Artificial Crosses Research Articles

BIOGEOGRAPHY AND ORIGIN OF LILIUM LONGIFLORUM AND L. FORMOSANUM I - INTERSPECIFIC ISOLATING MECHANISMS AND POPULATION GENETIC STRUCTURE

BIOGEOGRAPHY AND ORIGIN OF LILIUM LONGIFLORUM AND L. FORMOSANUM I - INTERSPECIFIC ISOLATING MECHANISMS AND POPULATION GENETIC STRUCTURE

Genetic variability in common wheat germplasm based on coefficients of parentage

The characterization of genetic variability and an estimate of the genetic relationship among varieties are essential to any breeding program, because artificial crosses among less similar parents allow a larger segregation and the combination of different favorable alleles. Genetic variability can be evaluated in different ways, including the Coefficient of Parentage (COP), which estimates the probability of two alleles in two different individuals being identical by descent. In this study, we evaluated the degree of genetic relationship among 53 wheat genotypes, and identified the ancestor genotypes which contributed the most to the current wheat germplasm, as a prediction of the width of the genetic base of this cereal. The results revealed a mean COP of 0.07 and the formation of 22 similarity groups. The ancestor genotypes Ciano 67 and Mentana were those which contributed the most to the current wheat germplasm. According to the COP analyses, the genetic base of wheat rests on a small number of ancestral genotypes.

The accuracy of land form presentation in forest road Cross sections

Accurate presentation of natural land forms directly affects the accuracy of earth volume calculation, the component of technical documentation of the forest road master project. Consistent to legal provisions, forest road master project is characterised by high accuracy of the planned scope of works compared to the realised scope of works, which should amount to ?3%. The volume of earth material is calculated based on the road cross-sectional area and the distance between the cross sections. The accuracy of the area of cross sections depends on the accuracy of land form presentation Accurate presentation of natural land forms depends on a great number of factors, the most significant of which are the methods of surveying and acquisition of data necessary for land form presentation, preciseness of equipment and instruments used in surveying and acquisition of data, and the method of land form presentation. The accuracy of earth material volume calculation depends on the method of computation, method of presentation of natural and artificial cross sections, and the phase of design. The presentation of natural land form in the width occupied by roadway cross section depends on the validity of the obtained station point elevation (Ht) and the elevations of detailed points (Hi). A relevant factor of the accuracy of cross sectional area, compared to its other elements, is the accuracy of the depth of cut or the height of fill (h) which should agree with the required accuracy, i.e. the adopted tolerance of the earthwork bill of quantities deviation up to 3%.

EFEITO DA POLINIZAÇÃO DIRIGIDA ENTRE PORTA-ENXERTOS DE MACIEIRA (Malus sp.) NA FRUTIFICAÇÃO EFETIVA E NO DESENVOLVIMENTO DE FRUTOS EM SÃO JOAQUIM-SC

Com o objetivo específico de obter uma população segregante, visando à avaliação na frutificação efetiva, quantidade de sementes normais e peso e diâmetro de frutos oriundos de polinização aberta e dirigida, foram realizados cruzamentos entre dois porta-enxertos de macieira, Marubakaido (Malus prunifolia Borkh.) e M.9 (Malus pumila Mill.) na Estação Experimental de São Joaquim -- EPAGRI/SC. 'Marubakaido' apresentou florescimento mais precoce e mais prolongado que a cultivar M.9. A percentagem de frutificação efetiva, para o porta-enxerto 'M.9' usado como progenitor feminino, foi de 26% e 32%, e usado como doador de pólen, foi de 5% e 25%, no anos de 1999 e 2000, respectivamente. Foram encontrados frutos deformados nos cruzamentos de 'M.9' X 'Marubakaido' e com um maior número de sementes atípicas quando comparadas ao sistema de polinização aberta. O mesmo não ocorreu no cruzamento recíproco. O peso e o diâmetro dos frutos foram maiores quando houve a polinização dirigida em 'M.9', o mesmo não acontecendo com 'Marubakaido', comparativamente à polinização aberta. A análise via contrastes ortogonais revelou valores de F significativos também para número de sementes normais e anormais frente aos dois sistemas de polinização em 'M.9'.

