Long-read bitter gourd (Momordica charantia) genome and the genomic architecture of nonclassic domestication.

The genetic architecture of quantitative traits is determined by both Mendelian and polygenic factors, yet classic examples of plant domestication focused on selective sweep of newly mutated Mendelian genes. Here we report the chromosome-level genome assembly and the genomic investigation of a nonclassic domestication example, bitter gourd (Momordica charantia), an important Asian vegetable and medicinal plant of the family Cucurbitaceae. Population resequencing revealed the divergence between wild and South Asian cultivars about 6,000 y ago, followed by the separation of the Southeast Asian cultivars about 800 y ago, with the latter exhibiting more extreme trait divergence from wild progenitors and stronger signs of selection on fruit traits. Unlike some crops where the largest phenotypic changes and traces of selection happened between wild and cultivar groups, in bitter gourd large differences exist between two regional cultivar groups, likely reflecting the distinct consumer preferences in different countries. Despite breeding efforts toward increasing female flower proportion, a gynoecy locus exhibits complex patterns of balanced polymorphism among haplogroups, with potential signs of selective sweep within haplogroups likely reflecting artificial selection and introgression from cultivars back to wild accessions. Our study highlights the importance to investigate such nonclassic example of domestication showing signs of balancing selection and polygenic trait architecture in addition to classic selective sweep in Mendelian factors.

Genomic characterization of a rare Carica papaya X chromosome mutant reveals a candidate monodehydroascorbate reductase 4 gene involved in all-hermaphrodite phenomenon.

Sex form is one of the most important characteristics in papaya cultivation in which hermaphrodite is the preferable form. Self-pollination of H*-TSS No.7, an inbred line derived from a rare X chromosome mutant SR*, produced all-hermaphrodite progeny. The recessive lethal allele controlling the all-hermaphrodite phenomenon was proposed to be the recessive Germination suppressor (gs) locus. This study employed next-generation sequencing technology and genome comparison to identify the candidate Gs gene. One specific gene, monodehydroascorbate reductase 4 (MDAR4) harboring a unique polymorphic 3 bp deletion in H*-TSS No.7 was identified. The function of MDAR4 is known to be involved in the hydrogen peroxide (H2O2) scavenging pathway and is associated with seed germination. Furthermore, MDAR4 showed higher expression in the imbibed seeds than that in the dry seeds indicating its potential role in the seed germination. Perhaps this is the very first report providing the evidences that MDAR4 is the candidate of Gs locus in H*-TSS No.7. In addition, Gs allele-specific markers were developed which would be facilitated for breeding all-hermaphrodite lines.

Shear bond strength between gingival composite resin and glazed gingival porcelain for implant-supported prostheses.

This study determined the shear bond strength (SBS) between an indirect gingival composite resin and glazed gingival porcelain after various surface treatments. A total of 176 porcelain disks with natural glazing were used and assigned to one of four groups: no surface treatment, airborne-particle abrasion, hydrofluoric acid etching, or a combination of airborne-particle abrasion followed by hydrofluoric acid etching. Each group was divided into two subgroups: one subgroup was unprimed, and the other was silanized. An indirect composite resin was then bonded to the porcelain disks. Half of the specimens in each group (n = 11) were exposed to 5000 thermocycles. SBSs were measured, and data were analyzed with the Kruskal-Wallis and Steel-Dwass tests. Among silanized specimens, those treated with the combination of airborne-particle abrasion and hydrofluoric acid etching exhibited the highest bond strengths both before and after thermocycling. However, the SBS values of the silanized and unprimed hydrofluoric acid etched specimens did not differ significantly. Airborne-particle abrasion followed by hydrofluoric acid etching with silane application yielded stronger, more durable bonds between the indirect gingival composite resin and glazed gingival porcelain.

Radiopacity of computer-aided design/computer-aided manufacturing composite resin blocks.

