The Recent Small Scale Duplication of Tetraspanin within Cultivated Soybean Genome and Its Impact on the Domestication

Tetraspanin has been found in mammals, insects, fungi, and plants. It is a membrane spanning protein containing a large extracellular loop which provides interactive binding sites and it reportedly has roles in development, pathogenesis and immune response. The distribution of this protein family surveyed in model plant Arabidopsis and found the 17 tetraspanins (AtTET1-17). The suggested function of tetraspanin is the cell-to-cell signaling which would be evolved with the environmental changes. In this study, we found the ~9.3kb large deletion which harbors the single copy of tetraspanin in Glycine soja using NGS re-sequencing method. The putative deletion site was validated in the population of Glycine max and G. soja by polymerase chain reaction (PCR) showing the absent/present pattern that discriminate G. max and G. soja. The phylogenetic analysis of the tetraspanin gene family within G. max reference genome showed that the deleted tetraspanin duplicated most recently compared to other protein. Our results suggest that recently occurred small scale duplication of tetraspanin was intensively selected to form the population of G. max and the presence of one more copy of tetraspanin might contribute the domestication of the cultivated soybean.