Improving Quantitative Traits in Self-Pollinated Crops Using Simulation-Based Selection With Minimal Crossing.

Genomic selection and marker-assisted recurrent selection have been applied to improve quantitative traits in many cross-pollinated crops. However, such selection is not feasible in self-pollinated crops owing to laborious crossing procedures. In this study, we developed a simulation-based selection strategy that makes use of a trait prediction model based on genomic information to predict the phenotype of the progeny for all possible crossing combinations. These predictions are then used to select the best cross combinations for the selection of the given trait. In our simulated experiment, using a biparental initial population with a heritability set to 0.3, 0.6, or 1.0 and the number of quantitative trait loci set to 30 or 100, the genetic gain of the proposed strategy was higher or equal to that of conventional recurrent selection method in the early selection cycles, although the number of cross combinations of the proposed strategy was considerably reduced in each cycle. Moreover, this strategy was demonstrated to increase or decrease seed protein content in soybean recombinant inbred lines using SNP markers. Information on 29 genomic regions associated with seed protein content was used to construct the prediction model and conduct simulation. After two selection cycles, the selected progeny had significantly higher or lower seed protein contents than those from the initial population. These results suggest that our strategy is effective in obtaining superior progeny over a short period with minimal crossing and has the potential to efficiently improve the target quantitative traits in self-pollinated crops.

Characterization of the genomic sequence data around common cutworm resistance genes in soybean (Glycine max) using short- and long-read sequencing methods.

The common cutworm (CCW, Spodopteraab litura Fabricius) is one of the pests that most severely infect soybean (Glycine max L. Merr.). In a previous report, quantitative trait loci (QTL) analysis of CCW resistance using a recombinant inbred line derived from a cross between a susceptible cultivar 'Fukuyutaka' and a resistant cultivar 'Himeshirazu', identified two antixenosis resistance QTLs, CCW-1 and CCW-2. To reveal sequence variation between the aforementioned two cultivars, whole genome resequencing was performed using Illumina HiSeq2000 (75,632,747 and 91,540,849 reads). The generated datasets can be used for fine mapping and gene isolation of CCW-1 and CCW-2 as well as for revealing more detailed genetic differences between 'Fukuyutaka' and 'Himeshirazu' .

Short chain fatty acids induced the type 1 and type 2 fimbrillin-dependent and fimbrillin-independent initial attachment and colonization of Actinomyces oris monoculture but not coculture with streptococci.

BACKGROUND: Actinomyces oris is an early colonizer and has two types of fimbriae on its cell surface, type 1 fimbriae (FimP and FimQ) and type 2 fimbriae (FimA and FimB), which contribute to the attachment and coaggregation with other bacteria and the formation of biofilm on the tooth surface, respectively. Short-chain fatty acids (SCFAs) are metabolic products of oral bacteria including A. oris and regulate pH in dental plaques. To clarify the relationship between SCFAs and fimbrillins, effects of SCFAs on the initial attachment and colonization (INAC) assay using A. oris wild type and fimbriae mutants was investigated. INAC assays using A. oris MG1 strain cells were performed with SCFAs (acetic, butyric, propionic, valeric and lactic acids) or a mixture of them on human saliva-coated 6-well plates incubated in TSB with 0.25% sucrose for 1 h. The INAC was assessed by staining live and dead cells that were visualized with a confocal microscope. RESULTS: Among the SCFAs, acetic, butyric and propionic acids and a mixture of acetic, butyric and propionic acids induced the type 1 and type 2 fimbriae-dependent and independent INAC by live A. oris, but these cells did not interact with streptococci. The main effects might be dependent on the levels of the non-ionized acid forms of the SCFAs in acidic stress conditions. GroEL was also found to be a contributor to the FimA-independent INAC by live A. oris cells stimulated with non-ionized acid. CONCLUSION: SCFAs affect the INAC-associated activities of the A. oris fimbrillins and non-fimbrillins during ionized and non-ionized acid formations in the form of co-culturing with other bacteria in the dental plaque but not impact the interaction of A. oris with streptococci.

Soybean antiviral immunity conferred by dsRNase targets the viral replication complex.

