Search

The Chinese chestnut (Castanea mollissima Bl.) was introduced into Japan about 100 years ago. Since then, a number of Chinese chestnut cultivars and Japanese–Chinese hybrid cultivars have been selected by farmers and plant breeders, but little information has been available about their origins and genetic relationships. A classification based on simple sequence repeat markers was conducted using 230 cultivars including Japanese chestnut (Castanea crenata Sieb. et Zucc.) cultivars originated in Japan, Japanese–Chinese hybrid cultivars, and Chinese chestnut cultivars originated in both Japan and China. First, a search for synonyms (cultivars with identical genotypes) revealed 23 synonym groups among the Chinese chestnut cultivars, and all but one cultivar from each synonym group was omitted from further analyses. Second, genetic structure analysis showed a clear division between Japanese and Chinese chestnut, and most of the Japanese and Chinese cultivars had a simple genetic structure corresponding to the expected species. On the other hand, most Japanese–Chinese hybrid cultivars had admixed genetic structure. Through a combination of parentage and chloroplast haplotype analyses, 16 of the 18 hybrid cultivars in this study were inferred to have parent–offspring relationships with other cultivars originated in Japan. Finally, Bayesian clustering and chloroplast haplotype analysis showed that the 116 Chinese chestnut cultivars could be divided into two groups: one originated in the Hebei region of China and the other originated in the Jiangsu and Anhui regions of China. The Chinese chestnut cultivars selected in Japan showed various patterns of genetic structure including Hebei origin, Jiangsu or Anhui origin, and admixed. The chestnut cultivar genetic classifications obtained in this study will be useful for both Japanese and Chinese chestnut breeding programs. [ABSTRACT FROM AUTHOR]

Highlights • We constructed a database of 48 Japanese chestnut cultivars genotyped with 20 SSRs. • Pollen dispersal was studied by seed paternity analysis using the SSR database. • The percentage of seeds sired by a given pollinizer was highest in the closest rows. • Bur set and yield per tree decreased as distance from the pollinizer row increased. • Planting different cultivars in adjacent rows maximizes cross-pollination. Abstract Chestnut (Castanea spp.) is mainly self-sterile, so interplanting of different cultivars in orchards is recommended. However, effective pollen dispersal distances for cross-pollination in chestnut orchards have not been determined. We examined pollen dispersal in three chestnut fields by tracking the movement of cultivar-specific pollen through paternity analysis based on simple sequence repeat (SSR) markers. We genotyped 48 major cultivars with 20 SSRs and constructed a reference database, from which we inferred the pollen parent of each seed. In Field A, which consisted of a single row of pollinizer 'Riheiguri' and four rows of 'Porotan' at distances of 4, 8, 12, and 16 m from the pollinizer row, the percentage of seeds sired by the pollinizer pollen was higher at 4 and 8 m from the pollinizer trees (65.3% and 61.1%, respectively) than at 12 and 16 m (37.5% and 43.1%, respectively). The percentages of bur set and yield per tree decreased as the distance from the pollinizer row increased (66.2%, 42.4%, 33.7%, and 24.8%; 7.0, 2.5, 1.6, and 1.1 kg: 4, 8, 12, and 16 m, respectively). In analyses of two other fields, which contained interplanted rows of different cultivars, the percentages of seeds sired by pollen from cultivars planted in adjacent rows were much higher than from cultivars planted in more distant rows. These results suggest that it is important to plant different cultivars in adjacent rows. [ABSTRACT FROM AUTHOR]

Japanese chestnuts ( Castanea crenata Sieb. et Zucc.) generally have difficult-peeling pellicles even after heating, making easy-peeling pellicle (EPP) an important breeding target. Recently, EPP cultivars ‘Porotan’ and ‘Porosuke’ were released by a government-funded breeding program. However, very few genotypes carry the major recessive gene responsible for the EPP trait, resulting in inbreeding within a narrow gene pool. To discover other genetic materials having the potential for EPP breeding, we evaluated the pellicle peelability of 59 accessions (51 Japanese local cultivars and 8 wild individuals) by using the high-temperature oil peeling method. We discovered that ‘Yakko’ had an exceptionally high pellicle peelability score (87%), close to that of ‘Porotan’ (94%). The results of segregation ratio analysis of pellicle peelability and genotype prediction by simple sequence repeat (SSR) markers among F 1 seedlings suggested that the EPP alleles of ‘Porotan’ and ‘Yakko’ are at the same locus. However, a haplotype structure analysis of the EPP genome region with SSR markers revealed that both haplotypes of ‘Yakko’ differed from those of ‘Porotan’, suggesting that the EPP gene of ‘Yakko’ had a different origin from that of ‘Porotan’ or was inherited from a common ancestor many generations ago. [ABSTRACT FROM AUTHOR]

