Xuhua Huang

Conventional immediate and high-temperature immediate acid treatment are crucial techniques for breaking the diapause state of silkworm eggs, but their molecular mechanisms remain unclear. This study prepared diapause eggs (CK), conventional immediate acid-treated eggs (46 °C, 5 min, and CG), and high-temperature immediate acid-treated eggs (47.5 °C, 7 min, and GW) and analyzed the transcriptome and metabolome to screen for key expressed genes and key metabolites. Transcriptome results showed that 688, 823, and 222 differentially expressed genes (DEGs) were obtained from CK vs. CG, CK vs. GW, and CG vs. GW, respectively, and 12 DEGs significantly upregulated in all three comparisons (CK vs. CG, CK vs. GW, and CG vs. GW), including glycine-N-methyltransferase, choline dehydrogenase, Hsp68, and Hsp70. The LC-MS analysis results showed that 854, 711, and 506 differential metabolites (DMs) were obtained from CK vs. CG, CK vs. GW, and CG vs. GW, respectively. A total of seven DMs upregulated in all three comparisons and with |log₂Fold Change| ≥ 0.5 in CG vs. GW, including tyrosine-isoleucine-histidine, phenylalanyl-tyrosine, tyrosine-phenylalanine-glutamate-lysine, and histidylleucine, as well as 12 downregulated DMs, were identified. Additionally, it was found that γ-linolenic acid and triglycerides were upregulated in CG vs. GW. The conjoint analysis results revealed that four small peptides, including tyrosine-isoleucine-histidine, phenylalanyl-tyrosine, tyrosine-phenylalanine-glutamate-lysine, and histidylleucine, exhibited a highly significant positive correlation with Hsp70 family genes such as Hsp68 and Hsp70. This suggests that these small peptides, along with γ-linolenic acid and triglycerides, may play a crucial role in the resistance of silkworm eggs to high-temperature stress and the associated oxidative stress.