Two light responsive genes exhibit positive and negative correlation with picroside content in Royle ex Benth, an endangered medicinal herb.

is an endangered herb known to produce the medicinally important picrosides through isoprenoid pathway. The present work showed the functionality of WRKY motifs (TGAC -acting elements) present in the promoters of regulatory genes 3-hydroxy-3-methylglutaryl coenzyme A reductase () and 1-deoxy-d-xylulose-5-phosphate synthase () of the picrosides biosynthetic pathway by electrophoretic mobility shift assay. Also, the two genes, and were characterized and found to contain double and single characteristic WRKY domains, respectively along with a zinc-finger motif in each domain. Expression analysis revealed that and exhibited a positive and negative correlation, respectively, with picrosides content under the environment of light and in different tissues. Functional evaluation in yeast showed DNA binding ability of both PksWRKY and PkdWRKY; however, only PkdWRKY exhibited transcriptional activation ability. Transient overexpression of and in tobacco modulated the expression of selected native genes of tobacco involved in MVA and MEP pathway suggesting functionality of and in planta. Collectively, data suggested that and might be positive and negative regulators, respectively in the picrosides biosynthetic pathway.