## 3 Discussion
Concerning gene expression, _GMP_ and _GalLDH_ (D-mannose/L-galactose pathway) duplicated gene pairs revealed similar expression profiles regarding all tissues and development stages under control conditions; however, differences were observed under stress conditions. Different expression profiles for _GME_ and _MIOX_ also prevailed regarding various tissues and stress conditions (Figures 3-9; Supplementary Tables S3-S7). Thus, these data indicate that duplicated genes in _G. max_ gained functional diversity (neofunctionalization) or divided original function (subfunctionalization) between duplicated genes, mainly induced by stress conditions. In addition, other genes such as _GalUR_3_ and _MIOX_3\(b\) were not detected (or scarcely detected) in any tissue/condition, suggesting a possible loss of function (_pseudogenization_--nonfunctional genes) [43; 44]. Regarding the general expression profiles of all genes from _G. max_, it was evident that genes from the D-mannose/L-galactose pathway were ubiquitously expressed with higher mRNA levels (Figure 3; Supplementary Table S3), showing fluctuations of up/downregulation among gene members during development and stress conditions (Figures 4-10; Supplementary Tables S4-S7). In contrast, genes from the L-glucose, D-galacturonate, and Myo-inositol pathways were usually expressed at low levels or not expressed under control conditions, despite some ubiquitously expressed genes (_GulLO_1c_ and \(3\), _GalUR_4, and MIOX_1a, _1b_ and _2b_). Specific gene members were strongly stimulated or induced under different stress conditions (Figures 5-9; Supplementary Tables S3-S7). These data highlight that the D-mannose/L-galactose pathway is the main constitutive AsA biosynthetic pathway in _G. max_. This outcome underlines studies in _Arabidopsis_ with mutants that had highlighted D-mannose/L-galactose as the main pathway for AsA supply in this model species [45; 46; 47; 48]. Other genetic and biochemical studies also suggested D-mannose/L-galactose as the major AsA biosynthetic pathway in streptophytes [49]. Despite the main role of the D-mannose/L-galactose pathway, our findings point to a mutual regulation with other AsA biosynthetic pathways regarding developmental stages and stress conditions. During germination, increased AsA levels (Figure 10) reflect a significant increase in the mRNA levels of most of the genes from all the AsA biosynthesis pathways (Figure 4; Supplementary Table S4), suggesting that all the proposed pathways cooperatively contribute to the total AsA level. It has been observed that a high upregulation of genes encoding proteins of the AsA-GSH cycle from different cellular compartments reinforces the critical role of AsA during _G. max_ seed germination [10]. Germination depends on ROS to break seed dormancy and promote germination [50]. However, this process needs to be fine-tuned to avoid excessive ROS. The presented data point to an interaction between AsA biosynthesis and the AsA-GSH cycle to maintain redox homeostasis during germination in _G. max_. AsA's beneficial effect on germination has been evidenced in other leguminous plants such as alfalfa [51] and cowpea [52], where the exogenous application of AsA increasedthe germination rate and stress tolerance. Advancing AsA biosynthesis regulation in _G. max_, we observed the adverse effect of PBZ (a gibberell inhibitor) on AsA biosynthesis genes (Figure 4; Supplementary Table S4); a similar response was previously detected for AsA-GSH cycle genes [10]. Gibberell (GA) and abscisic acid (ABA) are antagonistically acting phytohormones during seed germination, with ABA maintaining seed dormancy and GA promoting germination, and a homeostatic GA/ABA balance needs to be reached to boost germination [53; 54]. Therefore, GA inhibition could cause a GA/ABA ratio imbalance favoring the ABA effect and limiting germination by a mechanism involving AsA biosynthesis decrease.