## Materials and Methods
### Aquaporin and BOR Primers Design and Expression  
For primer design, an approximation strategy was followed, since the genome of _Ipomoea hatatas_ is not published and the data are not available; however, information is available for two close relatives, _Ipomoea trilboa_ and _Ipomoea trifida_, with these two species being possible progenitors of _Ipomoea hatatas_[30,31]. For this reason, in order to design suitable primers for sweet potatoes (batata), several aquaporins genes (NIPs) and boron transporters (BOR) were identified in _I. trilboa_ and _I. trifida_, and orthologous genes were paired and aligned to obtain consensus sequences using Geneious Prime 2020.1.2 software ([[https://www.geneious.com/](https://www.geneious.com/)]([https://www.geneious.com/](https://www.geneious.com/))), (accessed on 8 December 2021). Conserved sites from these consensus sequences were selected as the targets for primer design. The primer design was carried out manually, meeting the specific requirements imposed by the high homology of the sequences used and the technique used for the analysis. As housekeeping, IbACT, was used [32]. A virtual analysis of melting temperature, primer hairpins, self-dimers, hetero-dimers, and individual and total \(\Delta\)G was performed with PCR Primer Stats ([[https://www.bioinformatics.org/sms2/pcr_primer_st](https://www.bioinformatics.org/sms2/pcr_primer_st)]([https://www.bioinformatics.org/sms2/pcr_primer_st](https://www.bioinformatics.org/sms2/pcr_primer_st))), (accessed on 10 November 2021) and IDT OligoAnalyzer tools ([[https://eu.idtda.com/calc/analyzer/](https://eu.idtda.com/calc/analyzer/)]([https://eu.idtda.com/calc/analyzer/](https://eu.idtda.com/calc/analyzer/))), (accessed on 10 November 2021). The \(\Delta\)G accepted for dimer analysis was less than \(-6\) kcal/mol. The specificity of the amplicons was checked using the virtual nucleotide basic local alignment search tool (NCBI nucleotide BLAST: [[https://blast.ncbi.nlm.nih.gov/](https://blast.ncbi.nlm.nih.gov/)]([https://blast.ncbi.nlm.nih.gov/](https://blast.ncbi.nlm.nih.gov/)) Blast.cgi), (accessed on 25 November 2021). The efficiency of the primer sets was evaluated with the software QuantStudio 5 (QuantStudio TM Design and Analysis Software version 1.4.0.0, Waltham, MA USA), by analyzing the threshold cycle (Ct)/fluorescence ratio at six independent points of the PCR curves [33], obtaining values between 95 and 100%. Four housekeeping gene primers [18 ribosomal RNA (18 rRNA), elongation factor 1-alpha (EF1a), actin (ACT), and eukaryotic initiation factor 4A (elf4a)] for _Ipomoea trilboa_ were selected according to [PERSON] et al. (2020) [32] and checked with each cDNA used in the quantitative PCR (qPCR), after which, these were measured using a Visual Basic Application for Excel (GeNorm), which automatically calculates gene stability [34]. The most stable constitutive gene, ACT, was then selected as the reference gene for standardization. The sequences and features of the primers used for the 11 _I. batatas_ NIP genes, 5 BOR transporters, and one constitutively expressed gene, are shown in Table 1.  
Lastly, the expression level of all the aquaporin genes was measured from 2 \(\upmu\)L of 1:10 diluted cDNA following the system instructions in the QuantStudio 5 Flex, a Real-Time qPCR system (Applied Biosystems by Thermo Fisher Scientific, Waltham, MA, USA). The qPCR program consisted of a 10 min initial denaturation at 95 \({}^{\circ}\)C and then amplification in a two-step procedure: 15 s of denaturation at 95 \({}^{\circ}\)C and 60 s of annealing and extension at a primer-specific temperature for 40 cycles, followed by a dissociation stage. Real-time PCR measurements were carried out in four independent RNA samples per treatment (biological replicates), and the Ct was determined in triplicate (technical replicates) in 96-well plates. Negative controls without cDNA were used in all the PCR reactions. The transcript levels were calculated using the 2\({}^{-\Delta\Delta\text{Ct}}\) method [35].