Breeding Programmes (breeding + programme)

Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Breeding Programmes

  • future breeding programme


  • Selected Abstracts


    Pyramiding of genes conferring resistance to Tomato yellow leaf curl virus from different wild tomato species

    PLANT BREEDING, Issue 6 2008
    F. Vidavski
    Abstract Tomato (Solanum lycopersicum) production in tropical and subtropical regions of the world is limited by the endemic presence of Tomato yellow leaf curl virus (TYLCV). Breeding programmes aimed at producing TYLCV-resistant tomato cultivars have utilized resistance sources derived from wild tomato species. So far, all reported breeding programmes have introgressed TYLCV resistance from a single wild tomato source. Here, we tested the hypothesis that pyramiding resistances from different wild tomato species might improve the degree of resistance of the domesticated tomato to TYLCV. We have crossed TYLCV-resistant lines that originated from different wild tomato progenitors, Solanum chilense, Solanum peruvianum, Solanum pimpinellifolium, and Solanum habrochaites. The various parental resistant lines and the F1 hybrids were inoculated in the greenhouse using viruliferous whiteflies. Control, non-inoculated plants of the same lines and hybrids were exposed to non-viruliferous whiteflies. Following inoculation, the plants were scored for disease symptom severity, and transplanted to the field. Resistance was assayed by comparing yield of inoculated plants to those of the control non-inoculated plants of the same variety. Results showed that the F1 hybrids between the resistant lines and the susceptible line suffered major yield reduction because of infection, but all hybrids were more resistant than the susceptible parent. All F1 hybrids resulting from a cross between two resistant parents, showed a relatively high level of resistance, which in most cases was similar to that displayed by the more resistant parent. In some cases, the hybrids displayed better levels of resistance than both parents, but the differences were not statistically significant. The F1 hybrid between a line with resistance from S. habrochaites and a line with resistance from S. peruvianum (HAB and 72-PER), exhibited the lowest yield loss and the mildest level of symptoms. Although the resistance level of this F1 hybrid was not statistically different from the level of resistance displayed by the 72-PER parent itself, it was statistically better than the level of resistance displayed by the F1 hybrids between 72-PER and any other resistant or susceptible line. [source]


    Genetic diversity of endangered brown bear (Ursus arctos) populations at the crossroads of Europe, Asia and Africa

    DIVERSITY AND DISTRIBUTIONS, Issue 5 2009
    Sébastien Calvignac
    Abstract Aim, Middle East brown bears (Ursus arctos syriacus Hemprich and Ehrenberg, 1828) are presently on the edge of extinction. However, little is known of their genetic diversity. This study investigates that question as well as that of Middle East brown bear relationships to surrounding populations of the species. Location, Middle East region of south-western Asia. Methods, We performed DNA analyses on 27 brown bear individuals. Twenty ancient bone samples (Late Pleistocene to 20th century) from natural populations and seven present-day samples obtained from captive individuals were analysed. Results, Phylogenetic analyses of the mitochondrial sequences obtained from seven ancient specimens identify three distinct maternal clades, all unrelated to one recently described from North Africa. Brown bears from Iran exhibit striking diversity (three individuals, three haplotypes) and form a unique clade that cannot be linked to any extant one. Individuals from Syria belong to the Holarctic clade now observed in Eastern Europe, Turkey, Japan and North America. Specimens from Lebanon surprisingly appear as tightly linked to the clade of brown bears now in Western Europe. Moreover, we show that U. a. syriacus in captivity still harbour haplotypes closely linked to those found in ancient individuals. Main conclusion, This study brings important new information on the genetic diversity of brown bear populations at the crossroads of Europe, Asia and Africa. It reveals a high level of diversity in Middle East brown bears and extends the historical distribution of the Western European clade to the East. Our analyses also suggest the value of a specific breeding programme for captive populations. [source]


    Breeding for resistance: conventional breeding for Plum pox virus resistant apricots (Prunus armeniaca L.) in Greece

    EPPO BULLETIN, Issue 2 2006
    I. Karayiannis
    A large apricot breeding programme has been conducted at NAGREF-Pomology Institute, Naoussa-Greece, for the control of sharka disease, since 1989. Ten apricot cultivars of North American origin: ,Stark Early Orange', ,Stella', ,NJA2', ,Sunglo', ,Veecot', ,Harlayne', ,Henderson', ,Goldrich', ,Orangered' and ,Early Blush', selected for their resistance to the highly virulent local strain of Plum pox virus (PPV)-M (Marcus), have been used as parents in crosses with quality cultivars, mainly with the local cv. Bebecou, from 1989 to 2003. Approximately 7000 hybrids have been created. Resistance to PPV was the main criterion of selection. Most hybrids have been subjected to artificial inoculation by PPV-M and examined for symptom expression for more than five years. Indexing to GF-305, as well as laboratory diagnostic tests, have been applied. The genetic analysis showed that: (1) 50% of the hybrids inherited resistance to PPV in the families where cvs. Stark Early Orange, NJA2, Sunglo, Veecot and Harlayne were used as a parent, and (2) 100% of the hybrids inherited resistance to PPV in the families where cv. Stella was one of the parents. Resistance to PPV appears to be under simple genetic control involving one gene locus. Promising apricot selections resistant to PPV-M have been released. [source]


    Backhousia citriodora F. Muell.,Rediscovery and chemical characterization of the L -citronellal form and aspects of its breeding system

    FLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2001
    J. C. Doran
    Abstract The rare L -citronellal form of Backhousia citriodora F. Muell. was first reported in 1950 but attempts to relocate it were unsuccessful until 1996. The quest to relocate trees of this type has been driven by interest in L -citronellal for perfumery. The common, citral form of the species is already under cultivation for oil production in Australia. This paper reports on the rediscovery of the L -citronellal form, first in 1996 in a year-old provenance/progeny trial of B. citriodora in south-eastern Queensland, and then in a natural population on Queensland's Sunshine Coast in 1998. The three L -citronellal trees in the trial gave foliar oil concentrations (g/100 g dry weight) of 3.2, 2.2 and 1.8, respectively, when sampled in November 1996. The same trees sampled in March 1999 gave pale yellow oils consisting of 85,89% citronellal, 6,9% isopulegol isomers with small quantities of citronellol (approx. 3%) and several other compounds. Data on the physicochemical properties of these oils are given in the paper. Seed from a single mature L -citronellal tree gave progeny of both the L -citronellal and citral form in a ratio of approximately 1 : 1. Propagation material from many more plants of the L -citronellal form needs to be collected and assembled in breeding populations. This would form the basis of a selection and breeding programme, should this chemotype show economic potential. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    Methods for inoculum production and inoculation of Cistella japonica, the causal agent of resinous stem canker in Chamaecyparis obtusa

    FOREST PATHOLOGY, Issue 1 2008
    T. Yamanobe
    Summary The ascomycete Cistella japonica was cultured on potato dextrose agar medium (PDA) for inoculation into Chamaecyparis obtusa, enabling the development of an inoculation method suitable for use in a breeding programme aimed at selecting for families of Ch. obtusa resistant to resinous stem canker. Using PDA to generate the inoculum resolved the problems encountered with the previously used mixed medium of rice bran and wheat bran, including unfavourable characteristics, uncertain growth of Ci. japonica mycelia, and a complex culturing operation. The inoculation test induced resin exudation similar to that observed in natural infections, and reproduced clonal differences with regard to damage severity. [source]


    Dothistroma (red-band) needle blight of pines and the dothistromin toxin: a review

    FOREST PATHOLOGY, Issue 3 2004
    R. E. Bradshaw
    Summary Dothistroma (red-band) needle blight has been a problem in plantations of exotic pines in the southern hemisphere for many decades. The prevalence of this disease is currently increasing in the northern hemisphere and is now affecting trees in their native ranges. The fungal pathogen Mycosphaerella pini with its anamorph Dothistroma pini, which is responsible for the disease, produces a toxin, dothistromin, that is closely related to the potent carcinogen, aflatoxin. Understandably this has provoked concern about possible effects on the health of forestry workers. This review gives a broad coverage of literature on both disease and toxin. The fungus has a complicated taxonomy with many synonyms and in most countries only the anamorph is found. It is a necrotrophic pathogen that kills needle tissue and completes its life cycle in the lesion thus formed. Dispersal of the disease is normally by rain splash of conidiospores but there is evidence that long range dispersal has occurred by transport of contaminated plant tissue and by wind/cloud dispersal of spores in air currents. The severity of disease is affected by humidity, temperature and light. There is variation in susceptibility of different Pinus species and some achieve increased resistance with age. The current method of control in southern hemisphere plantation forests is through spraying with copper fungicides and, with P. radiata, increased disease resistance has been achieved through a breeding programme. The dothistromin toxin is a difuroanthraquinone and is similar in structure to the aflatoxin precursor versicolorin B. Part of a gene cluster encoding dothistromin biosynthetic genes has been cloned and this has confirmed parallels between the dothistromin and aflatoxin biosynthetic pathways. Dothistromin produces damaging oxygen radicals by reductive oxygen activation rather than by photosensitization, but is also thought to exert its toxic effects on specific cellular targets. Studies have shown that dothistromin is a weak mutagen and clastogen and is therefore a potential carcinogen. Although the risks to forest workers are considered very low it is prudent to avoid unnecessary exposure during periods when dothistromin levels are likely to be at their peak. Résumé La maladie des bandes rouges causée par Dothistroma est un problème dans les plantations de pins exotiques de l'hémisphère sud depuis de nombreuses années. La prévalence de cette maladie est en augmentation dans l'hémisphère nord et affecte maintenant les pins dans leurs régions d'origine. Le champignon pathogène Dothistroma pini, responsable de la maladie, produit une toxine, la dothistromine, proche de l'aflatoxine qui est un puissant carcinogène. Ceci pose donc la question des effets possibles sur la santé des travailleurs forestiers. Cette revue repose sur une large couverture de la littérature concernant aussi bien la maladie que la toxine. Le champignon a une taxonomie complexe avec de nombreux synonymes, et seul l'anamorphe se rencontre dans de nombreux pays. C'est un champignon nécrotrophe qui tue les tissus de l'aiguille et réalise son cycle biologique dans la lésion ainsi formée. La dissémination de la maladie s'effectue principalement par éclaboussures de pluie contenant les conidies mais une dissémination à longue distance a été mise en évidence par transport de matériel contaminé ou par dissémination des spores par le vent ou les nuages dans les courants aériens. La sévérité de la maladie est affectée par l'humidité, la température et la lumière. Il existe des différences de sensibilité entre espèces de Pinus, et certaines présentent une résistance accrue avec l'âge. La méthode actuelle de lutte dans les forêts de plantations de l'hémisphère sud consiste à pulvériser des fongicides à base de cuivre ; dans le cas de Pinus radiata, une augmentation de la résistance a été obtenue grâce à un programme d'amélioration génétique. La toxine dothistromine est une difuroanthraquinone, similaire en structure à la versicolorine B, précurseur de l'aflatoxine. Une partie d'une batterie de gènes comprenant des gènes de biosynthèse de la dothistromine a été clonée, confirmant les analogies entre les voies de biosynthèse de la dothistromine et de l'aflatoxine. La dothistromine produit des radicaux oxygène nocifs par activation de la réduction de l'oxygène plutôt que par photosensibilisation, mais ses effets toxiques s'exercent aussi probablement sur des sites cellulaires spécifiques. Des études montrent que la dothistromine est un mutagène et clastogène faible, et donc potentiellement carcinogène. Bien que les risques pour les ouvriers forestiers soient considérés comme très faibles, il est prudent d'éviter dans la mesure du possible de s'exposer dans les périodes où les niveaux de dothistromine sont supposés élevés. Zusammenfassung Die Dothistroma -Nadelbräune ist in der Südhemisphäre in Plantagen mit exotischen Kiefernarten seit vielen Jahren ein Problem. In der Nordhemisphäre nimmt die Bedeutung dieser Krankheit derzeit zu und sie befällt nun Bäume auch in ihren natürlichen Verbreitungsgebieten. Der Erreger ist der Ascomycet Mycosphaerella pini (Anamorphe: Dothistroma pini). Der Pilz bildet das Toxin Dothistromin, das eng mit dem hochtoxischen Karzinogen Aflatoxin verwandt ist. Daraus ergab sich die Frage nach möglichen Nebenwirkungen dieser Baumkrankheit auf die Gesundheit von Waldarbeitern. Dieser Review fasst die Information über die Krankheit und das Toxin zusammen. Der Pilz hat eine komplizierte Taxonomie mit vielen Synonymen und in den meisten Ländern wurde nur die Anamorphe nachgewiesen. Er ist ein nekrotrophes Pathogen, das Blattgewebe abtötet, und in den so gebildeten Läsionen seinen Lebenszyklus abschliesst. Der normale Ausbreitungsweg der Krankheit erfolgt über Konidiosporen mit Regentropfen, aber es gibt auch Hinweise auf einen Ferntransport mit infiziertem Pflanzenmaterial und über die Verbreitung von Sporen mit dem Wind bzw. Wolken in Luftströmungen. Die Krankheitsintensität wird durch Luftfeuchte, Temperatur und Licht beeinflusst. Es gibt Unterschiede in der Anfälligkeit zwischen verschiedenen Kiefernarten und manche davon werden mit zunehmendem Alter resistenter. Derzeit werden in Plantagen der südlichen Hemisphäre Kupferfungizide zur Kontrolle dieser Krankheit eingesetzt und für Pinus radiata wurde in Züchtungsprogrammen eine erhöhte Resistenz erreicht. Das Toxin Dothistromin ist ein Difuroanthrachinon und ähnelt in seiner Struktur dem Aflatoxin-Präkursor Versicolorin B. Ein Teil des Genclusters, das die Dothistromin-Biosynthese codiert, wurde geklont, und es wurden dabei Parallelen zwischen dem Dothistromin- und dem Aflatoxin-Biosyntheseweg bestätigt. Dothistromin bildet schädliche Sauerstoffradikale (wahrscheinlich eher durch reduktive Sauerstoffaktivierung als durch Photosensibilisierung), es dürfte aber auch auf spezifische Zellkomponenten toxisch wirken. Dothistromin zeigt schwache mutagene und chromosomenschädigende Wirkungen und ist deshalb ein potentielles Karzinogen. Obwohl das Risiko für Waldarbeiter als gering eingeschätzt wird, sollte man in Perioden, in denen der Dothistromingehalt hoch sein dürfte, eine unnötige Exposition vermeiden. [source]


