Embryo Rescue and Moleclar Marker-Assisted Selection of Hybrid Seedless Grape

Seedless grapes play an important role in fresh food and dry production. New varieties breeding by hybridization with seedless varieties as female parents is the most effective way to cultivate seedless varieties. However, the embryos of Seedless varieties can not develop normally, so it is difficult to obtain hybrid offspring as hybrid female parent. Moreover, grape is a perennial tree species with highly heterozygous genes, with long breeding cycle and low efficiency. In this study, embryo rescue technology was used to cultivate hybrid offspring by crossing with ‘Ruby Seedless’ as female parent and ‘Hongqitezao’ as male parent, so as to solve the problem that seedless varieties can not be female parent; and molecular technology was used to carry out assisted breeding research to solve the problems of long cycle and low efficiency. TP-M13-SSR technique was used to carry out authenticity breeding. SCAR marker SCF27-2000 was used to detect the seedless traits of hybrid plants, phenotypic traits was used to verify the results of molecular markers, and Seedless trait-related SSR markers VMC7F2, VrSD10 and P3_VvAGL11 was used to detect and verify the genotypes of individual plants with inconsistent detection results by the two methods. In this study, a total of 384 hybrid offspring were finally obtained, and the hybridization rate was 84.43%. A total of 163 fruit-bearing plants were identified, and the phenotypes of their seeds were identified. The coincidence rate of genotypic and phenotypic analyses was 93.88%. Additionally, 305 F1 plants were detected using the SCF27-2000 marker, and the abortion rate was 64.92%. We speculate that the inconsistent results were caused by parthenocarpy, SCF27 marker limitation, among other factors. Overall, this study shows that embryo rescue is an effective method for breeding seedless grape cultivars, and the application of molecular markers could facilitate the early identification of hybrid traits,and improve breeding efficiency.

Enhanced heterozygosity from male meiotic chromosome chains is superseded by hybrid female asexuality in termites

Although males are a ubiquitous feature of animals, they have been lost repeatedly in diverse lineages. The tendency for obligate asexuality to evolve is thought to be reduced in animals whose males play a critical role beyond the contribution of gametes, for example, via care of offspring or provision of nuptial gifts. To our knowledge, the evolution of obligate asexuality in such species is unknown. In some species that undergo frequent inbreeding, males are hypothesized to play a key role in maintaining genetic heterozygosity through the possession of neo-sex chromosomes, although empirical evidence for this is lacking. Because inbreeding is a key feature of the life cycle of termites, we investigated the potential role of males in promoting heterozygosity within populations through karyotyping and genome-wide single-nucleotide polymorphism analyses of the drywood termite Glyptotermes nakajimai. We showed that males possess up to 15 out of 17 of their chromosomes as sex-linked (sex and neo-sex) chromosomes and that they maintain significantly higher levels of heterozygosity than do females. Furthermore, we showed that two obligately asexual lineages of this species—representing the only known all-female termite populations—arose independently via intraspecific hybridization between sexual lineages with differing diploid chromosome numbers. Importantly, these asexual females have markedly higher heterozygosity than their conspecific males and appear to have replaced the sexual lineages in some populations. Our results indicate that asexuality has enabled females to supplant a key role of males.

Patterns of reproductive isolation in a haplodiploid mite, Amphitetranychus viennensis: prezygotic isolation, hybrid inviability and hybrid sterility

Background Evolution of reproductive isolation is an important process, generating biodiversity and driving speciation. To better understand this process, it is necessary to investigate factors underlying reproductive isolation through various approaches but also in various taxa. Previous studies, mainly focusing on diploid animals, supported the prevalent view that reproductive barriers evolve gradually as a by-product of genetic changes accumulated by natural selection by showing a positive relationship between the degree of reproductive isolation and genetic distance. Haplodiploid animals are expected to generate additional insight into speciation, but few studies investigated the prevalent view in haplodiploid animals. In this study, we investigate whether the relationship also holds in a haplodiploid spider mite, Amphitetranychus viennensis (Zacher). Results We sampled seven populations of the mite in the Palaearctic region, measured their genetic distance (mtDNA) and carried out cross experiments with all combinations. We analyzed how lack of fertilization rate (as measure of prezygotic isolation) as well as hybrid inviability and hybrid sterility (as measures of postzygotic isolation) varies with genetic distance. We found that the degree of reproductive isolation varies among cross combinations, and that all three measures of reproductive isolation have a positive relationship with genetic distance. Based on the mtDNA marker, lack of fertilization rate, hybrid female inviability and hybrid female sterility were estimated to be nearly complete (99.0–99.9% barrier) at genetic distances of 0.475–0.657, 0.150–0.209 and 0.145–0.210, respectively. Besides, we found asymmetries in reproductive isolation. Conclusions The prevalent view on the evolution of reproductive barriers is supported in the haplodiploid spider mite we studied here. According to the estimated minimum genetic distance for total reproductive isolation in parent population crosses in this study and previous work, a genetic distance of 0.15–0.21 in mtDNA (COI) appears required for speciation in spider mites. Variations and asymmetries in the degree of reproductive isolation highlight the importance of reinforcement of prezygotic reproductive isolation through incompatibility and the importance of cytonuclear interactions for reproductive isolation in haplodiploid spider mites.

