Investigating the Function of the Arabidopsis thaliana INDETERMINATE DOMAIN2 gene

Abstract

The INDETERMINATE DOMAIN (IDD) genes in Arabidopsis thaliana encode a transcription factor family found in all higher plants. IDD2, one of 16 IDD family genes in Arabidopsis, is highly expressed in hypocotyls, shoot apices and petioles. Loss-of-function idd2 mutants show no obvious differences in growth and development under a variety of conditions, suggesting that IDD2 may function redundantly. Constitutive overexpression of IDD2 causes altered seed coat morphology and defects in early growth. 35S::IDD2 overexpression seedlings show a constitutive response to the phytohormone auxin. Elucidation of IDD2 expression in IDD2::GFP:GUS reporter plants revealed a highly specific pattern, including expression in leaf and cotyledon vasculature, petioles, hypocotyl, shoot apex, root tip and emerging lateral roots, which all correspond to areas with high levels of auxin. Taken together, analysis of loss-of-function mutants, overexpression lines and the IDD2 expression pattern suggests that IDD2 has a redundant role in auxin sensing and response.