    Management of the Double-eyed or Red-browed fig parrot Cyclopsitta diophthalma macleayana at Currumbin Sanctuary, Queensland

    INTERNATIONAL ZOO YEARBOOK, Issue 1 2000
    L. ROMER
    The Double-eyed fig parrot Cyclopsitta diophthalma has three subspecies in Australia which occur in isolated populations. Since 1987 Currumbin Sanctuary has been involved in a breeding programme for the Red-browed fig parrot Cyclopsitta diophthalma macleayana, to develop techniques which might be applied for the management of the highly threatened Coxen's fig parrot Cyclopsitta diophthalma coxeni should the subspecies come into captivity in the future. The aim of the programme is primarily to produce parent-reared offspring, which would be most suited to reintroduction, but the work also involves egg-fostering trials and cross-fostering of chicks. The results of the breeding programme, the problems encountered and additional conservation work carried out by Currumbin Sanctuary are described. [source]


    Prevalence and inheritance of canine elbow dysplasia in German Rottweiler

    JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 6 2000
    R. Beuing
    Summary A total of 2114 scores of elbow arthrosis from the official screening programme of the German Rottweiler Breeding Association (ADRK) were analysed in respect of prevalence and genetic disposition. 45.8% showed no signs of arthritis, 40.6% were scored in Grade 1 with minor osteophytes and 13.6% were affected by arthritis of clinical relevance (Grade 2 and 3). REML estimates showed a heritability of 28% and a litter variance of 6.4%. The only significant environmental fixed effect was gender. 39.1% of the male and 51.5% of the female were free from ED which corresponds with 19.2% of the male and only 8.8% of the female in the critical ED classes of Grade 2 and 3. Differences between the years of examination could be explained by genetic gain. Month of birth as well as age at examination, in the range covered by this study, was not significant. It was stated that the effect of bodyweight should be tested before starting a breeding programme. Zusammenfassung 2114 Bewertungen der Ellbogenarthrose aus dem offiziellen Screening des Allgemeinen Deutschen Rottweiler Klub (ADRK) wurden in Hinblick auf Häufigkeit und genetische Praedisposition untersucht. 45,8% der Tiere hatten keine Anzeichen von Arthrose, 40,6% wurden mit Grad 1, geringgradige Osteophythenbildung, bewertet und 13,6% waren mit Arthrosen Grad 2 und 3 von klinischer Relevanz behaftet. REML-Schätzungen zeigten eine Heritabilität von 28% und eine wurfbedingte Varianz von 6.4%. Der einzige signifikante fixe Umwelteffekt war der Einfluß des Geschlechtes. 39,1% der Rüden und 51,5% der Hündinnen waren ED-frei. Das korrespondiert damit, daß 19,2% der Rüden und nur 8,8% der Hündinnen in die kritischen ED-Klassen 2 und 3 eingestuft wurden. Unterschiede zwischen den Untersuchungsjahren konnten als genetischer Trend erklärt werden. Der Geburtsmonat sowie das Alter beim Röntgen, zumindest in dem Altersbereich, den diese Studie umfasste, waren nicht signifikant. Es wurde als wichtig angesehen, den Einfluß des Körpergewichtes näher zu prüfen, bevor ein Zuchtprogramm begonnen wird. [source]


