Role of sorbitol dehydrogenase in silkworm ovarian physiology and metabolism: insights from mutant analysis and proteomic profiling

Sorbitol dehydrogenase (SDH) plays a pivotal role in the polyol pathway by regulating sorbitol and fructose metabolism. During silkworm (Bombyx mori) embryonic development, SDH catalyzes the conversion of sorbitol to glycogen to meet the metabolic demands of the growing embryo. However, its function in the ovarian physiology and metabolism remains poorly understood. In this study,we generated a homozygous BmSDH mutant strain using CRISPR/Cas9 and performed TMT-based proteomic analysis to investigate the impact of SDH knockout on the ovarian proteome at the 3rd-day pupal stage. Concurrently, we quantified glycogen, sorbitol, glycerol, and trehalose levels in mutant ovarian tissues to assess metabolic perturbations. The results revealed that a 6-base insertion in BmSDH disrupted enzymatic function. Proteomic profiling identified 204 differentially expressed proteins (DEPs) (124 upregulated, 80 downregulated), enriched in 90 GO terms and 107 KEGG pathways. Among the DEPs, 19 key proteins were identified, including Six downregulated proteins involved in amino acid/glucose metabolism indicated reduced metabolic flux in mutants. Eight proteins associated with growth, and development showed differential expression, with six upregulated and two downregulated, implicated BmSDH in ovarian development and diapause initiation. Furthermore, Five disease-associated proteins (e.g., cardiomyopathy-linked factors) revealed evolutionarily conserved BmSDH functions. Metabolomics showed elevated glycogen, trehalose, and glycerol in mutant ovaries, consistent with disrupted polyol pathway dynamics. These results elucidate BmSDH’s multifaceted roles in silkworm ovarian development, bridging metabolic regulation, reproductive programming, and conserved disease mechanisms.