Artificial Hybrids Research Articles

A Review of Experimental, Natural, and Anthropogenic Hybridization in Callithrix Marmosets

Natural and anthropogenic hybridization both occur in primates, but the effects of these distinct processes on primate evolution and population dynamics can be difficult to disentangle from one another. With most primate species being endangered, conservation prioritizes natural over anthropogenic hybrids. However, anthropogenic hybridization can generate genetic diversity and novelty, and fully understanding hybridization is important for primate conservation and evolutionary biology. The neotropical genus Callithrix, an emerging hybridization model, provides a good opportunity to study natural and anthropogenic hybridization separately, and here I review Callithrix hybridization work from the 1970s to the 2010s. Natural hybridization in these species occurs under secondary contact at their distribution borders. In contrast, C. jacchus and C. penicillata, species native to northern, northeastern, and central-eastern Brazil, have been widely introduced in southeastern Brazil. Such introductions have resulted in artificial sympatry and hybridization between exotic C. jacchus and C. penicillata with themselves or with native Callithrix species. Hybridization between native C. aurita and exotic Callithrix results in mixed pure species and hybrid groups, whereas hybridization between pairings of C. jacchus, C. penicillata, and C. geoffroyi results in populations of advanced hybrids. These findings indicate differences in reproductive isolation, and as such, distinct genomic and evolutionary consequences of these hybridization events. Genomic and genetic work is still rare for wild Callithrix populations, and most hybridization studies have been qualitative or descriptive. I point future priorities for Callithrix hybridization research toward hybrid fitness, reproduction, and health as well as investigation of genetic introgression among hybrids and nonhybrids.

Domestication of Temperate and Coastal Hybrids with Distinct Ancestral Gene Selection in Octoploid Strawberry

Garden strawberry ( × Duchesne ex Rozier) arose from spontaneous hybridization of distinct octoploid species 300 yr ago. Since its discovery in the 1700s, migration and selection restructured the genetic diversity of early hybrids to produce elite fruit-bearing groups. Breeders' understanding of the genetic architecture of domesticated populations is incomplete. To resolve the impacts of domestication on strawberry genetic diversity, we analyzed genome-wide DNA profiles of 1300 octoploid individuals (1814-present), including wild species, historic varieties, and the University of California germplasm collection. Commercially important California genotypes, adapted to mild coastal climates and accounting for a large fraction of global production, have diverged from temperate cultivars originating in eastern North America and Europe. Whereas temperate cultivars were shown to have selected North American Miller ssp. ancestral diversity at higher frequencies, coastal breeding increased selection of (L.) Miller (beach strawberry) alleles in . × , in addition to photoperiod-insensitive flowering alleles from nonancestral (S.Watson) Staudt ssp. , underscoring the role of continued adaptive introgressions in the domestication of artificial hybrids. Selection for mass production traits in coastal climates over the last 20 to 30 yr has restructured domesticated strawberry diversity on a scale similar to the first 200 yr of breeding; coastal × has diverged further from temperate × than the latter from their wild progenitors. Selection signatures indicate that strawberry domestication targeted genes regulating hormone-mediated fruit expansion, providing a blueprint for genetic factors underlying elite phenotypes.

The effects of environmental and genetic factors on the germination of basidiospores in the Cryptococcus gattii species complex

Natural and artificial hybridization has been frequently reported among divergent lineages within and between the two closely related human pathogenic fungi Cryptococcus gattii species complex and Cryptococcus neoformans species complex. However, the biological effects of such hybridization are not well known. Here we used five strains of the C. neoformans species complex and twelve strains of the C. gattii species complex to investigate the potential effects of selected environmental and genetic factors on the germination of their basidiospores from 29 crosses. We found that the germination rates varied widely among crosses and environmental conditions, ranging from 0% to 98%. Overall, the two examined media showed relatively little difference on spore germination while temperature effects were notable, with the high temperature (37 °C) having an overall deleterious effect on spore germination. Within the C. gattii species complex, one intra-lineage VGIII × VGIII cross had the highest germination rates among all crosses at all six tested environmental conditions. Our analyses indicate significant genetic, environmental, and genotype-environment interaction effects on the germination of basidiospores within the C. gattii species complex.

