The Cactus (Opuntia), which originated in Mexico and spread to arid and semiarid areas across the globe, is a genus of the Cactaceae family and the Opuntioideae subfamily. They are cultivated, and some are domesticated as ornamental plantsOrnamental plant due to their unusual biology and unique appearance. Opuntia ficus-indica (L.) Mill. is an economically important speciesSpecies due to its fruitFruit with high nutritional and medicinal value. Opuntia is a highly diverse genus with wide variations in morphological, physiological, and chemical traits. Germplasm diversityGermplasm diversity within the Opuntia genus is attributed to factors such as polyploidyPolyploidy, hybridizationHybridization, and self-fertilization. The geneticGenetic foundation of any speciesSpecies of plants is crucial in enhancing them, as it enriches the germplasmGermplasm with a diverse range of geneticGenetic variations that breeders can utilize to develop new cultivarsCultivars. Thus, Opuntia taxonomyTaxonomy was first based on morphological descriptions before being augmented with biochemical, physiological, and cytogeneticCytogenetics data over a period of time. DNADeoxyribonucleic acid (DNA)-based studies relying on various categories of molecular markersMolecular markers have been conducted to better understand the level of variability within the main speciesSpecies of Opuntia, to establish relationships among the primary close relative speciesSpecies and varietiesVarieties, and ultimately to assist breeders. In addition, in-situ and ex-situ conservationConservation methods have been used to conserve cactus genetic resourcesGenetic resources for future plant breedingPlant breeding and to preserve the natural populations. Due to the tremendous morphological variability among different Opuntia speciesSpecies, breedingBreeding and improvement programs are highly desirable. However, classical breedingClassical breeding techniques in Opuntia may be challenging due to the presence of apomixis and polyploidyPolyploidy. In addition, seed propagationSeed propagation, cross-pollination, selectionSelection, and hybridizationHybridization are used to develop new varietiesVarieties. However, Opuntia breedingBreeding faces various challenges, including the absence of dependable morphological characteristicsMorphological characteristics, frequent intra- and intergeneric hybridizationIntergeneric hybridization, frequent polyploidyPolyploidy, and phenotypic variabilityPhenotypic variability demonstrated by genotypes in varied environmental conditions.