Genome-wide comparative analysis of the HSP90 gene family in four Ipomoea species and functional insights into the potentiality of IbHSP90–2 in low temperature tolerance

Introduction The 90-kDa heat shock protein (HSP90) acts as an essential molecular chaperone, involving plantresilience against diverse abiotic and biotic stresses. Although HSP90 genes have been studied in various plant species,they have not yet been characterized in sweetpotato. Methods In this study, we performed genome-wide identification, chromosomal localization, phylogenetic analysis, collinearity analysis, and promoter analysis of HSP90 genes in I. batatas and three closely related Ipomoea species. We also investigated gene expression patterns under cold, salt, and PEG-induced drought stresses, constructed protein-protein interaction networks, and determined the subcellular localization and functional role of IbHSP90-2 via heterologous expression in yeast. Results We identified 10 HSP90 genes in I. batatas , 11 in I. trifida , and 10 each in I.triloba and I.cordatotriloba . Chromosomal localization analysis showed an uneven distribution of HSP90 genes across 15 chromosomes. Phylogenetic and collinearity analyses grouped these genes into four subfamilies,with segmental duplication being the main factor for gene family expansion. Promoter analysis revealed multiple stress-responsive cis-acting elements, indicating that IbHSP90 genes may play a role in stress regulation. Expression analysis revealed that most IbHSP90s were downregulated under cold, salt, and PEG-induced drought stresses. Additionally, we developed a protein -protein interaction network that identified connections with heat shock factors. Experiments on subcellular localization revealed that IbHSP90-2 is present in both the cytoplasm and nucleus. Finally, heterologous expression of IbHSP90-2 in yeast compromised cold resistance. Discussion This study offers a significant resource for comprehending the evolution of plant HSP90 proteins and supports the genetic enhancement of cold tolerance in sweetpotato.