DELLA genes restrict inflorescence meristem function independently of plant height

Gibberellins (GA) have a role in cell proliferation in the shoot apical meristem (SAM). GA binds to the receptor GID1, leading to DELLA protein degradation, thus promoting stem growth. In absence of GA, DELLAs inhibit growth. In this paper, Serrano-Mislata et al. explore how DELLAs, mainly GAI and RGA, control stem growth. Their results show that DELLAs have an important role in limiting inflorescence meristem size by affecting cell proliferation partially through the regulation of KARP2 expression, a cell cycle regulator. This function on meristem size determination is uncoupled from subsequent regulation of stem elongation. Furthermore, the effect of DELLAs on increasing meristem size is correlated with development of fewer floral buds. As this role was found to be conserved in barley, it sheds light on the many roles these proteins have on development and provides insights towards improving yield potential in many species of interest for humankind. (Summary by Gabriela Auge). Nature Plants 10.1038/s41477-017-0003-y