## 4 Discussion
### Color Development in Peel and Transcription of Related Enzymes  
Peel color in the C0 category (sound fruit) remained nearly green, and was not affected by SA application. Color in the C1 category (slightly-cracked fruit) remained rather stable and close to the one in C0, apart from a limited coloration following 1 mM SA application. Peel color changes were mostly evident in the C2 category (highly-cracked fruit). This implies that peel red color development mostly occurred in cracked fruit. This does not necessarily suggest that all cracked fruit are riper than sound fruit, since other factors, such as adequate sunlight reception, promote coloration [41]. Cracking stress could possibly induce anthocyanin synthesis as well. Preharvest salicate application enhanced color development in cherry [39] and grape [23; 42], whereas it delayed it in another sweet cherry study [40]. However, the direction of the effect may be altered by adjusting the applied concentration and developmental stage. For instance, coloring was drastically prevented with 0.5 mM MeSA in tomato [24] and 5 mM or 10 mM SA in grapes [23], whereas it was promoted at lower concentration than the ones used in both last cases. SA application (1 mM) resulted in slightly enhanced peel coloration as compared to the remaining treatments. However, cracking was alleviated more by the higher SA concentration (2 mM), and this is far more important for fruit marketability, as compared to coloration. The obtained results confirmed that the major peel anthocyanin was c-3-rut in the variety under study [31]. Similar findings have been obtained by examining other varieties [43; 44]. Indeed, here, TAN and c-3-rut contents were significantly positively related (\(r=0.978\)) (Table S1). Transcript accumulation of _PAL_, _ANS_, _UFGT1_, and _UFGT2_, corresponding to anthocyanin synthesis, did not seem to follow TAN or c-3-rut content changes (Figure 5; Table S1). In this study, PAL gene transcripts were the highest in green peel sound fruit after SA treatment, indicating its possible role for crack prevention. It is well known that PAL enzyme is the first step of phenylpropanol biosynthesis prosthetic pathway [45]. It is required for the biosynthesis of anthocyanins, but also of a diverse range of phenolic compounds, upregulating antioxidant defense [27; 46]. A similar defense stimulation due to salicate application was reported earlier in red cherry [39], plum [22], and goji berry [16]. PAL transcription and activity was also elicited by low temperature stress [47], exerting the above-mentioned positive effects on non-colored fruit tissue [46]. Therefore, salicate application effectively mimics the stress-induced increase in _PAL_ transcript levels. ANS converts the leucoanthocyanidins to colored anthocyanin [35]. In this study, _ANS_ transcript levels were similar among treatments. By contrast, earlier work indicatedthat _FcANS1_ gene expression and anthocyanin content were similarly upregulated during fig development and maturation [48]. The non-stable anthocyanins are further glycosylated by uridine diphosphate (UDP)-glucose: flavonoid 3-O-glycosl-transferase (UFGT), resulting in the stable anthocyanins [35]. This study revealed that the highest _UFGT1_ gene transcription was apparent in sound controls. A decrease in _UFGT1_ transcript accumulation in slightly- and highly-cracked fruit in comparison to the sound ones, as well as in SA-treated sound fruit was noted. On the contrary, _UFGT2_ gene transcription decreased cracking in controls and in 2 mM SA-treated fruit but increased considerably by cracking in 1 mM SA-treated fruit. Therefore, in this work, there was no relation of transcript levels of genes coding for PAL, ANS, UFGT1, and UFGT2 either among them or to any other variable under study (Table S1). Partially or completely different patterns of expression in genes coding for enzymes responsible for anthocyanin synthesis have also been previously observed in cherry [49] and pear [50]. It is worth noting that fig ripening physiology is unique in several aspects.