Unravelling molecular mechanisms for enhancing arsenic tolerance in plants: A review

Abstract

Many transcription factors associated with different gene families are involved in coordinating arsenic responsive genes, contributing to stress signaling, arsenic-toxicity and arsenic-tolerance. Identification and characterization of arsenic responsive genes, their transcriptional regulation, mechanisms of arsenic uptake, transport and sequestration, regulation of oxidative stress during stress have helped in understanding of arsenic tolerance mechanisms displayed by plants. For uptake and transport of arsenic from the soil, transporters belong to the families of aquaporins, phosphate transporters, NRAMP,MATE, INT, etc., while genes encoding the antioxidants, thioredoxins, glutathione s-transferase, kinases are crucial for regulation of oxidative stress. Significant progress has been made to identify different genes such as AP2/ERF or APETALA 2/ Ethylene response factor, bZIP (basic leucine zipper), WRKY, NAC (NAM, ATAF, and CUC) which are involved in regulation of plant abiotic response. The present review focuses on a wide range of arsenic responsive genes and in addition provides insights into the role of different proteins such as peroxidases, glutathioredoxins and germin like proteins, ferritins, patatin, ZFP (Zinc finger proteins), acid phosphatases, integral membrane proteins, serine threonine protein kinases and hydrolases in relation to As exposure and As tolerance. The mechanisms involved in regulation of different genes associated with As tolerance have also been described. Unravelling the molecular mechanisms associated with regulation of expression of As responsive genes and identification of genes and their products associated with As tolerance will help in a long way in our attempts to produce transgenic As tolerant crop plants.