Artificial endosperm of Cleopatra tangerine zygotic embryos: a model for somatic embryo encapsulation

Synthetic seed technology may be of value in breeding programs and allow the propagation of many elite genotype-derived plants in a short time. In this work, a range of artificial endosperm treatments of Cleopatra tangerine zygotic embryos were evaluated for suitability for encapsulation of somatic embryos. Different complexing ions in the form of alginate capsules, zeolite as an ion exchanger and the relationship between capsule-nutrient gel on germination of zygotic embryos, were evaluated. Artificial endosperm assays showed that abscisic acid (1 μM) and mannitol (0.25 M) delayed germination and conversion of zygotic embryos, whereas amino acid supplements (proline, glutamic acid and arginine) accelerated the conversion process. An artificial endosperm was used to encapsulate somatic and zygotic embryos. After encapsulation, zygotic embryos germinated after four days of culture while somatic embryos germinated asynchronously after 20 days. Somatic embryo-derived plantlets showed greater vigour than zygotic embryo-derived plantlets. Results showed that this artificial endosperm is adequate for Cleopatra tangerine somatic embryo germination and conversion into plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

Endogenous pararetroviral sequences in tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis>) and related species

Background  

Endogenous pararetroviral sequences (EPRVs) are a recently discovered class of repetitive sequences that is broadly distributed in the plant kingdom. The potential contribution of EPRVs to plant pathogenicity or, conversely, to virus resistance is just beginning to be explored. Some members of the family Solanaceae are particularly rich in EPRVs. In previous work, EPRVs have been characterized molecularly in various species of Nicotiana including N.tabacum (tobacco) and Solanum tuberosum (potato). Here we describe a family of EPRVs in cultivated tomato (Solanum lycopersicum L.) and a wild relative (S.habrochaites).     

Microsatellite variability in apricots (<Emphasis Type="Italic">Prunus armeniaca</Emphasis> L.) reflects their geographic origin and breeding history

A collection of 133 apricot cultivars and three related species originating from different geographical regions were studied with 10 polymorphic microsatellite markers developed in apricot. Altogether, 133 alleles were identified in the set of accessions, with an average of 13.30 alleles per locus. Out of them, 32 alleles occurred only once in the investigated samples, especially in apricots originating from different eco-geographic groups or in different species. The observed heterozygosity for individual loci ranged from 0.8636 to 0.3182, with an average of 0.6281. An unweighted pair group method with arithmetic mean dendrogram based on Nei's genetic distance grouped the accessions according to their eco-geographical origin and/or their pedigree information. Central Asian cultivars have a distinct position on the dendrogram, which supports the assumption that most cultivars have an Asian ancestor. Most East European cultivars analysed cluster together, and the data even revealed a few synonyms. Results show that American cultivars have not only European germ plasm in their pedigree, but they have also been enriched with germ plasm of Asian origin. The implications of these data for the use of simple sequence repeat (SSR) markers as a tool for fingerprinting cultivars in breeders' rights protection and apricot breeding are discussed. In this paper, we demonstrate for the first time the variability of apricot SSRs in a large collection of apricot cultivars and closely related species.