Development of 454 New Kompetitive Allele-Specific PCR (KASP) Markers for Temperate japonica Rice Varieties.

Temperate japonica rice varieties exhibit wide variation in the phenotypes of several important agronomic traits, including disease resistance, pre-harvest sprouting resistance, plant architecture, and grain quality, indicating the presence of genes contributing to favorable agronomic traits. However, gene mapping and molecular breeding has been hampered as a result of the low genetic diversity among cultivars and scarcity of polymorphic DNA markers. Single nucleotide polymorphism (SNP)-based kompetitive allele-specific PCR (KASP) markers allow high-throughput genotyping for marker-assisted selection and quantitative trait loci (QTL) mapping within closely related populations. Previously, we identified 740,566 SNPs and developed 771 KASP markers for Korean temperate japonica rice varieties. However, additional markers were needed to provide sufficient genome coverage to support breeding programs. In this study, the 740,566 SNPs were categorized according to their predicted impacts on gene function. The high-impact, moderate-impact, modifier, and low-impact groups contained 703 (0.1%), 20,179 (2.7%), 699,866 (94.5%), and 19,818 (2.7%) SNPs, respectively. A subset of 357 SNPs from the high-impact group was selected for initial KASP marker development, resulting in 283 polymorphic KASP markers. After incorporation of the 283 markers with the 771 existing markers in a physical map, additional markers were developed to fill genomic regions with large gaps between markers, and 171 polymorphic KASP markers were successfully developed from 284 SNPs. Overall, a set of 1225 KASP markers was produced. The markers were evenly distributed across the rice genome, with average marker density of 3.3 KASP markers per Mbp. The 1225 KASP markers will facilitate QTL/gene mapping and marker-assisted selection in temperate japonica rice breeding programs.

Family Management Style as a Mediator between Parenting Stress and Quality of Life of Children with Epilepsy.

PURPOSE: To examine the possible relationship between parenting stress and quality of life of children with epilepsy together with the mediating effects of family management styles on this relationship. DESIGN AND METHODS: We conducted a descriptive and exploratory study using data of participants were 93 parents with an epileptic child. Instruments were self-reported questionnaires including the Korean version of the Quality of Life (QOL) in Childhood Epilepsy Questionnaire (K-QOLCE), the Korean version of the Parenting Stress Index (PSI), and the Korean version of the Family Management Measure (FaMM). Six domains of FaMM were clustered into two domains: easy or difficult family management styles. Descriptive and Pearson correlation path analyses were used to analyze the data. RESULTS: The direct effects of PSI on QOL were not significant (b = -0.21, t = -0.94, p = .349). Indirect effects of PSI through easy family management styles on QOL were significant (b = -0.33, 95% CI = [-0.77, -0.05]). Additionally, two other effects (i.e., indirect effects through difficult family management styles and direct effects) were non-significant. All effects of PSI on QOL were fully mediated through easy family management styles. CONCLUSION: Easy family management styles are the most important factor in predicting QOL in childhood epilepsy patients. PRACTICE IMPLICATIONS: Comprehensive intervention programs are recommended for parents and families of epileptic children to promote positive perceptions of the child's life and to increase parental management ability of the child's condition and parental mutuality.

Measuring theory of mind in schizophrenia research: Cross-cultural validation.

Theory of mind (ToM) is the ability to understand mental states of others and it is crucial for building sensitivity to other persons or events. Measuring ToM is important for understanding and rehabilitating social cognitive impairments in persons with schizophrenia. The Social Attribution Task-Multiple Choice (SAT-MC) has been successfully employed to measure ToM between individuals with schizophrenia (SZ) and healthy controls (HC) in North America. Given that the SAT-MC uses geometric shapes, is nonverbal and less culturally loaded than other social cognition measures, it may serve for measuring ToM in schizophrenia across cultures. A total of 120 participants (30 per group; Korean SZ; Korean HC; North American SZ; North American HC) were selected from existing databases to examine the reliability and validity of the SAT-MC. Internal consistency, factor structure, measurement invariance, discriminant validity, and convergent/divergent validity were examined. The SAT-MC had good internal consistency regardless of the clinical and cultural group as evidence by Cronbach's α ≥ 0.78 in all groups. Confirmatory factor analysis confirmed the one-factor model with a good model fit (χ2 = 188.122, TLI = 0.958, CFI = 0.963, RMSEA = 0.045). The SAT-MC was sensitive to detect individual differences in ToM of SZ and HC, regardless of culture (p < 0.001), and significantly correlated with other social cognition tasks (Hinting and Reading the Mind in the Eyes Test) among Korean and North American patients. The SAT-MC is a reliable measure for evaluating ToM in both Koreans and North Americans with or without schizophrenia, supporting its potential utility in diverse language and cultures for schizophrenia research.

