Complete Mitochondrial Genome Assembly of an Upland Wild Rice Species, <i>Oryza granulata</i> and Comparative Mitochondrial Genomic Analyses of the Genus <i>Oryza</i>

oleh: Fen Zhang, Haiqi Kang, Lizhi Gao

Format: Article
Diterbitkan: MDPI AG 2023-10-01

Deskripsi

Wild upland rice species, including <i>Oryza granulata</i>, possess unique characteristics that distinguish them from other <i>Oryza</i> species. For instance, <i>O. granulata</i> characteristically has a GG genome and is accordingly classified as a basal lineage of the genus <i>Oryza</i>. Here, we deployed a versatile hybrid approach by integrating Illumina and PacBio sequencing data to generate a high-quality mitochondrial genome (mitogenome) assembly for <i>O. granulata</i>. The mitogenome of <i>O. granulata</i> was 509,311 base pairs (bp) with sixty-seven genes comprising two circular chromosomes, five ribosomal RNA (rRNA) coding genes, twenty-five transfer RNA (tRNA) coding genes, and thirty-seven genes coding for proteins. We identified a total of 378 simple sequence repeats (SSRs). The genome also contained 643 pairs of dispersed repeats comprising 340 palindromic and 303 forward. In the <i>O. granulata</i> mitogenome, the length of 57 homologous fragments in the chloroplast genome occupied 5.96% of the mitogenome length. Collinearity analysis of three <i>Oryza</i> mitogenomes revealed high structural variability and frequent rearrangements. Phylogenetic analysis showed that, compared to other related genera, <i>O. granulata</i> had the closest genetic relationship with mitogenomes reported for all members of <i>Oryza,</i> and occupies a position at the base of the <i>Oryza</i> phylogeny. Comparative analysis of complete mitochondrial genome assemblies for <i>Oryza</i> species revealed high levels of mitogenomic diversity, providing a foundation for future conservation and utilization of wild rice biodiversity.