title: The bHLH transcription factor SPATULA is a key regulator of organ size in Arabidopsis thaliana.
abstract: Plant organ size and thus plant size is determined by both cell proliferation and cell expansion. The bHLH transcription factor SPATULA (SPT) was originally identified as a regulator of carpel patterning. It has subsequently been found to control growth of the organs of the shoot. It does this at least in part by controlling the size of meristematic regions of organs in parallel to gibberellic acid (GA). It also acts downstream of several environmental signals, influencing growth in response to light and temperature. We have recently demonstrated that SPT functions to repress the size of the root meristem and thus root growth and size. It appears to do this using a similar mechanism to its control of leaf size. Based on the recent work on SPT, we propose that it is a growth repressor that acts to limit the size of meristems in response to environmental signals, perhaps by regulating auxin transport.
authors.affiliation: Plant Cellular and Molecular Biology Graduate Program; Ohio State University; Columbus, OH USA.
authors.forename: Srilakshmi
authors.initials: S
authors.lastname: Makkena
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Lamb
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology* / Q000201:enzymology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D008954:Models, Biological; D009929:Organ Size; D018517:Plant Roots / Q000033:anatomy & histology / Q000196:embryology / Q000378:metabolism; D012639:Seeds / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; C426006:SPT protein, Arabidopsis
keywords: SPT; auxin; environmental signals; gibberellic acid; organ size; root growth