Bioactive Glucosinolate-Rich Extract Promotes Growth in Broccoli Seedlings by Modulating Energy Allocation

Bioactive extracts derived from plants are emerging as the most innovative and promising alternative to traditional stimulants/chemicals in the agricultural market, given their high availability and rich content of bioactive compounds. Previously, the group synthesized and characterized a Brassicacea extract rich in secondary metabolites such as glucosinolates and phenols, which demonstrated a biostimulant effect in broccoli (Brassica oleracea L. var. italica) seedlings. Consequently, the main objective of this study was to investigate in detail the molecular mechanisms responsible for the stimulant capacity exhibited by the Brassicacea extract. For this aim, RNA sequencing was carried out to analyze gene expression in broccoli seedlings grown with the extract for 2 weeks, in combination with physiological measurements related to mineral composition, root transport, photosynthesis, and secondary metabolism. Treated seedlings exhibited an increase in macronutrients such as K, Ca, Mg, and S, along with a significant up-regulation of aquaporin genes and an enhancement in relative water content (RWC), indicating a clear improvement in mineral and water homeostasis. Additionally, root structure was enhanced, correlating with the overexpression of genes associated with suberin synthesis. Moreover, a general activation of genes involved in energy production, including those of the Krebs cycle, was observed. The results revealed that the extract plays a key role in modulating plant metabolism by shifting resources away from secondary metabolism and redirecting them toward primary metabolism, ultimately promoting a higher growth rate.