B‐ <scp>GATA</scp> factors are required for nitrogen‐responsive growth in <i>Physcomitrium patens</i> and <i>Arabidopsis thaliana</i>

We hypothesized that B-GATA family transcription factors have important roles in growth regulation in moss. We analyzed B-GATA family transcription factor mutants from Physcomitrium patens and Arabidopsis thaliana to assess growth, gene expression, and cytokinin-related processes under varying nitrogen conditions. We found that nitrogen-dependent growth and transcriptional regulation are strongly impaired in mutants from Physcomitrium and Arabidopsis. We detected altered cytokinin homeostasis or signaling in the mutants, linking hormonal imbalance to growth and transcription defects. We demonstrated a conserved, critical role of B-GATAs in plant nitrogen-responsive growth. Results suggest that B-GATAs influence nitrogen-regulated transcription downstream from cytokinin, supporting an ancient, evolutionarily conserved mechanism connecting nutrient signaling to growth. We provided experimental evidence for the long-speculated but as-yet not demonstrated role of GATA transcription factors in nitrogen-dependent growth in land plants.