Development and homeostasis of organs and whole body is critically dependent on the circulatory system. In particular, the circulatory system, the railways shuttling oxygen and nutrients among various organs, is indispensible for inter-organ humoral communication. Since the modern view of the anatomy and mechanics of the circulatory system was established in 17th century, it has been assumed that humoral factors are carried to and from organs via vascular branches of the central arteries and veins running along the body axis. Over the past few decades, major advances have been made in understanding molecular and cellular mechanisms underlying the vascularization of organs. However, very little is known about how each organ is linked by vasculature (i.e., inter-organ vascular networks). In fact, the exact anatomy of inter-organ vascular networks has remained obscure. Herein, we report the identification of four distinct vessels, V1LP, V2LP, V3LP and V4LP, that bridge between two organs, liver and pancreas in developing zebrafish. We found that these inter-organ vessels can be classified into two types: direct and indirect types. The direct type vessels are those that bridge between two organs via single distinct vessel, to which V1LP and V2LP vessels belong. The indirect type bridges between two organs via separate branches that emanate from a stem vessel, and V3LP and V4LP vessels belong to this type. Our finding of V1LP, V2LP, V3LP and V4LP vessels provides the proof of the existence of inter-organ vascular networks. These and other yet-to-be-discovered inter-organ vascular networks may facilitate the direct exchange of humoral factors that are necessary for the coordinated growth, differentiation and homeostasis of the connected organs. It is also possible that the inter-organ vessels serve as tracks for their connected organs to follow during their growth to establish their relative positions and size differences. [ABSTRACT FROM AUTHOR]

Myelination of central nervous system axons requires that oligodendrocytes extend multiple membrane processes that specifically recognize and wrap axons, which is followed by expression of proteins necessary for formation of myelin sheaths. To identify new genes that might be important for myelination, we used microarrays to analyze the expression profiles of cells sorted from transgenic zebrafish embryos and larvae under conditions that permitted or blocked oligodendrocyte development. Here, we describe eight genes that have not been previously implicated in oligodendrocyte development. Among the predicted functions of proteins encoded by these genes are lipid sensing, cell-cell junction formation, cytoskeleton regulation, and intracellular signaling. The predicted functions raise the possibility that these genes are involved in multiple cellular events during oligodendrocyte differentiation and myelin formation. Developmental Dynamics 239:2041-2047, 2010. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Motor function requires that motor axons extend from the spinal cord at regular intervals and that they are myelinated by Schwann cells. Little attention has been given to another cellular structure, the perineurium, which ensheaths the motor nerve, forming a flexible, protective barrier. Consequently, the origin of perineurial cells and their roles in motor nerve formation are poorly understood. Using time-lapse imaging in zebrafish, we show that perineurial cells are born in the CNS, arising as ventral spinal-cord glia before migrating into the periphery. In embryos lacking perineurial glia, motor neurons inappropriately migrated outside of the spinal cord and had aberrant axonal projections, indicating that perineurial glia carry out barrier and guidance functions at motor axon exit points. Additionally, reciprocal signaling between perineurial glia and Schwann cells was necessary for motor nerve ensheathment by both cell types. These insights reveal a new class of CNS-born glia that critically contributes to motor nerve development. [ABSTRACT FROM AUTHOR]

