Journal of Energy Bioscience 2025, Vol.16, No.3, 151-162 http://bioscipublisher.com/index.php/jeb 154 4 Breeding Strategies For Maize Varieties For Biofuels 4.1 Conventional breeding methods Breeders observe the appearance of maize (such as yield, straw and grain quality, etc.) and conduct multi-generation hybridization and screening. Grain yield and straw yield usually increase together, which shows that maize can provide raw materials for both food and biofuels (Lorenz et al., 2010; Gesteiro et al., 2023). The heritability of these traits is generally not low, and traditional breeding methods are still effective. Some local varieties and high-diversity maize resources can also be used in breeding to find materials suitable for different regions or different uses (Munaiz et al., 2021). Traits such as cellulose and lignin in straw are controlled by many genes and are affected by the environment. It is difficult to achieve good results quickly by selecting based on appearance alone. In addition, traditional breeding cycles are long and slow, and it is difficult to meet the needs of the biofuel industry. Therefore, conventional breeding methods are often used together with molecular techniques to form diversified breeding methods (Munaiz et al., 2021; Gesteiro et al., 2023). 4.2 Marker-assisted selection (MAS) MAS is a breeding method that can select target traits at the genetic level. Researchers can locate genes related to these traits, such as genes that control biomass, straw digestibility or lignin content. Through GWAS and QTL mapping technology, scientists have found many genetic pathways related to maize straw (Barrière et al., 2016; Gesteiro et al., 2023). Transcription factors such as ZmMYB and ZmNAC are in the same region as the QTL for cell wall digestibility, which provides clear genetic targets for MAS (Barrière et al., 2016). The advantage of MAS is that it can screen out plants with good genes in the early stage of breeding, thereby shortening the time and improving efficiency. For traits such as cellulose content that are greatly affected by the environment, MAS is more stable than traditional methods (Barrière et al., 2016; Choudhary et al., 2020). MAS can also be combined with conventional breeding, gene editing and other technologies to form a stronger breeding system and accelerate the breeding of biofuel-specific varieties (Choudhary et al., 2020). 4.3 Application of genomic selection (GS) in complex trait improvement Genomic selection (GS) does not need to find each key gene separately, but predicts the breeding potential of individuals by establishing a relationship model between the entire set of genes and traits. This method performs well in improving straw saccharification efficiency and other aspects (Gesteiro et al., 2023). Compared with traditional QTL or MAS methods, GS can discover the cumulative effects of more small-effect genes, which is very helpful for controlling complex traits. GS can screen materials in advance and on a large scale, without the need for too many field trials and trait determinations, saving time and cost. With the development of maize genomic data and molecular marker technology, GS is increasingly used in maize biofuel breeding (Barrière et al., 2016; Gesteiro et al., 2023). 4.4 The role of hybrid breeding in improving bioenergy performance Through hybridization, hybrid vigor can be used to make maize perform better in terms of yield, straw quality and resistance (Lorenz et al., 2010; Munaiz et al., 2021). Hybrids not only have high grain and straw yields, but also high harvest ratios, which can meet the needs of food and fuel at the same time. Breeders can also select materials with more cellulose and less lignin to improve the biofuel utilization value of straw (Pratikshya et al., 2025). Molecular technology and genomic selection are also used in hybrid breeding, which can help select good inbred lines and hybrid combinations more quickly (Wan et al., 2019; Pratikshya et al., 2025). Some new technologies, such as male sterility and double haploidy, also make breeding easier and improve seed purity and production efficiency (Wan et al., 2019; Mitiku, 2022).
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