    Estimation of heritability for hip dysplasia in German Shepherd Dogs in Finland

    JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2000
    M. Leppaänen
    The heritability of hip dysplasia in the German Shepherd Dog was estimated by applying the animal model and the Restricted Maximum Likelihood (REML) method to a data-set which consisted of the hip scores of 10 335 dogs. Fixed effects of the model were the month and the year of birth, screening age, the panelist responsible for screening and the origin of the animal's sire. The litter and the breeder had only minor effects on hip joints. Heritability estimates were moderate (0.31,0.35). The moderate heritability, which was found in this study, enables a much better genetic gain in the breeding programme, if proper evaluation methods, such as BLUP animal model, and effective selection is used instead of phenotypic selection. Zusammenfassung Schätzung der Heritabilität der Hüftgelenksdysplasie beim Deutschen Schäferhund in Finnland. Die Heritabilität der Hüftgelenksdysplasie beim Deutschen Schäferhund wurde mit Hilfe des Tiermodells und der Restricted Maximum Likelihood (REML) Methode anhand von Hüftgelenksgutachten von 10 335 Hunden geschätzt. Als fixe Effekte wurden im Modell ,Geburtsmonat' und ,-jahr', ,Röntgenalter', Einfluß des ,Gutachters' und ,Herkunft des Vaters' berücksichtigt. Die Effekte ,Wurf' und ,Züchter' hatten nur einen geringen Einfluß auf die Hüftgelenke. Die Heritabilitätsschätzungen betrugen 0.31 bis 0.35. Die in dieser Studie geschätzten Heritabilitäten ermöglichen es, zusammen mit geeigneten Methoden, wie beispielsweise dem BLUP-Tiermodell und einer effektiven Selektion, einen schnelleren Zuchtfortschritt zu erreichen, als nur phänotypisch zu selektieren. [source]


    Maternal parity affects neonatal survival rate in a colony of captive bred baboons (Papio hamadryas)

    JOURNAL OF MEDICAL PRIMATOLOGY, Issue 5 2008
    Neroli Sunderland
    Abstract Background, Non-human primates, particularly baboons, are valuable as animal models for reproductive research, because of their similarity to humans. Knowledge of colony-specific pregnancy and neonatal outcomes is essential for interpretation of such research. Methods, A retrospective review of the reproductive records of the Australian National Baboon Colony (ANBC) from 1994 to 2006 was performed. Results, The overall live birth rate was over 70% of recognized pregnancies. Pregnancy loss was due to equal proportions of spontaneous abortion and stillbirth, and was not affected by maternal age or parity. Stillbirth rates were increased by the use of animals in novel late pregnancy experimental protocols. Neonatal mortality rates were low overall, but significantly higher in primiparous compared with multiparous mothers (P < 0.05). There were no cases of maternal mortality. Conclusions, The success of the ANBC breeding programme is demonstrated by the low rate of pregnancy loss, high neonatal survival rate and lack of maternal mortality. [source]


    Rapid Screening Method of Cassava Cultivars for Resistance to Colletotrichum gloeosporioides f.sp. manihotis

    JOURNAL OF PHYTOPATHOLOGY, Issue 1 2002
    C. N. FOKUNANG
    An in vitro method for assessing cassava anthracnose disease (CAD) resistance was developed as a preliminary screen to a CAD-resistant breeding programme. Potato dextrose agar (PDA) media was amended by extracts from the stem cortex of 10 cassava cultivars (30001; 30572, 30211, 88/02549, 88/00695, 88/01336, 91/00344, 91/00313, 91/00684 and 91/00475), and assayed for efficacy of inhibition of the growth of Colletotrichum gloeosporioides f. sp. manihotis isolates (05FCN, 10FCN, 12FCN, and 18FCN). Morphological and physiological data indicated that there was a significant difference (P , 0.05), in mycelial growth, spore germination and sporulation among the four isolates on PDA amended with cassava stem extracts. Extracts from cassava cultivars 30211, 91/00684 and 91/00313 showed higher inhibition of germ tube development, mycelial growth and sporulation of the fungal isolates, whereas cultivars 88/02549 and 88/01336 showed the least inhibition. The 10 cultivars were further tested in both greenhouse and field conditions, under disease pressure for two planting seasons, to corroborate resistance to the fungus as observed in vitro. Greenhouse and field trials with the 10 cassava cultivars showed a significant difference (P , 0.05) in CAD resistance. Cultivars 88/02549 and 88/01336 were highly CAD-susceptible, as shown in the in vitro assays and confirmed in the greenhouse and field tests. The other eight cultivars were either resistant (30211, 91/00684), or moderately resistant (30572, 88/00695, 91/00475, 91/00344, 30001 and 91/00313) to CAD. The study shows that an in vitro screening assay of cassava for resistance to CAD could serve as a convenient preliminary screening technique to discriminate CAD-resistant from CAD-susceptible cassava cultivars. The in vitro screening method considerably reduces time and labour in comparison with the current screening techniques of cassava, which involve field planting, inoculation and evaluation. [source]


    Variation in Resistance of Camelina (Camelina sativa [L.] Crtz.) to Downy Mildew (Peronospora camelinae Gäum.)

