FibH Gene Complete Sequences (FibHome) Revealed Silkworm Pedigree

Area of Science:

• Genomics
• Molecular Biology
• Animal Genetics

Background:

• The fibroin heavy chain (FibH) gene is a key marker for silkworm identification due to its repetitive and variable nature.
• Limited knowledge of complete FibH sequences hinders detailed silkworm strain analysis and breeding strategies.

Purpose of the Study:

• To analyze a comprehensive dataset of 264 complete FibH sequences (FibHome) from a high-resolution silkworm pan-genome.
• To investigate the structural variations, conserved elements, and evolutionary patterns within the FibH gene across different silkworm strains.
• To explore the potential of the FibH gene as a molecular marker for silkworm classification and breeding.

Main Methods:

• Extraction and examination of 264 complete FibH gene sequences from a silkworm pan-genome.
• Comparative sequence analysis to identify conserved and variable regions, including terminal non-repetitive sequences and the repetitive core.
• Identification of mutation patterns, conserved transcriptional factor binding sites, and motif analysis within the FibH gene.
• Phylogenetic analysis and classification of silkworm strains based on FibH gene variations.

Main Results:

• Average FibH lengths varied significantly among wild (19,698 bp), local (16,427 bp), and improved (15,795 bp) silkworm strains.
• All sequences exhibited conserved 5' and 3' terminal non-repetitive sequences and a variable repetitive core (RC) with a shared motif.
• The FibH gene core unit mutation (GGTGCT) was identified as a key factor in domestication and breeding variations.
• Highly conserved transcriptional factor binding sites (100% identity) were observed in introns and upstream sequences.
• Silkworm strains were classified into four families based on FibH gene markers, with one family containing an optional FibH (Opti-FibH) gene.

Conclusions:

• The FibH gene displays significant variations and conserved elements that provide insights into silkworm domestication and breeding processes.
• The identified conserved regions and mutation patterns offer valuable markers for silkworm identification and strain classification.
• The study establishes the FibH gene as a robust marker for dividing silkworm strains into distinct families, aiding breeding programs.
• These findings contribute to a deeper understanding of silkworm genetics and facilitate the development of improved breeding strategies.