Apricot susceptibility to blossom brown rot (Monilia spp.) and leaf rust (Tranzschelia spp.) under low-input production system

Disease-susceptibility of apricot cultivars is a key-stone towards low-input production systems. Among the main diseases, the susceptibility to Monilinia spp. and leaf rust of apricot cultivars are economically important but rarely assessed. A 5-years study in two sites was conducted to assess the susceptibilities to Monilinia spp. and leaf rust of 16 apricot cultivars under natural conditions (no inoculation). No fungicide and insecticide were applied during the experiment. In Torreilles site, no significant Monilinia spp. was observed. In Gotheron site, the percentage of shoots necrosed by Monilinia spp. ranged from 13% to 100% during 2010-2011. A Genotype x Environment interaction was observed for Monilinia spp. damages. Concurrently a high variability to leaf rust was observed in both sites. The ranking of cultivars susceptibility to leaf rust was similar between both site

Linkage map saturation, construction, and comparison in four populations of Prunus

One of the objectives of the ISAFRUIT Project was to perform genetic analyses in four populations of Prunus, two of peach (P. persica) and two of apricot (P. armeniaca), in order to identify major genes and quantitative trait loci (QTLs) for characters related to fruit quality. This required the construction of saturated marker maps in each of these populations. Marker maps were available for an intra-specific peach X peach F(2), a BC(2) peach X P davidiana (using peach as the recurrent parent), and an apricot X apricot F(1). We have further saturated these maps mainly with SSR (simple sequence repeat) markers. A new map, constructed uniquely from SSRs was prepared for a fourth apricot X apricot F(1) population. Using anchor markers, we compared these four maps with the reference Prunus map, constructed using an almond X peach F(2) population. As previously observed, conservation of synteny and co-linearity were the general rule, providing additional evidence of the high level of similarity between all Prunus genomes. Comparisons of genetic distances between the maps suggested that those involving similar genomes had higher levels of recombination than those with more distant genomes, particularly the inter-specific crosses

Genetic structure of mediterranean apricots by ssr fingerprinting

Apricot (Prunus armeniaca L.) is an important fruit species especially in the Mediterranean basin area. The genetic structure of apricot cultivars in this region was studied in order to shed light on the evolutionary history of this species. A sample of 207 patrimonial accessions was collected from different Mediterranean countries: Algeria, France, Italy, Morocco, Tunisia, Turkey, and Spain. Molecular characterization was performed using 25 SSR markers, selected according to high level of polymorphism, transferability between Prunus species, and localisation over the eight linkage groups of the Prunus genome. Statistical treatment of the dataset was undertaken using a model-based Bayesian clustering analysis implemented in the STRUCTURE program. It allowed assignment of the studied accessions into four distinct genetic clusters (Fst=0.122). A gradient of decreasing genetic diversity from the east to the south-west of the Mediterranean area was also evidenced. An interesting new pattern based on the discrimination of a ‘Maghreb’ cluster was revealed for the first time. These results clearly open new research lines dealing with the establishment of a nested core collection at the Mediterranean level, and with the prospective development of genetic association studies

Optimisation of apricot breeding by a joint conventional and molecular approach applied to the main agronomics traits

Preliminary results of the European ABRIGEN (FAIR6 CT98-4345) are presented. The general objective is the optimization of the apricot selection methodology in order to improve breeding strategies. It is based on a multidisciplinary research dedicated to the genetic determinism of the main agronomic traits, the quality of the fruit and the resistance to major diseases. It is mainly focus on: (i) the inheritance of the major agronomic traits, fruit quality and resistance to sharka and bacteriosis; (ii) the analysis of possible linkages or associations between traits; (iii) the identification of associated molecular markers. The work is based on the analysis of a 9x9 diallel cross, with 61 families and more than 3700 offspring. Teams including geneticists, development biologists, plant pathologists, physiologists and molecular biologists have been joined to reach the objective

Prospection characterisation and assessment of apricot genetic resources in the mediterranean region for the production in arid and semi-arid areas

Under the frame of an EEC - INCO-DC programme, 'APRIMED' research project is under development with the objective to characterize, to preserve and to identify the apricot genetic resources in part of the Mediterranean Region (Turkey, Spain, Italy, France, Morocco and Tunisia). An integrated and multidisciplinary approach divided in 3 main tasks has been developed. Prospection and preservation of genetic resources - During the prospection, 103 accessions have been identified in Morocco and 58 in Tunisia; while the preservation of 430 clones has been performed in France, 279 in Italy and 94 in Turkey. Characterization - A phenotypic characterization under UPOV descriptor has been achieved on 204 clones. A molecular characterization has been applied onto a set of 83 accessions by means of 4 microsatellites. Assessment of agronomic performances - The agronomic value has been accessed onto a total of 242 clones and partly investigated on 158 clones - Flower fertility has been investigated on the productive clones. Male sterility and interincompatibility groups have been identified. Chilling requirements and Floral anomalies measurements were optimized and applied to the germplasm. Fruit quality traits have been characterized in France, Italy, Tunisia and Turkey. Resistance to pest and disease has been characterized on a part of the gene-pool against sharka, Monilia and Capnodis tenebrionis