    JOURNAL OF PHYTOPATHOLOGY, Issue 3-4 2001
    Vollmann
    Camelina (Camelina sativa) is a potential oilseed crop for both food and non-food utilization cultivated on a limited acreage in Europe and North America. An important low-input feature of camelina is its high level of resistance against plant diseases, which may partly be due to the production of antimicrobially efficient phytoalexins. In Central European countries such as Austria, downy mildew (Peronospora camelinae) is the only disease of camelina which has been found repeatedly, whereas other diseases and pests have been observed only occasionally. Therefore, the genotypic variation of downy mildew incidence was evaluated in two camelina field experiments carried out within a breeding programme. In both experiments, totally resistant breeding lines were identified and a continuous pattern of variation in disease incidence was observed, suggesting a horizontal type of resistance. In bi-parental populations, disease incidence of progeny appeared to be associated with disease scores of the parent genotypes, and transgressive segregation in disease incidence was also found. In 1998, the rate of downy mildew in camelina was lower than in 1999; in the latter growing season, grain yield was significantly affected by the disease, whereas other agronomic characters remained unaffected. Variation der Resistenz von Leindotter (Camelina sativa[L.] Crtz.) gegen Falschen Mehltau (Peronospora camelinae Gäum.) Leindotter (Camelina sativa) ist eine Ölpflanze, die zur Nahrungsmittelherstellung und für andere Zwecke genutzt werden kann und in Europa und Nordamerika auf relativ kleiner Fläche angebaut wird. Ein wichtiges Low-Input-Merkmal des Leindotters ist seine hohe Krankheitsresistenz, die vermutlich teilweise auf die Bildung antimikrobiell wirksamer Phytoalexine zurückgeht. In Österreich und anderen Ländern Mitteleuropas ist Falscher Mehltau (Peronospora camelinae) die einzige regelmäßig anzutreffende Krankheit des Leindotters, andere Krankheiten und Schädlinge werden nur gelegentlich beobachtet. Daher wurde die genotypische Variation der Inzidenz des Falschen Mehltaus im Rahmen eines Leindotter-Züchtungsprogramms in zwei Feldversuchen geprüft. In beiden Versuchen wurden vollständig resistente Zuchtlinien identifiziert, und ein kontinuierliches Variationsmuster der Krankheitsresistenz wurde beobachtet, was auf horizontale Resistenz schließen läßt. In biparentalen Populationen war die Befallshänfigkeit bei den Nachkommen offenbar mit den Boniturwerten der elterlichen Genotypen assoziiert, und bei der Befallshänfigkeit wurde auch eine transgressive Aufspaltung beobachtet. 1998 war der Befall des Leindotters mit Falschem Mehltau geringer als 1999; im letztgenannten Jahr war der Kornertrag infolge der Krankheit deutlich verringert, während andere agronomische Merkmale unbeeinflußt blieben. [source]


    Mitochondrial DNA control region diversity in the endangered blue chaffinch, Fringilla teydea

    MOLECULAR ECOLOGY, Issue 9 2000
    J. Pestano
    Abstract The blue chaffinch (Fringilla teydea) is found only on the two central Canary Islands of Gran Canaria and Tenerife, where it is restricted to pine forest habitat. It is reasonably abundant on the latter island but endangered on the former. Here, sequence variation was studied in a fragment spanning domains I and II of the mitochondrial DNA (mtDNA) control region. Phylogenetic analysis of all haplotypes with a F. coelebs outgroup indicated the two island populations were reciprocally monophyletic, supporting their individual conservation. Unlike in other species, most within-island haplotype diversity was due to mutations in the domain II region. Surprisingly, genetic diversity was greater in the smaller Gran Canarian population. We suggest that this is unlikely to be maintained under current population sizes although it may be mitigated by incorporating genetic information into the captive breeding programme. [source]


    Microsatellites from kousa dogwood (Cornus kousa)

    MOLECULAR ECOLOGY RESOURCES, Issue 4 2008
    PHILLIP A. WADL
    Abstract Microsatellite loci were identified from Cornus kousa,National'. Primer pairs for 86 loci were developed and of these, eight were optimized and screened using genomic DNA from 22 kousa cultivars. All optimized loci were polymorphic and the number of alleles per locus ranged from three to 17. Observed heterozygosity ranged from 0 to 0.3 and expected heterozygosity ranged from 0.38 to 0.91. These microsatellites will be useful in population studies, and a breeding programme for cultivar development of Cornus species. [source]


    Recurrent selection of cocoa populations in Côte d'Ivoire: comparative genetic diversity between the first and second cycles

    PLANT BREEDING, Issue 5 2009
    N. D. Pokou
    Abstract In Côte d'Ivoire, the cocoa breeding programme has been based on the creation of hybrids between different genetic groups. From 1990 onward, a reciprocal recurrent selection programme has been set up with the purpose of improving simultaneously the characteristics of the two main genetic groups: Upper Amazon Forastero (UA) and a mixture of Lower Amazon Forastero (LA) and Trinitario (T). Based on data obtained from 12 microsatellite primers, the genetic diversity and genetic distances of the parental populations used in the first and second selection cycles are presented. The results revealed that the diversity of populations UA0 and UA1 on the one hand and (LA+T)0 and (LA+T)1 on the other is similar. The genetic distances were small between the parental populations used for the first and second cycles. Genetic diversity was greater in the UA group than in the LA+T group. The number of rare and of private alleles was reduced for both genetic groups, as well as the number of the frequent alleles in the LA+T group. [source]


    Molecular mapping of genic male-sterile genes ms15, ms5 and ms6 in tetraploid cotton

