Characterization of twin embryos in almond

6 pages.-- En: ISHS Acta Horticulturae 591: III International Symposium on Pistachios and Almonds.Twin seeds (multiple embryos within the same seedcoat) occur spontaneously in certain almond cultivars including ‘Nonpareil’ and ‘Mission’. The occurrence of these multiple embryos varies greatly and is strongly influenced by environmental conditions. Seedlings from the same twin seed are frequently viable, though often, one of the seedlings shows weak growth and develops poorly. These dwarf seedlings are generally thought to be haploid. In this work, we characterized several seedlings from 'Nonpareil' almond twin seed, including their germination and later growth. Isozyme and Simple Sequence Repeat (SSR) markers were utilized to genetically analyze seedling genetic structure. For isozymes, AAT and PGM were analyzed using horizontal starch gel systems. For SSRs, 3 different markers were assayed using Metaphor agarose gel. In addition, individual (mitotic) karyotypes were determined from staining of root tips. Results suggest that the percentage of twin embryos showing aberrant growth was approximately 36% and that the majority of these aberrant seedlings appear to be aneuploids. The possible origin of these multiple embryos is discussed.Peer reviewe

Relationships among peach, almond, and related species as detected by simple sequence repeat markers

5 pages.The genetic relationships among peach [Prunus persica (L.) Batsch], almond [P. dulcis (Mill.) D.A. Webb or P. amygdalus (L.) Batsch] and 10 related Prunus species within the subgenus Amygdalus were investigated using simple sequence repeat (SSR) markers. P. glandulosa Pall. was included as an outgroup. Polymorphic alleles were scored as present or absent for each accession. The number of alleles revealed by the SSR analysis in peach and almond cultivars ranged from one to three whereas related Prunus species showed a range of one to 10 alleles. Results demonstrated an extensive genetic variability within this readily intercrossed germplasm as well as the value of SSR markers developed in one species of Prunus for the characterization of related species. Mean character difference distances were calculated for all pairwise comparisons and were used to construct an unrooted dendogram depicting the phenetic relationships among species. Four main groups were distinguished. Peach cultivars clustered with accessions of P. davidiana (Carr.) Franch. and P. mira Koehne. The second group contained almond cultivars. A third group included accessions of P. argentea (Lam) Rehd., P. bucharica Korschinsky, P. kuramica Korschinsky, P. pedunculata Pall, P. petunikowii Lits., P. tangutica (Spach) Batal., and P. webbii (Spach) Vieh.. P. glandulosa and P. scoparia Batal. were included in a fourth group.Peer reviewe

An extended interspecific gene pool available to peach and almond breeding as characterized using simple sequence repeat (SSR) markers

10 pages, 5 tables, 2 figures.Genetic diversity, as revealed by eighteenSimple Sequence Repeat (SSR) markers inthirty almond [P. dulcis (Mill.) D.A.Webb], twenty fresh-market peach [Prunus persica (L.), Basch], fifteenprocessing clingstone peach cultivars, andten rootstocks, established the geneticrelatedness among cultivars andcharacterized the variation within andbetween species. One accession each of thewild Prunus species, P.davidiana [(Carriere) Franch] and P.webbii [(Spach.) Vieh.], was included inthe analysis. The number of presumedalleles revealed by the SSR analysis rangedfrom one to six in peach whereas almondcultivars showed a range of three to nine.Peach cultivars clustered into ten groups,which are in general agreement withdocumented origin. Most processingclingstone peach cultivars clusteredseparately from fresh-market freestonecultivars supporting a distinct origin. Twomajor clusters were observed in almond withone containing California cultivars and theother containing European cultivars and theimportant California cultivar Mission.Results establish the value of SSR markersfor distinguishing different geneticlineages and characterize an extensive andlargely unexploited inter-species gene poolavailable to peach and almond breedingprograms.Peer reviewe

Caracterização molecular de cultivares de pessegueiro e nectarineira com microssatélites Molecular characterization of peach and nectarine cultivars though microsatellites markers

Na certificação de mudas de plantas frutíferas, a identificação genética é importante em todas as etapas do processo de produção. Em pessegueiro, a identificação de genótipos baseada somente em características morfofenológicas deixa dúvidas quanto à verdadeira identidade de algumas cultivares. Marcadores moleculares de microssatélies foram utilizados objetivando a caracterização molecular de 8 cultivares de nectarineira e 28 de pessegueiro. Para a análise, foram utilizados 13 incializadores de microssatélites (primers), sendo que todos foram marcadores produzindo polimorfismo suficiente para identificar 32 das 36 cultivares analisadas. A maior similaridade genética verificada nas cultivares para consumo in natura foi entre Coral e Planalto (0,94) e entre Della Nona e Marfim (0,90), enquanto, para os pessegueiros para indústria, foi de 0,93 entre Jubileu e Capdeboscq e de 0,92 entre Jade e Esmeralda. Os marcadores de microssatélites permitiram separar em grupos distintos as nectarineiras e os pessegueiros de consumo in natura dos de indústria, havendo uma elevada concordância entre os dados genealógicos das cultivares e os dados gerados pelos microssatélites, confirmando a grande utilidade da técnica para a caracterização genética.<br>Genetic identification of fruit tree plants is important in all phases of the production process. On peach the genotypes identification based only on the morphologic and phenologic characteristics leaves doubts on the true identity of some cultivars. Microsatellite markers were used aiming at the molecular characterization of eight nectarine and 28 peach cultivars. Thirteen microsatellite primers were used and all of them generated enough polimorfism that may identify 32 out of 36 of the analysed cultivars. The greatest genetic similarity was found between the fresh market 'Coral' and 'Planalto'(0,94) and between the 'Della Nona' and 'Marfim' cultivars (0,90), whereas for caning peaches the similarity was 0,93 between the 'Jubileu' and 'Capdeboscq' cultivars and 0,92 between the 'Jade' and 'Esmeralda' ones. The microsatellite markers made possible to separate into distinct groups of the nectarines and fresh market peaches from those caning cultivars that showed a high agreement among genealogical data and those of microsatellite markers that confirm tha this technique is useful for genetic characterization

Development of an SSR-based identification key for Tunisian local almonds

19 Pags., 4 Figs., 2 Tabls.Ten simple sequence repeat (SSR) loci were used to study polymorphism in 54 almond genotypes. All genotypes used in this study originated from almond-growing areas in Tunisia with different climatic conditions ranging from the sub-humid to the arid and are preserved in the national collection at Sidi Bouzid. Using ten SSR, 130 alleles and 250 genotypes were revealed. In order to develop an identification key for each accession, the data were analysed separately for each microsatellite marker. The most polymorphic microsatellite (CPDCT042) was used as a first marker. Two microsatellite loci (CPDCT042 and CPDCT025) were sufficient to discriminate among all accessions studied. Neighbour-joining clustering and principal coordinate analysis were performed to arrange the genotypes according to their genetic relationships and origin. The results are discussed in the context of almond collection management, conformity checks, identification of homonyms, and screening of the local almond germplasm. Furthermore, this microsatellite-based key is a first step toward a marker-assisted identification almond database.Financial support was provided in part by the Tunisian Ministry of Higher Education, Scientific Research and Technology, the Spanish Ministry of Science and Innovation (AGL2008-00283/AGR co-financed by FEDER), the Aragon Government (Group A44), and the Agencia Española de Cooperación Internacional (A/5339/06 and A/8334/07).Peer reviewe