Expression of a chimeric GUS gene construct as a tool to study nodule morphogenesis in chicory leaves

Leaves from micropropagated chicory plantlets were cultivated in vitro to regenerate organogenic nodules. The nodules were transformed with a 2.3 kb fragment of an apple calmodulin promoter region fused to the coding sequence of uidA reporter gene. Histochemical detection of β-glucuronidase expression in transgenic regenerants showed that vessel-associated cells were strongly stained. Previous histological investigations have shown that the differentiation of vascular elements is essential to nodule and bud-derived-nodule development. Therefore, β-glucuronidase activity was tested in a single transgenic chicory line during nodule morphogenesis and bud regeneration. The vascular connections between leaves and nodules, then between nodules and buds were stained blue, indicating an alternative system for determining the histological origin of nodules and adventitious buds from chicory leaf explants. This revised version was published online in June 2006 with corrections to the Cover Date.