A PHABULOSA-Controlled Genetic Pathway Regulates Ground Tissue Patterning in the Arabidopsis Root
Gaia Bertolotti, Simon Josef Unterholzner, Daria Scintu, Elena Salvi, Noemi Svolacchia, Riccardo Di Mambro, Veronica Ruta, Francisco Linhares Scaglia, Paola Vittorioso, Sabrina Sabatini, Paolo Costantino, Raffaele Dello Ioio
Abstract
However, little is known on how GAs are regulated during GT maturation. Here, we show that the HOMEODOMAIN LEUCINE ZIPPER III (HD-ZIPIII) transcription factor PHABULOSA (PHB) is a master regulator of MC formation, controlling the accumulation of CYCD6;1 in the endodermis in a cell non-autonomous manner. We show that PHB activates the GA catabolic gene GIBBERELLIN 2 OXIDASE 2 (GA2ox2) in the vascular tissue, thus regulating the stability of the DELLA protein GIBBERELLIN INSENSITIVE (GAI)-a GA signaling repressor-in the root and, hence, CYCD6;1 expression in the endodermis.