Myelinating oligodendrocytes arise from migratory and proliferative oligodendrocyte progenitor cells (OPCs). Complete myelination requires that oligodendrocytes be uniformly distributed and form numerous, periodically spaced membrane sheaths along the entire length of target axons. Mechanisms that determine spacing of oligodendrocytes and their myelinating processes are not known. Using in vivo time-lapse confocal microscopy, we show that zebrafish OPCs continuously extend and retract numerous filopodium-like processes as they migrate and settle into their final positions. Process remodeling and migration paths are highly variable and seem to be influenced by contact with neighboring OPCs. After laser ablation of oligodendrocyte-lineage cells, nearby OPCs divide more frequently, orient processes toward the ablated cells and migrate to fill the unoccupied space. Thus, process activity before axon wrapping might serve as a surveillance mechanism by which OPCs determine the presence or absence of nearby oligodendrocyte-lineage cells, facilitating uniform spacing of oligodendrocytes and complete myelination. [ABSTRACT FROM AUTHOR]

SUMMARY The T-box transcription factor gene Brachyury is important for the differentiation of notochord in all chordates, including the ascidians Halocynthia roretzi and Ciona intestinalis . We isolated Brachyury from molgulid ascidians, which have evolved tailless larvae multiple times independently, and found the genes appear functional by cDNA sequence analyses. We then compared the expression of Mocu-Bra in tailed Molgula oculata embryos to two tailless species, Molgula occulta (Mocc-Bra ) and Molgula tectiformis (Mt-Bra ). Here we show that both tailless species express Brachyury in the notochord lineage during embryogenesis. Initial expression of Mocu-Bra is normal in tailed M. oculata embryos; 10 precursor notochord cells divide twice to result in 40 notochord cells that converge and extend to make a notochord down the center of the tail. In contrast, in tailless Molgula occulta , Mocc-Bra expression disappears prematurely, and there is only one round of division, resulting in 20 cells in the final notochord lineage that never converge or extend. In M. occulta ×M. oculata hybrid embryos, expression of Mocu-Bra is prolonged, and the embryos form a tail with 20 notochord cells that converge and extend normally. However, in Molgula tectiformis , a different tailless ascidian, Mt-Bra was expressed only in the 10 notochord precursor cells, which never divide, converge, or extend. In summary, neither Brachyury function nor the early establishment of the notochord lineage appears to be impaired in tailless embryos. In light of these results, we are continuing to investigate how and why notochord development is lost in tailless molgulid ascidian embryos. [ABSTRACT FROM AUTHOR]

'Porotan' is a Japanese chestnut cultivar (Castanea crenata Sieb. et Zucc.) that was selected from offspring of the cross 550-40 x 'Tanzawa' and released in 2006. Its nut is distinguished by a pellicle that is easy to peel after roasting; previously, all Japanese chestnut cultivars were thought to have a pellicle that was difficult to peel. Both 550-40 and 'Tanzawa' are Japanese chestnuts, and 550-40 is a selection descended from 'Tanzawa'. Both 550-40 and 'Tanzawa' have a pellicle that is difficult to peel. Among 59 offspring of a cross of 550-40 x 'Tanzawa', 12 had an easy-peeling pellicle and 47 had a difficult-peeling pellicle; this ratio is not significantly different from the 1:3 expected ratio for monogenic inheritance based on a chi-square test at P= 0.05. A haif-diallel cross without selfings was made among 'Porotan', 'Tanzawa', and 'Tsukuba'. All the offspring from 'Tanzawa' x 'Tsukuba' and from 'Tsukuba' x 'Porotan' had a difficult-peeling pellicle; in contrast, 39 offspring from 'Tanzawa' x 'Porotan' segregated in a ratio of 19 difficult-peeling pellicle to 20 easy-peeling pellicle, which is not significantly different from the expected I:1 ratio for monogenic segregation based on a chi-square test at P = 0.05. These results suggest that the easy-peeling pellicle trait of 'Porotan' is controlled by a major recessive gene at a single locus. We designated the pellicle peelability locus as P/p. According to this model, the 'Tsukuba' genotype is homozygous-dominant (PP), the 'Tanzawa' genotype is heterozygous (Pp), and the 'Porotan' genotype is homozygous-recessive (pp). [ABSTRACT FROM AUTHOR]

