SUPERMAN attenuates positive INNER NO OUTER autoregulation to maintain polar development of Arabidopsis ovule outer integuments

• Published in: Development (Cambridge) Vol. 129; no. 18; pp. 4281 - 4289
• Main Authors: Meister, Robert J, Kotow, Louren M, Gasser, Charles S
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Limited 15.09.2002
• Subjects: Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - physiology; Arabidopsis Proteins; Base Sequence; Cell Polarity; Gene Expression Regulation, Plant; Genes, Reporter; Glucuronidase - genetics; Homeostasis; Mutation; Plant Proteins - genetics; Plants, Genetically Modified; Recombinant Fusion Proteins - metabolism; Restriction Mapping; Seeds - physiology; Suppression, Genetic; Transcription Factors - genetics; Zinc Fingers
• ISSN: 0950-1991; 1477-9129
• DOI: 10.1242/dev.129.18.4281

The outer integument of Arabidopsis ovules exhibits marked polarity in its development, growing extensively from the abaxial side, but only to a very limited extent from the adaxial side of the ovule. Mutations in two genes affect this asymmetric growth. In strong inner no outer ( ino ) mutants outer integument growth is eliminated, whereas in superman ( sup ) mutants integument growth on the adaxial side is nearly equal to wild-type growth on the abaxial side. Through complementation and reporter gene analysis, a region of INO 5′-flanking sequences was identified that contains sufficient information for appropriate expression of INO . Using this INO promoter (P-INO) we show that INO acts as a positive regulator of transcription from P-INO, but is not sufficient for de novo initiation of transcription in other plant parts. Protein fusions demonstrate nuclear localization of INO, consistent with a proposed role as a transcription factor for this member of the YABBY protein family. Through its ability to inhibit expression of the endogenous INO gene and transgenes driven by P-INO, SUP is shown to be a negative regulator of INO transcription. Substitution of another YABBY protein coding region ( CRABS CLAW ) for INO overcomes this negative regulation, indicating that SUP suppresses INO transcription through attenuation of the INO positive autoregulatory loop.