A review of the functions of transcription factors and related genes involved in cassava (<i>Manihot Esculenta</i> Crantz) response to drought stress

Abstract

Cassava navigates drought stress via diverse mechanisms including avoidance, tolerance, resistance or recovery from effects of drought. The crop's inherent tolerance to drought stress is underpinned by a set of genes involved in several molecular pathways. Among these include transcription factors (TFs) with key roles in abscisic acid (ABA) signaling pathways. ABA is a ubiquitous phytohormone that is critical in plant growth and development processes as well as responses to abiotic stresses such as drought. This review focuses on and summarizes the current developments in the identification, characterization and functions of TFs and related genes (RGEs) implicated in ABA pathways that regulate cassava's response to drought stress. The different drought-induced experiments set up either at the field or controlled environments and omics approaches applied by researchers for gene discovery and characterization are highlighted. The roles of these drought-induced genes in other crops or plants are compared with cassava. The review reveals functions of key candidate TFs and REGs including <italic>AREBs/ABFs, NACs, bHLH, WRKY, MYC/MYB,</italic> <italic>HD-Zip</italic>, <italic>TCP, HSFs, AP2/ERFBPs,</italic> <italic>NFYA5, SLAC1</italic>, <italic>ABI1, SCaBP5</italic>, <italic>PKS3, PYR1, AP2/ERFs</italic>, <italic>DREB1A, DREB2A/B</italic>, <italic>RD29A/B, RD19, ERD1</italic> among others. These genes are potential molecular markers that could aid in rapid introgression of drought tolerance traits not only in farmer-preferred and drought susceptible cassava genotypes, but also in other crops for improved production. Through this omics-based drought-mitigation, the negative effects of climate change could be reduced.