Abstract: Plant height, a vigor trait, in 1-year-old seedlings made from Japanese pear (Pyrus pyrifolia) cultivars/selections was measured using 994 individuals from 29 families. The family mean of plant height was negatively correlated (r =−0.72**) to the inbreeding coefficients (F). The regression of the family mean (Fm) on the F value (Fm=130−104F) showed that inbreeding depressions were 8%, 20%, and 40% for F =0.1, 0.25, and 0.5, respectively. According to the regression, the family mean at F =0 was estimated at 130cm. These results showed that the vigor was greatly influenced by inbreeding in Japanese pear. Within-family variances, the genetic segregation of offspring in a family, differed according to family. The proportions of offspring with plant height above 130cm (estimated Fm for F =0) were extremely low, i.e., 0–17% for 0.5≤ F <0.60 and 0–8% for F =0.75. [Copyright &y& Elsevier]

• The distribution of phenotypic values of peelability in Japanese chestnut populations preselected for a major peelability gene was biased toward maximum values. • Use of rank-based inverse normal transformation and categorization of peelability phenotypes was applied for GWAS to further identify QTLs associated with peelability. • A single QTL for peelability was identified at CCR1.0F_56177061 on chromosome F. Peelability is one of the most important traits in Japanese chestnut (Castanea crenata Sieb. et Zucc.) breeding. Previous studies revealed that the peelability of Japanese chestnut is controlled by a major recessive peeling gene (MRPG). This locus has been used effectively for marker-assisted selection in chestnut breeding programs, but there are also likely to be minor loci that would further improve the efficiency of breeding for peelability. We conducted a genome-wide association study (GWAS) based on a variational approximation version of BayesB using 27 cultivars and MRPG-preselected populations consisting of 520 F 1 seedlings from 22 families. Using double-digest restriction site-associated DNA sequencing (ddRAD-Seq), we obtained 9164 tag single-nucleotide polymorphisms. Because the phenotypic values of peelability were distributed very asymmetrically, with a peak at the high end due to the preselection for MRPG, we converted the original data set to both inverse normal transformed values and categorical scores, and we analyzed both sets of converted data by GWAS. In both analyses, a quantitative trait locus (QTL) for peelability at CCR1.0F_56177061 was identified with posterior probability values of 0.68 and 1.00, respectively. The average values of genotypes at CCR1.0F_56177061 for cultivars and seedlings in this study were 60.4% (peelability rate) for CC, 63.7% for CT, and 86.5% for TT. This analysis reveals a significant association between CCR1.0F_56177061 genotype and peelability, indicating that this newly identified QTL will be useful for improving peelability in chestnut breeding programs. [ABSTRACT FROM AUTHOR]

One of the most important breeding objectives for Japanese pear ( Pyrus pyrifolia Nakai) is to release early-ripening cultivars. To accelerate marker-assisted selection (MAS) for fruit ripening day (FRD), the molecular markers PPACS2 and BGA35, both associated with FRD, were evaluated in six populations by using variance components. The variance explained by PPACS2 ( σ ACS2 2 ) differed greatly among populations, ranging from 5.7 to 101.9. The percentage of total phenotypic variance accounted for by σ ACS2 2 ranged from 8.9% to 40.4%, 22.1% on average. The variance explained by BGA35 ( σ BGA35 2 ) was 44.4–46.3, and the percentage of the total phenotypic variance accounted for by σ BGA35 2 ranged from 18.3% to 24.9%, 21.6% on average. These values are high enough for these markers to be implemented in practical Japanese pear breeding. The 263-bp allele of PPACS2 and the 136-bp allele of BGA35 had early-ripening effects in six populations. No interaction was found between PPACS2 and BGA35, suggesting that the effects of both loci were additive. The 263-bp allele of PPACS2 was previously shown to increase PPACS2 expression and ethylene production, which might have a negative effect on fruit storage and fruit drop, so further investigation of this allele is required. The information obtained in this study will accelerate MAS for FRD using PPACS2 and BGA35 in Japanese pear breeding programs. [ABSTRACT FROM AUTHOR]

