The genetic variation and relationship among the natural hybrids of Mangifera casturi Kosterm

Mangifera casturi Kosterm., a mango plant from Kalimantan Selatan, Indonesia, has limited genetic information, severely limiting the research on its genetic variation and phylogeny. We collected M. casturi's genomic information using next-generation sequencing, developed microsatellite markers and performed Sanger sequencing for DNA barcoding analysis. These markers were used to confirm parental origin and genetic diversity of M. casturi hybrids. The clean reads of the Kasturi accession were assembled de novo, producing 259 872 scaffolds (N50 = 1 445 bp). Fourteen polymorphic microsatellite markers were developed from 11 040 microsatellite motif-containing sequences. In total, 58 alleles were produced with a mean of 4.14 alleles per locus. Microsatellite marker analysis revealed broad genetic variation in M. casturi. Phylogenetic analysis was performed using internal transcribed spacers (ITS), matK, rbcL, and trnH-psbA. The phylogenetic tree of chloroplast markers placed Kasturi, Cuban, Pelipisan, Pinari, and Hambawang in one group, with M. indica as the female ancestor. Meanwhile, the phylogenetic tree of ITS markers indicated several Mangifera species as ancestors of M. casturi. Thus, M. casturi very likely originated from the cross-hybridization of multiple ancestors. Furthermore, crossing the F1 hybrids of M. indica and M. quadrifida with other Mangifera spp. may have generated much genetic variation. The genetic information for M. casturi will be a resource for breeding improvement, and conservation studies.