Traits In Progeny Research Articles

Changes in Alternative Splicing Revealed Special Metabolic Pathways Related to Heterosis of Heading Chinese Cabbage

As an important genetic improvement technique in current production practice, heterosis is widely used to enhance the productive traits of hybrid progeny from their parents. Alternative splicing (AS) analysis can be used as a method for exploring the molecular manifestations of heterosis. In our research, 16 hybrids and their parents were utilized to analyze the heterosis performance and AS events. Statistics of plant gross weight (PGW) showed that these hybrids had prominent heterosis, with the mid-parent heterosis values (MPV) ranging from 15.69% to 233.98%. Through pairwise comparison among the female parent, male parent, and hybrid, there were 2980–3205 AS events in each combination, with intron retention being the most common type followed by alternate 3’ splice site, alternative 5’ splice site, skipped exon, and mutually exclusive exon.There were 263–409 differential AS genes (DASGs) between the female parent and the hybrid, and 234–425 DASGs between the male parent and the hybrid in cross combinations. The DASGs were significantly enriched in 33 metabolic pathways in 16 cross combinations, and DASGs of different cross combinations were enriched in different metabolic pathways. Moreover, 76 DASGs in the strong heterosis combinations were identified and significantly enriched in the metabolic pathways related to amino acid metabolism. Further analysis revealed that most of these DASGs in amino acid metabolism were expressed differently in strong heterosis combinations. In addition, the expression levels of BraA06g014310.3C and BraA03g041700.3C in amino acid metabolism significantly correlated with PGW. These results could provide an index for future studies of the genetic and molecular mechanism of heterosis in hybrids.

Epigenetic effects of selenium and vitamin E supplementation in broiler breeder diets on the performance of their progeny

Nutritional supplements have been commonly used in the poultry industry last few years. The study aimed to investigate the epigenetic effects of adding vitamin E and organic selenium to the diet of broiler breeders Ross-308 on their progeny meat production performance. The treatments included the control group fed with a standard diet without supplementation (T1), T2 using a standard diet supplemented with 500 mg of vitamin E / kg, T3 using a standard diet supplemented with 0.5 mg of organic selenium (Availa powder) /kg, and T4 using a standard diet supplemented with a mixture of vitamin E and organic selenium in proportions 500 and 0.5 mg/kg respectively. The eggs were collected from each treatment to obtain the progeny reared for 35 periods, and measurements were recorded for meat production and carcass traits. The results showed that the treatments had significant epigenetic effects on body weight at hatching. Hence, T2 had a significantly heavier body weight than T1, while no significant differences were observed between T3 and T4. The result of T2 recorded extremely high feed intake compared with T3. On the other hand, T3 and T4 recorded a hefty weight of breast parts compared with T1 and T2. In conclusion, organic selenium supplementation led to a significant increase in breast weight and a decrease in thigh part weight compared to the control group. In contrast, vitamin E supplementation led to an increase in chick weight at hatch, a reduction of total mortality and an improvement in feed conversion ratio compared to the control group. This refers to the epigenetic effects of organic selenium and vitamin E on progeny traits when added to the breeder diet. Keywords: Epigenetics, broiler, selenium supplementation, meat production

Epigenetic effects on broiler exposure to magnetic field on progeny meat production traits

This experiment was conducted to determine the effect of the exposure of Ross 308 broiler breeders to a magnetic field on the meat production traits of progeny. The experimental flock consisted of 60 hens and ten cocks of Ross 308 broiler breeders at 36 weeks of age, divided randomly into four groups; each group applied for treatment with three replicates. The treatments were control (T1), storage of semen in an 803 gauss magnetic field for 24 h (T2), storage of fertilized eggs in a magnetic field of 250 gausses for 72 h before entering the incubator (T3), and exposing individual cages to 250 gausses of magnetic field for 8 Weeks (T4). The progeny result from the broiler breeders groups was recorded for body weight and feed intake, compared with the control (T1). The results showed no significant differences among progeny groups in body weight, weekly weight gain and weekly feed intake during the rearing period. Keywords: Epigenetic, magnetic broiler breeders, broiler progeny performance

Correlation and path analysis of fruit, leaf and flower traits in Chinese jujube hybrid progeny

Correlation and path analysis of fruit, leaf and flower traits in Chinese jujube hybrid progeny

Single nucleotide polymorphism C994g of the cytochrome P450 gene possess pleiotropic effects in Bos taurus, L.

