Maize Genomics and Genetics 2025, Vol.16, No.2, 60-69 http://cropscipublisher.com/index.php/mgg 64 opaque2 (o2) gene mutations together, it was unexpectedly discovered that not only the sugar content of sweet corn increased, but also the anthocyanin and tryptophan content increased. Of course, the corn cultivated by this new method does perform well in terms of protein quality and has good antioxidant properties, but it may take some time to observe whether it can be actually promoted. In general, these improvements make fresh corn more nutritious, although it is still far from perfect. 4.4 Hybrid breeding and parental line selection Anyone who is engaged in corn breeding knows that it is not easy to breed high-yield and lodging-resistant varieties. In the past, parents were basically selected based on the experience of old masters, and the results were mixed. Now there are some new methods, such as hybridization with tropical and temperate germplasm (Ndou et al., 2021), and there is no need to worry about lodging even if the seeds are planted densely. But this is not enough. Recently, new technologies such as GS and GWAS have been of great help (Dang et al., 2023), especially in predicting difficult traits such as plant height and ear position, which are much more accurate than before. But in the final analysis, no matter how good the technology is, it must be based on high-quality germplasm resources. Although mixing these methods does improve efficiency, the specific operation still needs to be adjusted according to the actual situation. 5 Application of Modern Technology in the Utilization of Fresh Corn Germplasm Resources 5.1 Marker-assisted selection (MAS) When it comes to marker-assisted selection (MAS) in corn breeding, the earliest method used was actually traditional phenotypic screening, which was not very efficient. However, with the advent of molecular markers such as SNP, the situation is much better - although there are still some technical difficulties in actual operation. Interestingly, with the popularization of NGS technology, methods such as GBS have been developed (He et al., 2014), which can not only process a large number of samples at the same time, but also is relatively affordable. Of course, this technology is not omnipotent, but it has indeed helped a lot in GWAS and genetic diversity research (He et al., 2014; Kumawat et al., 2020). In general, screening for excellent traits is much faster now than before, but the specific effect depends on the experimental design and material selection. 5.2 Genomic selection (GS) Corn breeding used to rely mainly on experience, but now with genomic selection (GS) technology, the situation is indeed different. Although there are still problems such as too much data in actual operation, GS can indeed predict breeding value through whole genome markers (Crossa et al., 2017). Interestingly, it not only speeds up the breeding process, but also has a good effect on improving complex traits such as yield and resistance (He and Li, 2020), especially when combined with high-throughput data, even the interaction effect between genotype and environment can be taken into account (Rice and Lipka, 2021). Of course, the most practical use may be to cultivate varieties that adapt to climate change (Budhlakoti et al., 2022), after all, there are more and more extreme weather now. But then again, although GS improves the accuracy of prediction, the effect may still be different for each breeding project. 5.3 Gene editing technologies (CRISPR/Cas9) When it comes to improving fresh corn, breeding experts are now discussing the CRISPR/Cas9 technology. Although traditional breeding methods have been used for so many years, they do have problems with long cycles and low efficiency. Interestingly, this gene editing tool can directly and precisely modify corn DNA (He and Li, 2020), making it much easier to operate than before, whether it is to improve drought resistance or increase nutritional content. Of course, there are still some technical difficulties in actual application, but it is undeniable that CRISPR/Cas9 does make it faster to cultivate new varieties that are resistant to diseases and adapt to climate change. But then again, it may take time for this new technology to completely replace traditional breeding. 5.4 Integration of multi-omics technologies Now, when studying corn variety improvement, it is not enough to just look at the external characteristics. Researchers have found that combining transcriptomics, metabolomics, and proteomics is more effective (He and
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