    PLANT BREEDING, Issue 2 2009
    D. Chen
    Abstract Two genic male sterile (GMS) lines, Lang-A conditioned by ms15 and Zhongkang-A conditioned by ms5ms6 duplicate recessive genes in Gossypium hirsutum L., were chosen to map GMS genes. These two lines were crossed with Gossypium barbadense cv. ,Hai7124' to produce segregating populations. The ms15 gene was mapped on chromosome 12, and was flanked by two simple sequence repeat (SSR) markers, NAU2176 and NAU1278, with a genetic distance of 0.8 and 1.9 cM respectively. The ms5 and ms6 genes were mapped to one pair of homoeologous chromosomes, ms5 on chromosome 12 flanked by three SSR markers, NAU3561, NAU2176 and NAU2096, with genetic distances of 1.4, 1.8 and 1.8 cM, respectively, and ms6 on chromosome 26 flanked by two SSR markers, BNL1227 and NAU460, with a genetic distance of 1.4 and 1.7 cM respectively. These tightly linked markers with the ms15, ms5 and ms6 genes can be used in the marker-assisted selection among segregating populations in a breeding programme, and provide the foundation for gene isolation by map-based cloning for these three genes. [source]


    Trends in genetic variance components during 30 years of hybrid maize breeding at the University of Hohenheim

    PLANT BREEDING, Issue 5 2008
    S. Fischer
    Abstract The ratio of variance due to specific vs. general combining ability (GCA) (,2SCA:,2GCA) is of central importance for predicting hybrid performance from GCA effects. The objectives of our study were to (1) analyse the changes in estimates of ,2GCA, ,2SCA and their ratio during 30 years of hybrid maize breeding and (2) compare the observed trends in genetic variances with those expected under a simple genetic model. We analysed multilocation yield trials based on the North Carolina Design II conducted in the maize breeding programme of the University of Hohenheim from 1975 to 2004 for grain yield (GY) and dry matter content (DMC). GY showed a significant (P < 0.05) annual increase of 0.17 Mg/ha, but no linear trend was found for DMC. Since the beginning of hybrid breeding at the University of Hohenheim, the sum of estimates of ,2GCA of the flint and dent heterotic groups were higher than the estimates of their ,2SCA. This predominance did not change with ongoing inter-population improvement. Consequently, superior hybrids can be identified and selected mainly based on their prediction from GCA effects. [source]


    Consequences of a decentralized participatory barley breeding programme on changes in SSR allele frequency and diversity in one cycle of selection

    PLANT BREEDING, Issue 5 2007
    F. Fufa
    Abstract Changes in allele type, allele frequency and genetic diversity because of selection by individual farmers and breeders were assessed using simple sequence repeats (SSRs) during one cycle of selection in a decentralized participatory barley breeding programme. Selection by both breeders and farmers resulted in the loss of a number of alleles in the majority of the locations, with more alleles lost in the heterogeneous breeding materials than in the fixed genotypes, indicating selection against undesirable traits uncovered in the heterogeneous breeding materials that are presumably linked to SSR alleles. After selection, significant allelic frequency changes were observed at several loci in both the germplasm groups. As the selection was conducted independently in each location, an allele had a chance of being selected in more than one location, and therefore considering the whole study area the allelic composition and diversity of the original genetic materials was maintained after the selection. The study showed the importance of decentralized participatory plant breeding in maintaining genetic diversity that helps stabilize and sustain production in unpredictable production conditions. [source]


    Microsatellite marker for yellow rust resistance gene Yr5 in wheat introgressed from spelt wheat

    PLANT BREEDING, Issue 6 2002
    Q. Sun
    Abstract Yellow rust of wheat caused by Puccinia striiformis f sp. tritici has been periodically epidemic and severely damaged wheat production in China and throughout the world. Breeding for resistant cultivars has been proved to be an effective way to resolve the problem. A yellow rust resistance gene, Yr5, derived from Triticum spelta shows immunity or high resistance to the most popular isolates Tiaozhong 30 and 31 in China. Establishment of DNA markers for the Yr5 gene will facilitate marker-assisted selection and gene pyramiding in the breeding programme. Since the Yr5 gene was cytologically located on the long arm of chromosome 2B, By33, the donor of Yr5, was crossed and backcrossed with the susceptible line 441, and BC3F2 and BC3F3 segregating populations were screened for polymorphism by using 11 microsatellite primers mapped on chromosome 2B. A marker, Xgwm501-195 bp/160 bp, was found to be linked to Yr5, with a genetic distance of 10.5-13.3 cM. [source]


    A PCR-based DNA marker for detection of mutant and normal alleles of the Wx-D1 gene of wheat

    PLANT BREEDING, Issue 2 2001
    M. R. Shariflou
    Abstract To assist waxy wheat breeding a DNA marker was developed to discriminate mutant and normal alleles at the Wx-D1 locus. This polymerase chain reaction-based marker distinguishes the mutant from the normal allele by targeting the previously reported deletion basis of the mutant. The marker codominantly identifies the normal allele of the Wx-D1 gene from the mutant allele originated from the Chinese landrace ,Baihoumai'. However, attempts with a number of primer combinations targeting this deletion failed to amplify the corresponding fragment from an unrelated wheat line (NP150) that has a mutant null allele at the same locus. This indicates that NP150 has a different mutant allele from that of ,Baihoumai'. This marker is a useful tool to identify wheat cultivars with mutant and normal alleles of the Wx-D1 gene, and is used in marker-assisted selection of the Wx-D1 gene in our waxy wheat breeding programme. [source]


    A major SNP resource for dissection of phenotypic and genetic variation in Pacific white shrimp (Litopenaeus vannamei)

