AXR3 and SHY2 Interact to Regulate Root Hair Development

The document from December 1, 2003, explores the interaction between the AXR3/IAA17 and SHY2/IAA3 genes and their impact on root hair development in Arabidopsis thaliana. The study reveals that mutations in AXR3/IAA17 and SHY2/IAA3 have opposing effects on root hair growth: axr3-1 mutants exhibit almost no root hairs, while shy2-2 mutants have longer root hairs than the wild type. The axr3-1 mutation blocks root hair elongation at any stage, whereas the shy2-2 mutation alters the timing of root hair initiation. Co-expression of these genes results in a unique phenotype with irregular root hairs, indicating an interaction between AXR3 and SHY2 in root hair development. The study also finds that the balance of AXR3 and SHY2 protein levels is crucial for the timing of root hair initiation, with the AXR3:SHY2 ratio influencing the activity of ARF-regulated genes. Quantitative data were collected from at least 50 measurements per genotype, and root hair growth was monitored using time-lapse analysis, although the total number of plants studied is not specified. This research contributes to understanding the molecular mechanisms of root hair development and the complex role of auxin signaling in plant development.