Plant Gene and Trait 2024, Vol.15, No.5, 220-229 http://genbreedpublisher.com/index.php/pgt 223 estimate adjusted means and genetic parameters for ten traits over three harvest years using a mixed model, and to estimate genotypic correlation among those traits (Figure 1) (Barreto et al., 2021). Figure 1 Genotypic correlation between yield traits evaluated in the Brazilian Panel of Sugarcane Genotypes (BPSG) (Adopted from Barreto et al., 2021) Image caption: BRIX (in Brix), sucrose content of the cane (POL%C, in %), sucrose content of the juice (POL%J, in %), fiber content (FIB, in %), stalk height (SH, in m), stalk number (SN), stalk diameter (SD, in mm), stalk weight of the plot (SW, in kg), cane yield (TCH, in t/ha) and sucrose yield (TPH, in t/ha); For each trait, the density plots of the adjusted means (diagonal), scatterplots (below diagonal), and values of the genotypic correlation (above diagonal) between pairs of traits are shown; * Significant at the 5% global level (p<0.05). ** Significant at the 1% global level (p<0.01). *** Significant at the 0.1% global level (p<0.001) (Adopted from Barreto et al., 2021) The study by Barreto et al. (2021) showed high positive correlations between BRIX, POL%C, and POL%J (all > 0.98), indicating strong relationships among these sucrose-related traits, positive correlations of TCH and TPH with most traits, suggesting these are key yield determinants. SH and SW show moderate to strong correlations with yield traits. Conversely, FIB has a negative correlation with sucrose-related traits (BRIX, POL%C, POL%J), highlighting a trade-off between fiber content and sugar yield. This analysis highlights the interconnected nature of sugarcane yield components, crucial for breeding programs aimed at enhancing yield and sucrose content. Barreto et al. (2019) also utilized a diversity panel of sugarcane genotypes and employed SSR markers to analyze genetic diversity and population structure in 2019. The phenotypic data analysis revealed broad-sense heritability values above 0.48 and 0.49 for the first and second harvests, respectively. The SSR markers produced 1 483 fragments, with 99.5% being polymorphic, which helped estimate the number of subpopulations and the extent of LD. Meanwhile, the GWAS identified 23 MTAs for traits such as soluble solid content, stalk height, stalk number, stalk weight, and cane yield. 5.2 Implications for breeding programs and future research directions The findings from the BPSG study have significant implications for sugarcane breeding programs. The genotype correlation of major agronomic traits provides a basis for future association map research. And the identification of MTAs provides valuable markers that can be used for marker-assisted selection (MAS) to introgress favorable alleles into breeding populations. This can enhance the efficiency of selecting superior genotypes with desirable yield traits. Additionally, the study’s methodology and results can serve as a reference for future research aiming to validate these MTAs in other populations and environments. Future research should focus on fine-mapping the
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