Drought is an environmental stress that is known worldwide to be a major concern in the production of quality food crops. Several characteristics of drought tolerance have been confirmed in Amaranthus hypochondriacus, Amaranthus tricolor, Amaranthus hybridus, Vigna unguiculata and have been utilized in the breeding of drought-tolerant genotypes of several vegetables. Four techniques were described in this study for gene expression in Amaranthus. In sunflower, RNA sequencing by rtPCR is the major method used in gene expression. However, in Arabidopsis, microarray technology which includes cDNA or oligonucleotide microarrays is the technique analysed in the study. Several other vegetables have shown different ways of adapting to drought and the biochemical and physiological effects have been observed in some other neglected vegetables. Not much is available in the literature on a comparative review of expressed genes for drought tolerance in literature. This review aims to bridge such a gap by comparing gene expression analyses and providing a single front of information for a user.