Hybrid sterility is one of the earliest postzygotic isolating mechanisms to evolve between two recently diverged species. Here we identify causes underlying hybrid infertility of two recently diverged fission yeast species Schizosaccharomyces pombe and S. kambucha, which mate to form viable hybrid diploids that efficiently complete meiosis, but generate few viable gametes. We find that chromosomal rearrangements and related recombination defects are major but not sole causes of hybrid infertility. At least three distinct meiotic drive alleles, one on each S. kambucha chromosome, independently contribute to hybrid infertility by causing nonrandom spore death. Two of these driving loci are linked…
Novel microsatellite markers were characterized in the wind-dispersed and dioecious neotropical tree Triplaris cumingiana (Polygonaceae) for use in understanding the ecological processes and genetic impacts of pollen- and seed-mediated gene flow in tropical forests. •Sixty-two microsatellite primer pairs were screened, from which 12 markers showing five or more alleles per locus (range 5-17) were tested on 47 individuals. Observed and expected heterozygosities averaged 0.692 and 0.731, respectively. Polymorphism information content was between 0.417 and 0.874. Linkage disequilibrium was observed in one of the 66 pairwise comparisons between loci. Two loci showed deviation from Hardy-Weinberg equilibrium. An additional 14 markers exhibiting…
The availability of plant reference genomes has ushered in a new era of crop genomics. More than 100 plant genomes have been sequenced since 2000, 63% of which are crop species. These genome sequences provide insight into architecture, evolution and novel aspects of crop genomes such as the retention of key agronomic traits after whole genome duplication events. Some crops have very large, polyploid, repeat-rich genomes, which require innovative strategies for sequencing, assembly and analysis. Even low quality reference genomes have the potential to improve crop germplasm through genome-wide molecular markers, which decrease expensive phenotyping and breeding cycles. The next…
Allele-level resolution data at primary HLA typing is the ideal for most histocompatibility testing laboratories. Many high-throughput molecular HLA typing approaches are unable to determine the phase of observed DNA sequence polymorphisms, leading to ambiguous results. The use of higher resolution methods is often restricted due to cost and time limitations. Here we report on the feasibility of using Pacific Biosciences’ Single Molecule Real-Time (SMRT) DNA sequencing technology for high-resolution and high-throughput HLA typing. Seven DNA samples were typed for HLA-A, -B and -C. The results showed that SMRT DNA sequencing technology was able to generate sequences that spanned entire…
Sex chromosomes in plants and animals and fungal mating-type chromosomes often show exceptional genome features, with extensive suppression of homologous recombination and cytological differentiation between members of the diploid chromosome pair. Despite strong interest in the genetics of these chromosomes, their large regions of suppressed recombination often are enriched in transposable elements and therefore can be challenging to assemble. Here we show that the latest improvements of the PacBio sequencing yield assembly of the whole genome of the anther-smut fungus, Microbotryum lychnidis-dioicae (the pathogenic fungus causing anther-smut disease of Silene latifolia), into finished chromosomes or chromosome arms, even for the…
The Heliconius butterflies are a widely studied adaptive radiation of 46 species spread across Central and South America, several of which are known to hybridize in the wild. Here, we present a substantially improved assembly of the Heliconius melpomene genome, developed using novel methods that should be applicable to improving other genome assemblies produced using short read sequencing. First, we whole-genome-sequenced a pedigree to produce a linkage map incorporating 99% of the genome. Second, we incorporated haplotype scaffolds extensively to produce a more complete haploid version of the draft genome. Third, we incorporated ~20x coverage of Pacific Biosciences sequencing, and…
Domesticated grapevines (Vitis vinifera) have relatively small genomes of about 500 Mb (Lodhi and Reisch, 1995; Jaillon et al., 2007; Velasco et al., 2007), which is similar to other small-genomes species like rice (430 Mb; Goff et al., 2002), medicago (500 Mb; Tang et al., 2014), and poplar (465 Mb; Tuskan et al., 2006). Despite their small genome size, the sequencing and assembling of grapevine genomes is difficult because of high levels of heterozygosity. The high heterozygosity in domesticated grapes may be due, in part, to their domestication from an obligately outcrossing, dioecious wild progenitor. Domesticated grapes can be selfed,…