GIZA 95” A LONG STAPLE EGYPTIAN COTTON VARIETY FOR MIDDLE AND UPPER EGYPT

Giza95 is a new long-staple Egyptian cotton variety. It has been introduced by the Cotton Breeding Research Section through artificial hybridization between the variety Giza80 and the genotype [(Giza83xGiza75) x5844] followed by the pedigree method of selection. The variety Giza 95 has 6.90% higher seed cotton yield (SCY) and 16.32% higher lint yield (LY) than the commercial variety Giza 90. It slightly surpassed Giza 90 for boll weight (BW) and lint percentage (L %). Fiber quality traits for the new variety Giza 95 was nearly

The southwestern origin and eastward dispersal of pear (Pyrus pyrifolia) in East Asia revealed by comprehensive genetic structure analysis with SSR markers

Pyrus pyrifolia is considered one of the most important cultivated Pyrus species. Hundreds of landraces and bred cultivars have been developed through the natural and artificial hybridizations necessary due to self-incompatibility. In this study, the genetic diversity of 478 Pyrus accessions, including Chinese landraces, bred cultivars, and wild samples, as well as introduced pear cultivars from Japan and Korea, was investigated with a set of 17 simple sequence repeat (SSR) markers distributed across all 17 linkage groups of the pear genome. A total of 121 alleles were detected, including 4 rare alleles with a frequency lower than 5%. Diversity statistics indicated a high level of genetic variation as quantified by the average values of the observed heterozygosity, the expected heterozygosity, and Wright’s fixation index, at 0.76, 0.78, and 0.02, respectively. Population structure and discriminant analysis of principal component analysis implied extensive genetic communication between sand pears in China and revealed four contiguous geographical clusters with overlapping geographical regions. The diversity of the four clusters and approximate Bayesian computation (ABC) indicated that sand pear spread from west to east along the Pearl River and Yangtze River valleys. High diversity and polyphyletic genetic components of cultivars in southwestern China further support southwestern China as the probable center of divergence for Pyrus species. A core collection of 80 out of 470 cultivars was selected, accounting for about 17% of accessions, and capturing 91% of all alleles, including all rare alleles. Our research provides a comprehensive understanding of sand pear germplasm in East Asia and constructs a preliminary core collection, which will be useful for association genetics studies, germplasm conservation, and breeding programs.

The role of biodiversity in forest plant breeding: A case study on the development of new Acacia hybrid varieties (Acacia mangium x Acacia auriculiformis)

Sunarti S. 2018. Review: The role of biodiversity in forest plant breeding: A case study on the development of new Acacia hybrid varieties (Acacia mangium x Acacia auriculiformis). Pros Sem Nas Masy Biodiv Indon 4: 28-34. Tropical forest biodiversity in Indonesia has the third largest area in the world after Brazil and Congo with 300,000 species of plants and 55% of them are endemic. One species of plant which have a high economic value is Acacia mangium and Acacia auriculiformis. Center for Forest Biotechnology and Tree Improvement Research and Development (BBPPBPTH) since 1993 has developed both those species of Acacia comprehensively. In order to improve biodiversity, productivity and quality of wood and resistance to pests/diseases, new Acacia varieties were created through natural and artificial hybridization. A natural hybridization was done by establishing a hybridizing seed orchard and artificially carried out by controlled pollination in the breeding garden. From the hybridization has produced two hundreds of new varieties of Acacia hybrid with varied morphological characteristics and have been tested in several sites in Sumatra and Central Java with different site condition. Some of them are superior hybrid with straight and rounded trunk with lighter branching and 17% improvement in productivity compared to their parents. In addition, the properties of wood in the form of specific gravity, wood consumption, cellulose content is also better than the parents, that is respectively 402.1 kg/m3; 3.52 m3/Ton and 59.9%. Hybrid morphological markers have been applied with an accuracy of 97% compared to SCAR molecular markers. The creating of new varieties of Acacia hybrids continued to be done using the co-improvement method using selected parent trees from better generations.

