Plant Gene and Trait 2024, Vol.15, No.5, 220-229 http://genbreedpublisher.com/index.php/pgt 221 sugarcane, and discuss the potential of integrating GWAS findings with other genomic tools, so as to provide insights into future research directions and the potential impact of GWAS on sugarcane improvement. By consolidating findings from multiple studies, this study expects to offer a comprehensive understanding of how GWAS can be harnessed to improve sugarcane yield and agronomic traits, ultimately contributing to the development of more resilient and productive sugarcane varieties. 2 Overview of Sugarcane Genetics 2.1 Genetic complexity of sugarcane Sugarcane is characterized by an exceptionally complex genome, which includes high levels of polyploidy and frequent aneuploidy. This complexity poses significant challenges in understanding the relationships between genotype and phenotype (Racedo et al., 2016; Barreto et al., 2019). The genome of modern sugarcane hybrids is derived fromSaccharum officinarum, Saccharum spontaneumas well as wild relatives, and includes sub-genomes from those, with some chromosomes resulting from recombination between these sub-genomes (Thirugnanasambandam et al., 2018). The high heterozygosity and autopolyploid nature of sugarcane further complicate the development of a comprehensive genetic map (Meena et al., 2022). 2.2 Key traits of interest Key traits of interest in sugarcane breeding include yield, disease resistance, and tolerance to abiotic stresses. Yield traits such as cane yield, sugar content, and biomass are critical for both sugar and biofuel production (Racedo et al., 2016; Fickett et al., 2019; Yang et al., 2020). Disease resistance, particularly against major pathogens, is another crucial trait, with significant efforts directed towards identifying and incorporating resistance genes into breeding programs. Additionally, tolerance to abiotic stresses such as drought and salinity is essential for maintaining productivity in varying environmental conditions (Mahadevaiah et al., 2021). 2.3 Historical breeding efforts and challenges Historically, sugarcane breeding has relied on conventional methods, which are time-consuming and labor-intensive, often requiring 12~14 years to develop new varieties (Mahadevaiah et al., 2021). The high genetic complexity and polyploidy of sugarcane have made it difficult to achieve desired rates of genetic gain through traditional breeding methods. Despite these challenges, significant progress has been made in identifying superior agronomic traits and genes through quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and transcriptome approaches (Meena et al., 2022). Recent advances in genomic selection and next-generation sequencing technologies have opened new avenues for improving breeding efficiency and genetic gain in sugarcane (Zan et al., 2020; Hayes et al., 2021). These modern biotechnological tools have facilitated the identification and accumulation of favorable alleles, thereby enhancing the selection efficiency in breeding programs. 3 GWAS in Sugarcane: Current Status 3.1 Summary of major GWAS studies conducted in sugarcane Genome-wide association studies (GWAS) have been increasingly utilized to dissect the genetic basis of complex traits in sugarcane, a crop with a highly complex polyploid genome. Several significant studies have been conducted to identify marker-trait associations (MTAs) for various agronomic traits. For instance, a study on the Brazilian Panel of Sugarcane Genotypes (BPSG) identified 23 MTAs for traits such as soluble solid content, stalk height, stalk number, stalk weight, and cane yield (Barreto et al., 2019). Racedo et al. (2016) focused on a breeding population and identified 43, 42, and 41 markers associated with cane yield (CY) across three successive crop cycles, respectively, and 38, 34, and 47 markers associated with sugar content (SC). Additionally, research on the Louisiana sugarcane core collection identified MTAs for 11 cane yield and sucrose traits using SNP and Indel markers (Fickett et al., 2019). 3.2 Key findings from these studies The key findings from these GWAS studies highlight the potential of GWAS in identifying significant genetic markers associated with important agronomic traits in sugarcane. For example, the study on the BPSG revealed that the broad-sense heritability values for yield traits were above 0.48 and 0.49 for the first and second harvests,
RkJQdWJsaXNoZXIy MjQ4ODYzMg==