Whole Genome Sequencing Reveals the Islands of Novel Polymorphisms in Two Native Aromatic Japonica Rice Landraces from Vietnam

Elucidation of the rice genome will not only broaden our understanding of genetic characterization of the agronomic characteristics but also facilitate the rice genetic improvement through marker assisted breeding. However, the genome resources of aromatic rice varieties are largely unexploited. Therefore, the whole genome of two elite aromatic traditional japonica rice landraces in North Vietnam, Tam Xoan Bac Ninh (TXBN), and Tam Xoan Hai Hau (TXHH), was sequenced to identify their genome-wide polymorphisms. Overall, we identified over 40,000 novel polymorphisms in each aromatic rice landrace. Although a discontinuous 8-bp deletion and an A/T SNP just upstream the 5-bp deletion in exon 7 of BADH2 gene were present in both rice landraces, the number of SNP high resolution regions of TXBN was six times higher than that of TXHH. Furthermore, several hot spot regions of novel SNPs and indels were found in both genomes, providing their potential gene pools related to aroma formation. The genomic information of two aromatic rice landraces described in this study will facilitate the identification of fragrance-related genes and the genetic improvement of rice.