Creation of Large Hybrid Populations Using Male-sterile Germplasm as the Female Parent in Jujube

The establishment of large hybrid populations is the key basis to breeding new cultivars and genetic research, such as molecular mapping. However, it is extremely difficult to generate hybrid progeny using conventional artificial hybridization in Chinese jujube (Chinese date) (Ziziphus jujuba Mill.) because of its low fruit set of ≈0.01%. The objective of this study was to create large hybrid populations in Chinese jujube using bona fide male-sterile germplasm as the female parent. Two male-sterile varieties that lacked viable pollen (JMS1 and JMS2) previously discovered by our research group and three male-fertile genotypes (‘Xing16’, ‘Jiao5’, and ‘Wuhefeng’) were used as female and male parents, respectively. Bee-aided controlled hybridization of five combinations was conducted from 2014 to 2016. The results indicated that both JMS1 and JMS2 were stable male-sterile germplasm across the years examined. JMS2 showed more effective compatibility with the male parents tested than JMS1. A total of 7681 fruits were obtained from the five cross combinations, and 3120 of them contained seeds. The mean rate of the fruit with seed varied from 32.62% to 64.21%, and the highest rate (73.38%) was obtained from the cross of JMS2 × ‘Xing16’ in 2016. A total of 831 seedlings were obtained and consisted of 602 from JMS2 × ‘Xing16’, 221 from JMS2 × ‘Jiao5’, two from JMS1 × ‘Xing16’, five from JMS1 × ‘Wuhefeng’, and one from JMS2 × ‘Wuhefeng’. The 118 randomly selected progeny seedlings, including 96 from JMS2 × ‘Xing16’ and 22 from JMS2 × ‘Jiao5’, respectively, were identified to be authentic hybrids using SSR markers. Thus, JMS2 is a promising male-sterile female parent that possesses a good cross-compatibility and is free from the need for emasculation, embryo rescue, and hybrid identification. The largest hybrid population of 602 progeny was obtained in Chinese jujube using controlled hybridization. This study demonstrated the feasibility of a highly efficient crossbreeding approach using male-sterile germplasm as the female parent in Chinese jujube.

Naturally occurring variations in the nod-independent model legume Aeschynomene evenia and relatives: a resource for nodulation genetics

BackgroundAmong semi-aquatic species of the legume genus Aeschynomene, some have the unique property of being root and stem-nodulated by photosynthetic Bradyrhizobium lacking the nodABC genes necessary for the production of Nod factors. These species provide an excellent biological system with which to explore the evolution of nodulation in legumes. Among them, Aeschynomene evenia has emerged as a model legume to undertake the genetic dissection of the so-called Nod-independent symbiosis. In addition to the genetic analysis of nodulation on a reference line, natural variation in a germplasm collection could also be surveyed to uncover genetic determinants of nodulation. To this aim, we investigated the patterns of genetic diversity in a collection of 226 Nod-independent Aeschynomene accessions.ResultsA combination of phylogenetic analyses, comprising ITS and low-copy nuclear genes, along with cytogenetic experiments and artificial hybridizations revealed the richness of the Nod-independent Aeschynomene group with the identification of 13 diploid and 6 polyploid well-differentiated taxa. A set of 54 SSRs was used to further delineate taxon boundaries and to identify different genotypes. Patterns of microsatellite diversity also illuminated the genetic basis of the Aeschynomene taxa that were all found to be predominantly autogamous and with a predicted simple disomic inheritance, two attributes favorable for genetics. In addition, taxa displaying a pronounced genetic diversity, notably A. evenia, A. indica and A. sensitiva, were characterized by a clear geographically-based genetic structure and variations in root and stem nodulation.ConclusionA well-characterized germplasm collection now exists as a major genetic resource to thoroughly explore the natural variation of nodulation in response to different bradyrhizobial strains. Symbiotic polymorphisms are expected to be found notably in the induction of nodulation, in nitrogen fixation and also in stem nodulation. Subsequent genetic analysis and locus mapping will pave the way for the identification of the underlying genes through forward or reverse genetics. Such discoveries will significantly contribute to our understanding of the molecular mechanisms underpinning how some Aeschynomene species can be efficiently nodulated in a Nod-independent fashion.