Dexmedetomidine Inhibits Phenylephrine-induced Contractions via Alpha-1 Adrenoceptor Blockade and Nitric Oxide Release in Isolated Rat Aortae.

The goal of this in vitro study was to examine the effect of the alpha-2 adrenoceptor agonist dexmedetomidine on phenylephrine (alpha-1 adrenoceptor agonist)-induced contraction in isolated rat aortae and to elucidate the associated cellular mechanisms, with a particular focus on alpha-1 adrenoceptor antagonism. Dexmedetomidine dose-response curves were generated in isolated endothelium-intact and endothelium-denuded rat aortae precontracted with phenylephrine or 5-hydroxytryptamine. Endothelium-denuded aortic rings were pretreated with either dexmedetomidine or the reversible alpha-1 adrenoceptor antagonist phentolamine, followed by post-treatment with the irreversible alpha-1 adrenoceptor blocker phenoxybenzamine. Control rings were treated with phenoxybenzamine alone. All rings were repeatedly washed with Krebs solution to remove all pretreatment drugs, including phenoxybenzamine, phentolamine and dexmedetomidine. Phenylephrine dose-response curves were then generated. The effect of rauwolscine on the dexmedetomidine-mediated change in phenylephrine-induced endothelial nitric oxide synthase (eNOS) phosphorylation in human umbilical vein endothelial cells was examined using western blotting. The magnitude of the dexmedetomidine-mediated inhibition of phenylephrine-induced contraction was higher in endothelium-intact aortae than in endothelium-denuded aortae or endothelium-intact aortae treated with Nω-nitro-L-arginine methyl ester. However, dexmedetomidine did not significantly alter 5-hydroxytryptamine-induced contraction. In further experiments, prazosin attenuated dexmedetomidine-induced contraction. Additionally, pretreatment with either dexmedetomidine plus phenoxybenzamine or phentolamine plus phenoxybenzamine produced greater phenylephrine-induced contraction than phenoxybenzamine alone, suggesting that dexmedetomidine protects aortae from the alpha-1 adrenoceptor blockade induced by phenoxybenzamine. Rauwolscine attenuated the dexmedetomidine-mediated enhancement of phenylephrine-induced eNOS phosphorylation. Taken together, these results suggest that dexmedetomidine attenuates phenylephrine-induced contractions via alpha-1 adrenoceptor blockade and endothelial nitric oxide release in the isolated rat aorta.

Mepivacaine attenuates vasodilation induced by ATP-sensitive potassium channels in rat aorta.

The goal of this in vitro study was to investigate the effect of mepivacaine on vasodilation induced by the ATP-sensitive potassium (KATP) channel opener levcromakalim in isolated endothelium-denuded rat aortas. The effects of mepivacaine and the KATP channel inhibitor glibenclamide, alone or in combination, on levcromakalim-induced vasodilation were assessed in the isolated aortas. The effects of mepivacaine or combined treatment with a protein kinase C (PKC) inhibitor, GF109203X, and mepivacaine on this vasodilation were also investigated. Levcromakalim concentration-response curves were generated for isolated aortas precontracted with phenylephrine or a PKC activator, phorbol 12,13-dibutyrate (PDBu). Further, the effects of mepivacaine and glibenclamide on levcromakalim-induced hyperpolarization were assessed in rat aortic vascular smooth muscle cells. Mepivacaine attenuated levcromakalim-induced vasodilation, whereas it had no effect on this vasodilation in isolated aortas pretreated with glibenclamide. Combined treatment with GF109203X and mepivacaine enhanced levcromakalim-induced vasodilation compared with pretreatment with mepivacaine alone. This vasodilation was attenuated in aortas precontracted with PDBu compared with those precontracted with phenylephrine. Mepivacaine and glibenclamide, alone or in combination, attenuated levcromakalim-induced membrane hyperpolarization. Taken together, these results suggest that mepivacaine attenuates vasodilation induced by KATP channels, which appears to be partly mediated by PKC.

Comparative analysis of disease-linked single nucleotide polymorphic markers from Brassica rapa for their applicability to Brassica oleracea.

