Briefly, broccoli seeds (0.5 g per replication) were sanitized for 15 min in sodium hypochlorite (1.5%, v/v), rinsed with Milli-Q water and soaked with aeration overnight in darkness and at room temperature. After pouring off the soaking water, the seeds were spread evenly on standard 200 square cell plug trays (21.38 × 11.05 × 1.75) containing Canadian Sphagnum peat moss previously moistened. Sprouts were grown in a culture room with controlled temperature (25 ℃ ) and a photoperiod regime with cycles of 16 h light and 8 h darkness. Water (control) or a phytohormone solution were atomized every 12 h throughout the experiment.Six trays with broccoli sprouts seeds were prepared for this study, and were assigned for (A) Control (no UV or phytohormone application), (B) UVA treatment, (C) UVB treatment, (D) MJ treatment, (E) UVA + MJ treatment, and (F) UVB + MJ treatment.MJ treatments (D, E and F) were conducted based on Perez-Balibrea et al. with slight adjustments. Briefly, methyl jasmonate (MJ) was dissolved in 0.2% ethanol to obtain a 25 µM solution and applied every 12 h by exogenous spraying 65 mL of 25 µM MJ solution from sowing day until the end of the experiment (8th day after sowing). Due to the volatility of MJ and to avoid the fact that treatment to one tray may result in application to neighboring trays, the MJ solution was applied using physical separation. Control sprouts (A) and sprouts treated with UVA or UVB alone (B and C) were irrigated with the same frequency using 65 mL of Milli-Q water containing 0.04% ethanol.On the 7th day after sowing, UV (B and C) and UV + MJ (E and F) treatments were carried out in special UVA and UVB chambers based on Moreira-Rodriguez et al. with slight adjustments. Chambers used for treatments B and E were equipped with two 40 W UVA lamps (Sylvania F40W T12 BL350, Ledvance LLC., Wilmington, MA, USA), while chambers for treatments C and F consisted of two 40 W UVB lamps (Philips TL 40W/12 RS, Philips, Ljubljana, Slovenia). Trays with broccoli sprouts were placed 30 cm below the irradiation source. All UV treatments consisted of a single exposure for 120 min. The irradiation intensities were determined prior to the experiment as 9.47 and 7.16 W/m² for UVA and UVB, respectively, using a PMA 2200 radiometer equipped with PMA 2110 UVA and PMA 2106 UVB sensors (Solar Light, Glenside, PA, USA) measuring in the spectral range from 320-400 nm and 280-320 nm, respectively.After UV treatments, trays were returned to culture room and the proper irrigation with water or MJ solution continued for an additional (acclimatization) period of 24 h. Sprouts of all six trays were harvested at the 8th day after sowing, immediately flash-frozen in liquid nitrogen, placed at -80 ℃ , freeze-dried (Labconco, Kansas City, MO, USA), and then ground to a fine powder. Samples were stored at -80 ℃ until further analysis.

Simple pre-harvest treatments such as UV radiation, applied alone or in combination with exogenous MJ, can be used as an effective emerging technology that allows the accumulation of specific phytochemicals in broccoli sprouts. Furthermore, results demonstrated that the profile of glucosinolates accumulated in stressed broccoli sprouts could be tailored towards the over-production of most indole glucosinolates by applying 25 µM MJ alone or preferably in combination with a 120 min exposure to UVA or UVB radiation (9.47 and 7.16 W/m², respectively) 24 h prior harvest. Specifically, a synergistic effect in the accumulation of NGBS was achieved by combining UV and MJ stresses. On the other hand, the production of aliphatic or specific indole glucosinolates can be triggered by UVB supplementation alone. MJ treatments may be applied if an increase in gallic acid, its derivative GAH II, specific sinapic acid derivatives (e.g., 5-SQA) and ferulic acid derivatives (e.g., 1,2-diFG) is desired. However, such increases would be at the expense of the following compounds: GAH I, GTA, diGH, 3-O-H-K, 1-O-S-beta-d-g, sinapoyl malate, sinapic acid, K-3-O-S-so-7-O-g, 1,2-diSG, 1-S-2-FG, the majoritarian isomer of 1,2,2-triSG and 1,2-diS-1-FG; as they were significantly reduced after treatments with MJ. Application of UVA alone may be recommended to accumulate GAH I, 1-O-S-beta-d-g, sinapic acid, gallic acid, K-3-O-S-so-7-O-g, 1-S-2-FG and the second isomer of 1,2,2-triSG. Finally, a single 120 min exposure to UVA radiation should be applied to increase xanthophyll and chlorophyll content in broccoli sprouts.