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Wild Cherry (wild + cherry)

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Life Sciences	100%

Selected Abstracts

Determination of self-incompatible genotypes in sweet cherry (Prunus avium L.) accessions and cultivars of the German Fruit Gene Bank and from private collections

PLANT BREEDING, Issue 5 2007
M. Schuster
Abstract Sweet cherries are self-incompatible because of a gametophytic self-incompatibility system. S alleles in the style and pollen determine the crossing relationships. Knowledge of the S allele constitution of cultivars is very important for cherry growers and breeders, and recently, molecular methods have been developed to distinguish the S alleles in sweet cherries. The S allele genotypes of 149 sweet cherry cultivars and clones, including 126 not previously genotyped, were determined by using PCR analysis. Thirteen different S alleles in 40 combinations were distinguished and nine new incompatibility groups were documented. Two new S alleles were identified in five local sweet cherry processing cultivars from southwestern Germany using the second intron primers. The sequence of these alleles was determined and compared to all known sequences available in the NCBI database. The sequences obtained showed high similarities to the alleles S19 and S22, previously described only in wild cherries, Prunus avium L. [source]

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

FOREST PATHOLOGY, Issue 6 2004
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]

Comparative analysis of the within-population genetic structure in wild cherry (Prunus avium L.) at the self-incompatibility locus and nuclear microsatellites

MOLECULAR ECOLOGY, Issue 11 2006
SILVIO SCHUELER
Abstract Gametophytic self-incompatibility (SI) systems in plants exhibit high polymorphism at the SI controlling S -locus because individuals with rare alleles have a higher probability to successfully pollinate other plants than individuals with more frequent alleles. This process, referred to as frequency-dependent selection, is expected to shape number, frequency distribution, and spatial distribution of self-incompatibility alleles in natural populations. We investigated the genetic diversity and the spatial genetic structure within a Prunus avium population at two contrasting gene loci: nuclear microsatellites and the S -locus. The S -locus revealed a higher diversity (15 alleles) than the eight microsatellites (4,12 alleles). Although the frequency distribution of S -alleles differed significantly from the expected equal distribution, the S -locus showed a higher evenness than the microsatellites (Shannon's evenness index for the S -locus: E = 0.91; for the microsatellites: E = 0.48,0.83). Also, highly significant deviations from neutrality were found for the S -locus whereas only minor deviations were found for two of eight microsatellites. A comparison of the frequency distribution of S -alleles in three age-cohorts revealed no significant differences, suggesting that different levels of selection acting on the S -locus or on S- linked sites might also affect the distribution and dynamics of S -alleles. Autocorrelation analysis revealed a weak but significant spatial genetic structure for the multilocus average of the microsatellites and for the S -locus, but could not ascertain differences in the extent of spatial genetic structure between these locus types. An indirect estimate of gene dispersal, which was obtained to explain this spatial genetic pattern, indicated high levels of gene dispersal within our population (,g = 106 m). This high gene dispersal, which may be partly due to the self-incompatibility system itself, aids the effective gene flow of the microsatellites, thereby decreasing the contrast between the neutral microsatellites and the S -locus. [source]