The flowering plant Primula veris is a common spring blooming perennial that is widely cultivated throughout Europe. This species is an established model system in the study of the genetics, evolution, and ecology of heterostylous floral polymorphisms. Despite the long history of research focused on this and related species, the continued development of this system has been restricted due the absence of genomic and transcriptomic resources.We present here a de novo draft genome assembly of P. veris covering 301.8 Mb, or approximately 63% of the estimated 479.22 Mb genome, with an N50 contig size of 9.5 Kb, an N50 scaffold size of…
Dendrobium officinale Kimura et Migo is a traditional Chinese orchid herb that has both ornamental value and a broad range of therapeutic effects. Here, we report the first de novo assembled 1.35 Gb genome sequences for D. officinale by combining the second-generation Illumina Hiseq 2000 and third-generation PacBio sequencing technologies. We found that orchids have a complete inflorescence gene set and have some specific inflorescence genes. We observed gene expansion in gene families related to fungus symbiosis and drought resistance. We analyzed biosynthesis pathways of medicinal components of D. officinale and found extensive duplication of SPS and SuSy genes, which are related…
Although recent developed algorithms have integrated multiple signals to improve sensitivity for insertion and deletion (INDEL) detection, they are far from being perfect and still have great limitations in detecting a full size range of INDELs. Here we present BreakSeek, a novel breakpoint-based algorithm, which can unbiasedly and efficiently detect both homozygous and heterozygous INDELs, ranging from several base pairs to over thousands of base pairs, with accurate breakpoint and heterozygosity rate estimations. Comprehensive evaluations on both simulated and real datasets revealed that BreakSeek outperformed other existing methods on both sensitivity and specificity in detecting both small and large INDELs,…
Chromosomal rearrangements, which shuffle DNA throughout the genome, are an important source of divergence across taxa. Using a paired-end read approach with Illumina sequence data for archaic humans, I identify changes in genome structure that occurred recently in human evolution. Hundreds of rearrangements indicate genomic trafficking between the sex chromosomes and autosomes, raising the possibility of sex-specific changes. Additionally, genes adjacent to genome structure changes in Neanderthals are associated with testis-specific expression, consistent with evolutionary theory that new genes commonly form with expression in the testes. I identify one case of new-gene creation through transposition from the Y chromosome to…
Cerebral cavernous malformations (CCMs) are vascular lesions affecting the central nervous system. CCM occurs either sporadically or in an inherited, autosomal dominant manner. Constitutional (germline) mutations in any of three genes, KRIT1, CCM2 and PDCD10, can cause the inherited form. Analysis of CCM lesions from inherited cases revealed biallelic somatic mutations, indicating that CCM follows a Knudsonian two-hit mutation mechanism. It is still unknown, however, if the sporadic cases of CCM also follow this genetic mechanism. We extracted DNA from 11 surgically excised lesions from sporadic CCM patients, and sequenced the three CCM genes in each specimen using a next-generation…
Dubowitz syndrome is a rare disorder characterized by multiple congenital anomalies, cognitive delay, growth failure, an immune defect, and an increased risk of blood dyscrasia and malignancy. There is considerable phenotypic variability, suggesting genetic heterogeneity. We clinically characterized and performed exome sequencing and high-density array SNP genotyping on three individuals with Dubowitz syndrome, including a pair of previously-described siblings (Patients 1 and 2, brother and sister) and an unpublished patient (Patient 3). Given the siblings’ history of bone marrow abnormalities, we also evaluated telomere length and performed radiosensitivity assays. In the siblings, exome sequencing identified compound heterozygosity for a known…
The investigation of genetic diversity at molecular level has been proposed as a valuable complement and sometimes proxy to phenotypic diversity of local breeds and is presently considered as one of the FAO priorities for breed characterization. By recommending a set of selected molecular markers for each of the main livestock species, FAO has promoted the meta-analysis of local datasets, to achieve a global view of molecular genetic diversity. Analysis within the EU Globaldiv project of two large goat microsatellite datasets produced by the Econogene Consortium and the IAEA CRP–Asia Consortium, respectively, has generated a picture of goat diversity across…