Quelle sélection fruitière pour une production durable, à faible niveau d’intrants ? Méthodologie pour un réseau de sélection variétale décentralisée

In France Fruit production is cultivated on 140 thousand hectares, mainly conducted on intensive training system. Very few elements are available on low input training systems while they have to integrate the Global rule under the frame of Ecophyto 2018. In order to evaluate if another system of cultivation will be possible, a project has been developed to highlight the main factors to be integrated in low input training system. A low input multilocal experimental design has thus been investigated on apricot in two main regions of production: Rhone valley and Roussillon. A set of 9 common cultivars with 20 replications each, planted in a complete single-tree randomization design has been established. As already observed in apple orchard, a larger set of disease has been observed in our experimental plots by comparison with conventional training orchards. A large genetic variability has been set-up among the observed cultivars, but if some of them expressed components of resistance against the observed diseases no one appeared widely resistant to all the diseases. Taking in consideration the longevity of the orchard, a huge concern exists with the tested germplasm because the observed dieback was in between 10 and 80% of the trees according to the cultivars after only 6 years of observation. On the methodological point of view, a clear optimization of the experimental design is expected on the base of the observed results

Prunus - Réalités et perspectives de l'écologisation en arboriculture fruitière: Pour une approche intégrée à partir des cas des vergers de pêchers et d'abricotiers en Rhône-Alpes 2013-2015

Le projet « PRUNUS- Réalités et perspectives de l’écologisation en arboriculture fruitière » a été financé par le programme Pesticides* du ministère de l’environnement sur la période 2013-2015 avec pour objectif d’identifier les effets de verrouillage et les leviers de transition vers une écologisation des pratiques agricoles (réduction des pesticides) dans les vergers de pêchers et d’abricotiers de la basse Vallée du Rhône

Assessment of diseases susceptibility of peach cultivars in experimental plots and on-farm for organic and low-input systems. Baseline of French case studies

Despite a high turn-over of new peach cultivars, their suitability for organic and low-input systems remains unknown for most of them. Diseases susceptibility is an important criteria to consider since diseases control is a bottleneck to peach production in theses systems. Since 2001, 81 peach cultivars were assessed in 2 experimental sites and 7 on-farm plots

Loss of genetic diversity as a signature of apricot domestication and diffusion into the Mediterranean Basin

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699In order to reduce energy waste for artificial lights and subsequent air conditioning in plant growth chambers, the aim of this preliminary study was to evaluate the feasibility of growing the microvine under 100% of LED illumination. Plant growth under two different LED lights was compared amongst each other and with plants maintained in greenhouse conditions. Regarding the impact on the reproductive and vegetative systems, the study showed that LED light is suitable to grow microvines in confined environments. Plants exposed to LED light exhibited similar leaf emergence rate but reduced vegetative and reproductive organ size compared to plants grown in the greenhouse. Photosynthesis for plants exposed to LED light was higher than what is usually observed on grapevine under natural conditions

Phenolic compounds identified in apricot branch tissues and their role in the control of Monilinia laxa growth

Secondary metabolites, such as phenolics, are plant defence substances. In the present study, the impact of Monilinia laxa inoculation under controlled conditions on phenolic content of apricot branches was investigated. A bi-parental hybrid population issued from Bergeron and Bakour cultivars (BerBa) and consisting of 192 hybrids was studied. The susceptibility of the BerBa population to M. laxa was evaluated by measuring the length of the necrosed tissues and the concentration of fungal DNA by qPCR in the branches 8 days post-inoculation. The results exhibit significant differences between the two parental cultivars in terms of necrosis length, which confirm their different susceptibility to the pathogen. A considerably high content of 2′,6′-dihydroxy-4′–methoxyacetophenone hexoside was found in branch tissues of Bakour (tolerant parental cultivar), amounting to 1.72 mg/g and 1.41 mg/g of fresh weight in non-inoculated and inoculated samples, respectively. The content of this compound in Bergeron branch tissues was several times lower, amounting to 0.24 mg/g and 0.14 mg/g of fresh weight in non-inoculated and inoculated samples, respectively. In the inoculated branches, scopolin was almost twice as abundant in the tolerant parental cultivar branch tissues as in the susceptible ones. In general, after inoculation a lower content of phenolic compounds was observed for hybrids with longer necrosed tissue. A Principal Component Analysis showed that at 8 days post-inoculation M. laxa concentration in the branches and the content of phenolic compounds, such as scopolin and chlorogenic acids, were negatively correlated. Additionally, the antifungal activity of pure phenolic compounds against M. laxa mycelial growth and spore germination was investigated. At a concentration of 500 mg/L, up to 40 % inhibition of M. laxa mycelial growth by scopoletin, up to 60 % inhibition by 2′,4′,6′-trihydroxyacetophenone and total inhibition by 2′-hydroxy-4′-methoxyacetophenone was observed. Scopoletin and 2′,4′,6′-trihydroxyacetophenone also inhibited spore germination by about 50 %. These results can serve to improve breeding programs aiming to develop apricot cultivars resistant to brown rot blossom blight

