Étude des complémentarités entre gestion dynamique à la ferme et gestion statique en collection: Cas de la variété de blé Rouge de Bordeaux

National audienceWhile on-farm conservation was considered minor in the development of the National Charter on Genetic Resources in 1998, there is increasing recognition of its important role in the conservation of genetic diversity. In addition to amateur gardening associations that save and exchange seeds, farmers in France have formed networks around systems of shared seed conservation and exchanges, with the goal of protecting the diversity of cultivated species. Parallel to this, the contribution of farmers to the dynamic management of agricultural biodiversity has been recognized by many scientific studies and in international treaties. These developments led us to examine the complementary nature of on-farm and gene-bank conservation efforts in terms of the management of genetic resources. This study, which combines ethnobotanical and genetic approaches, was conducted on bread wheat, for which France has a national collection of 10 000 accessions. There is also an active network of farmers who cultivate historic varieties and landraces, including the Rouge de Bordeaux, which was chosen for a detailed study. By conducting individual interviews with farmers, we were able to understand better their management practices, seed exchanges with other farmers and with the national collection, and strategies for maintaining and selecting this variety on their own farms. We characterized the genetic diversity conserved by several farmers and in the samples preserved in the national collection for Rouge de Bordeaux by using a comparative genetic analysis of samples obtained from farmers and from the collection, in light of the management practices and exchange networks that exist among farmers and between farmers and the national collection. Our results demonstrate that the diversity of these populations is far from being redundant. While certain samples are quite homogeneous and similar to samples from the national collection, others are highly heterogeneous. There is also a high degree of genetic differentiation among populations, with clear groupings of populations identified. The structure of the diversity may be explained by the structure of exchanges and the development of local adaptation within the populations to environmental conditions and management practices, and by differing strategies of selection and conservation. Further analysis will help us understand more precisely what defines a variety and what type of genetic diversity or phenotypic traits are conserved with different management strategies. Our results also support a greater degree of seed circulation between farmers' fields and the national collection, to conserve the adaptive potential and a broader range of genetic diversity for each variety.Considérée comme mineure lors de la rédaction de la Charte nationale des ressources génétiques en 1998, la gestion à la ferme a depuis gagné en importance et en reconnaissance. En effet, après les associations de jardiniers amateurs, des réseaux d'agriculteurs se sont fédérés en France autour de systèmes mutualistes de sélection/conservation de la diversité cultivée. Parallèlement, la contribution des paysans à la gestion dynamique de l'agrobiodiversité a été scientifiquement et institutionnellement reconnue. Ces éléments nous ont conduit à examiner les complémentarités dans la gestion des ressources génétiques à la ferme et en collection. Cette étude, qui croise des approches ethnobotanique et génétique, a été menée sur le blé tendre pour lequel il existe en France une collection nationale de 10 000 accessions et un réseau actif d'agriculteurs-collectionneurs de variétés. Pour la variété Rouge de Bordeaux, nous avons tenté de caractériser la diversité dans les champs et en collection, en procédant à une analyse génétique d'échantillons obtenus auprès d'agriculteurs et auprès de la collection. Nos résultats montrent que les ressources génétiques conservées dans les deux compartiments sont loin d'être redondantes. La structuration de la diversité s'explique par les réseaux d'échanges de semences (entre paysans, et entre les paysans et la collection), par l'adaptation locale des populations aux conditions du milieu et aux pratiques de culture, et par les pratiques de sélection/conservation. Ces résultats appellent des analyses complémentaires pour comprendre précisément ce qui est conservé/cultivé sous un nom variétal donné, et plaident en faveur d'une circulation accrue des semences entre champs et collection

Set up of a methodology for participatory plant breeding in bread wheat in France

In Organic Agriculture, cultivation environments and agronomic practices are very diverse. This diversity can be handled with decentralized selection based on the knowledge of farmers and scientists. A collaborative work between associations from Réseau Semences Paysannes and the DEAP team from INRA du Moulon set up an innovative breeding approach on farm based on decentralization and participation of farmers. This approach makes it possible to (i) create new population varieties of bread wheat locally adapted (genetic innovation) (ii) set up an organizational scheme based on decentralization and co construction between actors (societal innovation) and (iii) develop experimental designs, create statistical and data management tools which stimulate these genetic and societal innovations

Rapid Differentiation of Experimental Populations of Wheat for Heading Time in Response to Local Climatic Conditions

• Background and Aims Dynamic management (DM) of genetic resources aims at maintaining genetic variability between different populations evolving under natural selection in contrasting environments. In 1984, this strategy was applied in a pilot experiment on wheat (Triticum aestivum). Spatio-temporal evolution of earliness and its components (partial vernalization sensitivity, daylength sensitivity and earliness per se that determines flowering time independently of environmental stimuli) was investigated in this multisite and long-term experiment

