Plant Gene and Trait 2024, Vol.15, No.1, 33-43 http://genbreedpublisher.com/index.php/pgt 39 Figure 5 A breeding scheme for cassava based on the use of inbred progenitors from two heterotic populations. Solid black arrows indicate the between heterotic group crosses for production and evaluation of experimental hybrids. White arrows indicate within-population variation. Line A is gradually improved for its heterotic response when crossed with line B. On the other hand, line B is improved for resistance or quality traits (Adopted from Ceballos et al., 2015) From a technical point of view, the development of markers requires high-throughput sequencing and precise bioinformatics analysis. Although recent reductions in sequencing costs and advances in analytical techniques have facilitated marker development, precise mapping of quantitative trait loci (QTLS) in cassava still requires large-scale genomic data and complex statistical analyses. Moreover, the association analysis of markers and traits often requires a large amount of genetic and phenotypic data to ensure that the markers found have stable expression in different environments and populations. 5.2 Effective QTL identification and marker development The genetic background of cassava is complex and contains a large number of repeated sequences, which makes the development and localization of genetic markers more difficult. Effective quantitative trait locus (QTL) identification is key to MAS success, but relies on high-density genetic linkage maps and large-scale phenotypic data, and the large size and high heterogeneity of cassava genomes require comprehensive analysis using high-throughput sequencing techniques (Chen et al., 2012). Not only is this costly, but the data processing is extremely complex. Marker development requires ensuring stable associations between genetic markers and target traits, which requires extensive validation experiments, including field trials and repeated testing across environments. These tests need to consider the influence of environmental variation on trait expression to ensure the effectiveness of markers in different environments. Effective QTL identification in cassava also faces the problem of limited genetic resources (Chen et al., 2012), and although international collaborative projects have made progress in expanding available genetic resources, further resource and information sharing is needed. 5.3 From laboratory to field: practical applications and limitations of marker-assisted selection Marker-assisted selection (MAS) technology has attracted a lot of attention in cassava breeding because it can effectively accelerate the improvement of cassava agronomic traits. MAS uses molecular markers to directly select genetic variants associated with important traits, thereby improving the accuracy and efficiency of selection. This approach allows screening based on genetic information at the seedling stage, significantly reducing the amount and time required for maintenance in mature plants (Hasan et al., 2021), and is particularly beneficial for complex traits such as pest resistance and adaptability. In this way, MAS can save a lot of time and resources and accelerate the development of superior varieties.
RkJQdWJsaXNoZXIy MjQ4ODYzMg==