Untargeted metabolome reveals key metabolites and genes underlying salinity tolerance in maize

Authors: BRAR, MANWINDER - Clemson University; DE SOUZA, AMANCIO - University Of California, Riverside; GHAI, AVINEET - University Of California, Riverside; Ferreira, Jorge; Sandhu, Devinder; SEKHON, RAJANDEEP - Clemson University

Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2025
Publication Date: 9/23/2025
Citation: Brar, M.S., De Souza, A., Ghai, A., Ferreira, J.F., Sandhu, D., Sekhon, R.S. 2025. Untargeted metabolome reveals key metabolites and genes underlying salinity tolerance in maize. The Plant Genome. 18: Article e70102. https://doi.org/10.1002/tpg2.70102.
DOI: https://doi.org/10.1002/tpg2.70102

Interpretive Summary: Salinity is a serious problem affecting agriculture worldwide, reducing crop yields and threatening food security. This study aimed to understand how maize plants cope with salty conditions by looking closely at two maize varieties—one sensitive to salt (C68) and another tolerant to salt (NC326). The salt-sensitive maize suffered significant growth setbacks, accumulating too much harmful sodium and chloride while failing to keep beneficial nutrients balanced. In contrast, the salt-tolerant maize showed better growth, maintained a healthier balance of nutrients, and produced more protective compounds (like proline and certain antioxidants). Using advanced techniques, the researchers identified specific metabolites in plants that help protect them from salt damage. Some of these protective molecules, including flavonoids and specialized fats, were naturally higher in the salt-tolerant maize, providing built-in defense. Others increased in both varieties only after exposure to salt, helping them adapt by stabilizing their cells and reducing damage. Importantly, the study also discovered several genes responsible for producing these helpful molecules. This information will be valuable to maize breeders and molecular biologists. Breeders can use these findings to identify and select key traits, accelerating the development of new maize varieties with enhanced salt tolerance. Molecular biologists can utilize the insights gained from the identified genes and metabolites to further investigate the genetic mechanisms underlying salt tolerance, facilitating the genetic engineering of maize and potentially other crop species for improved resilience to salinity stress. Overall, these findings represent a significant step toward developing stronger, more resilient maize varieties for a future facing increased soil salinity challenges.

Technical Abstract: Understanding the physiological, metabolic, and genetic mechanisms underlying salt tolerance is essential for improving crop resilience and productivity, yet their complex interactions remain poorly defined. We compared physiological and metabolic responses to salinity between two contrasting maize (Zea mays L.) inbred lines: the salt-sensitive C68 and the salt-tolerant NC326. The sensitivity of C68 was characterized by reduced shoot and root dry weights and plant height, high tissue accumulation of Na and Cl but low K, and lower leaf proline accumulation compared to the salt-tolerant NC326. Untargeted metabolomics identified 56 metabolites categorized as constitutively upregulated or salt-responsive. In NC326, constitutive accumulation of flavonoids, including schaftoside, tricin, and kaempferol-related compounds in leaves, suggests adaptive priming against oxidative stress, while constitutively higher lipids and fatty acids in roots may enhance membrane stability. Salt-responsive metabolites, notably antioxidants and lanosterol, highlighted inducible oxidative-stress mitigation and membrane-stabilization strategies. By integrating metabolomic and genetic analyses, we identified 10 candidate genes involved in the biosynthesis of key metabolites. These findings establish a comprehensive platform for functional validation of metabolites and candidate genes for developing maize varieties with improved resilience to soil salinity through targeted breeding or biotechnological strategies.