Cloning and expression analysis of 1-deoxy-D-xylulose 5-phosphate reductoisomerase gene from Gentiana macrophylla (GmDXR) Cloning and tissue-specific expression analysis of conserved fragments of DXR gene from Angelica sinensis Advances in studies on 1-deoxy-D-xylulose 5-phosphate reductoisomerase gene in medicinal plants