Differential Predation on Experimental Populations of Parental and Hybrid Leopard Frog (Rana blairi and Rana sphenocephala) Larvae

We estimated fitness components for parental and F1 hybrid genotypes between Rana blairi and Rana sphenocephala by measuring larval performance in wading pools. The effect of three predators (papershell crayfish, Orconectes immunis; eastern newt, Notophthalmus viridescens; green sunfish, Lepomis cyanellus) on larval growth and survival was used to assess differential performance of genotypes in a predatory aquatic environment Larval genotypes were obtained from artificial crosses between adults col- lected from a natural population sympatric with these predators in central Missouri. After hatching, larvae were reared in single-genotype groups in outdoor experimental wading pools for 14 days. A higher propor- tion of R. sphenocephala survived than did R. blairi, and F1 hybrids did not differ significantly in survival from either parental genotype. Fish predation was severe for all genotypes and reduced survival to a greater degree than other predators. Body mass did not differ significantly among genotypes or predator treatments. Relatively high survival and growth for F1 hybrid larvae suggests natural hybridization between R. blairi and R. sphenocephala can produce novel and relatively fit hybrid genotypes that can cope with predators just as successfully as parental genotypes. Furthermore, low survival of all genotypes in experimental pools containing fish is consistent with the observation that leopard frog larvae do not normally coexist with fish. Natural hybridization between closely related taxa may be an important evolutionary process, leading to novel diversification and adaptive evolution (Arnold, 1997; Arnold and Emms, 1998; Parris, 1999), or a process with evolution-

Genome Size and Pollen Viability as Taxonomic Criteria: Application to the Genus Hosta

Abstract: Genome size (C values) and pollen viability staining were applied as new criteria to investigate the taxonomy of the genus Hosta Tratt. (Hostaceae). Nearly all species of the genus Hosta have the same basic chromosome number (2n = 2x = 60). However, the nuclear DNA contents, as measured by flow cytometry with propidium iodide, could be demonstrated to range between 17.2 to 26.6 pg. This implies that the largest genome contains roughly 1010 more base pairs than the smallest. Therefore, nuclear DNA content is a very relevant taxonomic trait that can be measured simply by flow cytometry. In addition, differences in overall DNA composition were demonstrated by comparing to DAPI fluorescence. In general, genome size data confirmed the division into three subgenera. The geographical distribution of genome sizes indicates the migration pattern of Hosta throughout East Asia. The species belonging to the mainly Korean subgenus Bryocles, with a low nuclear DNA content (17.2 ‐ 19.3 pg), can now largely be distinguished from the mainly Japanese species of the subgenus Giboshi (21.3 ‐ 26.5 pg). The exception is H. longissima, that with only 19.6 pg provides a nice example of a decrease in DNA content. On the mainland, as well as on Honshu, species with increased and decreased DNA content have evolved independently. The usefulness of pollen viability to detect hybrids in Hosta was demonstrated in a large series of artificial crosses between bona fide species. Consequently, pollen viability was measured in all available Hosta described as species. Several had low pollen viability and were concluded to be hybrids. Morphology and DNA content confirmed this in most cases. The resulting 23 species approximate the number of Hosta species that follows from the combined studies by Fujita (197618) on the Japanese species and Chung (1991 a11) on the Korean species.

Valor taxonómico de la pilosidad de los frutos en Centranthus calcitrapae (L.) Dufresne (Valerianaceae)

Two different phenotypes have been observed with regard to fruit hairiness in Centranthus calcitrapae throughout the Iberian Peninsula, Baleario Island and France: hirsute and glabrous fruits. In this paper the inheritance of this character in two Andalusian populations has been inferredby using artificial crossings. It has been shown that fruit hairiness is based on a simple two-allele mendelian locus being hairiness dominant over the recessive glabrous fruits. Therefore,this character should not be used for separation of taxa.

Self-feeding activity patterns in gilthead sea bream ( Sparus aurata), red porgy ( Pagrus pagrus) and their reciprocal hybrids

This study was conducted to monitor feeding activity of gilthead sea bream (Sa) and red porgy (Pp) and to investigate the hereditary effects on feeding in their hybrids (female Sa×male Pp, female Pp×male Sa), obtained after artificial crosses. All fish groups were held in 500-l tanks under ambient temperature (15–25°C) and light conditions (daylength from 9 h 30 min to 14 h 48 min). Fish (initial body weight 100–165 g) were fed by means of self-feeders, which were connected to a computer, recording fish feeding activity for a year. Results showed that there was a 24-h periodicity in all fish types over the experiment. In their daily feeding patterns, both parental species were diurnal: red porgies had a stable daily pattern over the experiment, while gilthead sea bream shifted their activity from a general daylight fluctuation in warm periods to an afternoon peak in cold periods. The Sa×Pp hybrids showed intermediate feeding patterns compared to their parents in warm periods and a pattern that was similar to the red porgy in cold periods, while the Pp×Sa hybrids had rather unchangeable daily feeding patterns, which were not related to the parental ones. The proportion of night feed demands increased in cold periods independent of fish group. The relationship between temperature and feed intake was species-dependent. Finally, this study indicated that feeding expression in hybrids was related to the combination of the parental genome, supporting our hypothesis for a hereditary influence on feeding activity in fish.

