Diversity evolution in a collection of French bread wheat accessions (Triticum aestivum) from the 19th to the 20th century

摘要

A sample of 559 French bread wheat accessions (landraces and registered varieties), cultivated between 1800 and 2000, were evaluated both for agro-morphological traits (plant height, awnedness, frost resistance, disease susceptibility, flowering date,1000-kcrnel weight) and neutral polymorphism at 42 microsatellites loci (one per chromosome arm). When comparing landraces and registered varieties gathered in seven groups according to their registration year, quantitative evolution over time was clearly observed for some agro-morphological traits. For instance, over two centuries of selection, plant height decreased by about 60cm. In the same time and in average, the last registered varieties tended to be earlier in flowering. By contrast, changes inallelic richness related to temporal trends appeared more qualitative than quantitative, except at the end of the sixties where a bottleneck effect might have occurred. Consequences of such results for plant breeders and for managers of crop genetic resources were discussed.