Abstract
Anser cygnoides has a spherical crest on the beak roof, which is described as knob. However, the mechanisms affecting knob morphology are unclear. Here, we investigated the phenotypic characteristics and molecular basis of knob-size differences in Yangzhou geese. Anatomically, the knob was identified as frontal hump in the frontal area of the skull, rather than hump of upper beak. Although the frontal hump length, and height varied greatly in geese with different knob phenotypes, little was changed in the width. Histologically, knob skin in large-size knobs geese have a greater length in the stratum corneum, stratum spinosum, and stratum reticular than that in small-size knobs geese. Moveover, the 415 differentially expressed genes were found between the large knobs and small ones through transcriptome profiling. In addition, GO enrichment and KEGG pathway analysis revealed 455 significant GO terms and 210 KEGG pathways were enriched, respectively. Among these, TGF-β signaling and thyroid hormone synthesis-signaling pathways were identified to determine knob-size phenotype. Furthermore, BMP5, DCN, TSHR and ADCY3 were recognized to involve in the growth and development of knob. Our data provide comprehensive molecular determinants of knob size phenotype, which can potentially promote the genetic improvement of goose knobs.
Highlights
Anser cygnoides has a spherical crest on the beak roof, which is described as knob
These results provide an alternative strategy for the genetic improvement of goose knobs to meet consumer preferences
The size of frontal hump was highly correlated with that of the knob, suggested that the knob phenotype was determined by the frontal hump
Summary
Anser cygnoides has a spherical crest on the beak roof, which is described as knob. the mechanisms affecting knob morphology are unclear. We investigated the phenotypic characteristics and molecular basis of knob-size differences in Yangzhou geese. The knob was identified as frontal hump in the frontal area of the skull, rather than hump of upper beak. A few birds present protuberances of the upper beak (e.g., Pauxi unicornis)[1] Both Chinese geese (Anser cygnoides) and African geese (Anser cygnoides) possess a spherical crest across the beak roof, which is described as a knob. The genetic basis underlying differences in knob size phenotype is not fully understood. The genetic basis of knob-size differences was investigated by RNA sequencing technology. These results provide an alternative strategy for the genetic improvement of goose knobs to meet consumer preferences
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