The impact of supplementation in winter-run chinook salmon on effective population size.

Supplementation of young raised at a protected site, such as a hatchery, may influence the effective population size of an endangered species. A supplementation program for the endangered winter-run chinook salmon from the Sacramento River, California, has been releasing fish since 1991. A breeding protocol, instituted in 1992, seeks to maximize the effective population size from the captive spawners by equaling their contributions to the released progeny. As a result, the releases in 1994 and 1995 appear not to have decreased the overall effective population size and may have increased it somewhat. However, mistaken use of non-winter-run chinook spawners resulted in artificial crosses between runs with a potential reduction in effective population size, and imprinting of the released fish on Battle Creek, the site of the hatchery, resulted in limiting the contribution of the released fish to the target mainstem population. Rapid genetic analysis of captured spawners and a new rearing facility on the Sacramento River should alleviate these problems and their negative effect on the effective population size in future years.

Experimental Analysis of Hybridization in Leopard Frogs (Anura: Ranidae): Larval Performance in Desiccating Environments

Abstract Relative fitness of parental and hybrid Leopard Frogs was examined by measuring larval performance in artificial ponds and laboratory containers. Effect of a variable hydroperiod on growth, development, and survival was used to assess larval responses to a desiccating aquatic environment. Larvae for the artificial pond experiment were obtained from field-collected egg masses of Rana blairi and R. sphenocephala. Artificial crosses with adult animals produced larvae of one parental and three hybrid genotypes for laboratory performance assays. Experimental pond drying significantly reduced survival for both parental species. Rana blairi had higher survival than R. sphenocephala across all treatments. Both species reduced larval period lengths when exposed to a drying environment relative to constant water levels. The laboratory experiment revealed Backcross2 hybrid larvae exhibited longer larval period lengths than parental R. sphenocephala and certain F1 hybrid genotypes in the drying environment. ...

Jumping performance and short-term repeatability of newly metamorphosed hybrid and parental leopard frogs ( Rana sphenocephala and Rana blairi )

Differential fitness between hybrid and parental genotypes plays a critical role in explaining the maintenance of natural hybrid zones as well as the production of novel genetic variation that may lead to diversification. Because locomotor performance is a reliable and practical measure of potential fitness related to morphological variation, we tested for differences in jumping performance among parental and hybrid genotypes of newly metamorphosed leopard frogs (Rana sphenocephala and Rana blairi). Tadpoles of the parental species and primary and backcross hybrid tadpoles, generated from artificial crosses (a total of five genotypes), were reared at two initial larval densities. Locomotor performance of newly metamorphosed frogs, as measured by jumping ability, was tested three times over 6 days in the laboratory at 24-25°C. Maximum and average jump lengths were greater for metamorphs reared at low larval density than for those reared at high density. Regression analyses indicated that 70-79% of the variation in jump length was due to body mass. When reared at low density, metamorphs of two F1 backcross genotypes (HB and HS) and one primary hybrid genotype (SB) jumped shorter distances than either parental species. When reared at high density, hybrid performance was indistinguishable from that of the parentals, except for one backcross hybrid (HB). Moderately high short-term repeatabilities (0.47-0.66) of metamorphs reared at the high density indicate that measures of performance in newly metamorphosed frogs can be predictive. We suggest that, owing to poor jumping performance, some hybrid frogs would be at a selective disadvantage relative to their parental species in the terrestrial environment and thus would partially reinforce mechanisms of reproductive isolation in this leopard frog system. Yet equivalent performance of some hybrids relative to the parentals, at least when reared at low density, suggests that hybrid lineages also have the potential to evolve independently in some environments.