The effectiveness of detected quantitative trait loci (QTLs) and molecular markers associated with them in tree fruit breeding is measured by the percentages of the variance associated with detected QTL effects accounting for not phenotypic variance, but genetic variance of the trait. The genetic variance can be obtained by subtracting environmental variance from the phenotypic variance. Once accurate environmental variance components are obtained for a given selection field, environmental variances under any number of replications and measurement repetitions can be estimated. We estimated environmental variance components of fruit ripening date measured by days in a Japanese pear (Pyrus pyrifolia Nakai) breeding field in the National Institute of Fruit Tree Science, Tsukuba, Ibaraki, Japan. We estimated variance among fruits within a tree (σf²) as 25.6, among trees within a genotype (σt²) as 0.2, among years (σy²) as 9.4, associated with genotype x year interaction (σgy²) as 7.9, and associated with tree x year interaction (σty²) as 1.2. Because σf² was the largest environmental variance component, increasing the number of fruit evaluated would most effectively reduce the environmental variance, and tree replication would not because of very small σt² and σty². The 95% confidence limit of a genotypic value was ± 10 days in the evaluation of five fruits on a single tree in a year and ± 7 days over 2 years. Broad-sense heritability in a family, each offspring in which was evaluated using five fruits on a single tree in a single year, was estimated at 0.83 for three full-sib families analyzed. [ABSTRACT FROM AUTHOR]

Abstract: A total of 366 novel simple sequence repeat (SSR) markers were developed in Japanese chestnut (Castanea crenata), comprising 220 genomic SSRs derived from enriched genomic libraries and 146 expressed sequence tag (EST)–SSRs obtained from large-scale EST sequencing analysis. Thirty accessions, comprising Japanese, Chinese (C. mollissima), European (Castanea sativa), and American chestnuts (Castanea dentata), were used for evaluation of SSR polymorphism and transferability across species. The EST–SSRs showed less polymorphism than the genomic SSRs and were more transferable. The mean observed heterozygosity (H O) and the mean expected heterozygosity (H E) of genomic SSRs in the Japanese chestnuts were 0.63 and 0.68, respectively; those of EST-SSRs were each 0.47. Although about 80% of the genomic SSRs were amplified in all 4 species, more than 95% of the EST–SSRs were transferable across all 4 species. The many novel SSRs developed in this study will be applicable for the construction of genetic linkage maps, QTL analysis of phenotypic traits, high-throughput genotyping of marker-assisted selection, and association genetics. [Copyright &y& Elsevier]

The history of chestnut utilization in Japan is very long. Many cultivars have been preserved without being sufficiently organized and studied with respect to genetic variation. We developed 12 new SSR (simple sequence repeat) markers from Japanese chestnut (Castanea crenata) by using SSR-enriched genomic libraries. All 12 primer pairs selected for SSR analysis successfully amplified fragments in 6 Castanea species. The genetic diversity and relationships among 216 chestnut accessions were assessed by SSR markers, including 142 Japanese chestnuts, 38 Chinese chestnuts (C. mollissima), 2 European chestnuts (C. sativa), 9 American chestnuts (C. dentata), and 23 Japanese-Chinese hybrids. Among the 216 accessions, we identified 21 synonym groups (including 1 bud sport group), and 189 different genotypes. The mean values of observed heterozygosity (HO) and the expected heterozygosity (HE) in the Japanese chestnuts were 0.65 and 0.65, respectively. A phenogram of the 189 genotypes revealed 3 major groups, corresponding to Japanese, Chinese and American chestnuts. Japanese-Chinese hybrid cultivars were mainly included in the Chinese chestnut group. In the present study, genetic backgrounds could be identified for native and cultivated Japanese chestnuts and Japanese-Chinese hybrid cultivars, and many synonyms showing identical SSR genotypes were found. Genetic and geographical relationships of unique characteristics such as "Shidareguri" (weeping) and "Togenashi" (spineless) were also discussed. These results will improve the efficiency of cultivar identification and of chestnut breeding programs. [ABSTRACT FROM AUTHOR]

We developed 73 novel expressed sequence tag (EST)--simple sequence repeat (SSR) markers based on ESTs derived from 11 different cDNA libraries of the Japanese pear (Pyrus pyrifolia Nakai) cultivar 'Housui', comprising 30, 36, two, one, and four SSRs with repeat motifs of di-, tri-, tetra-, penta-, and hexa-nucleotides, respectively. Forty-eight EST sequences showed significant homology to Arabidopsis thaliana genes. The linkage groups and positions of 57 loci generated from 53 SSR markers covering all 17 linkage groups, were identified. These EST-SSRs will be useful for high-throughput genotyping of marker-assisted selection. The numbers of alleles and the observed and expected heterozygosities at single-locus EST-SSR markers in ten Japanese and ten European pears suggest high polymorphism and heterozygosity of the EST-SSRs. Di-nucleotide EST-SSRs showed two to three times the polymorphism and heterozygosity of tri-nucleotide EST-SSRs. Some of the EST-SSRs proved transferable to other species in the Rosaceae, paying the way for the development of markers for the same phenotypic traits among species of the Rosaceae. [ABSTRACT FROM AUTHOR]