The In Silico Predicton of the Chloroplast Maturase K Gene Polymorphism in Several Barley Varieties

Abstract This study was conducted to describe the role of the chloroplast maturase K (matK) genetic polymorphism in the reciprocal crossing between five barley varieties using several in vitro / in silico tools. Besides, the final consequences of the matK gene polymorphism on its protein structure, function, and interactions were predicted computationally. Five parental varieties were crossed to each other by full reciprocal crossing design, DNA was extracted from seeds and two different primers’ pairs were designed to scan matK gene. Then, polymerase chain reaction - single-stranded conformation polymorphism (PCR-SSCP) were performed. Two distinct haplotypes in both parents and artificial F1 hybrids in the matK gene were observed in both amplified fragments. This finding indicated that the studied gene had no participation in the reciprocal crossing performed. Three SNPs were identified; two of them are non-synonymous (nsSNPs), namely G387V and L459M. The effect of these missense mutations on the matK protein was analyzed by several in silico tools. It was shown that the coding SNP, L459M was predicted to have much more effective consequences on matK protein structure and function. While the I-Mutant 2.0 prediction tool showed a decrease in stability for these two nsSNPs, which may destabilize the protein interactions to some extent. In conclusion, though the observed missense mutations in the matK gene have no suggestive role in the reciprocally crossed barley varieties, they caused dramatic alterations in several matK protein moieties, which may lead to potential subsequent changes in the matK protein-mediated RNA splicing mechanisms.

Estudio prospectivo de la incidencia de patógenos genitales oportunistas y estrictos que crecen en medios de cultivo artificiales

Background and objectivePurulent or exudative genitourinary infections are a frequent reason for consultation in primary and specialized health care. The objective of this study was to determine the incidence of the microorganisms most commonly involved in the development of bacterial vaginosis, cervicitis, urethritis, vulvovaginitis, and balanitis in a general population attending 2tertiary level hospitals in the province of Granada (Spain). Patients and methodsAll the samples received for the microbiological diagnosis of acute lower genital tract infection between February and May 2015 were analysed following a standard protocol. Detection of the microorganisms in the samples was performed by cultivation in artificial media or nucleic acid hybridisation techniques (Affirm VPIII). ResultsThe analysis included a total of 2,017 samples, obtained from 1,722 different patients (1626 women and 96 men).. The presence of at least one microorganism with clinical significance was detected in 772 patients (44.8%; 745 women and 27 men). Among the women, the most frequent microorganism more found was Gardnerella vaginalis, present in the 26.7%, followed by Candida albicans (20.0%), Trichomonas. vaginalis (1.0%), and Ureaplasma urealyticum (0.4%). Neisseria gonorrhoeae and Haemophilus spp. were detected in 10.4% and 6.3% of samples of male origin, respectively. ConclusionsIn the studied population, bacterial vaginosis by G. vaginalis, vulvovaginitis by Candida spp., trichomoniasis, gonorrhea, and urethritis by Ureaplasma spp. and Haemophilus spp., were the most frequent exudative genital infections.

Intraspecific and intraorganismal copy number dynamics of retrotransposons and tandem repeat in Aegilops speltoides Tausch (Poaceae, Triticeae).

Transposable elements (TE) and tandem repeats (TR) compose the largest fraction of the plant genome. The abundance and repatterning of repetitive DNA underlie intrapopulation polymorphisms and intraspecific diversification; however, the dynamics of repetitive elements in ontogenesis is not fully understood. Here, we addressed the genotype-specific and tissue-specific abundances and dynamics of the Ty1-copia, Ty3-gypsy, and LINE retrotransposons and species-specific Spelt1 tandem repeat in wild diploid goatgrass, Aegilops speltoides Tausch. Copy numbers of TEs and TR were estimated by real-time quantitative PCR in vegetative and generative tissues in original plants from contrasting allopatric populations and artificial intraspecific hybrids. The results showed that between leaves and somatic spike tissues as well as in progressive microsporogenesis of individual genotypes, the copy numbers of three TEs correlatively oscillated between 2- to 4-fold and the TR copy numbers fluctuated by 18- to 440-fold. Inter-individual and intraorganismal TEs and TR copy number dynamics demonstrate large-scale parallelism with extensive chromosomal rearrangements that were detected using fluorescent in situ hybridization in parental and hybrid genotypes. The data obtained indicate that tissue-specific differences in the abundance and pattern of repetitive sequences emerge during cell proliferation and differentiation in ontogenesis and reflect the reorganization of individual genomes in changing environments, especially in small peripheral population(s) under the influence of rapid climatic changes.