Complex basis of hybrid female sterility and Haldane's rule in Heliconius butterflies: Z-linkage and epistasis

Hybrids between diverging populations are often sterile or inviable. Hybrid unfitness usually evolves first in the heterogametic sex -- a pattern known as Haldane's rule. The genetics of Haldane's Rule have been extensively studied in species where the male is the heterogametic (XX/XY) sex, but its basis in taxa where the female is heterogametic (ZW/ZZ), such as Lepidoptera and birds, is largely unknown. Here, we analyse a new case of female hybrid sterility between geographic subspecies of Heliconius pardalinus. The two subspecies mate freely in captivity, but female F1 hybrids in both directions of cross are sterile. Sterility is due to arrested development of oocytes after they become differentiated from nurse cells, but before yolk deposition. We backcrossed fertile male F1 hybrids to parental females, and mapped quantitative trait loci (QTLs) for female sterility. We also identified genes differentially expressed in the ovary, and as a function of oocyte development. The Z chromosome has a major effect, similar to the "large X effect" in Drosophila, with strong epistatic interactions between loci at either end of the Z chromosome, and between the Z chromosome and autosomal loci on chromosomes 8 and 20. Among loci differentially expressed between females with arrested vs. non-arrested ovary development, we identified six candidate genes known also from Drosophila melanogaster and Parage aegeria oogenesis. This study is the first to characterize hybrid sterility using genome mapping in the Lepidoptera. We demonstrate that sterility is produced by multiple complex epistastic interactions often involving the sex chromosome, as predicted by the dominance theory of Haldane's Rule.

Patterns of reproductive isolation in a haplodiploid mite, Amphitetranychus viennensis: prezygotic isolation, hybrid inviability and hybrid sterility

Background Evolution of reproductive isolation is an important process, generating biodiversity and driving speciation. To better understand this process, it is necessary to investigate factors underlying reproductive isolation through various approaches but also in various taxa. Previous studies, mainly focusing on diploid animals, supported the prevalent view that reproductive barriers evolve gradually as a by-product of genetic changes accumulated by natural selection by showing a positive relationship between the degree of reproductive isolation and genetic distance. Haplodiploid animals are expected to generate additional insight into speciation, but few studies investigated the prevalent view in haplodiploid animals. In this study, we investigate whether the relationship also holds in a haplodiploid spider mite, Amphitetranychus viennensis (Zacher). Results We sampled seven populations of the mite in the Palaearctic region, measured their genetic distance (mtDNA) and carried out cross experiments with all combinations. We analyzed how lack of fertilization rate (as measure of prezygotic isolation) as well as hybrid inviability and hybrid sterility (as measures of postzygotic isolation) varies with genetic distance. We found that the degree of reproductive isolation varies among cross combinations, and that all three measures of reproductive isolation have a positive relationship with genetic distance. Based on the mtDNA marker, lack of fertilization rate, hybrid female inviability and hybrid female sterility were estimated to be nearly complete (99.0–99.9% barrier) at genetic distances of 0.475–0.657, 0.150–0.209 and 0.138–0.204, respectively. Conclusions The prevalent view on the evolution of reproductive barriers is supported in the haplodiploid spider mite we studied here. According to the estimated minimum genetic distance for total reproductive isolation in parent population crosses in this and previous studies, a genetic distance of 0.152–0.210 in mtDNA (COI) appears required for speciation in spider mites. Due to a lack of hybrid males, we could not address Haldane’s rule, which can be extended to haplodiploids, even though we focused on a young diverging group of spider mites. Our results highlight the importance of cytonuclear interactions for reproductive isolation in haplodiploid spider mites.

ELECTROPHYSIOLOGICAL EVALUATION OF THE FUNCTIONAL STATE OF PERIPHERAL AUDITORY ANALYZER IN AN ACOUSTIC INJURY MODEL WITH PREVENTIVE TAKING OF AN ANTIHYPOXANT (TRIAZINOINDOLE DERIVATIVE)

The paper reports the results of testing efficiency of a triazinoindole derivative in an experiment with modeled acoustic injury. Animals (116 (CBA x C57BL/6) F1 hybrid female mice) were randomly distributed in 5 groups. Groups A, B and C received I/M triazinoindole at 5, 7 and 10 mg/kg/d respectively. Group D was injected with the cytoflavin (reference medicine) at 1.7 ml/7 мl/kg. Group E was a control that received injections of 2 ml of 0.9 % sodium chloride solution. Following 5 days of injections, the mice were exposed to white noise of 107 dB. Analysis of auditory evoked potentials demonstrated a dose-dependent oto-protective effect of the triazinoindole derivative.

Yellow mealworm (Tenebrio molitor L.) larvae inclusion in diets for free-range chickens: effects on meat quality and fatty acid profile

This study evaluated the effects of a diet containing yellow mealworm (Tenebrio molitor L.; TM) larva meal on quality parameters (pH24, color and drip losses), proximate composition and fatty acid (FA) profile of meat from free-range chickens. A total of 140 medium-growing hybrid female chickens were free-range reared and randomly allotted to two dietary treatments: a control group and a TM group, in which TM meal was included at 75 g kg−1 as fed in substitution of corn gluten meal. Each group consisted of five pens as replicates, with 14 chicks per pen. At 97 days of age, ten birds (two birds/pen) from each feeding group were slaughtered at a commercial abattoir. Quality parameters and proximate composition of breast and thigh meat were not affected by treatment. The effects of dietary TM larva meal on the FA profile of thigh meat were negligible. Breast meat from TM-fed chickens showed higher oleic and α-linolenic acid percentages as well as lower atherogenicity and thrombogenicity indexes. In conclusion, this study demonstrated that TM inclusion in diets for free-range chickens did not prejudice meat quality traits. The obtained results confirm that TM can be considered a promising insect protein source for the poultry feed industry.