This study aimed to clarify the degree of difference in radiopacity between sixteen CAD/CAM composite resin blocks, one ceramic block, and teeth of the same thickness on radiographs. The radiographic density of CAD/CAM composite resin blocks was measured and the results were compared with the corresponding values for enamel and dentin. Additionally, the study analyzed the constituent elements of each type of CAD/CAM composite resin block and conducted an examination to identify those elements exerting an influence on radiopacity. Compared to the enamel, there were five blocks with significantly higher radiopacity, two blocks with the same level in radiopacity, and ten blocks with notably lower radiopacity. Compared to the dentin, there were ten blocks with significantly higher radiopacity, one block with the same level in radiopacity, and six blocks with notably lower radiopacity. All of the CAD/CAM composite resin blocks for molars contained barium and strontium. This result suggests that the addition of heavy metals, for example, barium, strontium, and zirconium, would be effective in providing CAD/CAM composite resin blocks with radiopacity.

OsHKT1;5 mediates Na+ exclusion in the vasculature to protect leaf blades and reproductive tissues from salt toxicity in rice.

Salt tolerance quantitative trait loci analysis of rice has revealed that the SKC1 locus, which is involved in a higher K+ /Na+ ratio in shoots, corresponds to the OsHKT1;5 gene encoding a Na+ -selective transporter. However, physiological roles of OsHKT1;5 in rice exposed to salt stress remain elusive, and no OsHKT1;5 gene disruption mutants have been characterized to date. In this study, we dissected two independent T-DNA insertional OsHKT1;5 mutants. Measurements of ion contents in tissues and 22 Na+ tracer imaging experiments showed that loss-of-function of OsHKT1;5 in salt-stressed rice roots triggers massive Na+ accumulation in shoots. Salt stress-induced increases in the OsHKT1;5 transcript were observed in roots and basal stems, including basal nodes. Immuno-staining using an anti-OsHKT1;5 peptide antibody indicated that OsHKT1;5 is localized in cells adjacent to the xylem in roots. Additionally, direct introduction of 22 Na+ tracer to leaf sheaths also demonstrated the involvement of OsHKT1;5 in xylem Na+ unloading in leaf sheaths. Furthermore, OsHKT1;5 was indicated to be present in the plasma membrane and found to localize also in the phloem of diffuse vascular bundles in basal nodes. Together with the characteristic 22 Na+ allocation in the blade of the developing immature leaf in the mutants, these results suggest a novel function of OsHKT1;5 in mediating Na+ exclusion in the phloem to prevent Na+ transfer to young leaf blades. Our findings further demonstrate that the function of OsHKT1;5 is crucial over growth stages of rice, including the protection of the next generation seeds as well as of vital leaf blades under salt stress.

Magnaporthe oryzae Glycine-Rich Secretion Protein, Rbf1 Critically Participates in Pathogenicity through the Focal Formation of the Biotrophic Interfacial Complex.

Magnaporthe oryzae, the fungus causing rice blast disease, should contend with host innate immunity to develop invasive hyphae (IH) within living host cells. However, molecular strategies to establish the biotrophic interactions are largely unknown. Here, we report the biological function of a M. oryzae-specific gene, Required-for-Focal-BIC-Formation 1 (RBF1). RBF1 expression was induced in appressoria and IH only when the fungus was inoculated to living plant tissues. Long-term successive imaging of live cell fluorescence revealed that the expression of RBF1 was upregulated each time the fungus crossed a host cell wall. Like other symplastic effector proteins of the rice blast fungus, Rbf1 accumulated in the biotrophic interfacial complex (BIC) and was translocated into the rice cytoplasm. RBF1-knockout mutants (Δrbf1) were severely deficient in their virulence to rice leaves, but were capable of proliferating in abscisic acid-treated or salicylic acid-deficient rice plants. In rice leaves, Δrbf1 inoculation caused necrosis and induced defense-related gene expression, which led to a higher level of diterpenoid phytoalexin accumulation than the wild-type fungus did. Δrbf1 showed unusual differentiation of IH and dispersal of the normally BIC-focused effectors around the short primary hypha and the first bulbous cell. In the Δrbf1-invaded cells, symplastic effectors were still translocated into rice cells but with a lower efficiency. These data indicate that RBF1 is a virulence gene essential for the focal BIC formation, which is critical for the rice blast fungus to suppress host immune responses.

An in vitro evaluation of fracture load of implant-supported zirconia-based prostheses fabricated with different veneer materials.

