International Journal of Molecular Evolution and Biodiversity 2024, Vol.14, No.3, 120-132 http://ecoevopublisher.com/index.php/ijmeb 127 4.3 The implications of genetic findings for future breeding The genetic insights gained from studying cassava’s adaptation to arid climates have significant implications for breeding programs aimed at improving drought tolerance. The identification of drought-responsive genes and alleles provides targets for both conventional breeding and genetic modification (Lokko et al., 2007; Welsch et al., 2010; Okogbenin et al., 2012). For instance, the discovery of a PSY gene allele that enhances carotenoid production offers a means to improve provitamin A content in cassava roots (Welsch et al., 2010). Additionally, understanding the genetic basis of traits associated with drought tolerance can inform the selection of varieties specifically adapted to drought-prone environments (Okogbenin et al., 2003). The development of molecular markers from EST datasets enriched for drought-responsive genes will further facilitate the dissection of complex traits like drought tolerance and accelerate the breeding of improved varieties (Lokko et al., 2007). Figure 5 A model adopted and modified from Shinozaki and Yamaguchi-Shinozaki (2007) (Photo credit：Orek et al., 2020) Image caption: A model represents selected Drought Responsive Genes (DRGs) profiled in cassava and categorized into either ABA-D or ABA-I molecular pathways. ABA-D refers to ABA-Dependent; ABA-I refers to ABA-Independent (Adapted from Orek et al., 2020) 5 Evolutionary Trajectories and Domestication Pathways of Cassava 5.1 Migration and spread Cassava, a staple food crop with significant economic importance, is believed to have originated in the southern Amazon basin. Genetic analyses using SNPs (single nucleotide polymorphisms) and SSR (simple sequence repeat) variation have traced cassava’s evolutionary and geographical origins, suggesting that it was likely domesticated from a single wild species, M. esculenta ssp. flabellifolia, rather than from multiple hybridizing species (Olsen, 2004). The crop’s spread from its place of origin to other parts of the world involved the migration of people and the exchange of planting materials. As cassava was introduced to new environments, it underwent genetic changes, including adaptations to different climates and agricultural practices. The genetic diversity in cassava is a subset of that found in its wild relatives, indicating that the domesticated varieties were derived from their conspecific wild relatives (Ding et al., 2016).
RkJQdWJsaXNoZXIy MjQ4ODYzNA==