Numerous studies using single nucleotide polymorphisms (SNPs) have been conducted in humans, and other animals, and in major crops, including rice, soybean, and Chinese cabbage. However, the number of SNP studies in cabbage is limited. In this present study, we evaluated whether 7,645 SNPs previously identified as molecular markers linked to disease resistance in the Brassica rapa genome could be applied to B. oleracea. In a BLAST analysis using the SNP sequences of B. rapa and B. oleracea genomic sequence data registered in the NCBI database, 256 genes for which SNPs had been identified in B. rapa were found in B. oleracea. These genes were classified into three functional groups: molecular function (64 genes), biological process (96 genes), and cellular component (96 genes). A total of 693 SNP markers, including 145 SNP markers [BRH--developed from the B. rapa genome for high-resolution melt (HRM) analysis], 425 SNP markers (BRP--based on the B. rapa genome that could be applied to B. oleracea), and 123 new SNP markers (BRS--derived from BRP and designed for HRM analysis), were investigated for their ability to amplify sequences from cabbage genomic DNA. In total, 425 of the SNP markers (BRP-based on B. rapa genome), selected from 7,645 SNPs, were successfully applied to B. oleracea. Using PCR, 108 of 145 BRH (74.5%), 415 of 425 BRP (97.6%), and 118 of 123 BRS (95.9%) showed amplification, suggesting that it is possible to apply SNP markers developed based on the B. rapa genome to B. oleracea. These results provide valuable information that can be utilized in cabbage genetics and breeding programs using molecular markers derived from other Brassica species.

Transcriptome analysis of Capsicum annuum varieties Mandarin and Blackcluster: assembly, annotation and molecular marker discovery.

Next generation sequencing technologies have proven to be a rapid and cost-effective means to assemble and characterize gene content and identify molecular markers in various organisms. Pepper (Capsicum annuum L., Solanaceae) is a major staple vegetable crop, which is economically important and has worldwide distribution. High-throughput transcriptome profiling of two pepper cultivars, Mandarin and Blackcluster, using 454 GS-FLX pyrosequencing yielded 279,221 and 316,357 sequenced reads with a total 120.44 and 142.54Mb of sequence data (average read length of 431 and 450 nucleotides). These reads resulted from 17,525 and 16,341 'isogroups' and were assembled into 19,388 and 18,057 isotigs, and 22,217 and 13,153 singletons for both the cultivars, respectively. Assembled sequences were annotated functionally based on homology to genes in multiple public databases. Detailed sequence variant analysis identified a total of 9701 and 12,741 potential SNPs which eventually resulted in 1025 and 1059 genotype specific SNPs, for both the varieties, respectively, after examining SNP frequency distribution for each mapped unigenes. These markers for pepper will be highly valuable for marker-assisted breeding and other genetic studies.

De novo transcriptome assembly and novel microsatellite marker information in Capsicum annuum varieties Saengryeg 211 and Saengryeg 213.

BACKGROUND: Pepper, Capsicum annuum L., Solanaceae, is a major staple economically important vegetable crop worldwide. Limited functional genomics resources and whole genome association studies could be substantially improved through the application of molecular approach for the characterization of gene content and identification of molecular markers. The massive parallel pyrosequencing of two pepper varieties, the highly pungent, Saengryeg 211, and the non-pungent, Saengryeg 213, including de novo transcriptome assembly, functional annotation, and in silico discovery of potential molecular markers is described. We performed 454 GS-FLX Titanium sequencing of polyA-selected and normalized cDNA libraries generated from a single pool of transcripts obtained from mature fruits of two pepper varieties. RESULTS: A single 454 pyrosequencing run generated 361,671 and 274,269 reads totaling 164.49 and 124.60 Mb of sequence data (average read length of 454 nucleotides), which assembled into 23,821 and 17,813 isotigs and 18,147 and 15,129 singletons for both varieties, respectively. These reads were organized into 20,352 and 15,781 'isogroups' for both varieties. Assembled sequences were functionally annotated based on homology to genes in multiple public databases and assigned with Gene Ontology (GO) terms. Sequence variants analyses identified a total of 3,766 and 2,431 potential (Simple Sequence Repeat) SSR motifs for microsatellite analysis for both varieties, where trinucleotide was the most common repeat unit (84%), followed by di (9.9%), hexa (4.1%) and pentanucleotide repeats (2.1%). GAA repeat (8.6%) was the most frequent repeat motif, followed by TGG (7.2%), TTC (6.5%), and CAG (6.2%). CONCLUSIONS: High-throughput transcriptome assembly, annotation and large scale of SSR marker discovery has been achieved using next generation sequencing (NGS) of two pepper varieties. These valuable informations for functional genomics resource shall help to further improve the pepper breeding efforts with respect to genetic linkage maps, QTL mapping and marker-assisted trait selection.