Eukaryotic positive-strand RNA viruses replicate their genomes in membranous compartments formed in a host cell, which sequesters the dsRNA replication intermediate from antiviral immune surveillance. Here, we find that soybean has developed a way to overcome this sequestration. We report the positional cloning of the broad-spectrum soybean mosaic virus resistance gene Rsv4, which encodes an RNase H family protein with dsRNA-degrading activity. An active-site mutant of Rsv4 is incapable of inhibiting virus multiplication and is associated with an active viral RNA polymerase complex in infected cells. These results suggest that Rsv4 enters the viral replication compartment and degrades viral dsRNA. Inspired by this model, we design three plant-gene-derived dsRNases that can inhibit the multiplication of the respective target viruses. These findings suggest a method for developing crops resistant to any target positive-strand RNA virus by fusion of endogenous host genes.

Highly multiplexed AmpliSeq technology identifies novel variation of flowering time-related genes in soybean (Glycine max).

Whole-genome re-sequencing is a powerful approach to detect gene variants, but it is expensive to analyse only the target genes. To circumvent this problem, we attempted to detect novel variants of flowering time-related genes and their homologues in soybean mini-core collection by target re-sequencing using AmpliSeq technology. The average depth of 382 amplicons targeting 29 genes was 1,237 with 99.85% of the sequence data mapped to the reference genome. Totally, 461 variants were detected, of which 150 sites were novel and not registered in dbSNP. Known and novel variants were detected in the classical maturity loci-E1, E2, E3, and E4. Additionally, large indel alleles, E1-nl and E3-tr, were successfully identified. Novel loss-of-function and missense variants were found in FT2a, MADS-box, WDR61, phytochromes, and two-component response regulators. The multiple regression analysis showed that four genes-E2, E3, Dt1, and two-component response regulator-can explain 51.1-52.3% of the variation in flowering time of the mini-core collection. Among them, the two-component response regulator with a premature stop codon is a novel gene that has not been reported as a soybean flowering time-related gene. These data suggest that the AmpliSeq technology is a powerful tool to identify novel alleles.

Role of SCFAs for Fimbrillin-Dependent Biofilm Formation of Actinomyces oris.

Actinomyces oris expresses type 1 and 2 fimbriae on the cell surface. Type 2 fimbriae mediate co-aggregation and biofilm formation and are composed of the shaft fimbrillin FimA and the tip fimbrillin FimB. Short-chain fatty acids (SCFAs) are metabolic products of oral bacteria, but the effects of exogenous SCFAs on FimA-dependent biofilm formation are poorly understood. We performed two types of biofilm formation assays using A. oris MG1 or MG1.ΔfimA to observe the effects of SCFAs on FimA-dependent biofilm formation in 96-well and six-well microtiter plates and a flow cell system. SCFAs did not induce six- and 16-hour biofilm formation of A. oris MG1 and MG1.ΔfimA in saliva-coated 96-well and six-well microtiter plates in which metabolites produced during growth were not excluded. However, 6.25 mM butyric acid and 3.125 mM propionic acid induced FimA-dependent biofilm formation and cell death in a flow cell system in which metabolites produced during growth were excluded. Metabolites produced during growth may lead to disturbing effects of SCFAs on the biofilm formation. The pure effects of SCFAs on biofilm formation were induction of FimA-dependent biofilm formation, but the stress responses from dead cells may regulate its effects. Therefore, SCFA may play a key role in A. oris biofilm formation.

PVR/CD155 Ala67Thr Mutation and Cleft Lip/Palate.

The 19q13 locus has been linked to cleft lip and palate by our group and independently by others. Here we fine mapped the region in an attempt to identify an etiological variant that can explain cleft lip and palate occurrence. A total of 2739 individuals born with cleft lip and palate, related to individuals born with cleft lip and palate, and unrelated were studied. We used linkage and association approaches to fine map the interval between D19S714 and D19S433 and genotypes were defined by the use of TaqMan chemistry. We confirmed our previous findings that markers in PVR/CD155 are associated with cleft lip and palate. We studied the mutation Ala67Thr further and calculated its penetrance. We also attempted to detect PVR/CD155 expression in human whole saliva. Our results showed that markers in PVR/CD155 are associated with cleft lip and palate and the penetrance of the Ala67Thr is very low (between 1% and 5%). We could not detect PVR/CD155 expression in adult human whole saliva and PVR/CD155 possibly interacts with maternal infection to predispose children to cleft lip only.

Development of a high-density linkage map and chromosome segment substitution lines for Japanese soybean cultivar Enrei.