The chronic consumption of mycotoxin-contaminated forage tends to the weight loss of young cattle, decreasing the reproductive success of adult animals, milk yield, and tolerance to high temperatures. The aim of this paper was to study the eff ects of the SNP C994G in the CYP3A28 gene on the productive and reproductive characteristics of dairy and beef breeds. Cows were measured by body weight dynamics, exterior, reproduction, milk production traits, bone mineral density, bulls were analyzed estimating their progeny traits. Dairy cows received dietary betaine supplement with the measurement of homocysteine levels. Molecular genetic was performed by PCR-RFLP method. The effects of SNP C994G were shown in relation to the udder size, the constitution and birth weight of Abredin-Angus cows, as well as the fat and protein content of Ukrainian Red-and-White Dairy cows milk. The higher sensitivity of the GG genotype to less homocysteine level after the addition of betaine was shown. Given the identifi ed correspondence, pleiotropic eff ects of CYP3A28 gene can be concluded. A microscopic analysis of forage supported the findings in relation to greater efficiency of the CC genotype under conditions of low mycotoxins contamination, to which CYP3A28 is selective.

Parental methylation mediates how progeny respond to environments of parents and of progeny themselves.

Environments experienced by both parents and offspring influence progeny traits, but the epigenetic mechanisms that regulate the balance of parental vs. progeny control of progeny phenotypes are not known. We tested whether DNA methylation in parents and/or progeny mediates responses to environmental cues experienced in both generations. Using Arabidopsis thaliana, we manipulated parental and progeny DNA methylation both chemically, via 5-azacytidine, and genetically, via mutants of methyltransferase genes, then measured progeny germination responses to simulated canopy shade in parental and progeny generations. We first found that germination of offspring responded to parental but not seed demethylation. We further found that parental demethylation reversed the parental effect of canopy in seeds with low (Cvi-1) to intermediate (Col) dormancy, but it obliterated the parental effect in seeds with high dormancy (Cvi-0). Demethylation did so by either suppressing germination of seeds matured under white-light (Cvi-1) or under canopy (Cvi-0), or by increasing the germination of seeds matured under canopy (Col). Disruption of parental methylation also prevented seeds from responding to their own light environment in one genotype (Cvi-0, most dormant), but it enabled seeds to respond to their own environment in another genotype (Cvi-1, least dormant). Using mutant genotypes, we found that both CG and non-CG DNA methylation were involved in parental effects on seed germination. Parental methylation state influences seed germination more strongly than does the progeny's own methylation state, and it influences how seeds respond to environments of parents and progeny in a genotype-specific manner.

Strategies for utilization of crop wild relatives in plant breeding programs.

Crop wild relatives (CWRs) are weedy and wild relatives of the domesticated and cultivated crops, which usually occur and are maintained in natural forms in their centres of origin. These include the ancestors or progenitors of all cultivated species and comprise rich sources of diversity for many important traits useful in plant breeding. CWRs can play an important role in broadening genetic bases and introgression of economical traits into crops, but their direct use by breeders for varietal improvement program is usually not advantageous due to the presence of crossing or chromosome introgression barriers with cultivated species as well as their high frequencies of agronomically undesirable alleles. Linkage drag may subsequently result in unfavourable traits in the subsequent progeny when segments of the genome linked with quantitative trait loci (QTL), or a phenotype, are introgressed from wild germplasm. Here, we first present an overview in regards to the contribution that wild species have made to improve biotic, abiotic stress tolerances and yield-related traits in crop varieties, and secondly summarise the various challenges which are experienced in interspecific hybridization along with their probable solutions. We subsequently suggest techniques for readily harnessing these wild relatives for fast and effective introgression of exotic alleles in pre-breeding research programs.

Non-neutral clonal selection and its potential role in mammalian germline stem cell dysfunction with advancing age.

