Pleiotropic drug resistance （PDR） transporters belonging to the ABCG subfamily of ATP-binding cassette （ABC） transporters are identified only in fungi and plants. Members of this family are expressed in plants in response to various biotic and abiotic stresses and transport a diverse array of moleculesacross membranes, Although their detailed transport mechanism is largely unknown, they play important roles in detoxification processes, preventing water loss, transport of phytohormones, and secondary metabolites. This review provides insights into transport mechanisms of plant PDR transporters, their expression profiles, and multitude functions in plants.
Mohammed NuruzzamanRu ZhangHong-Zhe CaoZhi-Yong Luo
Plants produce a wide spectrum of secondary metabolites that play critical roles in plant-environment interactions and against biotic and abiotic stresses. Moreover, many secondary metabolites have pharmaceu- tical efficacy for a wide range of diseases （cancer, malaria, etc.）. Controlled transcription of biosynthetic genes is one of the major mechanisms regulating sec- ondary metabolism in plants. Several transcription factor families such as MYC, MYB, WRKY and AP2/ERF have been found to be involved in the regulation of secondary metabolism in different medicinal plants. In addition, the biosynthesis and proper accumulation of secondary metabolites are also induced by signaling molecule jasmonic acid （JA）. This review provides an insight into JA signaling pathway and JA-mediated transcriptional regu- lation of secondary metabolism （vinblastine, nicotine, artemisinin, taxol and ginsenoside） in a range of medicinal plant species.
