BackgroundCoix, Sorghum and Zea are closely related plant genera in the subtribe Maydeae. Coix comprises 9–11 species with different ploidy levels (2n = 10, 20, 30, and 40). The exclusively cultivated C. lacryma-jobi L. (2n = 20) is widely used in East and Southeast Asia for food and medicinal applications. Three fertile cytotypes (2n = 10, 20, and 40) have been reported for C. aquatica Roxb. One sterile cytotype (2n = 30) closely related to C. aquatica has been recently found in Guangxi of China. This putative hybrid has been named C. aquatica HG (Hybrid Guangxi). The genome composition and the evolutionary history of C. lacryma-jobi and C. aquatica HG are largely unclear.ResultsAbout 76% of the genome of C. lacryma-jobi and 73% of the genome of C. aquatica HG are repetitive DNA sequences as shown by low coverage genome sequencing followed by similarity-based cluster analysis. In addition, long terminal repeat (LTR) retrotransposable elements are dominant repetitive sequences in these two genomes, and the proportions of many repetitive sequences in whole genome varied greatly between the two species, indicating evolutionary divergence of them. We also found that a novel 102 bp variant of centromeric satellite repeat CentX and two other satellites only appeared in C. aquatica HG. The results from FISH analysis with repeat probe cocktails and the data from chromosomes pairing in meiosis metaphase showed that C. lacryma-jobi is likely a diploidized paleotetraploid species and C. aquatica HG is possibly a recently formed hybrid. Furthermore, C. lacryma-jobi and C. aquatica HG shared more co-existing repeat families and higher sequence similarity with Sorghum than with Zea.ConclusionsThe composition and abundance of repetitive sequences are divergent between the genomes of C. lacryma-jobi and C. aquatica HG. The results from fine karyotyping analysis and chromosome pairing suggested diploidization of C. lacryma-jobi during evolution and C. aquatica HG is a recently formed hybrid. The genome-wide comparison of repetitive sequences indicated that the repeats in Coix were more similar to those in Sorghum than to those in Zea, which is consistent with the phylogenetic relationship reported by previous work.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1025) contains supplementary material, which is available to authorized users.

CENH3 is a centromere-specific histone H3 variant and has been used as a marker to identify active centromeres and DNA sequences associated with functional centromere/kinetochore complexes. In this study, up to four distinct CENH3 (BrCENH3) cDNAs were identified in individuals of each of three diploid species of Brassica. Comparison of the BrCENH3 cDNAs implied three related gene families: BrCENH3-A in Brassica rapa (AA), BrCENH3-B in B. nigra (BB), and BrCENH3-C in B. oleracea (CC). Each family encoded a histone fold domain and N-terminal histone tails that vary in length in all three families. The BrCENH3-B cDNAs have a deletion of two exons relative to BrCENH3-A and BrCENH3-C, consistent with the more ancient divergence of the BB genome. Chromatin immunoprecipitation and immunolabeling tests with anti-BrCENH3 antibodies indicated that both centromeric tandem repeats and the centromere-specific retrotransposons of Brassica are directly associated with BrCENH3 proteins. In three allotetraploid species, we find either co-transcription of the BrCENH3 genes of the ancestral diploid species or gene suppression of the BrCENH3 from one ancestor. Although B genome centromeres are occupied by BrCENH3-B in the ancestral species B. nigra, in allotetraploids both BrCENH3-A and BrCENH3-C proteins appear to assemble at these centromeres.

BackgroundRadish (Raphanus sativus L., 2n = 2x = 18) is a major root vegetable crop especially in eastern Asia. Radish root contains various nutritions which play an important role in strengthening immunity. Repetitive elements are primary components of the genomic sequence and the most important factors in genome size variations in higher eukaryotes. To date, studies about repetitive elements of radish are still limited. To better understand genome structure of radish, we undertook a study to evaluate the proportion of repetitive elements and their distribution in radish.ResultsWe conducted genome-wide characterization of repetitive elements in radish with low coverage genome sequencing followed by similarity-based cluster analysis. Results showed that about 31% of the genome was composed of repetitive sequences. Satellite repeats were the most dominating elements of the genome. The distribution pattern of three satellite repeat sequences (CL1, CL25, and CL43) on radish chromosomes was characterized using fluorescence in situ hybridization (FISH). CL1 was predominantly located at the centromeric region of all chromosomes, CL25 located at the subtelomeric region, and CL43 was a telomeric satellite. FISH signals of two satellite repeats, CL1 and CL25, together with 5S rDNA and 45S rDNA, provide useful cytogenetic markers to identify each individual somatic metaphase chromosome. The centromere-specific histone H3 (CENH3) has been used as a marker to identify centromere DNA sequences. One putative CENH3 (RsCENH3) was characterized and cloned from radish. Its deduced amino acid sequence shares high similarities to those of the CENH3s in Brassica species. An antibody against B. rapa CENH3, specifically stained radish centromeres. Immunostaining and chromatin immunoprecipitation (ChIP) tests with anti-BrCENH3 antibody demonstrated that both the centromere-specific retrotransposon (CR-Radish) and satellite repeat (CL1) are directly associated with RsCENH3 in radish.ConclusionsProportions of repetitive elements in radish were estimated and satellite repeats were the most dominating elements. Fine karyotyping analysis was established which allow us to easily identify each individual somatic metaphase chromosome. Immunofluorescence- and ChIP-based assays demonstrated the functional significance of satellite and centromere-specific retrotransposon at centromeres. Our study provides a valuable basis for future genomic studies in radish.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0480-y) contains supplementary material, which is available to authorized users.