Using progeny of a cross between Japanese soybean Enrei and Chinese soybean Peking, we developed a high-density linkage map and chromosomal segment substitution lines (CSSLs). The map consists of 2,177 markers with polymorphism information for 32 accessions and provides a detailed genetic framework for these markers. The marker order on the linkage map revealed close agreement with that on the chromosome-scale assembly, Wm82.a2.v1. The differences, especially on Chr. 5 and Chr. 11, in the present map provides information to identify regions in the genome assembly where additional information is required to resolve marker order and assign remaining scaffolds. To cover the entire soybean genome, we used 999 BC3F2 backcross plants and selected 103 CSSLs carrying chromosomal segments from Peking in the genetic background of Enrei. Using these low-genetic-complexity resources, we dissected variation in traits related to flowering, maturity and yield into approximately 50 reproducible quantitative trait loci (QTLs) and evaluated QTLs with small genetic effects as single genetic factors in a uniform genetic background. CSSLs developed in this study may be good starting material for removing the unfavourable characteristics of Peking during pre-breeding and for isolation of genes conferring disease and stress resistance that have not yet been characterized.

QTL mapping of antixenosis resistance to common cutworm (Spodoptera litura Fabricius) in wild soybean (Glycine soja).

The common cutworm (CCW; Spodoptera litura Fabricius) is a serious herbivorous insect pest of soybean (Glycine max) in Asia and Oceania. Previously, we identified quantitative trait loci (QTLs) for CCW-antibiosis-resistance, CCW-1 and CCW-2, and antixenosis-resistance, qRslx1 and qRslx2, in the cultivar 'Himeshirazu'. The effects of these QTLs are useful in the breeding of CCW-resistant cultivars. In this study, we conducted an antixenosis bioassay on CCW using recombinant inbred lines derived from a cross between a wild soybean (Glycine soja) and the leading cultivar 'Fukuyutaka' to identify CCW-resistance genes in G. soja. The QTL analysis revealed six and four novel antixenosis-resistance QTLs in 2012 and 2013, respectively. Among them, the QTLs on chromosomes 2 and 7, designated qRslx4 and qRslx3, respectively, were stably detected in both years. qRslx3 exhibited the largest effect in both years, suggesting that qRslx3 can be exploited in the breeding of CCW-resistant soybean. Furthermore, qRslx3 and qRslx4 can be used, along with previously reported QTLs from 'Himeshirazu', to enhance the CCW-resistance of soybean cultivars because their chromosomal positions are unique. These new CCW-resistance QTLs from G. soja should play important roles in the breeding of CCW-resistant soybean cultivars.

Streptococcal adhesin SspA/B analogue peptide inhibits adherence and impacts biofilm formation of Streptococcus mutans.

Streptococcus mutans, the major causative agent of dental caries, adheres to tooth surfaces via the host salivary glycoprotein-340 (gp340). This adherence can be competitively inhibited by peptides derived from the SspA/B adhesins of Streptococcus gordonii, a human commensal microbe that competes for the same binding sites. Ssp(A4K-A11K), a double-lysine substituted SspA/B peptide analogue, has been shown to exhibit superior in vitro binding affinity for a gp340-derived peptide (SRCRP2), suggesting that Ssp(A4K-A11K) may be of clinical interest. In the present work, we tested the inhibitory effects of Ssp(A4K-A11K) on adherence and biofilm formation of S. mutans by reconstructing an artificial oral environment using saliva-coated polystyrene plates and hydroxyapatite disks. Bacterial adherence (adherence period: 1 h) was assessed by an enzyme-linked immunosorbent assay using biotinylated bacterial cells. Biofilm formation (periods: 8, 11, or 14 h) was assessed by staining and imaging of the sessile cells, or by recovering biofilm cells and plating for cell counts. The pH values of the culture media were measured as a biofilm acidogenicity indicator. Bactericidality was measured by loss of optical density during culturing in the presence of the peptide. We observed that 650 µM Ssp(A4K-A11K) significantly inhibited adherence of S. mutans to saliva-coated polystyrene; a similar effect was seen on bacterial affinity for SRCRP2. Ssp(A4K-A11K) had lesser effects on the adherence of commensal streptococci. Pretreatment of polystyrene and hydroxyapatite with 650 µM Ssp(A4K-A11K) significantly attenuated biofilm formation, whether tested with glucose- or sucrose-containing media. The SspA/B peptide's activity did not reflect bactericidality. Strikingly, pH in Ssp-treated 8-h (6.8 ± 0.06) and 11-h (5.5 ± 0.06) biofilms showed higher values than the critical pH. Thus, Ssp(A4K-A11K) acts by inhibiting bacterial adherence and cariogrnic biofilm formation. We further consider these results in the context of the safety, specificity, and stability properties of the Ssp(A4K-A11K) peptide.

