Involvement of glucosinolates and phenolics in the promotion of broccoli seedling growth through the modulation of primary and secondary metabolism

Secondary metabolites play an essential role in plant defense. However, the role of glucosinolates and phenols in brassica crop yield in the context of environmentally friendly agricultural practices has not been established. Our study investigated the effects of a Brassica extract, rich in these metabolites, on the physiology and metabolism of broccoli (Brassica oleracea L. var. italica) seedlings and the subsequent development of the plants in adult stages. The results showed an increase in growth in the extract-treated seedlings, which was associated with an alteration of primary and secondary metabolism. In particular, there was an increase in the levels of amino acids, phenolic compounds and hormones, while the levels of glucosinolates decreased. Lipid peroxidation diminished in treated plants, indicating improved membrane integrity. Treated plants subsequently grown in hydroponically showed increased water use efficiency, transpiration, and internal carbon, which contributed to the improved growth of these plants. Overall, our findings underscore the potential of the glucosinolates and phenols ratio as essential to improve crop growth and stress tolerance, as well as revealed the interest of studying the mechanisms involved in the possible uptake and integration of GSLs by broccoli seedlings after external application.