    ANIMAL GENETICS, Issue 1 2010
    D. C. Ciobanu
    Summary Bioinformatics and re-sequencing approaches were used for the discovery of sequence polymorphisms in Litopenaeus vannamei. A total of 1221 putative single nucleotide polymorphisms (SNPs) were identified in a pool of individuals from various commercial populations. A set of 211 SNPs were selected for further molecular validation and 88% showed variation in 637 samples representing three commercial breeding lines. An association analysis was performed between these markers and several traits of economic importance for shrimp producers including resistance to three major viral diseases. A small number of SNPs showed associations with test weekly gain, grow-out survival and resistance to Taura Syndrome Virus. Very low levels of linkage disequilibrium were revealed between most SNP pairs, with only 11% of SNPs showing an r2 -value above 0.10 with at least one other SNP. Comparison of allele frequencies showed small changes over three generations of the breeding programme in one of the commercial breeding populations. This unique SNP resource has the potential to catalyse future studies of genetic dissection of complex traits, tracing relationships in breeding programmes, and monitoring genetic diversity in commercial and wild populations of L. vannamei. [source]


    Detection of QTL affecting harvest traits in a commercial Atlantic salmon population

    ANIMAL GENETICS, Issue 5 2009
    R. D. Houston
    Summary Genetic variation in performance and quality traits measured at harvest has previously been demonstrated in Atlantic salmon aquaculture populations. To map major loci underlying this variation, we utilized data from 10 families from a commercial breeding programme. Significant QTL were detected affecting harvest weight and length traits on linkage group 1, and affecting waste weight on linkage group 5. In total, 11 of the 29 linkage groups examined showed at least suggestive evidence for a QTL. These data suggest that major loci affecting economically important harvest characteristics are segregating in commercial salmon populations. [source]


    Biological performance of Myzus persicae and Macrosiphum euphorbiae (Homoptera: Aphididae) on seven wild Solanum species

    ANNALS OF APPLIED BIOLOGY, Issue 3 2010
    Y. Pelletier
    Resistance level of seven accessions of wild Solanum species (Solanaceae) to Myzus persicae and Macrosiphum euphorbiae (Homoptera: Aphididae) was evaluated by measuring survival and fecundity during sleeve cage experiments and population growth on whole plants in a controlled environment. The survival was lowest on the Solanum circaeifolium spp. capsicibaccatum, Solanum pinnatisectum and Solanum trifidum accessions for M. persicae and on the S. circaeifolium spp. capsicibaccatum, Solanum okadae and S. trifidum, accessions with M. euphorbiae. Plant species significantly influenced the fecundity of both aphid species. Aphid population growth on whole plants was negatively affected by the age of the plant, but generally followed the levels of net reproductive rate on different plant species observed during the sleeve cage experiment. The population of M. persicae varied among the seven wild potato accessions with the lowest growth rates on S. circaeifolium spp. capsicibaccatum, Solanum polyadenium, Solanum tarijense and S. trifidum. The number of M. euphorbiae also varied among accessions but the smallest population was collected from S. polyadenium. The results can be used to identify sources of resistance to aphids within those accessions already known to be resistant to the Colorado potato beetle. This study highlights the difficulties involved in developing a high-throughput screening test for aphid resistance compatible with a potato breeding programme. [source]


    Rapid techniques for assessing fibre quality of flax breeding lines and cultivars using visible and near infrared spectroscopy, and thermal analysis

    ANNALS OF APPLIED BIOLOGY, Issue 2 2006
    Z. Jankauskien
    Abstract Fifteen different flax cultivars and breeding lines (E-68, Baltu,iai, Belinka, Vega 2, Ilona, Elise, Kasty,iai, Evelin, 1963-3, Ariane, Hermes, 01057-12, 1698-13a, 2017-3, 1864-24) were cultivated, harvested, water-retted, scutched and resulting fibres passed through pin frames to produce representative samples for each variety. The aim of this investigation was to develop rapid techniques for assessing quality of fibre obtained from a comparative agronomical trial. The fibres produced were then assessed using visible and near infrared spectroscopy (Vis,NIRS), thermal analysis, scanning electron microscopy and airflow method for measuring fibre fineness. The relationships between agronomical characteristics, fibre fineness, thermal and spectral results were assessed using principal component analysis and partial least squares regression methods. The micrographs of the samples revealed the presence of residual pectic and cuticular tissues on all fibres, and significant differences between the 15 fibre samples were not observed. A significant relationship of the differences in fibre fineness of the test samples as measured by airflow method and Vis,NIR spectra was observed with an R2 of 0.97 and standard error of calibration (SEC) of 1.69 dtex, and the former parameter also correlated with the measured thermal combustion parameters showing an R2 of 0.91 and SEC of 2.86 dtex, indicating that the two rapid techniques could be used for the assessment of fibre quality of selected plants from the breeding programme. The advantages of using the two instrumental techniques compared with the existing airflow method are briefly discussed. [source]


    Parentage assignment in Haliotis midae L.: a precursor to future genetic enhancement programmes for South African abalone

    AQUACULTURE RESEARCH, Issue 9 2010
    Nicol-Candice Van Den Bergb
    Abstract The establishment and evaluation of family lines using pedigree information provides an advanced understanding of the variability that exists for complex, economically valuable traits and is a necessary step in the execution of an effective breeding programme. The aim of this study was to assign parentage to mass-spawned Haliotis midae juveniles using species-specific microsatellite markers. Screening of wild abalone individuals revealed that the nine loci selected complied with the minimum requirements for parentage analyses: a null allele frequency <5% as well as a high number and frequency of alleles per locus. A total of 598 individuals were genotyped (198 breeding individuals and 400 F1 progeny) from two farms, with parentage results yielding 91% and 90% successful assignment for Farms A and B respectively. This study, therefore, provided the necessary pedigree information required for controlled breeding of individual adult abalone and indicated the usefulness of the panel of microsatellite markers selected for parentage assignment. [source]


    Divergent selection for shell length in two stocks of small abalone Haliotis diversicolor