The concept of natural selection, or "survival of the fittest", refers to an evolutionary process in nature whereby traits emerge in individuals of a population through random gene alterations that enable those individuals to better adapt to changing environmental conditions. This genetic variance allows certain members of the population to gain an advantage over others in the same population to survive and reproduce in greater numbers under new environmental pressures, with the perpetuation of those advantageous traits in future progeny. Here we present that the behavior of adult stem cells in a tissue over time can, in many respects, be viewed in the same manner as evolution, with each stem cell clone being representative of an individual within a population. As stem cells divide or are subjected to cumulative oxidative damage over the lifespan of the organism, random genetic alterations are introduced into each clone that create variance in the population. These changes may occur in parallel to, or in response to, aging-associated changes in microenvironmental cues perceived by the stem cell population. While many of these alterations will be neutral or silent in terms of affecting cell function, a small fraction of these changes will enable certain clones to respond differently to shifts in microenvironmental conditions that arise with advancing age. In some cases, the same advantageous genetic changes that support survival and expansion of certain clones over others in the population (viz. non-neutral competition) could be detrimental to the downstream function of the differentiated stem cell descendants. In the context of the germline, such a situation would be devastating to successful propagation of the species across generations. However, even within a single generation, the “evolution” of stem cell lineages in the body over time can manifest into aging-related organ dysfunction and failure, as well as lead to chronic inflammation, hyperplasia, and cancer. Increased research efforts to evaluate stem cells within a population as individual entities will improve our understanding of how organisms age and how certain diseases develop, which in turn may open new opportunities for clinical detection and management of diverse pathologies.

Effect of Hermaphrodite–Gynomonoecious Sexual System and Pollination Mode on Fitness of Early Life History Stages of Offspring in a Cold Desert Perennial Ephemeral

Gynomonoecy, the occurrence of both pistillate (female) and perfect (hermaphroditic) flowers on the same plant, has received little attention compared to gynodioecy and other plant sexual systems. Eremurus anisopterus is a perennial ephemeral in the cold desert of northwest China with a hermaphrodite–gynomonoecious sexual system in the same population. The primary aim of this study was to compare the early life history traits and inbreeding depression between progeny from pistillate and hermaphrodite flowers in hermaphrodites and gynomonoecious individuals. All of the traits of progeny from outcrossed pistillate flowers on gynomonoecious plants were significantly greater than for other pollination types. Selfing (vs. outcrossing) resulted in a decrease in all traits, indicating inbreeding depression (ID) during early life history stages of gynomonoecious and hermaphroditic plants. ID for seed mass, seed germination and seedling survivorship under water stress for pistillate flowers on gynomonoecious plants was significantly higher than it was for hermaphrodite flowers on both gynomonoecious and hermaphrodite plants. The advantage of the offspring of pistillate (vs. hermaphrodite) flowers may contribute to the maintenance of gynomonoecy in E. anisopterus in its cold desert sand dune habitat.

Comparative assessment of egg and larval quality traits of progeny from wild-collected and captive-matured brooders of endangered golden mahseer, Tor putitora: A prelude to quality broodstock development and seed production

In this study, we assessed the differences in reproductive outputs (fertilization and hatching rates); egg quality (egg size increase during hardening, biochemical composition, carotenoid content, and characteristics of ovarian fluid); and larval performance traits (growth, microanatomical development, survival, starvation response, and critical thermal tolerance) of progeny from captive-matured and wild-collected golden mahseer brooders. Fertilization and hatching rates were significantly higher in wild-collected brooders than in captive broodstock. Captive brooder eggs were significantly larger in size and weight but had significantly lower energy/nutrient (total protein, glucose, and triglyceride) reserves and total carotenoids. On the contrary, ovarian fluid from captive females had significantly higher levels of total protein, glucose, and triglycerides, possibly indicating weaker egg membrane and nutrient leakage due to membrane damage or lysis. During water hardening, the cumulative weight increase due to a higher water uptake rate was significantly higher in the wild origin eggs than captive brooder eggs. CTmax of larvae obtained from captive-matured brooders was lower during the early developmental stages (15 dph), but became similar to the CTmax of wild brooder's larvae at 35 dph. On the other hand, CTmin of captive origin larvae was higher than their wild counterparts at all examined stages. There were no differences in starvation tolerance of larvae between the two brooder types. Histological observations revealed that the intestinal nutrient absorption and hepatic nutrient accumulating efficiency during the early developmental stages was relatively lower in captive origin larvae, corresponding to the comparative growth metrics observed until 35 dph. Also, the survival percentage at 90 dph was lower in the larvae of captive brooders than their wild counterparts. Collectively, these findings indicate potential areas for improvement in the captive broodstock management of the endangered cyprinid, golden mahseer.