In vivo neurochemical evidence that delta1-, delta2- and mu2-opioid receptors, but not mu1-opioid receptors, inhibit acetylcholine efflux in the nucleus accumbens of freely moving rats.

Cholinergic neurons in the nucleus accumbens express delta- and mu-opioid receptors that are thought to inhibit neural activity. Delta- and mu-opioid receptors are divided into delta1- and delta2-opioid receptors and mu1- and mu2-opioid receptors, respectively. We analysed the roles of delta- and mu-opioid receptor subtypes in regulating accumbal acetylcholine efflux of freely moving rats using in vivo microdialysis. Other than naloxonazine, given intraperitoneally, delta- and mu-opioid receptor ligands were administered intracerebrally through the dialysis probe. Doses of these compounds indicate total amount (mol) over an infusion time of 30-60min. To monitor basal acetylcholine, a low concentration of physostigmine (50nM) was added to the perfusate. The delta1-opioid receptor agonist DPDPE (3 and 300pmol) and delta2-opioid receptor agonist deltorphin II (3 and 30pmol) decreased accumbal acetylcholine in a dose-related manner. DPDPE (300pmol)- and deltorphin II (3pmol)-induced reductions in acetylcholine were each inhibited by the delta1-opioid receptor antagonist BNTX (0.3pmol) and delta2-opioid receptor antagonist naltriben (15pmol), respectively. The mu-opioid receptor agonists endomorphin-1 and endomorphin-2 (6 and 30nmol) decreased acetylcholine in a dose-related manner. Endomorphin-1- and endomorphin-2 (30nmol)-induced reductions in acetylcholine were prevented by the mu-opioid receptor antagonist CTOP (3nmol). The mu1-opioid receptor antagonist naloxonazine (15mg/kg ip), which inhibits endomorphin-1 (15nmol)-induced accumbal dopamine efflux, did not alter endomorphin-1- or endomorphin-2 (30nmol)-induced reductions in acetylcholine efflux. This study provides in vivo evidence for delta1-, delta2- and mu2-opioid receptors, but not mu1-opioid receptors, that inhibit accumbal cholinergic neural activity.

Construction of a high-density mutant library in soybean and development of a mutant retrieval method using amplicon sequencing.

BACKGROUND: Functions of most genes predicted in the soybean genome have not been clarified. A mutant library with a high mutation density would be helpful for functional studies and for identification of novel alleles useful for breeding. Development of cost-effective and high-throughput protocols using next generation sequencing (NGS) technologies is expected to simplify the retrieval of mutants with mutations in genes of interest. RESULTS: To increase the mutation density, seeds of the Japanese elite soybean cultivar Enrei were treated with the chemical mutagen ethyl methanesulfonate (EMS); M2 seeds produced by M1 plants were treated with EMS once again. The resultant library, which consisted of DNA and seeds from 1536 plants, revealed large morphological and physiological variations. Based on whole-genome re-sequencing analysis of 12 mutant lines, the average number of base changes was 12,796 per line. On average, 691 and 35 per line were missense and nonsense mutations, respectively. Two screening strategies for high resolution melting (HRM) analysis and indexed amplicon sequencing were designed to retrieve the mutants; the mutations were confirmed by Sanger sequencing as the final step. In comparison with HRM screening of several genes, indexed amplicon sequencing allows one to scan a longer sequence range and skip screening steps and to know the sequence information of mutation because it uses systematic DNA pooling and the index of NGS reads, which simplifies the discovery of mutants with amino acid substitutions. CONCLUSIONS: A soybean mutant library with a high mutation density was developed. A high mutation density (1 mutation/74 kb) was achieved by repeating the EMS treatment. The mutation density of our library is sufficiently high to obtain a plant in which a gene is nonsense mutated. Thus, our mutant library and the indexed amplicon sequencing will be useful for functional studies of soybean genes and have a potential to yield useful mutant alleles for soybean breeding.

Genetic architecture of variation in heading date among Asian rice accessions.