    AQUACULTURE RESEARCH, Issue 6 2010
    Wei-Wei You
    Abstract To determine whether genetic improvement can be attained through a selective breeding programme, divergent selection for shell length was applied to two stocks of Haliotis diversicolor. Stock A was descended from the cross between males from a Japanese wild population and females from a Taiwan aquacultured population and Stock B was from the Taiwan cultured population, which had been successively cultured in mainland China for about 10 generations. The 10% largest and 10% smallest abalones for each of these two stocks were selected as parents for the large-selected and small-selected lines respectively. Equal numbers of abalone were randomly chosen from the two stocks to serve as parents for the control lines before the selection. The selected and control lines were reared under the same conditions at early juvenile, later juvenile and grow-out stages. Stock A showed a significantly higher response to selection and realized heritability than Stock B (P<0.01). The large-selected line of Stock A and Stock B grew 12.79% and 4.58% faster than their control lines on shell length respectively. The average realized heritability for shell length was 0.441±0.064 for Stock A and 0.113±0.013 for Stock B. Responses to selection were different at different ages in each stock and the body weights of the selected lines were significantly different from the control lines in both stocks at the grow-out stage. Asymmetric responses to selection in the two directions were also observed in both stocks. Differences in response to selection and realized heritability between the two stocks are presumably due to genetic variability. [source]


    Genetic variability revealed with microsatellite markers in an introduced population of the abalone Haliotis discus hannai Ino

    AQUACULTURE RESEARCH, Issue 3 2009
    S Marchant
    Abstract One of the challenges for the culture of any species is to control the loss of genetic variability, which may result in a decrease in the quality of commercially important traits. The goal of this study is to assess the genetic diversity of a hatchery population of the Pacific abalone (Haliotis discus hannai) from the Center for Abalone Production of the Universidad Católica del Norte (CAP-UCN) that is maintained under a breeding programme. We used six polymorphic microsatellite markers within the cultivated population. The loci Awb033 and Awb079 had the highest number of alleles (11 and 10 respectively) and the loci Awb022 and Awb026 the lowest (two and four respectively). The mean number of alleles per locus was 6.83. The average observed and expected heterozygosities were 0.71 and 0.70, respectively, and the average FIS (f) index was ,0.023. We compared the population genetic parameters of the CAP-UCN population with previously published data of wild and hatchery populations of the same species. Results indicate lower genetic diversity estimated as allelic richness in the introduced population with a loss of 11,58% alleles per locus. Despite the high allelic loss, the estimated inbreeding coefficient suggests that the breeding programme carried out in the CAP-UCN has controlled and maintained heterozygosity levels successfully. A temporal study is necessary to determine whether the genetic diversity loss detected was caused during the initial introduction of breeders or to the breeding programme actually implemented. [source]


    Genetic differences in growth among wild populations of the yabby, Cherax destructor (Clark)

    AQUACULTURE RESEARCH, Issue 12 2002
    D R Jerry
    Abstract Before commencing a breeding programme on a new aquaculture species, it is prudent to identify populations or strains with superior characteristics for commercial production. Information on the comparative performance of populations allows informed decisions to be made on the starting genetic base for the programme. As a precursor to a breeding programme in the decapod species, Cherax destructor (Clark), five geographically isolated populations were evaluated for the traits weight at age, abdomen length and abdomen width over a period of 9 months. Mean weight at age was found to vary among the populations by up to 42%, whereas mean abdomen length was similar among four out of the five populations. No differences were found in abdomen width. This study emphasizes that rapid genetic gains can be made simply by starting a breeding programme based on faster growing populations. [source]


    Integrating molecular genetic technology with traditional approaches for genetic improvement in aquaculture species

    AQUACULTURE RESEARCH, Issue 1 2000
    G P. Davis
    Genetic improvement of aquaculture species offers a substantial opportunity for increased production efficiency, health, product quality and, ultimately, profitability in aquacultural enterprises. Technolo-gies exist that can be implemented immediately to improve multiple traits that have economic value, while simultaneously accounting for inbreeding effects. Genetic improvement techniques for delivering genetic gain include formal definition of the breeding objective, estimation of genetic parameters that describe populations and their differences, evaluation of additive and non-additive genetic merit of individuals or families and defining the structure of a breeding programme in terms of mating plans. Novel genetic technologies involving the use of DNA-based tools are also under development for a range of aquaculture species. These gene marker technologies can be used for identification and monitoring of lines, families and individuals, monitoring and control of inbreeding, diagnosis of simply inherited traits and genetic improvement through selection for favourable genes and gene combinations. The identification of quantitative trait loci (QTL), and direct or linked markers for them, will facilitate marker-assisted selection in aquaculture species, enabling improvement in economically important traits, particularly those that are difficult to breed for, such as food conversion efficiency and disease resistance. [source]


    Scorpiurus muricatus L. subsp. subvillosus (L.) Thell., a potential forage legume species for a Mediterranean environment: a review

    GRASS & FORAGE SCIENCE, Issue 1 2010
    V. Abbate
    Abstract Prickly scorpion's tail, Scorpiurus muricatus L. subsp. subvillosus (L.) Thell., is an annual legume species, widespread in pastures of the basin of the Mediterranean Sea. It has been neglected by researchers and farmers for a long time, although the species has promise as a forage crop for its high nutritive value, self-reseeding capability and its preference by ruminants. Harvesting and threshing of seed, however, are difficult and it has seed-coat dormancy, which delays and reduces germination, hindering its use as a forage crop. It is suggested that plant breeding programmes would allow the selection of ecotypes and varieties for field crop cultivation. In this study, the main botanical, biological, ecological and agronomic traits are reviewed to identify those issues that currently limit its introduction into cultivation as a forage crop in Mediterranean areas. [source]