Selection of Elite dura-Type Parents to Produce Dwarf Progenies of Elaeis guineensis Using Genetic Parameters

The low annual growth rate of the stipe in oil palm progenies is desirable to increase these crops’ productive and economic life. Recurrent reciprocal selection (R.R.S.) has allowed the development of oil palm populations through several breeding cycles with an increased frequency of favorable alleles associated with traits of interest. The present study evaluated families derived from Deli dura × African dura crosses. For 12 years, the yield, vegetative characteristics, and the amount of oil in seven dura progenies were assessed to estimate, from the information collected, the genetic parameters, heritability, and phenotypic correlations among quantitative genetic traits of high-yielding dwarf progenies. The analysis was carried out using analysis of variance, followed by a comparison of means for all estimated traits. The effect of the progenies was highly significant (p ≤ 0.01) for most traits. The yield values, expressed in fresh fruit bunches (FFB) for the progenies, ranged from 165 to 208 kg per palm per year. The oil-to-bunch ratio (O/B) ranged from 17% to 19%, with an overall average of 18%. One of the essential characteristics in this study was the vertical growth of the stipe. Progenies P6 and P7 were identified as those with the lowest annual increase in height, with values of 0.29 and 0.33 m year−1. The values indicate that these are slow-growing cultivars with a high FFB yield and O/B. The highest heritabilities were found for the vegetative trait height (71.62%) and the number of leaflets (46.64%). The development of dura parents with slow growth characteristics in combination with a high bunch and oil production allows extending the productive life of the crop to more than 35 years, providing added value to obtaining differentiated cultivars of oil palm.

The degree of maternal nutrient restriction during late gestation influences the growth and endocrine profiles of offspring from beef cows

Context Cow–calf operations in Argentina are managed under extensive grazing condition and the quality of forages is often poor during the second half of gestation. The severity of nutrient restriction in bovine gestation, caused by seasonal pasture production, often results in poor production traits in progeny. Aims The objective of the current study was to determine whether different levels of maternal nutrient intake in beef cows during late gestation affect fetal and postnatal growth, glucose metabolism, and insulin-like growth factor 1 (IGF1) concentrations in offspring of beef cattle. Methods At 180 ± 4 days of gestation, multiparous Angus cows (n = 56) were blocked by bodyweight (BW) and expected calving date, and assigned to pens (2 or 3 cows/pen). Pens (n = 8 per treatment) were then randomly assigned to the following treatments: severely restricted (SR; 50% of net energy and 58% of CP requirements), moderately restricted (MR; 75% of net energy and 85% of CP requirements), or control (CON; 100% of net energy and 116% of CP requirements). Pen was the experimental unit and data were analysed by ANOVA or repeated measures analysis, as appropriate. After calving, all cows were managed in a single group until weaning. Key results Cow BW and body condition score decreased as nutritional restriction increased (P < 0.05). At parturition, birth weight of calves from SR dams and MR dams was lower than that of calves from CON dams (P = 0.05; 4.9 kg and 2.1 kg respectively). Average daily gain of calves from birth to 24 days of age was higher (P = 0.01) in calves from SR dams than in calves from CON and MR dams. Calves from MR dams were lighter (P = 0.04) than were calves from SR and CON dams at weaning. Treatments did not affect milk production or composition (P > 0.10) or glucose–insulin metabolism of offspring during lactation (P > 0.10). Concentration of IGF1 tended to be lower in MR progeny than in SR and CON progeny during lactation (P = 0.09). Conclusions Late gestation maternal nutrient restriction, irrespective of the severity of the restriction, decreased birth weight of offspring; however, severe nutrient restriction induced early postnatal compensatory growth. Implications The severe nutritional restriction produced calves with weaning weights indistinguishable from the control cows due to early postnatal compensatory growth. However, the longer-term effects of nutritional restriction of the dam in the second half of pregnancy on metabolic and reproductive performance in replacement heifers or meat production/quality in steers is yet to be determined.

