## 3 Discussion
Therefore, results suggest that SA and ET signaled an increase in ascorbate levels by stimulation of L-galactose, complemented by myo-inositol and L-glucose pathways, and its decrease is triggered by Meja and mainly by ABA. According to [73], ethylene and ABA act antagonistically in the regulation of ascorbate biosynthesis. While ethylene or its precursor ACC increased Asc levels, ABA reduced it. As a result, ethylene prevented but ABA promoted the accumulation of ROS. In addition, ascorbate-deficient vtc-1 _Arabidopsis_ mutant accumulated ABA and the oxidized form, dehydrorosorbate [74]. Moreover, ABA reduced the _AceGGP3_ expression and Asc amounts in kiwifruit by repressing the expression of _AceMYBS1_[49]. In this sense, ABA application reduced ascorbic acid and glutathione levels, but increased the expression levels of antioxidant enzymes in _C. annuum_[75]. Moreover, exogenous ethylene and gibberellin augmented Asc content in citrus [76], while _GPP_ mRNA levels increased in tomato fruits treated with ethylene [44]. In accordance, SA treatment increased endogenous Asc levels and expression of L-galactose pathway genes and reduced chilling injury of kiwi and pomergnate fruits [53; 61; 77]. In contrast, Asc levels were increased by ABA application in kiwi [53; 61] and Meja in carambola fruits [78], despite _GPP_ and _GME_ expression remaining unaffected by ABA. Regarding the contribution of pathways, genes of the L-galactose pathway revealed ubiquitous, high expressing levels and up-/down-regulation pattern that highlight its constitutive and central role in Asc-biosynthesizing process in all pepper organs, and stress and phytohormone stimuli are evaluated here (Figures 6-11; Tables S6-S11), as verified in tomato [44; 55], _Arabidopsis_[73; 74], acerola [25; 27], and tea [52] species. However, expression profile supports evidence that alternative pathways could play a significantly secondary role, and even an insignificant one, given its genes' low- and even non-expression patterns (cpm normally \(<3\)). Under normal conditions (including fruit development), the effects of heat, salt, osmotic, and ABA treatments on alternative pathways appear to be insignificant, despite slight fluctuation in gene expression (Figures 3-6 and 11 and Tables S3-S6 and S11), whereas under cold, waterlogging, pathogenic infection, Meja, SA and ethophone, and induction of genes from myo-inositol and/or L-glucose pathways indicate some complementary role in attenuation of, maintenance of, or increase in Asc biosynthesis activity in attempt to balance L-galactose fluctuations (Figures 6-11 and and Tables S6-S11). Nevertheless, further wet lab experimentations are required to clarify the relevance of these pathways. Regarding potentially key regulatory genes, these findings indicate the major role of _GGP2_, and the complementary role of _GME1_, 2, and _GallLDH_ members from the principal Asc biosynthesis pathways for fine-tuning adjustments in the biosynthetic process in specific stress/phytohormone types and exposure periods. For instance, cold stress remarkably increased _GGP2_ transcripts amounts, followed by the up-regulation of _GME_, and _GPP1_ (Figures 6 and 7 and Tables S6 and S7). Under waterlogging recovery and SA application, _GGP2_ overexpression was assisted by _GallDH_ (Figures 8 and 11 and Tables S8 and S11); while under longer periods of heat, NaCl, osmotic, and biotic stresses, _GGP2_ was sharply down-regulated, followed by _GME_, _GallDH_, and _GallLDH_. Interestingly, _GME1_ and _GME2_ were the most responsive to pathogen and ET (Figures 9 and 11 and Tables S9 and S11). Among genes from alternative pathways, _MIOX3_ and _GullO2_ were notably responsive to cold, waterlogging, ET, SA, and pathogenic infections (Figures 6-10 and Tables S6-S10). Various studies using these genes to manipulate Asc metabolism successfully increased ascorbate content and plant tolerance to environmental stresses, thus clarifying their key regulatory role.