Flower Characteristics and Pollination Behavior of <i>Euryale ferox</i> (Salisb.)

The Euryale ferox (Salisb.) or gorgon or makhana is one of the most important non cereal food crops of commerce from wetland ecosystem in India. Flower is cleistogamous (CLS) and predominantly self-pollinated. The variations in floral characters were observed in 10 types of germplasm viz., Manipur-2, Manipur-4, Manipur-7, Manipur-9, Selection-17, Selection-23, Selection-27, Selection-28, Superior Selection-1 and cv. Swarna Vaidehi. In our present study, the number of flowers varied from 8.33 (Manipur-9) to 16.33 (Superior Selection-1) per plant and flowering period was about 40 days. However, peak pollination was observed between 60 - 70 days after transplanting. The weather of August and September were ideal for pollination and fruit set. The temperature and humidity of this period were 29°C - 31°C and 79% - 81%, respectively. Besides cleistogamy (CL), chasmogamy (CH) is also observed after July flowering in Euryale, when crop gets matured, water level considerably goes down, and flowers are generally opened in air. There were rare chances for cross pollination by insect. In later stage, chasmogamous (CHS) flower increases up to 22.50% in October. Seed formation of the CHS flower was very less and seed number varies from July (11.25/fruit) to September (28.33/fruit). Artificial hybridization can be performed in CHS flower. The complete flower development was noticed within 72 - 96 hrs from floral initiation. Therefore, getting of CHS flower outside water is very less. There were strong correlations between number of embryos (r = 0.762), ovary area (longitudinal) (r = 0.681) with the yield of the Euryale plant.

Saccharomyces interspecies hybrids as model organisms for studying yeast adaptation to stressful environments.

The strong development of molecular biology techniques and next-generation sequencing technologies in the last two decades has significantly improved our understanding of the evolutionary history of Saccharomyces yeasts. It has been shown that many strains isolated from man-made environments are not pure genetic lines, but contain genetic materials from different species that substantially increase their genome complexity. A number of strains have been described as interspecies hybrids, implying different yeast species that under specific circumstances exchange and recombine their genomes. Such fusing usually results in a wide variety of alterations at the genetic and chromosomal levels. The observed changes have suggested a high genome plasticity and a significant role of interspecies hybridization in the adaptation of yeasts to environmental stresses and industrial processes. There is a high probability that harsh wine and beer fermentation environments, from which the majority of interspecies hybrids have been isolated so far, influence their selection and stabilization as well as their genomic and phenotypic heterogeneity. The lessons we have learned about geno- and phenotype plasticity and the diversity of natural and commercial yeast hybrids have already had a strong impact on the development of artificial hybrids that can be successfully used in the fermentation-based food and beverage industry. The creation of artificial hybrids through the crossing of strains with desired attributes is a possibility to obtain a vast variety of new, but not genetically modified yeasts with a range of improved and beneficial traits. Copyright © 2017 John Wiley & Sons, Ltd.