Future development of apricot blossom blight under climate change in Southern France

International audienceClimate change will have several consequences for agro-systems, one of which will concern changes to the development of pathogens. Because of the losses it causes, particularly in organic farming, Monilinia laxa is an important pathogen affecting apricot crops. This study focuses on the consequences of climate change regarding blossom and twig blight (Monilinia laxa) of apricot. To achieve this, a Climatic Index of cumulated Blight risk (CIB) was built, to obtain the weighted sum of blossom blight incidence throughout the blooming period. An epidemiological model to calculate the incidence of blossom blight during every potentially infectious episode and based on biological parameters, was calibrated using a trap pot experiment where trees were placed in orchards and subject to various meteorological conditions. The CIB derived from this model was evaluated on field data, and was shown to be a robust and useful tool to predict the effects of climate change on the development of apricot blight. Then, using the CIB with a phenological model to predict blooming periods in the future, we estimated the risks of apricot blight until 2100 on four contrasted apricot cultivars and in three geographical zones under climate change scenarios RCP 4.5 and 8.5. This study revealed different effects of climate change depending on the cultivar and altitude. Apricot trees would bloom earlier (up to a difference of 50 days between 1950 and 2100) under climate change. Under the combined effects of these shifts of blooming period and changing climatic conditions, late cultivars such as Bergarouge might see a reduction in the risk of blossom blight (down to 31%) because of warmer but dryer blooming periods. Other varieties (e.g.: Bergeron) could experience an increase in this risk by up to 27% with a shift of the blooming period towards rainier conditions at the highest altitudes. The results of this study could be used to anticipate future changes as well as be used at present as a decision-support tool for farmers

Evaluer la sélection génomique au sein de croisements bi-parentaux d’espèces pérennes fruitières génotypés par séquençage : point d’étape du projet FruitSelGen

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Grafting versus seed propagated apricot populations: two main gene pools in Tunisia evidenced by SSR markers and model-based Bayesian clustering

Apricot was introduced into the Mediterranean Basin from China and Asian mountains through the Middle-East and the Central Europe. Traditionally present in Tunisia, we were interested in accessing the origin of apricot species in the country, and in particular in the number and the location of its introductions. A set of 82 representative apricot accessions including 49 grafted cultivars and 33 seed propagated ‘Bargougs’ were genotyped using 24 microsatellite loci revealing a total of 135 alleles. The model-based Bayesian clustering analysis using both Structure and InStruct programs as well as the multivariate method revealed five distinct genetic clusters. The genetic differentiation among clusters showed that cluster 1, with only four cultivars, was the most differentiated from the four remaining genetic clusters, which constituted the largest part of the studied germplasm. According to their geographic origin, the five identified groups (north, centre, south, Gafsa oasis and other oases groups) enclosed a similar variation within group, with a low level of differentiation. Overall results highlighted the distinction of two apricot gene pools in Tunisia related to the different mode of propagation of the cultivars: grafted and seed propagated apricot, which enclosed a narrow genetic basis. Our findings support the assumption that grafting and seed propagated apricots shared the same origin

The quasi-universality of nestedness in the structure of quantitative plant-parasite interactions

Understanding the relationships between host range and pathogenicity for parasites, and between the efficiency and scope of immunity for hosts are essential to implement efficient disease control strategies. In the case of plant parasites, most studies have focused on describing qualitative interactions and a variety of genetic and evolutionary models has been proposed in this context. Although plant quantitative resistance benefits from advantages in terms of durability, we presently lack models that account for quantitative interactions between plants and their parasites and the evolution of these interactions. Nestedness and modularity are important features to unravel the overall structure of host-parasite interaction matrices. Here, we analysed these two features on 32 matrices of quantitative pathogenicity trait data gathered from 15 plant-parasite pathosystems consisting of either annual or perennial plants along with fungi or oomycetes, bacteria, nematodes, insects and viruses. The performance of several nestedness and modularity algorithms was evaluated through a simulation approach, which helped interpretation of the results. We observed significant modularity in only six of the 32 matrices, with two or three modules detected. For three of these matrices, modules could be related to resistance quantitative trait loci present in the host. In contrast, we found high and significant nestedness in 30 of the 32 matrices. Nestedness was linked to other properties of plant-parasite interactions. First, pathogenicity trait values were explained in majority by a parasite strain effect and a plant accession effect, with no parasite-plant interaction term. Second, correlations between the efficiency and scope of the resistance of plant genotypes, and between the host range breadth and pathogenicity level of parasite strains were overall positive. This latter result questions the efficiency of strategies based on the deployment of several genetically-differentiated cultivars of a given crop species in the case of quantitative plant immunity