Flowering time trait, gene and microsatellite differentiation among experimental populations of wheat

International audienc

Flowering time trait, gene and microsatellite differentiation among experimental populations of wheat

International audienc

Data from: Diversifying mechanisms in the on-farm evolution of crop mixtures

While modern agriculture relies on genetic homogeneity, diversifying practices associated with seed exchange and seed recycling may allow crops to adapt to their environment. This socio-genetic model is an original experimental evolution design referred to as on-farm dynamic management of crop diversity. Investigating such model can help in understanding how evolutionary mechanisms shape crop diversity submitted to diverse agro-environments. We studied a French farmer-led initiative where a mixture of four wheat landraces called ‘Mélange de Touselles’ (MDT) was created and circulated within a farmers' network. The 15 sampled MDT subpopulations were simultaneously submitted to diverse environments (e.g. altitude, rainfall) and diverse farmers' practices (e.g. field size, sowing and harvesting date). Twenty-one space-time samples of 80 individuals each were genotyped using 17 microsatellite markers and characterized for their heading date in a ‘common-garden’ experiment. Gene polymorphism was studied using four markers located in earliness genes. An original network-based approach was developed to depict the particular and complex genetic structure of the landraces composing the mixture. Rapid differentiation among populations within the mixture was detected, larger at the phenotypic and gene levels than at the neutral genetic level, indicating potential divergent selection. We identified two interacting selection processes: variation in the mixture component frequencies, and evolution of within-variety diversity, that shaped the standing variability available within the mixture. These results confirmed that diversifying practices and environments maintain genetic diversity and allow for crop evolution in the context of global change. Including concrete measurements of farmers' practices is critical to disentangle crop evolution processes

La gestion dynamique à la ferme en contexte d'agriculture industrialisée: un modèle original d'implication sociétale auto-organisée.

National audienc

Experimental Estimation of Mutation Rates in a Wheat Population With a Gene Genealogy Approach

Microsatellite markers are extensively used to evaluate genetic diversity in natural or experimental evolving populations. Their high degree of polymorphism reflects their high mutation rates. Estimates of the mutation rates are therefore necessary when characterizing diversity in populations. As a complement to the classical experimental designs, we propose to use experimental populations, where the initial state is entirely known and some intermediate states have been thoroughly surveyed, thus providing a short timescale estimation together with a large number of cumulated meioses. In this article, we derived four original gene genealogy-based methods to assess mutation rates with limited bias due to relevant model assumptions incorporating the initial state, the number of new alleles, and the genetic effective population size. We studied the evolution of genetic diversity at 21 microsatellite markers, after 15 generations in an experimental wheat population. Compared to the parents, 23 new alleles were found in generation 15 at 9 of the 21 loci studied. We provide evidence that they arose by mutation. Corresponding estimates of the mutation rates ranged from 0 to 4.97 × 10−3 per generation (i.e., year). Sequences of several alleles revealed that length polymorphism was only due to variation in the core of the microsatellite. Among different microsatellite characteristics, both the motif repeat number and an independent estimation of the Nei diversity were correlated with the novel diversity. Despite a reduced genetic effective size, global diversity at microsatellite markers increased in this population, suggesting that microsatellite diversity should be used with caution as an indicator in biodiversity conservation issues

Типовая учебная программа для высших учебных заведений по специальности 1-23 01 12 Музейное дело и охрана историко-культурного наследия

Because of the lack of varieties for organic agriculture, associations of organic farmers in several European countries have begun cultivating landraces and historic varieties, effectively practicing in situ conservation of agricultural biodiversity. To promote agrobiodiversity conservation, a special list for ‘‘conservation varieties’’ was implemented in 2008 by the EU because for any exchange and marketing of seeds in the EU, a variety must be registered in an official catalog. Our study aimed at improving knowledge on the phenotypic diversity and evolution of such varieties when cultivated on organic farms in Europe, in order to better define their specific characteristics and the implications for the registration process. We assessed multi-trait phenotypic evolution in eight European landraces and historic varieties of bread wheat and in two pureline variety checks, each grown by eight organic farmers over 2 years and then evaluated in a common garde experiment at an organic research farm. Measurements on each farmer’s version of each variety included several standard evaluation criteria for assessing distinctness, uniformity and stability for variety registration. Significant phenotypic differentiation was found among farmers’ versions of each variety. Some varieties showed considerable variation among versions while others showed fewer phenotypic changes, even in comparison to the two checks. Although farmers’ variety would not satisfy uniformity or stability criteria as defined in the catalog evaluation requirements, each variety remained distinct when assessed using multivariate analysis. The amount of differentiation may be related to the initial genetic diversity within landraces and historic varieties