Association of European plum varieties in the orchards

The flowering phenology, blooming time and inter-fertility relations of 63 European plum varieties has been studied at growing sites with different ecological conditions during a 10 year long period. The purpose was to develop a system of variety combinations which approaches an optimum in fertility as long as inter-fertility relations will cease to be a limiting factor of yield. According to their blooming time, varieties are assigned to 5 groups: very early, early, medium, late and very late. As for their fertility relations, four groups are formed: self-sterile (0%), partially self-fertile (0.1 to 10 %), self-fertile (10.1 to 20 %) and highly self-fertile (more than 20 % fruit set with self pollination). The four categories of fruit set at free pollination are also relevant to the grower: low (less than 10 %), medium (10 to 20 %), high (20 to 40 %) and very high (more than 40 % fruit set).
 By artificial cross pollination, one combination Cacanska najbolja x Stanley proved to be mutually inter-incompatible. Blocks planted to a single self-sterile variety flanking a pollinizer variety proved the spacial distribution of the pollen. The reduction in fruit set was already apparent in the second row away from the pollinizer trees. In a large plantation, without bee hives, relatively low yield was stated on self-sterile trees even close to the pollinizer.
 In the case of self-sterile and partially self-fertile varieties, a combination of three varieties is recommended. The blooming period of the pollinizer variety should overlap the period of the self-sterile variety at least by 70 %, and the distance should not exceed 15 to 20 meters. Association of self-fertile varieties may also enhance the productivity of the trees. In that case an overlap of 50 % in blooming time and a maximum distance between the varieties of 30 to 40 meters will be sufficient.

Isolation and inheritance of novel microsatellites in Chinook Salmon (Oncorhynchus tschawytscha)

We describe the isolation, PCR amplification, and characterization of 10 new microsatellite loci (Ots-1-Ots-10) for the federally protected chinook salmon (Oncorhynchus tschawytscha). We investigate the inheritance and linkage of these loci as well as a previously published locus, Oneμ13, in families obtained from artificial crosses. Mendelian transmission is confirmed for 76 of 80 segregations observed. Of the four deviations, two appear to have resulted from gametic segregation distortion. The other two provide evidence for the existence of at least one null allele. We also identify 'drop out' of large alleles in these two families owing to competitive PCR amplification of smaller alleles. There is no evidence for linkage between any pair of loci. One mutation observed at Ots-2 is reported and confirmed by DNA sequencing. We estimate the mutation rate of this locus to be 6.5 x 10-4 (95%) confidence interval 3.6 x 10-3 to 1.6 x 10-4, respectively). Characterizing a mutant allele at Ots-2 offers the first step toward understanding mutation rates for chinook microsatellites. Owing to their Mendelian inheritance, these new loci provide reliable markers for high-resolution population genetics studies of this species.

Genetic diversity in the threatened insular endemic plantAster asa-grayi (Asteraceae)

Genetic diversity in an insular endemic plantAster asa-grayi was examined using enzyme electrophoresis. Distribution ofA. asa-grayi is restricted to only four subtropical islands of Japan, and this species is listed as ‘vulnerable to extinction’ in the Red Data Book of Japanese wild plants. A total of 161 individuals were sampled from five populations on four islands. Genetic diversity values at the population level were very low, compared to other plant species with a similar life history. Genetic variability at the species level is comparable to the mean value of endemic species. Genetic differentiation among populations is extremely high (GST= 0.71), indicating that the gene flow among populations is highly impeded, and pollen and seed dispersal is limited due to the pollinators and the seed morphology. This is because the four islands are geographically isolated. Fixation indices suggested that most populations do not randomly cross. To conserve the genetic diversity of the species, artificial crossings among different island populations are necessary.

Preliminary Results on Rearing of Sparus Aurata × Pagrus Pagrus Hybrids. Performance Comparison With the Parental Species

Hybridization between gilthead sea bream, Sparus aurata, and red porgy, Pagrus pagrus, was undertaken and viable hybrids were produced by an artificial hormonal-induced cross. The hybrids, from the cross of female red porgy and male gilthead sea bream (Pp × Sa), survived through the yolk-sac larval stage. The hybrids produced from the cross of female gilthead sea bream and male red porgy (Sa × Pp) presented higher mortality in the larval stage (98.4%) compared to gilthead sea bream (80.0%) and red porgy (92.5%). Afterwards, the Sa × Pp hybrid was compared to the offspring of its parental species under the same rearing conditions (tanks of 500 l capacity, natural light, ambient temperature, self-feeding with commercial feed) in a 40–week experiment. In this comparative study, the Sa × Pp hybrid had intermediate mortality rate (6%), compared to gilthead sea bream (0%) and red porgy (21%). The growth profile of this hybrid resembled the slow growing phases of its parents (red porgy in warm period and gilthead sea bream in cold period). The feed conversion ratio between fish forms was not significantly different (1.54–1.84 in the Sa × Pp hybrid, 1.53–1.56 in the maternal species and 1.33–1.40 in the paternal one). The body weight variation in the Sa × Pp hybrid was quite high (31.7–37.9%), compared to that in gilthead sea bream (19.7–24.7%) and red porgy (18.0–31.3%). With respect to body coloration, the Sa × Pp hybrid was distinguishable and classified into groups of red porgy-like (55.1%), gilthead sea bream-like (40.6%), and intermediate forms (4.3%). The preliminary results of this study proved that the produced Sa × Pp hybrid had too low a performance for aquaculture use, but the interesting consequent hereditary potential could be a useful tool in fish hybridization practice.

