Assembly and analysis of a male sterile rubber tree mitochondrial genome reveals DNA rearrangement events and a novel transcript

BACKGROUND: The rubber tree, Hevea brasiliensis, is an important plant species that is commercially grown to produce latex rubber in many countries. The rubber tree variety BPM 24 exhibits cytoplasmic male sterility, inherited from the variety GT 1. RESULTS: We constructed the rubber tree mitochondrial genome of a cytoplasmic male sterile variety, BPM 24, using 454 sequencing, including 8 kb paired-end libraries, plus Illumina paired-end sequencing. We annotated this mitochondrial genome with the aid of Illumina RNA-seq data and performed comparative analysis. We then compared the sequence of BPM 24 to the contigs of the published rubber tree, variety RRIM 600, and identified a rearrangement that is unique to BPM 24 resulting in a novel transcript containing a portion of atp9. CONCLUSIONS: The novel transcript is consistent with changes that cause cytoplasmic male sterility through a slight reduction to ATP production efficiency. The exhaustive nature of the search rules out alternative causes and supports previous findings of novel transcripts causing cytoplasmic male sterility

Characterization of microsatellites and gene contents from genome shotgun sequences of mungbean (<it>Vigna radiata </it>(L.) Wilczek)

Abstract Background Mungbean is an important economical crop in Asia. However, genomic research has lagged behind other crop species due to the lack of polymorphic DNA markers found in this crop. The objective of this work is to develop and characterize microsatellite or simple sequence repeat (SSR) markers from genome shotgun sequencing of mungbean. Result We have generated and characterized a total of 470,024 genome shotgun sequences covering 100.5 Mb of the mungbean (Vigna radiata (L.) Wilczek) genome using 454 sequencing technology. We identified 1,493 SSR motifs that could be used as potential molecular markers. Among 192 tested primer pairs in 17 mungbean accessions, 60 loci revealed polymorphism with polymorphic information content (PIC) values ranging from 0.0555 to 0.6907 with an average of 0.2594. Majority of microsatellite markers were transferable in Vigna species, whereas transferability rates were only 22.90% and 24.43% in Phaseolus vulgaris and Glycine max, respectively. We also used 16 SSR loci to evaluate phylogenetic relationship of 35 genotypes of the Asian Vigna group. The genome survey sequences were further analyzed to search for gene content. The evidence suggested 1,542 gene fragments have been sequence tagged, that fell within intersected existing gene models and shared sequence homology with other proteins in the database. Furthermore, potential microRNAs that could regulate developmental stages and environmental responses were discovered from this dataset. Conclusion In this report, we provided evidence of generating remarkable levels of diverse microsatellite markers and gene content from high throughput genome shotgun sequencing of the mungbean genomic DNA. The markers could be used in germplasm analysis, accessing genetic diversity and linkage mapping of mungbean.</p