Genetic regulation of vascular development in Arabidopsis thaliana

Vascular tissues distribute water and nutrients throughout the plant. To achieve this, cells of the vascular system are elongated and interconnected and undergo specialized differentiation. Manipulation of auxin distribution has shown that this hormone plays a pivotal role in vascular patterning and differentiation, although the molecular genetic basis of this is largely missing. Here we show that the expression of PIN1, an auxin efflux carrier, is gradually narrowed down to the sites of leaf vein formation and that PIN1 is a potential component of a positive feedback loop involving auxin and the transcription factor MP. In a separate study, we assessed whether auxin-induced vascular overgrowth could be used to identify genes expressed in vascular tissues based on increased mRNA abundance as assessed by microarray analysis. We found strong support for this hypothesis as we analyzed the expression of 40 up-regulated genes in detail and initiated a phenotypic study.