SummaryAcrylamide is produced in a wide variety of carbohydrate-rich foods during high-temperature cooking. Dietary acrylamide is a suspected human carcinogen, and health concerns related to dietary acrylamide have been raised worldwide. French fries and potato chips contribute a significant proportion to the average daily intake of acrylamide, especially in developed countries. One way to mitigate health concerns related to acrylamide is to develop potato cultivars that have reduced contents of the acrylamide precursors asparagine, glucose and fructose in tubers. We generated a large number of silencing lines of potato cultivar Russet Burbank by targeting the vacuolar invertase gene VInv and the asparagine synthetase genes StAS1 and StAS2 with a single RNA interference construct. The transcription levels of these three genes were correlated with reducing sugar (glucose and fructose) and asparagine content in tubers. Fried potato products from the best VInv/StAS1/StAS2-triple silencing lines contained only one-fifteenth of the acrylamide content of the controls. Interestingly, the extent of acrylamide reduction of the best triple silencing lines was similar to that of the best VInv-single silencing lines developed previously from the same potato cultivar Russet Burbank. These results show that an acrylamide mitigation strategy focused on developing potato cultivars with low reducing sugars is likely to be an effective and sufficient approach for minimizing the acrylamideforming potential of French fry processing potatoes.

Parthenocarpic fruit is a very attractive trait for consumers and especially in eggplants where seeds can lead to browning of the flesh and bitterness. However, the molecular mechanisms underlying parthenocarpy in eggplant still remain unknown. Some auxin response factors have been previously shown in model species, such as Arabidopsis and tomato, to play an important role in such a process. Here, we have identified a natural parthenocarpic mutant and showed that ARF8 from eggplant (SmARF8), is down-regulated in buds compared to wild-type plants. Further characterization of SmARF8 showed that it is a nuclear protein and an active transcriptional regulator. We determined that amino acids 629-773 of SmARF8 act as the transcriptional activation domain, the C terminus of SmARF8 is the protein-binding domain, and that SmARF8 might form homodimers. Expression analysis in eggplant showed that SmARF8 is expressed ubiquitously in all tissues and organs and is responsive to auxin. Eggplant transgenic lines harboring RNA interference of SmARF8 exhibited parthenocarpy in unfertilized flowers, suggesting that SmARF8 negatively regulates fruit initiation. Interestingly, SmARF8-overexpressing Arabidopsis lines also induced parthenocarpy. These results indicate that SmARF8 could affect the dimerization of auxin/indole acetic acid repressors with SmARF8 via domains III and IV and thus induce fruit development. Furthermore, the introduction of SmARF8 full-length cDNA could partially complement the parthenocarpic phenotypes in Arabidopsis arf8-1 and arf8-4 mutants. Collectively, our results demonstrate that SmARF8 may act as a key negative regulator involved in parthenocarpic fruit development of eggplant. These findings give more insights into the conserved mechanisms leading to parthenocarpy in which auxin signaling plays a pivotal role, and provide potential target for eggplant breeding.

Background Newborn screening (NBS) has been implemented for neonatal inborn disorders using various technology platforms, but false-positive and false-negative results are still common. In addition, target diseases of NBS are limited by suitable biomarkers. Here we sought to assess the feasibility of further improving the screening using next-generation sequencing technology. Methods We designed a newborn genetic sequencing (NBGS) panel based on multiplex PCR and next generation sequencing to analyze 134 genes of 74 inborn disorders, that were validated in 287 samples with previously known mutations. A retrospective cohort of 4986 newborns was analyzed and compared with the biochemical results to evaluate the performance of this panel. Results The accuracy of the panel was 99.65% with all samples, and 154 mutations from 287 samples were 100% detected. In 4986 newborns, a total of 113 newborns were detected with biallelic or hemizygous mutations, of which 36 newborns were positive for the same disorder by both NBGS and conventional NBS (C-NBS) and 77 individuals were NBGS positive/C-NBS negative. Importantly, 4 of the 77 newborns were diagnosed currently including 1 newborn with methylmalonic acidemia, 1 newborn with primary systemic carnitine deficiency and 2 newborns with Wilson’s disease. A total of 1326 newborns were found to be carriers with an overall carrier rate of 26.6%. Conclusion Analysis based on next generation sequencing could effectively identify neonates affected with more congenital disorders. Combined with C-NBS, this approach may improve the early and accurate identification of neonates with inborn disorders. Our study lays the foundation for prospective studies and for implementing NGS-based analysis in NBS.

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Whole-genome shotgun reads were analyzed to determine the repeat sequence composition in the genome of black mustard, Brassica nigra (L.) Koch. The analysis showed that satellite DNA sequences are very abundant in the black mustard genome. The distribution pattern of 7 new tandem repeats (BnSAT13, BnSAT28, BnSAT68, BnSAT76, BnSAT114, BnSAT180, and BnSAT200) on black mustard chromosomes was visualized using fluorescence in situ hybridization (FISH). The FISH signals of BnSAT13 and BnSAT76 provided useful cytogenetic markers; their position and fluorescence intensity allowed for unambiguous identification of all 8 somatic metaphase chromosomes. A karyotype showing the location and fluorescence intensity of these tandem repeat sequences together with the position of rDNAs and centromeric retrotransposons of Brassica (CRB) was constructed. The establishment of the FISH-based karyotype in B. nigra provides valuable information that can be used in detailed analyses of B. nigra accessions and derived allopolyploid Brassica species containing the B genome.