Loss of Function of SPATULA Partially Suppresses Root Growth and Meristem Organization Defects in GCN5 Mutants in Arabidopsis thaliana

GENERAL CONTROL NON-DEREPRESSIBLE 5 (GCN5) is a histone acetyltransferase that plays a central role in regulating plant development and responses to environmental stimuli. In root development, GCN5 promotes the maintenance of the stem cell niche and proliferation of transit-amplifying cells. SPATULA (SPT) is a basic helix-loop-helix (bHLH) transcription factor with established roles in gynoecium and carpel development, as well as broader functions in plant growth. In roots, SPT negatively regulates quiescent center size, root meristem size, and overall root growth, without substantially affecting root patterning or cell-type differentiation. To investigate a potential genetic interaction between SPT and GCN5 in root meristem development, we generated and characterized spt;gcn5 double mutants. Notably, loss of SPT substantially suppressed some developmental defects associated with gcn5 mutations, including abnormalities in root meristem size, meristem organization, and root growth. These data suggest that a complex genetic interaction between SPT and GCN5 regulates important aspects of root meristem growth and organization.