Flavonoid scutellarin positively regulates root length through NUTCRACKER

Exploring approaches to regulate meristem is of special importance and broad interest. In this study, we found that the flavonoid scutellarin, which has a 6-hydroxyl and a 7-glucoside, increased root length through the transcription factor NUTCRACKER (NUC). This root lengthening disappeared in NUC-knockout and reappeared in NUC-rescue plants. Scutellarin induced NUC expression and promoted the division of cortex/endodermal initials. In contrast, naringenin, which has same chemical backbone but without 6-hydroxyl and with 7-hydroxyl group, showed the opposite or no effects. Our results demonstrate that scutellarin promotes root length through NUC-mediated regulatory pathways and reveal that flavonoids with and without the 6-hydroxyl and 7-glucoside have positive and negative effects on meristem size, respectively.