Maize Genomics and Genetics 2025, Vol.16, No.2, 89-97 http://cropscipublisher.com/index.php/mgg 92 yield (Yu et al., 2020). This actually illustrates a problem: tropical germplasm is not only used in tropical areas. With the right combination, they can also help temperate varieties improve their performance. In other words, the hybridization strategy requires vision, not just pairing. 4.4 About genomic selection and marker-assisted breeding Traditional seed selection relies on vision, while modern technology relies on computing power. Genomic selection (GS) is a typical example. It uses whole genome information to predict the genetic potential of a material and then selects seeds based on this (Crossa et al., 2017). This method is particularly suitable for multi-trait and multi-gene targets, and the effect is more obvious when combined with high-throughput phenotyping technology. As for marker-assisted selection (MAS), it is no longer a new thing. For example, the work done by Bouchez et al. in 2002 used MAS to introduce favorable genes related to early maturity and high yield into breeding lines. Although this method is sophisticated, it requires high accuracy in the positioning of QTL (quantitative trait loci). In a 2007 study, Ribaut and Ragot further demonstrated that the yield of tropical corn was significantly improved after the introduction of favorable alleles in five key areas under drought conditions. It can be said that these methods have accelerated breeding and improved accuracy. 5 Case Study: Finding Solutions to Fall Armyworm from Germplasm Resources 5.1 Why pay special attention to fall armyworm? Most people who grow corn have heard of the fall armyworm (Spodoptera frugiperda), especially corn farmers in Africa and Asia - it is not a new problem. It was first discovered in West and Central Africa in 2016, and then it quickly spread to many regions, causing serious damage to corn fields (Goergen et al., 2016; Wan et al., 2021). It is highly adaptable, reproduces quickly, and is easily resistant to pesticides, which makes prevention and control work more complicated. Chemical methods are not very reliable, and breeding has become a necessary way. Especially for small farmers with limited resources, they do not have much budget to use pesticides frequently, and they need varieties that can "defend themselves" (Figure 1) (Assefa et al., 2019; Baudron et al., 2019). Although no variety can completely resist the fall armyworm, reducing losses through resistance breeding is a realistic and sustainable direction. Figure 1 a: Corn ear damaged by caterpillar of Spodoptera frugiperda and b: Fifth instar larva of S. frugiperda (Adopted from Assefa et al., 2019) 5.2 How to select corn resistant to fall armyworm? Finding germplasm resources sounds like a very academic thing, but it can actually be understood as "picking out those that can withstand insects from a pile of corn materials." This process requires both testing in a controlled laboratory environment and observing in the field to see which type is less susceptible to insect damage. The judgment criteria are not complicated, such as the degree of leaf bites, the proportion of insect survival, the growth of the entire plant, etc. Of course, not all results are determined solely by genetics. Studies have shown that simple field management measures such as frequent weeding or less tillage can actually help reduce insect damage (Baudron et al., 2019). In addition, pathogenic fungi such as Metarhizium rileyi, or some natural enemy insects, also play a role in
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