Mediterranean agriculture has to face great challenges to overcome global warming and improve farming system sustainability while maintaining crop production and quality. Turnips (Brassica rapa) and cabbages (Brassica oleracea), which largely contribute to food production worldwide, are native of the Mediterranean basin. This geographical region comprises a large diversity of landscapes and exhibits highly contrasted environmental conditions (climate, soils and biotic factors). The phenotypic and genetic variations of natural populations or traditionally cultivated populations growing along these environmental gradients have been shaped by the local environmental contexts under highly contrasted environments from the North of Europe to Saharan regions. This diversity has been poorly explored. We propose in the BrasExplor project to explore the genetic basis of plant adaptation to different climatic constraints. The project will combine the different skills of eleven partners belonging to six different countries. Collects will be performed along the climatic gradient with a precise description of contrasted environmental conditions, edaphic and microbiome composition of the soil. From 100 populations of cabbages (B. oleracea) and 100 of turnips (B. rapa), we will sequence (Next Generation Sequencing) each population in bulk for genome-wide scans, looking for associations between nucleotide polymorphisms and environmental variables, including soil composition. More precisely, we will finely search for genetic determinants of adaptation to suboptimal conditions. These results will thereafter be experimentally validated (under controlled conditions) for water and temperature stress, as well as in contrasted field conditions for different traits. From these experiments, we will propose to produce prebreeding populations as genetic sources for variety breeding adapted to each country and the promotion of local landraces.
We propose to explore the unknown diversity of two economically important vegetable species of the Brassica genus, B. oleracea and B. rapa growing from North of France to South of North Africa, by collecting more than 100 populations of each species collected on a large geographic and climatic gradient. More precisely, we are collecting locally cultivated varieties such as cauliflower, broccoli, cabbage, kale, kohlrabi for B. oleracea and turnip or turnip rape for B. rapa. In addition, we are collecting wild populations of these two species across a broad environmental gradient encompassing climate and soil variation. From this unique plant material, the goal is to determine the genetic basis of plant adaptation in order to combine favorable alleles in prebreeding populations adapted to each climatic condition. For economic development, crosses will allow production of adapted prebreeding populations as source of future adapted varieties for each country and the promotion of local landraces according to the climatic and soil variations.
This broad sampling of the wild populations and local landraces from two species, B. oleracea and B. rapa along a climatic and soil gradient will be used to (i) characterize the genetic diversity (population structure, core collections) through sequencing data, (ii) identify genomic regions and genes involved in the adaptation of B. oleracea and B. rapa to environmental variations and the genetic bases of the traits underlying local adaptation, (iii) develop new agronomic material with relevant traits in the context of climate change for both Brassica species and (iv) promote local varieties.
The major impact of the project will be the preservation of natural and local resources and optimization of the use of this diversity in the context of global change for Brassica vegetables. The detailed assessment of local landraces will allow (i) the preservation of endangered varieties, (ii) the development of niche market appropriate to small-scale farming systems from well-adapted varieties corresponding to local uses. It is expected that this collaborative work will highlight the interest for specific varieties that are associated with the Mediterranean diet. They will be presented to farmers and consumers with publication of adapted cooking recipes book. They will be deposited in Genetic Resource Centers (BrACySol in France, KIS in Slovenia) following the international protocols. From the data obtained, we will build core-collections for both species maximizing allelic and adaptive diversity. These collections will be tested in the different countries offering the opportunity to identify the most relevant diversity in each environment for further uses. The identification of soil microbiota-plant interaction genetic bases will allow in perspective studies to: i) select for microbial communities protecting Brassica species to environmental fluctuations or extreme conditions, ii) breed new varieties with the ability to select for beneficial bacterial responsible for the uptake of key-nutrients and helping plants to adapt to climate change. Sequencing of each population and identification of genomic regions involved in the response to different abiotic stresses will open the avenue for new breeding strategies through marker-assisted selection. Communication (website, twitter, meetings…) of the results will be presented to the different actors, breeders, farmers, consumers in addition to the scientific community. Academic formation will be proposed to students.
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