GC–MS Maps Sugar Compounds in Sweet Corn

Sweet corn is popular with consumers mainly because of its sweet taste, which comes down to how sugars are processed within the kernels. Even though this matters so much for the corn's appeal, we still don't fully understand the genes and regulatory processes behind that sugar processing. To help close this gap, researchers used gas chromatography–mass spectrometry (GC–MS) to identify 27 different sugar-related compounds at various stages as the kernels developed. At the same time, they used advanced sequencing technology to track which genes were active at three key stages of kernel development, helping them pinpoint candidate genes likely involved in controlling sugar levels.

“This investigation,” wrote the authors of the resulting paper, which was published in the journal iScience,¹ “substantially enhances our comprehension of the transcriptional regulatory frameworks governing sugar metabolism and provides a foundation for the molecular breeding of sweet corn.

Why Is Sweet Corn Important?

Sweet corn (Zea mays var. rugosa Bonaf.) is grown widely around the world a nd is considered an important crop both as a vegetable and fruit. People appreciate it for its great taste and nutritional benefits, and it's typically eaten fresh or used to make canned corn and other corn-based products.^2,3

Why Is Studying the Sugar Metabolism of Corn Worth Doing?

Sugar metabolites are basic building blocks that all living things need to survive. Beyond just adding sweetness, they play key roles in keeping plants alive and functioning, including helping them grow, regulating their hormones, powering photosynthesis, keeping their internal clocks on schedule, and helping them cope with environmental stresses like drought or extreme temperatures.^4-7Even though researchers have put a lot of work into identifying the sugar-related compounds in sweet corn, a clear picture of the genetic processes that control how those sugars are produced and managed has still not emerged.^8-10

What Did the Study Find?

For this study, the researchers closely tracked sugar-related compounds at three key stages of sweet corn kernel growth, called the blister, milky, and waxy stages. Their results suggest that the length of a certain RNA tail (called the poly(A) tail) may influence sugar metabolism during kernel development by affecting how much of a gene's product gets made.¹

What Do the Researchers Say Their Findings Contribute?

“Despite the identification of several critical regulatory genes implicated in sugar metabolism,” write the authors of the paper,¹ “the exact mechanisms underlying their interactions and functional impacts remain inadequately characterized. This study presents a thorough transcriptomic analysis of differentially expressed genes across multiple stages of kernel development. Furthermore, it explores the association between these genes and sugar metabolism, thereby clarifying their biological functions from a transcriptomic standpoint. The results provide a theoretical basis for further investigations into the nutritional quality of sweet corn and support the breeding of improved cultivars.”

The researchers admit to some limitations with their study. While they used a cutting-edge gene-sequencing technology (from Oxford Nanopore) to get a sense of how genes might be turned on and off to control sugar levels as sweet corn kernels develop, they were unable to confirm these candidate genes' roles through hands-on lab techniques, like boosting their activity or using gene-editing tools such as CRISPR. The sequencing method used, which skips a DNA-copying step, also has some limitations: it can struggle to detect genes that are only weakly active and to precisely measure the length of a certain RNA tail (called the poly(A) tail). Additionally, while their results hint that the length of this RNA tail might affect sugar metabolism by changing how much of a gene's product is made, this is only based on a pattern they observed; they haven't yet directly proven a cause-and-effect link.¹

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References

1. Feng, H.; Guo, J.; Xu, C. et al. Elucidation of Sugar Metabolic Profiles and Transcriptional Regulatory Networks During the Developmental Stages of Sweet Corn Kernels. iScience 2026, 29 (6), 116247. DOI: 10.1016/j.isci.2026.116247
2. Xie, L.; Yu, Y. ; Mao, J. et al. Evaluation of Biosynthesis, Accumulation and Antioxidant Activity of Vitamin E in Sweet Corn (Zea mays L.) During Kernel Development. Int. J. Mol. Sci. 2017, 18, 2780. DOI: DOI: 10.3390/ijms18122780
3. Lertrat, K.; Pulam, T. Breeding for Increased Sweetness in Sweet Corn.Int. J. Plant Breed. 2007, 1, 27-30. http://www.globalsciencebooks.info/Online/GSBOnline/images/0706/IJPB_1(1)/IJPB_1(1)27-30o.pdf
4. Lastdrager, J. ; Hanson, J. ; Smeekens, S. Sugar Signals and the Control of Plant Growth and Development. J. Exp. Bot. 2014, 65, 799-807. DOI: 10.1093/jxb/ert474
5. Graf, A.; Schlereth, A.; Stitt, M. et al. Circadian Control of Carbohydrate Availability for Growth in Arabidopsis Plants at Night. Proc. Natl. Acad. Sci. USA. 2010, 107, 9458-9463. DOI: 10.1073/pnas.0914299107
6. Chen, J.; Huang, B.; Li, Y. et al. Synergistic Influence of Sucrose and Abscisic Acid on the Genes Involved in Starch Synthesis in Maize Endosperm. Carbohydr. Res. 2011, 346, 1684-1691. DOI: 10.1016/j.carres.2011.05.003
7. Keunen, E.; Peshev, D. ; Vangronsveld, J. et al. Plant Sugars are Crucial Players in the Oxidative Challenge During Abiotic Stress: Extending the Traditional Concept. Plant Cell Environ. 2013, 36, 1242-1255. DOI: DOI: 10.1111/pce.12061
8. Yang, R. ; Li, Y.; Zhang, Y. et al. Widely Targeted Metabolomics Analysis Reveals Key Quality-Related Metabolites in Kernels of Sweet Corn. Int. J. Genomics. 2021, 2021, 1-12. DOI: 10.1155/2021/2654546
9. Chen, B.; Feng, S. ; Hou, J. et al. Genome-Wide Transcriptome Analysis Revealing the Genes Related to Sugar Metabolism in Kernels of Sweet Corn. Metabolites 2022, 12, 1254. DOI: 10.3390/metabo12121254
10. Chen, S.; Zheng, Y.; Fan, W. et al. Unravelling the Postharvest Quality Diversities of Different Sweet Corn Varieties. Postharvest Biol. Technol. 2024, 209, 112718. DOI: 10.1016/j.postharvbio.2023.112718