OBJECTIVES: The purpose of this in vitro study was to evaluate fracture loads of implant-supported zirconia-based prostheses fabricated with different veneer materials (resin-based material and lithium disilicate ceramics). MATERIAL AND METHODS: Forty-four zirconia-based molar prostheses were fabricated on dental implants and divided into four groups (n = 11): zirconia-based prostheses veneered with feldspathic porcelain (ZVF), zirconia-based prostheses bonded with the lithium disilicate glass-ceramic veneer (ZBD), zirconia-based prostheses veneered with indirect composite resin (ZVC), and zirconia-based prostheses bonded with composite materials fabricated from a CAD/CAM resin block (ZBC). The zirconia-based prostheses and abutments were adhesively bonded with a dual-polymerized resin-based luting material. Fracture load was determined using compression load to the prostheses with a universal testing machine. The data were analyzed with one-way analysis of variance (ANOVA) and Tukey's HSD test (α = .05). RESULTS: The mean fracture load was significantly higher in the ZBC group (3.95 kN) than in the ZVC group (3.28 kN). No significant difference in fracture load was found among the ZVF (3.52 kN), ZBD (3.48 kN), and ZVC groups. CONCLUSIONS: The adhesively bonded veneering technique enhances fracture resistance of implant-supported zirconia-based prostheses fabricated with a resin-based material. All implant-supported zirconia-based restorations tested should resist physiologic masticatory forces in the oral environment.

Effect of preparation design on marginal and internal adaptation of translucent zirconia laminate veneers.

This study investigated the effect of preparation design on the marginal and internal adaptation of laminate veneers (LVs) fabricated from translucent zirconia. Thirty-three resin teeth were prepared for LVs of three designs: window preparation (WP); incisal shoulder preparation (ISP); and incisal palatal chamfer preparation (IPP). Marginal adaptation was evaluated by measuring the vertical discrepancy between the LV margin and the finish line at 60 points. The internal adaptation was assessed by measuring the internal space width as the distance between the LV and the tooth at cervical, central, and incisal sites after sectioning. At the incisal, mesial, and distal sites, mean marginal discrepancies were significantly lower in the WP group than in the other two groups; the IPP group had the highest marginal discrepancies. At incisal sites, the median internal space was significantly higher in the IPP group than in the WP and ISP groups and higher in the ISP group than in the WP group. At the incisal site, marginal and internal adaptations were better for the non-overlap translucent zirconia LV design (WP) than for the overlap designs (ISP and IPP). The characteristics of the translucent zirconia LVs used in the present study indicate acceptable clinical performance.

Genome sequencing of the staple food crop white Guinea yam enables the development of a molecular marker for sex determination.

BACKGROUND: Root and tuber crops are a major food source in tropical Africa. Among these crops are several species in the monocotyledonous genus Dioscorea collectively known as yam, a staple tuber crop that contributes enormously to the subsistence and socio-cultural lives of millions of people, principally in West and Central Africa. Yam cultivation is constrained by several factors, and yam can be considered a neglected "orphan" crop that would benefit from crop improvement efforts. However, the lack of genetic and genomic tools has impeded the improvement of this staple crop. RESULTS: To accelerate marker-assisted breeding of yam, we performed genome analysis of white Guinea yam (Dioscorea rotundata) and assembled a 594-Mb genome, 76.4% of which was distributed among 21 linkage groups. In total, we predicted 26,198 genes. Phylogenetic analyses with 2381 conserved genes revealed that Dioscorea is a unique lineage of monocotyledons distinct from the Poales (rice), Arecales (palm), and Zingiberales (banana). The entire Dioscorea genus is characterized by the occurrence of separate male and female plants (dioecy), a feature that has limited efficient yam breeding. To infer the genetics of sex determination, we performed whole-genome resequencing of bulked segregants (quantitative trait locus sequencing [QTL-seq]) in F1 progeny segregating for male and female plants and identified a genomic region associated with female heterogametic (male = ZZ, female = ZW) sex determination. We further delineated the W locus and used it to develop a molecular marker for sex identification of Guinea yam plants at the seedling stage. CONCLUSIONS: Guinea yam belongs to a unique and highly differentiated clade of monocotyledons. The genome analyses and sex-linked marker development performed in this study should greatly accelerate marker-assisted breeding of Guinea yam. In addition, our QTL-seq approach can be utilized in genetic studies of other outcrossing crops and organisms with highly heterozygous genomes. Genomic analysis of orphan crops such as yam promotes efforts to improve food security and the sustainability of tropical agriculture.