Cross-dataset validation of TaSOS۱ homeolog responses to salinity stress in bread wheat reveals conserved induction with tissue- and homeolog-specific divergence

Salinity imposes simultaneous osmotic and ionic constraints on plants, with maintenance of cellular Na+ homeostasis representing a central component of salt tolerance. In allohexaploid bread wheat (Triticum aestivum L.), the three TaSOS۱ homeologs located on chromosomes ۳A, ۳B and ۳D provide an informative system for evaluating homeolog-specific responses to salt stress. Here, we performed an independently validated cross-dataset analysis of TaSOS۱ expression using two publicly available wheat transcriptomic datasets, GSE۲۲۵۵۶۵ (C۰۲) and GSE۱۶۶۲۶۰ (C۰۳). The three TaSOS۱ homeologs-TaSOS۱-A (TraesCS۳A۰۲G۰۲۳۲۰۰), TaSOS۱-B (TraesCS۳B۰۲G۰۲۱۶۰۰), and TaSOS۱-D (TraesCS۳D۰۲G۰۲۲۹۰۰)—were evaluated in root and shoot/leaf tissues after explicit tissue harmonization. Expression-derived log۲ fold changes were calculated from validated mean expression values using dataset-specific pseudocounts. In C۰۲, all six homeolog-tissue combinations showed positive expression-derived responses, ranging from ۰.۰۳۸۱ for TaSOS۱-B in shoot to ۰.۷۶۰۶ for TaSOS۱-D in root. In C۰۳, five combinations were positive, whereas TaSOS۱-D in root showed a negative response (-۰.۲۳۰۰). Cross-dataset comparison demonstrated directional concordance in five of six matched combinations (۸۳.۳%), with TaSOS۱-D/root being the sole discordant combination (Δlog۲FC = -۰.۹۹۰۶). Across the six matched observations, the Pearson correlation between C۰۲ and C۰۳ effect sizes was -۰.۳۷۲, indicating that directional concordance did not translate into strong quantitative agreement in response magnitude. Importantly, the reported log۲FC values are descriptive expression-derived effect sizes and are not DESeq۲-derived inferential statistics. Independent S۳ genetic and phenotypic evidence comprising ۳۱۷ verified accessions, ۳۷ significant SNPs, ۱۶ reconstructed loci and five reported candidate genes provide broader salt-response context, but no direct accession-level linkage to TaSOS۱ expression was established. Together, the results support a broadly conserved TaSOS۱-associated salt-responsive pattern while identifying substantial homeolog- and tissue-dependent heterogeneity, particularly for TaSOS۱-D in root.

کلیدواژه ها:

Triticum aestivum ، TaSOS۱ ، salinity stress ، homeolog ، Na+/H+ antiporter ، RNA-seq ، cross-dataset validation ، expression-derived log۲FC ، wheat ، salt tolerance