Genetic gains in wood property can be achieved by indirect selection and nondestructive measurements in full-sib families of Japanese cedar (Cryptomeria japonica. D. Don) plus tree clones

We assessed the narrow-sense heredity and genetic gains of multiple traits obtained using the indirect selection method for progeny of Cryptomeria japonica D. Don by artificial crossing. Using stress wave velocity and Pilodyn penetration depth as indicative parameters, wood properties could be improved in future generations of C. japonica plus trees and forest breeding programs will become more efficient. To advance generations of C. japonica D. Don breeding populations, the narrow-sense heredity and genetic gain of traits of progenies are required to assess the practical genetic performance of parental trees and improve traits. We assessed the genetic gains in both growth characteristics and wood properties by indirect selection using full-sib progenies of C. japonica plus trees produced through artificial crosses. In 18-year-old progenies of 549 trees, we assessed growth characteristics, dynamic modulus of elasticity, basic density, stress wave velocity, and Pilodyn penetration depth. Genetic parameters were calculated using a mixed model and the breedR package. The genetic correlation between growth characteristics and wood properties was low. The efficiencies of indirect selection for dynamic modulus of elasticity by stress wave velocity and for basic densities by Pilodyn penetration depth were higher than those for growth characteristics by stress wave velocity and Pilodyn penetration depth, respectively. Strong correlations were found between the parental clonal values and breeding values of parental trees predicted from progeny using stress wave velocity and Pilodyn penetration depth. Using stress wave velocity and Pilodyn penetration depth as indicative parameters, future generations of C. japonica plus trees could produce superior wood properties. Growth characteristics and wood properties are independent; thus, both traits could be genetically improved compatibly.

Phenotypic correlations between body weight and morphometric traits in progenies of mongrel rabbits

One of the pre-requisites for genetic improvement is knowledge of genetic parameters for important economic traits A research was conducted with progenies of mongrel rabbits to investigate the phenotypic correlations between body weight and morphometric traits. Rabbits were managed intensively for six months, and fed ad libitum proprietary feed (15% CP and 2300 kcal/kg ME), supplemented with forages. Progenies were identified with their dams for data collection. Body weight, and linear body measurements of head and neck circumferences, body, ear and face lengths, hind and forelimbs were analyzed. Measurements were taken once weekly for 10 weeks (70 days old). Body weights were taken from 7 days old whereas linear body parameters were taken from 14 days old. Phenotypic correlations between pairs of traits, estimated were positive, showed weak and very strong relationships. Values ranged between 0.455 and 0.986 (1 to 28 days old), 0.288 and 0.841 (29 to 49 days old), 0.174 and 0.781 (50 to 70 days old). The weakest relationship (0.174) existed between neck and head circumferences (50 to 70 days old) whereas the strongest relationship (0.986) existed between body and ear lengths (1 to 28 days old). Higher values (0.539 to 0.917) indicating strong relationships were obtained when estimates were not age specific. Correlated responses in body weight in progenies of mongrel rabbits are expected at varying strengths by selecting and improving any of the linear body parameters. Further breeding researches should investigate phenotypic correlations between body weight and morphometric traits in progenies of mongrel rabbits beyond 70 days of age. Phenotypic correlations involving more parameters should be investigated.

A short review: Comparisons of high-throughput phenotyping methods for detecting drought tolerance

Drought is a major threat worldwide for crop production, especially due to the rapid climate changes. Current drought solutions involve improving irrigation system, rainwater harvesting, damming, cloud seeding, and changes of cultivation methods. Despite effective, each solution has economic, environmental, and temporal drawbacks. Among all solutions, the most effective, inexpensive and manageable method is the use of drought-tolerant cultivars via plant breeding. However, conventional plant breeding is a time-consuming and laborious task, especially for phenotypic data acquisition of target traits of numerous progenies. High-throughput phenotyping (HTP) is a recently developed method and has potential to overcome the mentioned issues. HTP offers massive, accurate, rapid, and automatic data acquisition in the breeding procedure and can be a breakthrough for developing drought resistant/tolerant cultivars. This study introduces various methods of HTP to detect drought stress, which can accelerate the breeding processes of drought-tolerant cultivars to provide helpful guidelines for breeders and researchers to choose appropriate methods.

