## 1 Introduction
Interestingly, nor _MYB28-29_ nor _MYB76_ were shown to be modulated at transcriptional level by the _MYC2-4_ expression, suggesting independent roles in GSL regulation [17]. AG structure-related bioactivity and their differential synthesis and accumulation depending on developmental stages, growth conditions, type of organs and tissues have been the subject of many studies [18]. AGs have also been exploited in the development of bioproducts for diverse applications, ranging from agriculture (e.g., amendments, biotherapics, and biopesticides for pest and pathogen control both in open field and in post-harvest), to animal and human health [19; 20; 21; 22; 23; 24]. For this reason, there is a growing interest in strategies aimed at developing ideotype crops with the desired GSL profile. It is well known that, despite their biological diversity and in planta function, the modulation of secondary metabolites biosynthesis such as GSLs can be achieved by the application of diverse exogenous elicitors [25]. Chemical, physical and hormone-like treatments can be applied to plant tissues and organs to mimic biotic and abiotic cues, thereby triggering a defense response and promoting the accumulation of specific bioactive compounds. Elicitation strategies can be tested under various experimental designs (in vitro, in vivo establishing trials in pot, etc.) to identify optimal conditions, such as agronomic practices, to direct the metabolites flux towards the selective accumulation of phytochemicals. These strategies can be used to both increase the production of specific compounds in plant cells and stimulate the synthesis of novel metabolites [18; 26; 27; 28]. Indeed, over the past years several attempts at modulating GSLs biosynthesis and accumulation through molecular strategies [29] and treatments with elicitors have been carried out [30; 31]. In particular, exposure to salinity influences the synthesis of GSLs, with variations in both AGs and indolic GSLs, that depend also on the ionic composition of the salts [31; 32]. Among the crops belonging to the Brassicaceae family, there is one species particularly interesting for its abundant methionine-derived AGs: _Eruca sativa_ Mill [33], synonym of _Eruca vesicularia_ subsp. _s sativa_ (Mill.) Hegi (wfoplantlist.org (accessed on 24 June 2025)), commonly known as rocket or arguula. It is an annual allogamous species having a diploid genome whose sequence was recently released [34], known since ancient times for both food and diverse industrial uses [35; 36]. In the current study, with the intention to modulate AGs in _E. sativa_ to then exploit them for the development of new bioproducts, plants were treated with Na\({}_{2}\)SO\({}_{4}\), selected as a simple elicitor, which had already proven to be able to modulate GSL content in different organ of _Brassica rapa_[31]. Moreover, benefitting from the knowledge on the GSL pathway from other Brassicaceae and the available information about _E. sativa_ GSL orthologous genes identified in silico [37], as well as putative MYBs encoding genes with regulatory function [34], the expression profiles of selected biosynthetic and regulatory genes that could be involved in AG synthesis were correlated with the GSL content [31]. Four key members of _E. sativa_ genes families involved in the first and second step of AG biosynthesis and encoding for the enzymes Branched-Chain Aminotransferase 4 (BCAT4), Methylthioalkylmalate Synthase 1 (MAM1), Superroot 1 (SUR1) and Cytochromes P450 83A1 monooxygenase (CYP83A1) were selected. Indeed, BCAT4 and MAM1 have a central function in the chain elongation steps of methionine-derived AG biosynthesis, also determining their structural diversity (Figure 1). The C-S lyase SUR1, involved in the core formation step of both AG and indole GSL biosynthesis, and CYP83A1, which in _A.