Blue-enriched LED light modulates biochemical and proteomic traits without affecting yield in indoor-grown cress microgreens

Light spectral composition is a key driver of plant growth and quality in controlled-environment agriculture. This study evaluated the effects of two LED light spectra differing in blue, green, red, and far-red proportions on growth, nutritional traits, and proteomic profiles of indoor-grown cress (Lepidium sativum L.) microgreens. Plants were cultivated under two B:G:R:FR ratios (13:15:61:11 and 24:12:56:8) at identical photosynthetic photon flux density (255 μmol m-2 s-1). Growth parameters, including plantlet height, fresh and dry weight, dry matter percentage, and yield, did not differ significantly between treatments. Similarly, nitrate content, total chlorophylls, total carbon, total nitrogen, and the C/N ratio remained unchanged. In contrast, the blue-enriched and far-red-reduced spectrum significantly enhanced secondary metabolite accumulation, increasing anthocyanin concentration and phenolic index rising by 77% and 52%, respectively. Microgreen proteomics revealed a general plant reprogramming depending on LED light irradiation, mostly involving components associated with photosynthesis, protein physical control/biosynthesis/homeostasis/modification, multi-process regulation, RNA biosynthesis, vesicle trafficking, redox homeostasis or with unknown function, which showed over- or down-represented trends according to their nature. Notably, these molecular adjustments occurred without compromising growth or productivity. Overall, these results demonstrate that targeted manipulation of LED light quality can enhance the functional and nutritional quality of microgreens through proteomic reprogramming while maintaining yield, highlighting light spectrum modulation as a promising strategy for sustainable indoor and vertical farming systems. Repository data: PRIDE accession number PXD077094 (ProteomeXchange).