Genomic selection in American mink (Neovison vison) using a single-step genomic best linear unbiased prediction model for size and quality traits graded on live mink.

Genomic selection relies on single-nucleotide polymorphisms (SNPs), which are often collected using medium-density SNP arrays. In mink, no such array is available; instead, genotyping by sequencing (GBS) can be used to generate marker information. Here, we evaluated the effect of genomic selection for mink using GBS. We compared the estimated breeding values (EBVs) from single-step genomic best linear unbiased prediction (SSGBLUP) models to the EBV from ordinary pedigree-based BLUP models. We analyzed seven size and quality traits from the live grading of brown mink. The phenotype data consisted of ~20,600 records for the seven traits from the mink born between 2013 and 2016. Genotype data included 2,103 mink born between 2010 and 2014, mostly breeding animals. In total, 28,336 SNP markers from 391 scaffolds were available for genomic prediction. The pedigree file included 29,212 mink. The predictive ability was assessed by the correlation (r) between progeny trait deviation (PTD) and EBV, and the regression of PTD on EBV, using 5-fold cross-validation. For each fold, one-fifth of animals born in 2014 formed the validation set. For all traits, the SSGBLUP model resulted in higher accuracies than the BLUP model. The average increase in accuracy was 15% (between 3% for fur clarity and 28% for body weight). For three traits (body weight, silky appearance of the under wool, and guard hair thickness), the difference in r between the two models was significant (P < 0.05). For all traits, the regression slopes of PTD on EBV from SSGBLUP models were closer to 1 than regression slopes from BLUP models, indicating SSGBLUP models resulted in less bias of EBV for selection candidates than the BLUP models. However, the regression coefficients did not differ significantly. In conclusion, the SSGBLUP model is superior to conventional BLUP model in the accurate selection of superior animals, and, thus, it would increase genetic gain in a selective breeding program. In addition, this study shows that GBS data work well in genomic prediction in mink, demonstrating the potential of GBS for genomic selection in livestock species.

Application of growth traits and qualitative indices for selection of Scots pine (Pinus sylvestris l.) elite trees. A case study from Volyn region, western ukraine

Abstract Since the plus trees are selected based on phenotype, it is necessary to evaluate them in progeny test. The aim of this study is an indication of selecting elite mother trees based on the results from half-sib progeny test trials. As study sites, two Scots pine half-sib progeny tests were selected. During evaluation, the progenies had reached the age of 38 and 40 years, respectively. In both progeny trials, quantitative parameters and qualitative traits of Scots pine half-sib progenies were investigated. Based on these data, complex evaluation of half-sib families was carried out. We concluded that, Scots pine progenies at the age of 38 and 40 years in fresh and moist mixed forests are characterised by acceptable quality, with the survival being 25%–33% per progeny test trial. Based on a complex evaluation of 38- and 40-year-old half-sib progenies of plus trees, we proposed to select 31% of tested plus/mother trees as candidates for elite trees. Further, the list of candidates for elite trees was created with five plus trees from the Volyn region (26% of the total tested from the region) and four plus trees from the Lviv region (40% of the total tested from the region). With age, the share of the best and undesirable trees decreases, while the proportion of intermediate trees increases in both control trees and half-sib progenies. At the age of 38 and 40 years, the proportion of fast-growing offspring was from 0% to 36%, while the declining trend that was observed in previous years was being continued. Thus, due to the declining trend in the proportion of fast-growing offspring observed at the age of 38 and 40 years, we propose to select candidate trees for an elite group not early than after 40 years of test their progenies.

Comparative Transcriptome Profiling Analysis Uncovers Novel Heterosis-Related Candidate Genes Associated with Muscular Endurance in Mules.