: BackgroundHypertriglyceridemia accompanied by low levels of high-density lipoprotein cholesterol (HDL-C) is a risk factor for coronary artery disease. High-density lipoprotein 2 (HDL2) and 3 (HDL3) are believed to suppress the progress of atherosclerosis through reverse cholesterol transport. As a result, peripheral tissues can be protected against excessive accumulation of cholesterol. Although bezafibrate is known to accelerate the increase of HDL-C, results are not standardized regarding increases of HDL3 and HDL2 subfractions.: ObjectiveThis study assessed the effects of bezafibrate on serum triglyceride (TG) fractional clearance rate (K2) and HDL2 and HDL3 cholesterol (HDL2-C and HDL3-C, respectively) levels in patients with primary hypertriglyceridemia (serum TG ≥150 mg/dL).: MethodsOutpatients with primary hypertriglyceridemia were enrolled in this 8-week study conducted at the Third Department of Internal Medicine, Nagoya City University Hospital (Nagoya, Japan). Oral bezafibrate was administered at a dose of 400 mg/d (200-mg tablet BID, morning and evening) for 8 weeks. After 8 weeks, serum levels of total cholesterol (TC), TG, HDL-C, HDL2-C, and HDL3-C were measured. A fat emulsion tolerance test to assess K2 and measurements of plasma lipoprotein lipase (LPL) mass, LPL activity, and hepatic triglyceride lipase (HTGL) activity in postheparin plasma were performed before bezafibrate administration and after the course of treatment.: ResultsSixteen patients (10 men, 6 women; mean [SD] age, 54 [12] years [range, 30–69 years]; mean [SD] body mass index, 23 [2] kg/m2) entered the study. The following findings were observed in male and female patients after 8 weeks of treatment. A statistically significant reduction was observed in mean serum TG level (P<0.01). Significant increases were seen in HDL-C, HDL2-C, and HDL3-C (all P<0.01), K2 (P<0.01), and in plasma LPL mass (P<0.01) and LPL activity (P<0.05). TC level and HTGL activity did not change significantly. No adverse effects related to the use of bezafibrate were documented.: ConclusionsIn this study, bezafibrate treatment resulted in significant decreases in serum TG level and significant increases in HDL2-C and HDL3-C levels and plasma LPL mass and activity. We hypothesize that bezafibrate may increase HDL3-C by promoting TG-rich lipoprotein catabolism and may increase HDL2-C by promoting the conversion of HDL3 to HDL2. [Copyright &y& Elsevier]

• Watercore is a disorder characterized by watery translucent areas in Japanese pear fruit flesh. • Use of F1 sibs helped to solve its poor reproducibility problem. • F1 sibs enabled differential transcriptome analysis before symptoms become visible. • Susceptible sibs highly expressed metallothionein, invertase and hormone-related genes. • Our data provide new insights into the mechanisms of watercore development. Watercore is a physiological disorder of Japanese pear fruits, in which a watery translucent area appears in the flesh of fruits on the tree. The disorder leads to the loss of commercial value, and resistance to watercore is one of the most important features to be studied in the breeding of Japanese pear. Even in susceptible cultivars such as 'Hosui' (syn. 'Housui'), the degree of watercore development varies markedly from year to year, which makes it difficult to analyze the characteristics of this phenomenon prior to visible watercore development. We used two F1 sib pairs from 'Hosui' × 'Hougetsu' and 'Akiakari' × 'Taihaku' crosses. Each pair contains a susceptible sib and a resistant sib. In these pairs, susceptible sibs developed severe watercore in all the fruits examined in each year, whereas no watercore was found even in overmature fruits of resistant sibs. To search for genes related to watercore, we used a custom pear microarray and studied differential gene expression in susceptible and resistant sibs prior to visible watercore development. We identified 115 differentially expressed genes including sugar metabolism–, hormone–, and cell wall–related genes. Some of these genes were differentially expressed only in immature fruits prior to watercore development. These genes would be useful as molecular markers to predict watercore at early developmental stages or in pear breeding programs. [ABSTRACT FROM AUTHOR]

