Analyses of Ipomoea batatas cultivated species and wild relatives based on mtDNA and cpDNA sequences

Objective  To conduct molecular identification and genetic relationship analysis of Ipomoea batatas cultivated species and wild relatives based on mitochondrial DNA (mtDNA) and chloroplast DNA (cpDNA) matK sequences, and provide theoretical bases for germplasm identification, protection, development and utilization.

Method  Three cultivated species and eight wild relatives were used as materials, from which total DNA was extracted by the CTAB method. Their mtDNA and cpDNA matK sequences were amplified by PCR. DnaSP 6.0 was used to analyze nucleotide diversity, haplotype diversity and other characteristics. The phylogenetic tree of three cultivated species and eight wild relatives was constructed based on the neighbor-joining method.

Result  The length of five mtDNA regions and one cpDNA region was 6 713 bp after sequencing, alignment and splicing, the GC proportion was 47.79%−48.31%, and the haplotype number, nucleotide diversity, variable site number, singleton variable site number, parsimony informative site number, insertion/deletion site number were 9, 0.003 25, 69, 39, 30, 111, respectively. The neutrality test showed there was no significant difference between Tajima’sD values at the level of P>0.10, which indicated that variation of those regions followed neutral theory of molecular evolution. The genetic distances among three cultivated species and eight wild relatives ranged from 0.000 00 to 0.005 84, with an average genetic distance of 0.003 26, indicating low genetic diversity. The phylogenetic tree divided the 11 species into two categories with close genetic relationship within the category.

Conclusion  The sequences used in this study can accurately identify I. batatas cultivated species and wild relatives, and provide references and theoretical guidance for the evolution and utilization of I. batatas wild relatives.