Hemorheology and microvascular disorders.

The present review presents basic concepts of blood rheology related to vascular diseases. Blood flow in large arteries is dominated by inertial forces exhibited at high flow velocities, while viscous forces (i.e., blood rheology) play an almost negligible role. When high flow velocity is compromised by sudden deceleration as at a bifurcation, endothelial cell dysfunction can occur along the outer wall of the bifurcation, initiating inflammatory gene expression and, through mechanotransduction, the cascade of events associated with atherosclerosis. In sharp contrast, the flow of blood in microvessels is dominated by viscous shear forces since the inertial forces are negligible due to low flow velocities. Shear stress is a critical parameter in microvascular flow, and a force-balance approach is proposed for determining microvascular shear stress, accounting for the low Reynolds numbers and the dominance of viscous forces over inertial forces. Accordingly, when the attractive forces between erythrocytes (represented by the yield stress of blood) are greater than the shear force produced by microvascular flow, tissue perfusion itself cannot be sustained, leading to capillary loss. The yield stress parameter is presented as a diagnostic candidate for future clinical research, specifically, as a fluid dynamic biomarker for microvascular disorders. The relation between the yield stress and diastolic blood viscosity (DBV) is described using the Casson model for viscosity, from which one may be able determine thresholds of DBV where the risk of microvascular disorders is high.

Sequence information on simple sequence repeats and single nucleotide polymorphisms through transcriptome analysis of mungbean.

Mungbean (Vigna radiata (L.) Wilczek) is a unique species in its ability to fix atmospheric nitrogen, with early maturity, and relatively good drought resistance. We used 454 sequencing technology for transcriptome sequencing. A total of 150 159 and 142 993 reads produced 5 254 and 6 374 large contigs (≥ 500 bp) with an average length of 833 and 853 for Sunhwa and Jangan, respectively. Functional annotation to known sequences yielded 41.34% and 41.74% unigenes for Jangan and Sunhwa. A higher number of simple sequence repeat (SSR) motifs was identified in Jangan (1 630) compared with that of Sunhwa (1 334). A similar SSR distribution pattern was observed in both varieties. A total of 8 249 single nucleotide polymorphisms (SNPs) and indels with 2 098 high-confidence candidates were identified in the two mungbean varieties. The average distance between individual SNPs was approximately 860 bp. Our report demonstrates the utility of transcriptomic data for implementing a functional annotation and development of genetic markers. We also provide large resource sequence data for mungbean improvement programs.

Shotgun proteomic analysis for detecting differentially expressed proteins in the reduced culm number rice.

To survey protein expression patterns in the reduced culm number (RCN) rice, a comparative shotgun proteomic analysis was conducted. For large-scale protein identification, multidimensional protein identification technology (MudPIT) coupled with pre-fractionation of plant shoot proteins led to the identification of 3004 non-redundant rice proteins. By statistically comparing relative amounts of 1353 reproducibly identified proteins between the RCN rice and the wild-type rice, 44 differentially expressed proteins were detected, where 42 proteins were increased and 2 proteins were decreased in the RCN rice. These proteins appear to have roles in glycolysis, trichloroacetic acid cycle, secondary metabolism, nutrient recycling, and nucleotide metabolism and repair. Consequently, we hypothesized that the RCN rice might fail to maintain sugar nutrient homeostasis. This was confirmed with the observation that the sucrose concentration was increased significantly in the RCN rice compared with the wild-type rice. Also, the RCN rice showed a hypersensitive response to exogenous sucrose treatment.

Molecular genetic diversity and population structure in Lycium accessions using SSR markers.

This study was conducted to assess the genetic diversity and population structure of 139 Lycium chinense accessions using 18 simple sequence repeat (SSR) markers. In total, 108 alleles were detected. The number of alleles per marker locus ranged from two to 17, with an average of six. The gene diversity and polymorphism information content value averaged 0.3792 and 0.3296, with ranges of 0.0793 to 0.8023 and 0.0775 to 0.7734, respectively. The average heterozygosity was 0.4394. The model-based structure analysis revealed the presence of three subpopulations, which was consistent with clustering based on genetic distance. An AMOVA analysis showed that the between-population component of genetic variance was less than 15.3%, in contrast to 84.7% for the within-population component. The overall F(ST) value was 0.1178, indicating a moderate differentiation among groups. The results could be used for future L. chinense allele mining, association mapping, gene cloning, germplasm conservation, and designing effective breeding programs.