Genotype- and Cell-Specific Dynamics of Tandem Repeat Patterns in Aegilops speltoides Tausch (Poaceae, Triticeae)

In wild plant populations, chromosome rearrangements lead to the wide intraspecific polymorphisms in the abundance and patterns of highly repetitive DNA. However, despite the large amount of accumulated data, the impact of the complex repetitive DNA fraction on genome reorganization and functioning and the mechanisms balancing and maintaining the structural integrity of the genome are not fully understood. Homologous recombination is thought to play a key role in both genome reshuffling and stabilization, while the contribution of nonhomologous recombination seems to be undervalued. Here, tandem repeat patterns and dynamics during pollen mother cell development were addressed, with a focus on the meiotic recombination that determines chromosome/genome repatterning and stabilization under cross-pollination and artificial hybridization in wild goatgrass, Aegilops speltoides. Native plants from contrasting allopatric populations and artificially created intraspecific hybrids were investigated using a FISH approach. Cytogenetic analysis uncovered a wide spectrum of genotype- and cell-specific chromosomal rearrangements, suggesting intensive repatterning of both parental and hybrid genomes. The data obtained provide evidence that repetitive elements serve as overabundant and ubiquitous resources for maintaining chromosome architecture/genome integrity through homologous and nonhomologous recombination at the intraorganismal level, and genotype-specific repatterning underlies intrapopulation polymorphisms and intraspecific diversification in the wild.

Catasetum ×Dunstervillei (Orchidaceae: Catasetinae), a Natural Hybrid Confirmed by Artificial Hybridization

The parentage of Catasetum ×dunsterville, a natural hybrid or nothospecies, formally proposed in 1989 from the vicinity of Puerto Ayacucho, Amazonas state, Venezuela, was confirmed via artificial hybridization. The originally proposed putative parents were Catasetum pileatum and C. discolor. In nature, both species are pollinated by the same male Euglossine bees, Eulaema meriana and E. cingulata, and the two orchids are found in close proximity and have overlapping flowering seasons: the hybrid is relatively common. The artificial hybrid took 44 months (January 2014–September 2017) from the time seeds were planted to the first flowering.

Chloroplast Noncoding DNA Sequences Reveal Genetic Distinction and Diversity between Wild and Cultivated Prunus yedoensis

Cultivated flowering cherries (Prunus subgenus Cerasus), which are one of the most popular ornamental trees around the world, have been developed through artificial hybridizations among wild flowering cherries. Among the hundreds of cultivars of flowering cherries, Prunus ×yedoensis ‘Somei-yoshino’ is the most common and widespread. However, its origin and genetic relationship to wild P. yedoensis, naturally occurring on Jeju Island, South Korea, have long been debated. We used sequence polymorphisms in eight chloroplast DNA (cpDNA) noncoding regions to distinguish wild and cultivated flowering cherries among 104 individuals (55 accessions). We were able to distinguish two distinct groups, one corresponding to wild P. yedoensis collections from Jeju Island and the other collections of cultivated P. ×yedoensis from Korea, Japan, and the United States. The chlorotype diversity of wild P. yedoensis in Jeju Island and cultivated P. ×yedoensis collections in the United States was quite high, suggesting multiple natural hybrid origins and long history of cultivation from different original sources, respectively.

The complete mitochondrial genome of the hybrid of Leiocassis longirostris (♂)×Pelteobagrus fulvidraco (♀)

In this work, we reported the complete mitochondrial DNA sequence of the hybrid of Leiocassis longirostris (♂)×Pelteobagrus fulvidraco (♀), which was obtained by artificial hybridization. The total length of the mitochondrial genome is 16,527 bp, with the base composition of 30.86% for A, 25.56% for T, 28.20% for C, and 15.38% for G. It contains two ribosomal RNA genes, 13 protein-coding genes, 22 transfer RNA genes, and a major non-coding control region (D-loop region). The arrangement of these genes is the same as that found in the teleosts. All the protein initiation codons are ATG, except for COX1 that begins with GTG. The complete mitogenome of the hybrid provides an important data set for the study in mitochondrial inheritance mechanism. Both the termination-associated sequence and critical central conserved sequences (CSB-D, CSB-E, and CSB-F) were also detected.

