We isolated and sequenced 26 microsatellites from two genomic libraries of peach cultivar 'Redhaven', enriched for AC/GT and AG/CT repeats, respectively. For 17 of these microsatellites, it was possible to demonstrate Mendelian inheritance. Microsatellite polymorphism was assayed in 50 peach and nectarine cultivars. Of the 1300 PCRs carried out, all but two produced amplified products of the expected size. All microsatellites were polymorphic, showing 2-8 alleles per locus. Heterozygosity ranged from 0.04-0.74 (mean 0.47); the discrimination power (PD) ranged from 0.04-0.84 (mean 0.60). Cultivar heterozygosity varied greatly, with one cultivar ('Independence') being homozygous at all loci. The set of microsatellites discriminated all cultivars investigated, except several sport mutations, i.e., 'Dixitime' vs. 'Springcrest', 'Compact Redhaven' vs. 'Redhaven', and two pairs of cultivars, 'Venus' vs. 'Orion' and 'Elegant Lady' vs. 'Rome Star', whose pedigrees are controversial. We were able to analyze the paternity of several cultivars. In most cases, the parenthood was confirmed. The comparison of three long-living 'Redhaven' accessions supplied by different repositories did not provide any evidence of somatic instability of microsatellites. Hence, microsatellites, ranked according to their information content, are recommended as markers of choice for peach fingerprinting and suggestions are provided for interpreting band profiles and the correct sizing of alleles.
This work presents a simple in vitro system to study physiological, biochemical and molecular changes occurring in a pear callus (Pyrus communis L., cv. Beurré Bosc) grown in close proximity to spatially separated undifferentiated homologous (pear) or heterologous (quince; Cydonia oblonga Mill., East Malling clone C) cells in its neighboring environment. After a 7-day co-culture period, the presence of heterologous cells produced negative effects on the pear callus, whose relative weight increase and adenylate energy charge decreased by 30 and 24%, respectively. Such behavior was associated with a higher O(2) consumption rate (+125%) which did not seem to be coupled to adenosine triphosphate synthesis. Analyses of alternative oxidase and enzymatic activities involved in reactive oxygen species (ROS) detoxification strongly suggested that the higher O(2) consumption rate, measured in the pear callus grown in the heterologous combination, may probably be ascribed to extra-respiratory activities. These, in turn, might contribute to generate metabolic scenarios where ROS-induced oxidative stresses may have the upper hand. The increase in the levels of 2-thiobarbituric acid reactive metabolites, considered as diagnostic indicators of ROS-induced lipid peroxidation, seemed to confirm this hypothesis. Moreover, reverse transcription polymerase chain reaction analysis revealed that the expression levels of a few senescence-associated genes were higher in the pear callus grown in the heterologous combination than in the homologous one. Taken as a whole, physiological and molecular data strongly suggest that undifferentiated cells belonging to a pear graft-incompatible quince clone may induce an early senescence-like status in a closely co-cultured pear callus.
The strength of the sweet cherry industry throughout Europe and Asia is due to the breeding efforts of France, Germany, Hungary, Italy, Denmark, the UK, the Czech Republic, Romania, Estonia and Ukraine, Turkey, Japan, and China. The last decade has seen the release of more than 140 novel cultivars that have provided the major thrust in extending the crop's seasonal calendar and improving fruit quality traits such as size, flavour, flesh firmness and colour. Fruit crack resistance has been enhanced and there are now a dozen cultivars with only 5-10% of fruit affected by cracking due to rain-damages. Molecular studies have brought new light to bear upon the genetic control mechanisms of key tree and fruit traits and this should enhance future breeding efforts. The introduction of new self-fertile cultivars with mutated S-locus alleles, has been a key factor in upgrading crop yields, especially in Italy. Notable releases include very early-season 'Primulat' and 'Early Bigi' (France); the self-fertile 'Sweet Early' and 'Grace Star' (Italy); the mid-season ripeners 'Giorgia' (Italy) and 'Vera' (Hungary); the mid-to-late 'Kordia', 'Vanda', 'Techlovan' (Czech Republic) and 'Black Star' (Italy); and the late ripeners 'Regina' (Denmark) and 'Alex' (Hungary). specific section seeking data on average number of yearly crosses, main parents, number of seedlings produced, number of plants in selection phases 2 and 3, total number of cultivars released, date of release, and the main objectives pursued (see Table 2); (3) methods of cultivar release, (free release, patents, trademarks), and the kind of field performance tests and trial set-up.
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