Sex Differences in Polymorphism and Expression of AAT-1 in the Hiroshima Population of Buergeria buergeri (Anura, Rhacophoridae)

Buergeria buergeri is female heterozygous in sex determination; chromosome pair No. 7 in this species is a pair of sex chromosomes of the ZZ/ZW type. Genetic analysis of AAT-1 variants was carried out to elucidate the mode of inheritance of this locus by starch-gel electrophoresis using field-caught females and males and their offspring produced by artificial crossings. The results showed that the AAT-1 locus is sex-linked and that alleles are expressed on the Z chromosome, but not the W chromosome. It is evident that the AAT-1 gene of female offspring is hemizygous and that the allele present is on the Z chromosome, which is derived from the male parent.

Species-characteristic and subspecies- characteristic haemoglobins in some tilapiine fishes and a comparative study on their globin chains

Haemoglobins of ten tilapia species of the genera Oreochromis, Sarotherodon and Tilapia, three subspecies of the Nile tilapia, O. niloticus, and an artificial hybrid cross were analysed by isoelectric focusing aimed at characterizing the taxonomic value of these oxygen-binding molecules. Heterogeneous haemoglobin phenotypes were observed in haemolysate samples of all the fishes, and species-characteristic as well as subspecies-characteristic patterns could be identified. F1 hybrids were distinguishable from pure parental specimens. Globin chain studies by AU- and AUT-PAGE systems confirmed the heterogeneity and species specificity observed by isoelectric focusing of the tetrameric molecules. A total of eight different α-chains and eight different β-chains were detected by AU-PAGE and species-characteristic globin chain variants were shown to occur in almost all species. Globin chain profiles of hybrid specimens were characterized by the presence of all parental globin chain variants. © Rapid Science Ltd. 1998

Plant height reduction in populations of triticale (X triticosecale Wittmack) by induced mutations and artificial crosses

Induced mutations by gamma radiation (0, 5, 10, 20 and 40 kR doses) and reciprocal crosses were tested as mechanisms of enhancing genetic variability for plant height in two triticale cultivars, BR4 and EMBRAPA18. The reciprocal crosses and all doses of radiation showed similar increase in genetic amplitude for this trait, being suitable for increasing variability in breeding programs. Genotypes showed different responses as the gamma ray doses were increased, expressing shorter plant height. The decision of using induced mutations or artificial crosses depends on the resources available and the selection method to be used

X Alpingera martinica (Zingiberaceae): An Intergeneric Hybrid between Alpinia purpurata and Etlingera elatior

Artificial intergeneric crosses between Alpinia purpurata and Etlingera elatior (Zingiberaceae) have produced hybrids. Data are presented with a Latin diagnosis and the name X Alpingera martinica F. Luc-Cayol proposed for these hybrids. The shape and color of the inflorescence of this hybrid species are an improvement relative to the ornamental value of the parents.

Evaluation of a lucerne germplasm collection in relation to traits conferring grazing tolerance

A collection of 90 accessions of different germplasm groups from the Medicago sativa complex was evaluated at Lodi, Italy, for dry-matter yield, time to anthesis, height of regrowth, plant diameter, stem density, vegetative recovery after winter, and presence of deep-set crown and ability to spread with creeping roots or rhizomes, these latter characters possibly contributing to grazing tolerance. The germplasm groups proved rather distinct for these traits, but all included types potentially suitable for grazing. Interesting types combining deep-set crown and high yield occurred mainly in subsp. x varia and materials originated from artificial crosses involving at various extent the subspecies falcata, sativa and x varia. Though belonging to subsp. sativa, “mielga” wild populations from Spain had aerial traits similar to those of the long-dormant, low-yielding subsp. falcata. Deep-crowned plants had greater plant diameter than shallow-crowned plants, and could be categorised into four distinct top-growth models according to their habit and vigour. One of these models combined spreading ability with high yield. The about 150 plants selected for their combination of deep crown, wide diameter, and good yield were characterised by a branch-rooted system. There was general correspondence between top-growth and root morphology of each model. Of the four deep-crowned models, three had rhizomes, with wide range of underground development and morphology, while the fourth had creeping roots. The latter model was the most rare among the examined accessions, never appearing in either cultivated or wild subsp. sativa. The implications of the results on the development of grazing-tolerant lucerne varieties are discussed.