Françoise Dosba

The use of molecular markers for germplasm management in a French olive collection.

Abstract.With more than 100 accessions, the CBNMP olive collection includes a major part of the French germplasm. We used molecular markers to characterise all accessions and to study genetic relationships between cultivars. Firstly, 497 olive trees were genotyped using 32 RAPD markers. We identified 114 RAPD profiles and detected several cases of mislabelling, synonymy and homonymy. Secondly, for each RAPD profile, one tree was analysed using mtDNA RFLPs to determine the cytoplasmic lineage of each cultivar and using five nuclear SSR loci. French germplasm displayed ME1, MOM and MCK mitotypes with ME1 prevailing (84%). Based on SSR markers, we revealed a slight differentiation between French cultivars growing in the West and the East side of the Rhône Valley. This study allowed us to construct a molecular data-base for the reference collection and to analyse genetic diversity for further prospecting, and for introducing new olive accessions.

Study of wheat phylogeny by coRI analysis of chloroplastic and mitochondrial DNAs

Summary Electrophoregrams of DNA fragments obtained after EcoRI specific cleavage of chloroplastic (cp) and mitochondrial (mt) DNAs isolated from diploid, tetraploid and hexaploid wheat species are compared. HexaploidTriticum aestivum, tetraploidsT. turgidum andT. timopheevi and diploidAegilops speltoides appear to be characterized by an identical chloroplastic genome and can be differentiated from diploidsT. monococcum andAe. squarrosa. Considering the mitochondrial genome,T. aestivum andT. turgidum are similar, butT. timopheevi, T. monococcum, Ae. squarossa andAe. speltoides present a distinct diagram each. Consequently, the B genome of wheat cannot have originated from contemporaryAe. speltoides.

In vitro adventitious shoot regeneration from leaves of Prunus spp.

Abstract A high level of adventitious shoot regeneration was obtained from proliferating shoots in vitro for a range of Prunus spp. There was a significant variability in clone response to a range of adventitious shoot regeneration treatments. Treatment of apricot clone H.152 with Quoirin macroelements (C.R. Rech., Stu. Cult. Fruit. Maraicheres Gemblaux (1977) 93–117), and both apricot clone H.146 and hybrid plum clone P.1869 with half-strength Murashige and Skoog medium, consistently induced regeneration. Thidiazuron (TDZ) alone, or in combination with naptthaleneacetic acid (NAA), was most effective in stimulating adventitious shoot production, the optimum concentration being clone-dependent. Addition of silver nitrate (AgNO3) to regeneration media enhanced regeneration by 10–40% and reduced the variability between experiments. Regeneration with AgNO3 was obtained also for three other plum clones belonging to the P. marianna, P. domestica and P. insititia species.

Studies on maternal inheritance in polyploid wheats with cytoplasmic DNAs as genetic markers

SummaryRestriction fragment patterns of DNA fragments obtained after EcoRI cleavage of chloroplastic (cp) and mitochondrial (mt) DNAs isolated from different wheat species were compared. T. aestivum, T. timopheevi, Ae. speltoides, Ae. sharonensis and T. urartu gave species specific mt DNA patterns. Consequently, the cytoplasmic genomes of wheat cannot have originated from contemporary Ae. speltoides, Ae. sharonensis and T. urartu species. It is shown that cp and mt DNAs of Ae. ventricosa, a tetraploid used to transfer eyespot resistance into T. aestivum, contains cp and mt DNAs differing from DNAs isolated from T. aestivum and other wheats. In contrast, the cytoplasmic DNAs of Ae. ventricosa and Ae. squarrosa reveal an important homology, suggesting that Ae. squarrosa was the female parent of Ae. ventricosa. Disomic addition lines (T. aestivum — Ae. ventricosa) in both Ae. ventricosa cytoplasm and T. aestivum cytoplasm contained cytoplasmic DNAs identical to those of the maternal parent. Restriction patterns of the cp and mt DNAs isolated from eight lines of Triticale differing in their cytoplasm have been compared to those of the maternal parent. A strict maternal inheritance has been observed in each case.

Cryopreservation of in vitro grown shoot tips of two interspecific Prunus rootstocks

Abstract Shoot tips of two in vitro grown interspecific Prunus rootstocks, Fereley-Jaspi (R) and Ferlenain-Plumina (R), were successfully cryopreserved using a two step freezing method. Excised shoot tips from hardened plantlets were precultured for 24 h on solid medium (modified half strength Murashige and Skoog medium (MS)) supplemented with 5% dimethylsulfoxide and 2% proline. They were transferred to 1.2-ml cryotubes and treated with 0.5 ml of modified PVS2 cryoprotective solution for 20–40 min. Cryotubes were then cooled at 1°C/min to −40°C before being immersed in liquid nitrogen (LN 2 ). After 1 min warming at 40°C, shoot tips were rinsed with MS medium containing 1.2 M sucrose and then plated. First regrowth occurred after 5 days and was evaluated 21 days after plating. The average rate of shoot formation was 69% and 74% for Fereley and Ferlenain respectively, compared with 86% for controls of both hybrids. The roles of several factors, especially hardening procedures and meristem size, in the improvement of survival rates, were discussed.

Prunus genetic resources in Europe: Achievement and perspectives of a networking activity

Under the auspices of IPGRI (International Plant Genetics Resources Institute) and with the support of European Union from 1996 to 1999, a European network on Prunus Genetic resources has been progressively organized in the context of European Cooperative Programme for Crop Genetic Resources Networks (ECP/GR). More than 20 countries are involved in the survey of national collections, the elaboration of the different descriptors for their documentation, and the development of the European Prunus database (EPDB). At present, the permanent collections gathered more than 8000 accessions for which passport and characterization data are registered in the EPDB. EPDB has been made available on the Internet. The objectives of the Prunus working group are to define and implement the European Prunus Collection (ECP) on the basis of a common strategy for the Rosaceae fruit groups.

STUDYING THE GENETIC DETERMINISM OF OLIVE TREE ARCHITECTURE IN A F1 PROGENY 'OLIVIÈRE' × 'ARBEQUINA'

Tree architecture is of major importance for the agronomic performance of fruit tree orchards. It influences tree adaptability to cultivations systems, but also yields and fruit quality. In the present study, we aim at investigating the genetic determinism of architectural traits in the olive tree. A F1 hybrid population was created between two genotypes with contrasted architectures, ‘Oliviere’ and ‘Arbequina’. A phenotyping methodology was applied to analyze traits related to growth, branching and fruiting behaviour, that were measured during the first 4 years of tree growth. Taking into account the influence of tree ontogeny, the phenotypic variability was decomposed into genotypic and residual effects in order to identify the most heritable characters. Topological and geometrical variables showed relatively low to medium broad sense heritability values. The highest heritability values were found for the number of internodes and short laterals per growth unit, and the mean internodes length with H2 value greater than 0.5. Flowering variables showed high heritability values exceeding 0.6. A first QTL (quantitative trait loci) was detected for the number of lateral inflorescences, on the basis of a framework genetic map constructed with 44 SSR loci and 494 AFLP markers.