International Journal of Molecular Evolution and Biodiversity 2024, Vol.14, No.3, 120-132 http://ecoevopublisher.com/index.php/ijmeb 125 3.3 Adaptive traits and selection The process of domestication has led to the selection of certain adaptive traits in cassava. For instance, domesticated cassava exhibits epigeal germination and photosynthetic cotyledons, which confer high initial growth rates in agricultural habitats, contrasting with the hypogeal germination of its wild relatives that is more suited to their savanna environment (Pujol et al., 2005). These traits are likely the result of selection pressures in agricultural environments favoring rapid growth. Moreover, throughout its domestication, more specific traits in cassava have been emphasized to meet human needs and environmental challenges. Traits such as increased yield, enhanced drought resistance, and improved pest resistance have been particularly crucial. Phylogenetic and genomic research has identified several adaptive traits that were selected during the domestication process: 1) Yield: Selection for higher yield is reflected in the genetic modifications that enhance root bulk, starch content and root-rot resistance. Hohenfeld et al. (2024) analyzed the transcriptome of two contrasting genotypes (BRS Kiriris/resistant and BGM-1345/susceptible) using RNA-Seq to understand the molecular response and identify candidate genes for resistance (Figure 4). Figure 4 Fresh root weight (g) and staining of fungal structures across collection time-periods (Photo credit: Hohenfeld et al., 2024) Image caption: (A) Fresh root weight (g) of resistant (BRS Kiriris) and susceptible (BGM-1345) cassava genotypes grown in soil infested with root rot pathogens between 5 and 60 days after planting. (B) Clarification of root fragments and staining of fungal structures of the cassava genotype BGM-1345 at seven collection time-periods after planting in infested soil (5, 10, 15, 20, 30, 45, 60 days after planting). (C) Clarification of root fragments and staining of fungal structures of cassava genotype BRS Kiriris at seven collection time-periods after planting in infested soil (5, 10, 15, 20, 30, 45, 60 days after planting). hy = hyphae; cla: chlamydospore (Adopted from Hohenfeld et al., 2024)
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