Breeding Approach (breeding + approach)

Distribution by Scientific Domains

Selected Abstracts

Use of a breeding approach for improving biocontrol efficacy of Phlebiopsis gigantea strains against Heterobasidion infection of Norway spruce stumps

Hui Sun
Abstract Sixty-four wild heterokaryotic isolates of Phlebiopsis gigantea were analysed for asexual spore production, growth rate and competitive ability against Heterobasidion in vitro, as well as growth rate in Norway spruce wood. These P. gigantea traits were considered important for controlling infection of Norway spruce stumps by spores of Heterobasidion spp. Ten most promising P. gigantea isolates were crossed with each other and 172 F1 progeny heterokaryons were analysed for the above-mentioned traits. Thirteen most promising progeny heterokaryons were selected and their biocontrol ability against infection by Heterobasidion was compared with the parental isolates in stem pieces of Norway spruce. The results indicated that the progeny strains had generally better traits and control efficacy than the parental strains. The genetic effects accounted for a part of the variations between progeny and parental strains. This further suggests that there is a potential to improve the biocontrol properties of P. gigantea through breeding. [source]

Screening wild cherry (Prunus avium) for resistance to bacterial canker by laboratory and field tests

F. Santi
Summary Currently, bacterial canker caused by Pseudomonas syringae is a major cause of dieback and tree death in wild cherry (Prunus avium) plantations. The evaluation of breeding collections is needed to produce less susceptible clones or cultivars. Resistance tests were performed using excised shoots (1 and 2 years old) from 79 clones in the laboratory. A subset of 10 clones was also tested in the field. The clones were inoculated with four to seven isolates of a set of 15 isolates of P. s. pv. morsprunorum, P. s. pv. syringae, P. s. pv. persicae, P. syringae pv. avii and P. fluorescens. In the laboratory tests, older and larger shoots were more susceptible. In the field test, size and age of the shoots were not related to girdling by the bacterial canker. Two-year-old shoots were best for clonal discrimination. Correlations between 1 and 2-year-old shoots were significant but not high. The isolates varied a lot between experiments, but as the clone × isolate interactions were always low, breeding could thus be facilitated. The ranking of clones was conserved quite well between two laboratory tests, but not between two others. Good agreement was found for the best clones in the laboratory tests and in the field test. However, the two worst clones in the latter were among the best in one laboratory test. At least two independent tests in the laboratory are needed to evaluate resistance/susceptibility of clones. Broad sense heritability for resistance varied from 0.27 to 0.51. Although moderate, such heritability clearly encourages a breeding approach to reduce the problem of bacterial canker. Résumé Le chancre bactérien (Pseudomonas syringae) est une cause majeure de dépérissement dans les plantations de merisier du nord de la France. Nous devons évaluer les collections pour produire des variétés moins sensibles. Des branches coupées de un ou deux ans de 79 clones ont été testées au laboratoire. Dix de ces clones ont également été testés dans un test en extérieur. Les clones ont été inoculés avec un total de 15 isolats de P. s. pv. morsprunorum, P. s. pv. syringae, P. s. pv. persicae, P. s. pv. avii et P. fluorescens. Les plus fortes infections, mesurées par la longueur du chancre, ont été observées sur les branches les plus âgées et les plus épaisses, mais la taille et l'âge des branches n'ont eu aucune influence sur la note de ceinturation du test au champ. Les branches de deux ans se sont révélées meilleures pour discriminer les clones. Les corrélations entre moyennes de clones avec les branches de un et deux ans étaient significatives mais pas très élevées. Les isolats variaient beaucoup entre expériences, mais comme les interactions clone × bactérie étaient toujours faibles, la sélection clonale en devrait être facilitée. Le classement des clones était bien conservé entre deux tests de laboratoire, mais pas entre deux autres. Le classement entre tests au laboratoire et au champ se trouvait conservé, mais les deux plus mauvais clones dans ce dernier ont été bien classés dans un test de laboratoire, ce qui signifie qu'un seul test a laboratoire est insuffisant pour l'évaluation des clones. Les héritabilités au sens large variaient de 0.27 à 0.51. Bien que modérées, de telles héritabilités encouragent clairement à sélectionner des génotypes moins sensibles pour solutionner le problème du chancre bactérien. Zusammenfassung Der durch Pseudomonas syringae verursachte Bakterienkrebs ist eine der häufigsten Ursachen für das Absterben von Süsskirschen (Prunus avium) in Pflanzungen. Die Prüfung von Zuchtformen auf Resistenz ist nötig, um weniger anfällige Klone und Sorten zu fördern. Die Resistenz von 79 Klonen wurde im Labor an abgeschnittenen ein- und zweijährigen Trieben getestet. Zehn Klone wurden auch im Feld getestet. Die Klone wurden mit je vier bis sieben von insgesamt 15 Isolaten von P. s. pv. morsprunorum, P. s. pv. syringae, P. s. pv. persicae, P. s. pv. avii und P. fluorescens inokuliert. In den Labortests waren die älteren, dickeren Triebe anfälliger, währenddem in den Feldversuchen weder Alter noch Dicke der Triebe eine Rolle spielten. Zweijährige Triebe eigneten sich zur Differenzierung der Klone hinsichtlich ihrer Resistenz besser. Korrelationen zwischen ein- und zweijährigen Trieben waren signifikant aber nicht hoch. Die Reaktionen auf die Isolate variierten stark zwischen den Experimenten, aber die statistisch nachgewiesenen Wechselwirkungen zwischen Klonen und Isolaten waren stets schwach, was die Züchtung neuer Klone erleichtern dürfte. In zwei Labortests erzielten die Klone analoge Bewertungen, währenddem sie in zwei anderen Labortests unterschiedlich reagierten. Die Resultate aus Labor- und Feldversuchen stimmten für die resistentesten Klone gut überein, die anfälligsten Klone im Feldversuch waren jedoch unter den resistentesten in den Laborversuchen. Es sind also mindestens zwei unabhängige Labortests nötig, um den Grad der Resistenz eines Klones zu bestimmen. Der Vererbarkeit der Resistenz variierte zwischen 0.27 und 0.51. Obschon diese Werte moderat sind, sollen sie dazu ermuntern, mittels Züchtung auf eine Reduktion von durch den Bakterienkrebs bedingten Ausfällen hinzuarbeiten. [source]

