Selective and Mild Transcriptional Modulation of Lectin Genes in Soy Leaves Under Drought Stress

Drought is the single largest abiotic threat to soybean yield, yet the lectin genes that mediate drought perception and signaling in this crop have never been systematically mapped. We reanalyzed the public RNA-seq dataset GSE237798 (Williams 82 leaves, 7-day water withdrawal) with an updated fastp–HISAT2–featureCounts–DESeq2 pipeline and a curated catalog of 359 soybean lectin loci. Of the 127 lectin transcripts showing any drought-dependent shift, only 15 were stringently differentially expressed with substantial fold changes: 7 were upregulated and 8 downregulated. These genes span four families, GNA, legume, LysM and Nictaba-related lectins, and are heavily biased toward lectin receptor-like kinases (11 of 15), pinpointing the plasma membrane as the main control node. Gene Ontology enrichment highlights protein autophosphorylation and signal-transduction terms, and the inspection of AlphaFold models together with established lectin knowledge indicates that G- and L-type lectin domains have largely lost canonical carbohydrate-binding residues, whereas LysM and Nictaba proteins retain conserved folds compatible with ligand binding. The data expose a focused, modular lectin program rather than the broad activation often assumed: most soybean lectins stay silent under drought conditions, and only a defined subset toggles their expression, albeit mildly.