Maize Genomics and Genetics 2025, Vol.16, No.5, 251-257 http://cropscipublisher.com/index.php/mgg 256 regulation and adaptation to environmental stress in other crops. Combining expression profile data and transgenic analysis, it is not difficult to see that these candidate genes provide many useful molecular targets for green-preserving traits, and also provide support for subsequent marker-assisted selection and genetic improvement (Zhang et al., 2019). 7 Conclusion and Perspectives People have actually been paying attention to the green retention property of corn for a long time. Especially in terms of increasing yield and stress resistance, maintaining the green color of leaves for a longer time is regarded as a practical trait. At present, through meta-analysis, a large number of QTLS related to green conservation, yield and stress resistance have been identified and integrated, among which some regions share multiple traits. Transcription factors in the NAC domain like nac7 are believed to be closely related to the regulation of aging and resource allocation. Although these genes have long existed in the corn genome, it is precisely because of the current methods such as BSA-seq, RNA-seq, and GWAS, along with high-throughput genotyping and better mapping populations, that these key loci have been able to be precisely located and their functions further verified. Not all QTL mapping work can directly guide breeding, but those markers known to be closely linked to green-retaining traits undoubtedly bring more initiative to breeders. With these tools, breeders can precisely introduce outstanding alleles into target varieties, which not only extends the photosynthetic duration of corn but also makes its resistance more stable. More importantly, under different environmental conditions, strains with these excellent QTLS tend to perform better. This means that even in the face of adverse conditions such as drought and high temperatures, the output can still be maintained at a relatively ideal level. Of course, relying solely on green retention is not enough. How to combine it with other important traits such as drought resistance and maturity period is the difficulty and key point in actual breeding. Interestingly, many green-preserving QTLS are precisely aligned with traits such as drought tolerance and yield. That is to say, while choosing one trait, another may have been improved incidentally. In this regard, the introduction of marker-assisted backcrossing and genomic selection techniques is very timely. They give breeders the opportunity to integrate stably expressed QTLS and environmentally sensitive QTLS, thereby cultivating hybrid corns that are both green-preserving and drought-tolerant, and can also adapt to the maturity requirements of different regions. This approach of integrating multiple traits might just be the direction for future corn improvement. Acknowledgments We are grateful to Dr. Z. Xu for his assistance with the serious reading and helpful discussions during the course of this work. Conflict of Interest Disclosure The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest. References Belicuas P., Aguiar A., Bento D., Câmara T., and Júnior C., 2014, Inheritance of the stay-green trait in tropical maize, Euphytica, 198: 163-173. https://doi.org/10.1007/s10681-014-1106-4 Bhadmus O., Badu‐Apraku B., Adeyemo O., Agre P., Queen O., and Ogunkanmi A., 2022, Genome-wide association analysis reveals genetic architecture and candidate genes associated with grain yield and other traits under low soil nitrogen in early-maturing white quality protein maize inbred lines, Genes, 13(5): 826. https://doi.org/10.3390/genes13050826 Chibane N., Caicedo M., Martínez S., Marcet P., Revilla P., and Ordás B., 2021, Relationship between delayed leaf senescence (stay-green) and agronomic and physiological characters in maize (Zea mays L.), Agronomy, 11(2): 276. https://doi.org/10.3390/AGRONOMY11020276 Eichten S., Foerster J., De León N., Kai Y., Yeh C., Liu S., Jeddeloh J., Schnable P., Kaeppler S., and Springer N., 2011, B73-Mo17 near-isogenic lines demonstrate dispersed structural variation in maize, Plant Physiology, 156(4): 1679-1690. https://doi.org/10.1104/pp.111.174748 Fang Y.F., Li Y.S., Bai J.P., Mu P., Meng Y.X., Zhang J.L., Wang H.N., and Shang X.W., 2012, Construction of integration QTL map and identification of candidate genes for stay-green in maize, Acta Pratacultural Science, 21: 175-185.
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