Reverse breeding: a novel breeding approach based on engineered meiosis

Rob Dirks
Summary Reverse breeding (RB) is a novel plant breeding technique designed to directly produce parental lines for any heterozygous plant, one of the most sought after goals in plant breeding. RB generates perfectly complementing homozygous parental lines through engineered meiosis. The method is based on reducing genetic recombination in the selected heterozygote by eliminating meiotic crossing over. Male or female spores obtained from such plants contain combinations of non-recombinant parental chromosomes which can be cultured in vitro to generate homozygous doubled haploid plants (DHs). From these DHs, complementary parents can be selected and used to reconstitute the heterozygote in perpetuity. Since the fixation of unknown heterozygous genotypes is impossible in traditional plant breeding, RB could fundamentally change future plant breeding. In this review, we discuss various other applications of RB, including breeding per chromosome. [source]

Backcross breeding for improved resistance to common bacterial blight in pinto bean (Phaseolus vulgaris L.)

PLANT BREEDING, Issue 3 2005
N. Mutlu
Abstract Common bacterial blight (CBB) caused by Xanthomonas campestris pv. phaseoli reduces common bean (Phaseolus vulgaris L.) yield and quality worldwide. Genetic resistance provides effective disease control; however. a high level of resistance is difficult to attain and does not exist in pinto bean, the most important dry bean market class in North America. Our objective was to determine if a backcross breeding approach with the aid of molecular markers linked to quantitative trait loci (QTL) for resistance to CBB in a donor parent could be used to attain higher levels of resistance to CBB in pinto bean. QTL conditioning CBB resistance from the donor parent XAN 159 were introgressed into the recurrent parent,Chase'using classical backcross breeding and intermittent marker-assisted selection.,Chase'pinto bean is moderately resistant and the breeding line XAN 159 is highly resistant to Xanthomonas campestris. Marker assays confirmed the presence of independent QTL from GN no. 1 Sel 27 and XAN 159 in advanced backcross-derived pinto bean lines with improved CBB resistance. Agronomic characteristics of,Chase'were fully recovered in the backcross-derived lines. An important QTL for CBB resistance from XAN 159 on linkage group B6 was not introgressed because tight linkage between this QTL and the dominant V allele that causes an unacceptable black-mottled seed coat colour pattern in pinto bean could not be broken. [source]

Overexpression of the acidic dehydrin WCOR410 improves freezing tolerance in transgenic strawberry leaves

Mario Houde
Summary Progress in freezing tolerance (FT) improvement through plant breeding approaches has met with little success in the last 50 years. Engineering plants for greater FT through plant transformation is one possible way to reduce the damage caused by freezing. Here, we report an improvement of the selection procedure and the transfer of the wheat Wcor410a acidic dehydrin gene in strawberry. The encoded protein has previously been shown to be associated with the plasma membrane, and its level of accumulation has been correlated with the degree of FT in different wheat genotypes. The WCOR410 protein was expressed in transgenic strawberry at a level comparable with that in cold-acclimated wheat. Freezing tests showed that cold-acclimated transgenic strawberry leaves had a 5 °C improvement of FT over wild-type or transformed leaves not expressing the WCOR410 protein. However, no difference in FT was found between the different plants under non-acclimated conditions, suggesting that the WCOR410 protein needs to be activated by another factor induced during cold acclimation. These data demonstrate that the WCOR410 protein prevents membrane injury and greatly improves FT in leaves of transgenic strawberry. A better understanding of the limiting factors allowing its activation may open up the way for engineering FT in different plant organs, and may find applications for the cryopreservation of human tissues and organs. [source]

Inheritance of useful traits in cassava grown in subhumid conditions

PLANT BREEDING, Issue 2 2006
N. T. Cach
Abstract A diallel study among nine parental clones of cassava was conducted in the subhumid environment on the northern coast of Colombia. Analysis of variance suggested significant effects for the six variables analysed: fresh-root yield, harvest index, root dry matter content, height of first branching, reaction to thrips and plant-type scores. General and specific combining ability effects and their interaction with the environment were significant for most of the variables as well. Results suggested that dominance plays a particularly important role in the cases of fresh-root yield and harvest index but had relatively little importance in the reaction to thrips, dry matter content or height of first branching. Specific breeding approaches are suggested for these traits, depending on the relative importance of additive or non-additive effects in their inheritance. The correlations among different traits were also analysed and in several cases their magnitude reached statistical and biological significance. [source]