## 3 Results and Discussion  
### L-DOPA Content  
With regard to L-DOPA concentration in control tissues: Although low contents were found in seeds, an increasing tendency in time could be observed until stage S3 (2-4 leaves emerged, 15 days approx), reaching concentrations up to 14.2 \(\pm\) 0.38 mg g\({}^{-1}\) DW (1.42 \(\pm\) 0.03% DW) (Figure 1). Steady high concentrations were found in sprouts and roots as time progressed. Indeed, concentrations as high as 125.87 \(\pm\) 17.18 mg g\({}^{-1}\) DW (12.5 \(\pm\) 1.7% DW) were observed in sprouts (S2 stage: 8-9 days), i.e., 10 times higher than in seeds, sprouts being the richest sources of L-DOPA found (Figure 1). This is in accordance with [PERSON] [11], who observed similar trends as germination took place in a _V. faba_embryo axis with a concentration range of 20.3 mg g\({}^{-1}\) DW (at day 0) up to approximately 80 mg g\({}^{-1}\) DW at 9 days, in light germination as well. The L-DOPA content decreased with tyrosine treatment at almost all stages of roots and sprouts. In seeds, no significant differences in L-DOPA concentrations were detected at almost all stages, except for stage S1 (3-4 days) (Figure 1), in which a slight increase in such content was found. It must be noted that light exposure during germination seems to be an important factor in the accumulation of L-DOPA, since [PERSON] et al. [27], [PERSON] et al. [21], and [PERSON] et al. [28] describe a totally different trend, i.e., decreasing L-DOPA content at the early stages of _V. fuba_ being germinated in darkness (values in the order of 4 mg g\({}^{-1}\) to 1.5 mg g\({}^{-1}\) FW in from day 0 to day 8, respectively). Indeed, they report L-DOPA contents that decrease gradually as plant growth proceeds, which suggests that L-DOPA is only synthesized, or even that it could be possibly only imported, at the early developmental stages, in dark germination [28; 29]. On the contrary, increasing DOPA contents were observed in light germinating faba bean (4 to 7 mg g\({}^{-1}\) FW from day 12 to day 16, respectively) [30]. Moreover, [PERSON] et al. [31] reported an apparent light effect in L-DOPA content in _Mucuna pruriens_ cell liquid culture (a threefold increase as compared with dark condition). In that sense, our results agree with those of [PERSON] et al. [11] and [PERSON] et al. [31] in that they both worked with legumes in light environments, finding, in [PERSON]'s study, a very high L-DOPA content in germinating faba bean harvested 9 days after imbibition (80 mg g\({}^{-1}\) DW) [11] and, in [PERSON] et al. [31], comparing a light versus a dark condition, finding more than three times L-DOPA under light culturing experiments with suspended Mucuna cells in liquid medium. From a physiological perspective, light enhanced L-DOPA production is consistent with developmental needs, i.e., more L-DOPA content needed as the plantule emerges above ground as an herbivory preventive strategy. Therefore, if L-DOPA maximal yield potential is sought, dark germination should be avoided in the experimental set ups. Recently, in a long-term greenhouse light germinating study, the highest L-DOPA concentration found in _V. faba_ seedlings harvested after 15 days of germination was 13.3 mg g\({}^{-1}\) DW [32]. It must be noted that the study weighed the whole seedling and did not separate individual tissues at that first stage of plant development, which could be one of the causes of a lower value than the former ones. Figure 1: Effect of tyrosine treatment on Levo-3,4-dihydroxyphenylalanine (L-DOPA) content in _Vicia fuba_ seeds, roots, and sprouts at the early stages of development: S1: 3–4 days, S2: 8–9 days, and S3: 2–4 leaves. The bars indicate \(\pm\) standard error (\(n=3\)). \({}^{*}\) indicates significant differences between controls and tyrosine treatments according to [PERSON] (\(P<0.05\)). Additionally, the same study determined L-DOPA content in leaf, weighing just that specific organ tissue, finding 10.5 mg g\({}^{-1}\) DW.