Complete mitochondrial genome of a natural triploid crucian carp mutant, Carassius auratus var. pingxiangnensis, and phylogenetic analysis of different ploidies in crucian carp

Abstract

Carassius auratusvar. pingxiangnensis is a natural triploid crucian carp mutant. In order to understand its placement and genetic background at the gene level, the characteristics of mitochondrial DNA sequences and phylogenetic relationship were examined. The results showed that the mitochondrial DNA is a circular doublestranded DNA molecule that is 16,576 bp in length with 13 proteincoding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a non-coding control region. Mitochondrial genes overlapped by a total of 40 bp in 11 different locations from 1 to 14 bp. The base composition of the C. auratus mitogenome was estimated to be 29.70% A, 26.74% C, 15.35% G, and 28.21% T. The central conserved blocks and the conserved blocks were compared and were similar among C. auratus var. pingxiangnensis and six other cyprinids with different ploidies. The origin of light strand replication was similar to that of other vertebrates; it was 33 bp, but the characteristic sequence motif 5′-GCCGG-3′ at the base of the stem within tRNACys was mutated to 5′-GGCGG-3′. Our phylogenetic analysis based on whole mitogenome sequences indicated that C. auratus var. pingxiangnensiswas clustered with C. auratusand then sister-grouped with Carassius gibelio. The systemic developmental tree of crucian carp with different chromosome ploidies showed that diploid C. auratus auratuswas clustered with triploid C. auratus auratus, sister-grouped with tetraploid C. auratus auratus, and clustered with other diploid, triploid, and tetraploid C. auratus. © FUNPEC-RP.