The effects of a whole-watershed calcium addition on the chemistry of stream storm events at the Hubbard Brook Experimental Forest in NH, USA.

Patterns of storm runoff chemistry from a wollastonite (calcium-silicate mineral, CaSiO(3)) treated watershed (W1) were compared with a reference watershed (W6) at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire (NH), USA to investigate the role of Ca(2+) supply in the acid-base status of stream chemistry. In the summer of 2003, six storm events were studied in W1 and W6 to evaluate the effects of the wollastonite treatment on the episodic acidification of stream waters. Although mean values of Ca(2+) concentrations decreased slightly from 33.8 to 31.7 mumol/L with increasing stream discharge in W1 during the events, the mean value of acid neutralizing capacity (ANC) was positive (1.2 mueq/L) during storm events, compared to negative values (-0.2 mueq/L) in W6. This pattern is presumably due to enhanced Ca(2+) supply in W1 (20.7 to 29.0% of dissolved Ca(2+) derived from the added wollastonite) to stream water as a result of interflow along shallow flowpaths. In addition, the application of wollastonite increased pH and dissolved silica (H(4)SiO(4)) concentrations, and decreased the concentration of inorganic monomeric Al (Al(i)) in W1 in comparison with W6 during storm events. Despite an increase in SO(4)(2-) concentration, likely due to desorption of sulfate from soil after the treatment, the watershed showed an increase in ANC compared to the reference watershed, serving to mitigate episodic acidification.

Middle cerebral artery fenestration in patients with cerebral ischemia.

BACKGROUND: We report five cases of middle cerebral artery (MCA) fenestration that might have caused cerebral infarction or ischemia. CASE REPORT: Unilateral fenestration of the MCA was observed in five patients with artery-relevant cerebral infarction or ischemia. Enhanced magnetic resonance imaging (MRI) and three-dimensional MR angiography (MRA) were performed in the patients, and a division of the lumen after fenestration was observed using virtual arterial endoscopy. In one patient, MRA and virtual endoscopy showed an obstruction in one limb of the fenestration. The MCA fenestrations were observed in the proximal portion in three cases and the intermediate portion in two cases, and there was no associated aneurysm near or far from the fenestration. METHODS: The five patients underwent both contrast-enhanced magnetic resonance imaging (MRI) and 3D MRA. Virtual arterial endoscopy was then performed to visualize the division of the lumen, a landmark of fenestration. CONCLUSIONS: The association between cerebral ischemia and MCA fenestration in the five cases suggests that the fenestration disturbing local flow hemodynamics seems to cause cerebral ischemia, even a direct causative relationship should be elucidated further.

Identification of QTLs for some agronomic traits in rice using an introgression line from Oryza minuta.

Wild progenitor species provide potential gene sources for complex traits such as yield and multiple resistances to biotic and abiotic stresses, and thus are expected to contribute to sustainable food supplies. An introgression line 'IR71033-121-15' was derived from a wild species Oryza minuta (2n = 48, BBCC, Acc No. 101141) at IRRI. Introgression analysis using 530 SSR and STS markers revealed that at least 14 chromosomal segments distributed over 12 chromosomes had been introgressed from O. minuta. An F2:3 population from the cross between IR71033 and Junambyeo (a Korean japonica cultivar) consisting of 146 lines was used for quantitative trait loci (QTL) analysis of 16 agronomic traits. A total of 36 single-locus QTLs (S-QTLs) and 45 digenic epistasis (E-QTLs) were identified. In spite of it's inferiority of O. minuta for most of the traits studied, its alleles contributed positively to 57% of the QTLs. The other QTLs originated from either parent, IR71033 or Junambyeo. QTLs for phenotypically correlated traits were mostly detected on introgressed segments. Fourteen QTLs corresponded to QTLs reported earlier, indicating that these QTLs are stable across genetic backgrounds. Twenty-two QTLs controlling yield and its components had not been detected in previous QTL studies. Of these, thirteen consisted of potentially novel alleles from O. minuta. QTLs from O. minuta introgression could be new sources of natural variation for the genetic improvement of rice.

Identification of QTLs associated with physiological nitrogen use efficiency in rice.