BACKGROUND: Heading date, a crucial factor determining regional and seasonal adaptation in rice (Oryza sativa L.), has been a major selection target in breeding programs. Although considerable progress has been made in our understanding of the molecular regulation of heading date in rice during last two decades, the previously isolated genes and identified quantitative trait loci (QTLs) cannot fully explain the natural variation for heading date in diverse rice accessions. RESULTS: To genetically dissect naturally occurring variation in rice heading date, we collected QTLs in advanced-backcross populations derived from multiple crosses of the japonica rice accession Koshihikari (as a common parental line) with 11 diverse rice accessions (5 indica, 3 aus, and 3 japonica) that originate from various regions of Asia. QTL analyses of over 14,000 backcrossed individuals revealed 255 QTLs distributed widely across the rice genome. Among the detected QTLs, 128 QTLs corresponded to genomic positions of heading date genes identified by previous studies, such as Hd1, Hd6, Hd3a, Ghd7, DTH8, and RFT1. The other 127 QTLs were detected in different chromosomal regions than heading date genes. CONCLUSIONS: Our results indicate that advanced-backcross progeny allowed us to detect and confirm QTLs with relatively small additive effects, and the natural variation in rice heading date could result from combinations of large- and small-effect QTLs. We also found differences in the genetic architecture of heading date (flowering time) among maize, Arabidopsis, and rice.

Role of estrogen related receptor beta (ESRRB) in DFN35B hearing impairment and dental decay.

BACKGROUND: Congenital forms of hearing impairment can be caused by mutations in the estrogen related receptor beta (ESRRB) gene. Our initial linkage studies suggested the ESRRB locus is linked to high caries experience in humans. METHODS: We tested for association between the ESRRB locus and dental caries in 1,731 subjects, if ESRRB was expressed in whole saliva, if ESRRB was associated with the microhardness of the dental enamel, and if ESRRB was expressed during enamel development of mice. RESULTS: Two families with recessive ESRRB mutations and DFNB35 hearing impairment showed more extensive dental destruction by caries. Expression levels of ESRRB in whole saliva samples showed differences depending on sex and dental caries experience. CONCLUSIONS: The common etiology of dental caries and hearing impairment provides a venue to assist in the identification of individuals at risk to either condition and provides options for the development of new caries prevention strategies, if the associated ESRRB genetic variants are correlated with efficacy.

Use of surface-enhanced Raman scattering for detection of cancer-related serum-constituents in gastrointestinal cancer patients.

Laser-mediated surface-enhanced Raman scattering (SERS) has industrial and biological applications. We have developed a rapid and simple method for generating silver nanoscale hexagonal columns (NHCs) on the surface of a phosphor bronze chip for measurement of SERS spectra. This was used to detect SERS spectra from blood samples obtained from patients with gastric cancer, colorectal cancer, or benign diseases (n=12 each) using a low intensity helium-neon red laser beam with a 632.8-nm wavelength; the intensity of the SERS spectra was compared among the patient groups. The peak heights of SERS spectra from patients with benign diseases were significantly lower than those from patients with gastric or colorectal cancer, whereas those from patients with gastric cancer and colorectal cancer did not differ significantly. Thus, SERS using NHC chips holds promise for the easier and faster detection of cancer-related serum-constituents as biomarkers. FROM THE CLINICAL EDITOR: In this study, laser-mediated surface-enhanced Raman scattering (SERS) was utilized as a sensitive detection method of cancer-related serum-constituents in gastric and colorectal cancer, via the use of silver nanoscale hexagonal columns on the surface of a phosphor bronze chip for measurement of SERS spectra, paving the way to the development of a rapid and high throughput tool for cancer screening and therapy monitoring.

Genetic mapping of agenesis of the third molars in mice.

EL/Sea mice are characterized by 100% incidence of agenesis of the third molars (M3). In a previous study, chromosomal mapping of the ninth generation EL/Sea congenic strains revealed a major locus for agenesis of M3, designated am3, in the 125-137 Mbp region of chromosome 3. In the present study, to determine the precise location of the am3 locus, we produced further generations of the EL/Sea congenic strains for am3 in which the restricted interval on chromosome 3 of EL/Sea was replaced by a MSM/Msf-derived homolog. The eleventh generation congenic mice that were either heterozygous or homozygous for the MSM/Msf-derived interval exhibited a significant decrease in the incidence of M3 agenesis (p < 0.00001). Results confined the am3 locus to an interval of 1 Mbp on chromosome 3, demonstrating that Lef1, one of the essential transcription factors for early tooth development, is the strongest candidate for am3.

Role of TRAV locus in low caries experience.

