NMR-based metabolomics and pathway analysis of leaves and fruits of Cucumis melo L. cultivated under saline stress conditions

Abstract

The consumption of healthy food has become increasingly present and eating fresh, quality fruit is part of this trend. Nevertheless, the scarcity of fresh water and the increasing demand for food have been driving the search for more sustainable agricultural practices worldwide. In this context, cultivation with lower-quality water, characterized by a high concentration of salts, emerges as alternative to enhance water use efficiency and ensure food security in regions prone to water scarcity. In this regard, the aim of this work was to use an NMR-based metabolomics approach to investigate the growth and metabolomic profile of yellow melon fruits and leaf cultivated under water salinity conditions (1.5, 2.5, and 4.5 dS m⁻¹). The research was conducted in a protected environment at Embrapa Agroindústria Tropical (3°44′S, 38°33′W, altitude 19.5 m, Fortaleza, Ceará, Brazil). Melon plants (yellow type, inodorous group, non-climacteric) were grown in 12 L pots filled with coconut fiber substrate and irrigated using a drip irrigation system. Salinity reduced fruit weight and metabolic activity, but did not significantly alter soluble solids content. Metabolic profile determinate by NMR showed that essential pathways in the leaves produced metabolites for defense, energy maintenance, and cellular integrity, minimizing the impact on fruit composition. Under salinity, hexoses (glucose and fructose) were more efficiently converted into sucrose, indicating that melon plants maintain its essential metabolism in leaves under saline stress, enhancing tolerance. The increased sucrose content in the fruit, important for consumers, is preserved, making melon a viable option for implementation of efficient water use strategies.