Interspecific Hybridization Processes between Michelia yunnanensis and M. crassipes and Embryogenesis of the Heterozygote

The investigation of hybridization processes and embryogenesis of heterozygote is an effective approach for early hybrids’ identification, which could provide reliable information for successful crossbreeding. In this study, we reported the whole hybridization processes of the direct cross and reciprocal cross between Michelia yunnanensis Franch. ex Finet et Gagnep. and Michelia crassipes Law using fluorescence microscopy after aniline blue staining, with the pollen germination on stigmas, pollen tube growth in styles, and subsequent extension into the embryo sac as well as the double fertilization processes are documented in detail. The M. yunnanensis × M. crassipes combination displayed considerable cross-compatibility, and the heterozygote embryogenesis was further observed with an approach of modified cryosectioning technique. Besides, the whole formation processes of hybrid seeds from artificial pollination to maturation were successfully observed. However, in the reciprocal cross, we found incompatibility between pollen grains of M. yunnanensis and stigmas of M. crassipes for the reason of hysteretic identification, as well as the abnormal callose deposition which belongs to the prefertilization barriers. This is the first study in which the complete and clear hybridization processes in Michelia were reported. We inferred that unilateral incompatibility of M. crassipes detected in this study may also exist in some other Michelia species. In artificial hybridization practices, we suggest some special treatments for overcoming prefertilization barrier should be taken when treating M. crassipes as the maternal parent.

Fertility and ploidy of gametes of allodiploid and allotriploid loaches produced by diploid Misgurnus anguillicaudatus females and Paramisgurnus dabryanus males.

Artificial and natural hybridization of dojo loach Misgurnus anguillicaudatus (2N=50, DD for short) and large-scale loach Paramisgurnus dabryanus (2N=48, PP for short) are well-grown. However, these hybrid loaches have not yet been examined for fertility and ploidy of gametes. Here, histological observations, artificial propagation, observations of embryonic development, larval morphology, and ploidy analyses were conducted to determine the fertility and ploidy of gametes of allodiploid (DP for short) and allotriploid (DDP for short) loaches, produced by DD females × PP males and induced from fertilized eggs of DD females × PP males by cold shock to prevent the second polar body release, respectively. The ovaries of DP and DDP included smaller number of eggs when compared with those of the control DD, while full-grown oocytes were observed. Testes of these two loaches were delayed-developed without spermatids or mature spermatozoa. Results obtained here showed that DP and DDP were fertility-weakened female and sterile male. Moreover, DP females and DDP females could, respectively, produce few viable haploid eggs and few viable haploid and diploid eggs. This study will provide valuable information for fish hybrid researches.

Karyotype analysis by FISH and GISH techniques on artificial backcrossed interspecific hybrids involving Passiflora sublanceolata (Killip) MacDougal (Passifloraceae)

Karyotype analysis of first generation (F1) and backcrossed (BC1) interspecific hybrids were preformatted, suggesting important cytological events in the origin of artificial hybrids. Characterization was performed in 16 backcrossed plants and their genitors by conventional staining, fluorescence in situ hybridization (FISH) with probes for 5S and 45S rDNA and telomeric probes. Genomic identification of hybrids was performed by Genomic In Situ Hybridization (GISH). The chromosome number (2n = 22) was F1 verified in both genitor species P. sublanceolata and P. foetida of the F1 hybrids. However, greater variations in chromosome numbers (2n = 20, 21 and 22) were verified in F1 and BC1 hybrids. A triploid BC1 hybrid was also found suggesting non-reduced female gamete in P. sublanceolata. Variation for number and position of 45S and 5S rDNA sites was also verified in the population, suggesting recombination in homeologous and in non-homeologous chromosomes. Telomeric sites were restricted to terminal regions, discarding the hypotheses of translocation involving telomere sites. GISH clearly distinguished genomes from the genitor species, genome-S (P. sublanceolata) and genome-F (P. foetida), in F1 and BC1 plants, thereby revealing differences in the origin of recombinant chromosomes. Differences in the number and nature of recombinant chromosomes in BC1 hybrids suggests there is high homology between the progenitor genomes, but differences in meiotic recombination in F1 plants. Numerical chromosome modifications, such as chromosome elimination and polyploidization and also chromosome recombination and/or translocations, are hypothesized as common events for the establishment of artificial Passiflora hybrids involving taxa from the Section Dysosmia.