Caries is the most common chronic, multifactorial disease in the world today; and little is still known about the genetic factors influencing susceptibility. Our previous genome-wide linkage scan has identified five loci related to caries susceptibility: 5q13.3, 13q31.1, 14q11.2, 14q 24.3, and Xq27. In the present study, we fine mapped the 14q11.2 locus to identify genetic contributors to caries susceptibility. Four hundred seventy-seven subjects from 72 pedigrees with similar cultural and behavioral habits and limited access to dental care living in the Philippines were studied. An additional 387 DNA samples from unrelated individuals were used to determine allele frequencies. For replication purposes, a total of 1,446 independent subjects from four different populations were analyzed based on their caries experience (low versus high). Forty-eight markers in 14q11.2 were genotyped using TaqMan chemistry. Transmission disequilibrium test was used to detect over transmission of alleles in the Filipino families, and Chi-square, Fisher's exact and logistic regression were used to test for association between low caries experience and variant alleles in the replication data sets. We finally assessed the mRNA expression of TRAV4 in the saliva of 143 study subjects. In the Filipino families, statistically significant associations were found between low caries experience and markers in TRAV4. We were able to replicate these results in the populations studied that were characteristically from underserved areas. Direct sequencing of 22 subjects carrying the associated alleles detects one missense mutation (Y30R) that is predicted to be probably damaging. Finally, we observed higher expression in children and teenagers with low caries experience, correlating with specific alleles in TRAV4. Our results suggest that TRAV4 may have a role in protecting against caries.

Evaluation of soybean germplasm conserved in NIAS genebank and development of mini core collections.

Genetic variation and population structure among 1603 soybean accessions, consisted of 832 Japanese landraces, 109 old and 57 recent Japanese varieties, 341 landrace from 16 Asian countries and 264 wild soybean accessions, were characterized using 191 SNP markers. Although gene diversity of Japanese soybean germplasm was slight lower than that of exotic soybean germplasm, population differentiation and clustering analyses indicated clear genetic differentiation among Japanese cultivated soybeans, exotic cultivated soybeans and wild soybeans. Nine hundred ninety eight Japanese accessions were separated to a certain extent into groups corresponding to their agro-morphologic characteristics such as photosensitivity and seed characteristics rather than their geographical origin. Based on the assessment of the SNP markers and several agro-morphologic traits, accessions that retain gene diversity of the whole collection were selected to develop several soybean sets of different sizes using an heuristic approach; a minimum of 12 accessions can represent the observed gene diversity; a mini-core collection of 96 accession can represent a major proportion of both geographic origin and agro-morphologic trait variation. These selected sets of germplasm will provide an effective platform for enhancing soybean diversity studies and assist in finding novel traits for crop improvement.

Effects on flowering and seed yield of dominant alleles at maturity loci E2 and E3 in a Japanese cultivar, Enrei.

'Enrei' is the second leading variety of soybean (Glycine max (L.) Merr.) in Japan. Its cultivation area is mainly restricted to the Hokuriku region. In order to expand the adaptability of 'Enrei', we developed two near-isogenic lines (NILs) of 'Enrei' for the dominant alleles controlling late flowering at the maturity loci, E2 and E3, by backcrossing with marker-assisted selection. The resultant NILs and the original variety were evaluated for flowering, maturity, seed productivity and other agronomic traits in five different locations. Expectedly, NILs with E2 or E3 alleles flowered later than the original variety in most locations. These NILs produced comparatively larger plants in all locations. Seed yields were improved by E2 and E3 in the southern location or in late-sowing conditions, whereas the NIL for E2 exhibited almost the same or lower productivity in the northern locations due to higher degrees of lodging. Seed quality-related traits, such as 100-seed weight and protein content, were not significantly different between the original variety and its NILs. These results suggest that the modification of genotypes at maturity loci provides new varieties that are adaptive to environments of different latitudes while retaining almost the same seed quality as that of the original.

Enamel formation genes influence enamel microhardness before and after cariogenic challenge.

There is evidence for a genetic component in caries susceptibility, and studies in humans have suggested that variation in enamel formation genes may contribute to caries. For the present study, we used DNA samples collected from 1,831 individuals from various population data sets. Single nucleotide polymorphism markers were genotyped in selected genes (ameloblastin, amelogenin, enamelin, tuftelin, and tuftelin interacting protein 11) that influence enamel formation. Allele and genotype frequencies were compared between groups with distinct caries experience. Associations with caries experience can be detected but they are not necessarily replicated in all population groups and the most expressive results was for a marker in AMELX (p=0.0007). To help interpret these results, we evaluated if enamel microhardness changes under simulated cariogenic challenges are associated with genetic variations in these same genes. After creating an artificial caries lesion, associations could be seen between genetic variation in TUFT1 (p=0.006) and TUIP11 (p=0.0006) with enamel microhardness. Our results suggest that the influence of genetic variation of enamel formation genes may influence the dynamic interactions between the enamel surface and the oral cavity.