are specified and maintained during post-embryogenic development. Here, we show that a tomato mutant with fasciated stems, flowers and fruits, due to impaired stem cell activity, is defective in a LITTLE ZIPPER gene denoted as DEFECTIVE TOMATO MERISTEM ( DTM ). DTM forms a negative feedback loop with class III homeodomain-leucine zipper (HD-ZIP III) transcription factors to confine CLV3 and WUS expression to specific domains of the shoot meristems. Our findings reveal a new layer of complexity in the regulation of plant stem cell homeostasis.
Competing Interests: The authors declare no competing interests.