Self-compatibility is a highly desirable trait for pear breeding programs. Our breeding program previously developed a novel self-compatible pollen-part Japanese pear mutant ( Pyrus pyrifolia Nakai), '415-1', by using γ-irradiated pollen. '415-1' carries the S -genotype S 4 dS 5 S 5 , with " d " indicating a duplication of S 5 responsible for breakdown of self-incompatibility. Until now, the size and inheritance of the duplicated segment was undetermined, and a reliable detection method was lacking. Here, we examined genome duplications and their inheritance in 140 F 1 seedlings resulting from a cross between '515-20' ( S 1 S 3 ) and '415-1'. Amplicon sequencing of S-RNase and SFBB18 clearly detected S -haplotype duplications in the seedlings. Intriguingly, 30 partially triploid seedlings including genotypes S 1 S 4 dS 5 , S 3 S 4 dS 5 , S 1 S 5 dS 5 , S 3 S 5 dS 5 , and S 3 S 4 dS 4 were detected among the 140 seedlings. Depth-of-coverage analysis using ddRAD-seq showed that the duplications in those individuals were limited to chromosome 17. Further analysis through resequencing confirmed an 11-Mb chromosome duplication spanning the middle to the end of chromosome 17. The duplicated segment remained consistent in size across generations. The presence of an S 3 S 4 dS 4 seedling provided evidence for recombination between the duplicated S 5 segment and the original S 4 haplotype, suggesting that the duplicated segment can pair with other parts of chromosome 17. This research provides valuable insights for improving pear breeding programs using partially triploid individuals., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Nishio, Shirasawa, Nishimura, Takeuchi, Imai, Mase and Takada.)

Black spot disease, which is caused by Alternaria alternata (Fries) Keissler Japanese pear pathotype, is one of the most harmful diseases in Japanese pear cultivation. Because of the potential harm of fungicides to consumers and the environment, resistant cultivars are desired. In this study, to enable efficient marker-assisted selection in pear breeding, we conducted comprehensive inoculation tests and genotyping with 207 pear cultivars. We identified a marker set (Mdo.chr11.27 and Mdo.chr11.34) suitable for selection for black spot resistance. In most susceptible cultivars, Mdo.chr11.27 amplified a 220-bp band and Mdo.chr11.34 amplified a 259-bp band. The genotype of Mdo.chr11.34 corresponds perfectly to the estimated genotype of Japanese pears susceptible to black spot disease. Using linkage analysis, we identified the positions of the gene for susceptibility to black spot disease in Chinese pear. Mdo.chr11.27 and Mdo.chr11.34 were tightly linked to susceptibility in Chinese pear, and the susceptibility gene was mapped at the top of linkage group 11, similar to that in Japanese pear. This marker set and the accumulation of phenotypic data will enable efficient marker-assisted breeding for black spot resistance in pear breeding., (Copyright © 2021 by JAPANESE SOCIETY OF BREEDING.)

The cardiovascular system facilitates body-wide distribution of oxygen, a vital process for the development and survival of virtually all vertebrates. However, the zebrafish, a vertebrate model organism, appears to form organs and survive mid-larval periods without a functional cardiovascular system. Despite such dispensability, it is the first organ to develop. Such enigma prompted us to hypothesize other cardiovascular functions that are important for developmental and/or physiological processes. Hence, systematic cellular ablations and functional perturbations were performed on the zebrafish cardiovascular system to gain comprehensive and body-wide understanding of such functions and to elucidate the underlying mechanisms. This approach identifies a set of organ-specific genes, each implicated for important functions. The study also unveils distinct cardiovascular mechanisms, each differentially regulating their expressions in organ-specific and oxygen-independent manners. Such mechanisms are mediated by organ-vessel interactions, circulation-dependent signals, and circulation-independent beating-heart-derived signals. A comprehensive and body-wide functional landscape of the cardiovascular system reported herein may provide clues as to why it is the first organ to develop. Furthermore, these data could serve as a resource for the study of organ development and function., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2017. Published by The Company of Biologists Ltd.)