Simple SummaryMules have better and greater muscle endurance than hinnies and their parents. However, the molecular mechanisms underlying heterosis in their muscles are still much less understood. In this study, we conducted comparative transcriptome and alternative splicing analysis on the heterosis mechanism of muscular endurance in mules. Our results showed that 8 genes were significantly enriched in the “muscle contraction” pathway. In addition, 68% of the genes with alternative splicing events from the mule muscle tissue were validated by the long transcript reads generated from PacBio sequencing platform. Our findings provide a research foundation for studying the genetic basis of heterosis in mules.Heterosis has been widely exploited in animal and plant breeding programs to enhance the productive traits of hybrid progeny from two breeds or species. However, its underlying genetic mechanisms remain enigmatic. Transcriptome profiling analysis can be used as a method for exploring the mechanism of heterosis. Here, we performed genome-wide gene expression and alternative splicing (AS) analyses in different tissues (muscle, brain, and skin) from crosses between donkeys and horses. Our results indicated that 86.1% of the differentially expressed genes (DEGs) and 87.2% of the differential alternative splicing (DAS) genes showed over-dominance and dominance in muscle. Further analysis showed that the “muscle contraction” pathway was significantly enriched for both the DEGs and DAS genes in mule muscle tissue. Taken together, these DEGs and DAS genes could provide an index for future studies of the genetic and molecular mechanism of heterosis in the hybrids of donkey and horse.

Construction of a high-density genetic map and mapping of growth related QTLs in the grass carp (Ctenopharyngodon idellus)

BackgroundGrass carp (Ctenopharyngodon idellus) are important species in Asian aquaculture. A draft genome for grass carp has already been published in 2015. However, there is still a requirement for a suitable genetic linkage map to arrange scaffolds on chromosomal frameworks. QTL analysis is a powerful tool to detect key locations for quantitative traits, especially in aquaculture. There no growth related QTLs of grass carp have been published yet. Even the growth trait is one of the focuses in grass carp culture.ResultsIn this study, a pair of distantly related parent grass carps and their 100 six-month-old full-sib offspring were used to construct a high-density genetic map with 6429 single nucleotide polymorphisms (SNPs) by 2b-RAD technology. The total length of the consensus map is 5553.43 cM with the average marker interval of 1.92 cM. The map has a good collinearity with both the grass carp draft genome and the zebrafish genome, and it assembled 89.91% of the draft genome to a chromosomal level. Additionally, according to the growth-related traits of progenies, 30 quantitative trait loci (QTLs), including 7 for body weight, 9 for body length, 5 for body height and 9 for total length, were identified in 16 locations on 5 linkage groups. The phenotypic variance explained for these QTLs varies from 13.4 to 21.6%. Finally, 17 genes located in these regions were considered to be growth-related because they either had functional mutations predicted from the resequencing data of the parents.ConclusionA high density genetic linkage map of grass carp was built and it assembled the draft genome to a chromosomal level. Thirty growth related QTLs were detected. After the cross analysis of Parents resequencing data, 17 candidate genes were obtained for further researches.

Relationships between yield and some anatomical and morphological traits in rubber tree progenies

The present work evaluated the relationship of rubber yield with morphological and structural traits of the laticiferous system in rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. Arg] open-pollinated progenies to understand the cause and effect relationships between traits in order to enable future early selection. The progenies were installed in Jaú, Pindorama and Votuporanga in a randomized block design, with five replications and 10 plants per plot at a spacing of 2.0 × 2.0 m. The traits evaluated at three years of age were rubber yield (Yld); girth (Grt), expressed by the stem perimeter; bark thickness (BT); number of latex vessel rings (RG); length (PL), diameter (PD) and petiole index (PI); leaflet length(LFL) and width (LFW); leaf width (LW), area (LA) and index (LI); and number of leaf storeys (NLS). Coefficients of the genotypic correlations were used for a graphical representation of the correlation network created in the Genes program. Subsequently, the diagnosis of multicollinearity, as well as the analysis of the direct and indirect genotypic correlations of bark anatomical traits, leaf morphological traits, girth, and rubber yield, were performed. The traits that showed significant genotypic correlations with rubber yield at the three evaluated sites were girth, bark thickness, and number of leaf storeys. The girth character had the largest direct effect on rubber yield. Canonical correlation analysis showed that selection for the number of leaf storeys may increase at least three of the traits (yield, girth, bark thickness, and number of latex vessel rings) for most locations studied. There is an association between the yield traits (yield, girth, and the laticiferous system) and the morphological traits.