Demand for low-input sustainable crop cultivation is increasing to meet the need for environment-friendly agriculture. Consequently, developing genotypes with high nutrient use efficiency is one of the major objectives of crop breeding programs. This study was conducted to identify QTLs for traits associated with physiological nitrogen use efficiency (PNUE). A recombinant inbred population (DT-RILs) between Dasanbyeo (a tongil type rice, derived from an indica x japonica cross and similar to indica in its genetic make-up) and TR22183 (a Chinese japonica variety) consisting of 166 F8 lines was developed and used for mapping. A frame map of 1,409 cM containing 113 SSR and 103 STS markers with an average interval of 6.5 cM between adjacent marker loci was constructed using the DT-RILs. The RILs were cultivated in ordinary-N (N-P2O5-K2O = 100-80-80 kg/ha) and low-N (N-P2O5-K2O= 50-80-80 kg/ha) (100 kg/ha) conditions. PNUE was positively correlated with the harvest index and grain yield in both conditions. Twenty single QTLs (S-QTLs) and 58 pairs of epistatic loci (E-QTLs) were identified for the nitrogen concentration of grain, nitrogen concentration of straw, nitrogen content of shoot, harvest index, grain yield, straw yield and PNUE in both conditions. The phenotypic variance explained by these S-QTLs and E-QTLs ranged from 11.1 to 44.3% and from 16.0% to 63.6% , respectively. The total phenotypic variance explained by all the QTLs for each trait ranged from 35.8% to 71.3%, showing that the expression of PNUE and related characters depends significantly upon genetic factors. Both S-QTLs and E-QTLs may be useful for marker-assisted selection (MAS) to develop higher PNUE genotypes.

Characterization and mapping of a shattering mutant in rice that corresponds to a block of domestication genes.

Easy shattering reduces yield due to grain loss during harvest in cereals. Shattering is also a hindrance in breeding programs that use wild accessions because the shattering habit is often linked to desirable traits. We characterized a shattering mutant line of rice, Hsh, which was derived from a nonshattering japonica variety, Hwacheong, by N-methyl-N-nitrosourea (MNU) treatment. The breaking tensile strength (BTS) of the grain pedicel was measured using a digital force gauge to evaluate the degree of shattering of rice varieties at 5, 10, 15, 20, 25, 30, 35, and 40 days after heading (DAH). The BTS of Hwacheong did not decrease with increasing DAH, maintaining a level of 180-240 gf, while that of Hsh decreased greatly during 10-20 DAH and finally stabilized at 50 gf. Optical microscopy revealed that Hsh had a well-developed abscission layer similar to the wild rice Oryza nivara (accession IRGC105706), while Hwacheong did not produce an abscission layer, indicating that the shattering of Hsh was caused by differentiation of the abscission layer. On the basis of the BTS value and morphology of the abscission layer of F(1) plants and segregation data in F(2) populations, it was concluded that the easy shattering of Hsh was controlled by the single recessive gene sh-h. The gene sh-h was determined to be located on rice chromosome 7 by bulked segregant analysis. Using 14 SSR markers on rice chromosome 7, the gene sh-h was mapped between the flanking markers RM8262 and RM7161 at distances of 1.6 and 2.0 cM, respectively. An SSR marker Rc17 cosegregated with the gene sh-h. The locus sh-h for shattering was tightly linked to the Rc locus conferring red pericarp, as well as a QTL qSD(s)-7-1 for seed dormancy, implying that this region might represent a domestication block in the evolutionary pathway of rice.

Molecular mapping of a gene 'ld(t)' controlling cleistogamy in rice.

Cleistogamy is the self-pollination within closed spikelets and is expected to be a useful genetic tool for prevention of possible gene transfer in transgenic crops, for maintenance of genetic purity in autogamous crops, and for increased tolerance to biotic and abiotic stresses. Mapping of the gene ld(t), which is responsible for lack of lodicules inside spikelets and causes cleistogamy, was carried out using F2 and F3 populations derived from a cleistogamous (CL) mutant CL-SNU x Milyang 23 cross. A number of STS markers along chromosomes were developed and bulked segregant analysis was adopted for preliminary mapping. The results showed that the ld(t) was located at the end region of chromosome 1L, flanked by S01178b (an STS marker developed for the locus at 178 cM based on the rice genetic map reported by Japanese Rice Genome Project) at 0.8 cM and co-segregated with S01181a and S01181b (an STS marker developed for the locus at 181 cM).