Triticeae Genomics and Genetics, 2024, Vol.15, No.2, 88-99 http://cropscipublisher.com/index.php/lgg 93 Figure 3 The distribution of quantitative trait loci (QTLs) associated with grain quality traits in the wheat recombinant inbred line (RIL) population (Adapted from Goel et al., 2019) Image caption: The vertical bars represent the confidence intervals of QTLs on different chromosomes, with chromosome numbers indicated on the left side of the figure; The color bands on each chromosome denote different QTLs, with color variations potentially indicating QTL differences under various traits or environmental conditions; This distribution map provides visual information for understanding the relative positions of each QTL within the genome and their potential interactions, aiding further genetic analysis and variety improvement efforts (Adapted from Goel et al., 2019) Another study utilized a RIL population from the cross between Taejoong and Keumkang, identifying eight QTLs for yield potential traits such as days to heading date, spike length, tiller number, and length of center rachis (Kang et al., 2020). These studies highlight the effectiveness of RIL populations in uncovering genetic loci that contribute to important agronomic traits in wheat. 4.2 Use of advanced statistical methods The application of advanced statistical methods in QTL mapping has significantly enhanced the precision and accuracy of detecting QTLs. These methods have evolved to handle the complexity of genetic data and the multifaceted nature of traits controlled by multiple genes. These methods include Interval Mapping, Composite Interval Mapping, and Multiple-trait Composite Interval Mapping. 4.2.1 Interval mapping Interval Mapping (IM) is a method that estimates the position and effect of QTLs within a defined interval between genetic markers. Interval mapping is one of the foundational techniques in QTL analysis. This method scans the genome at regular intervals to identify regions associated with phenotypic variation. This method was employed in a study that mapped QTLs for root traits in a RIL population of hexaploid wheat. In the study by Li et al. (2023), the interval mapping (IM) method was used to physically locate quantitative trait loci (QTLs) related
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