One of the proven solutions to adapt to Climate Change is varietal improvement. However, due to long life cycles and environmental sensitivity, breeding of Fruit tree crops as coffee or cocoa, is a formidable challenge, and breeders generally lack the capacity to generate new cultivars quickly in response to a crisis.

In addition, the selection of the aerial parts of a plant for resilience while simultaneously maintaining commercial attributes of products (e.g. shapes, sizes, colours, flavours,etc.) unaffected is both technically and economically demanding.

 Moreover, the underground parts have never been a target for FTC resilience to CC4, presumably because of the difficulty of profiling root system architecture in Fruit Tree Crops.

Rootstock can confer enhanced tolerance to abiotic and biotic stressors, providing a valuable mechanism to improve and expand Fruit Tree Crop cultivation and global food production in the face of Global warming.
BOLERO’s main goal is to optimize Root system architecture traits allowing Fruit tree crop abiotic resilience and sustainability by devising new ways of Fruit tree crop rootstock breeding. For this, we will use coffee (Coffea canephora, i.e. Robusta) as a model and cocoa as a validation of our tools’ adaptability.

The Objectives of BOLERO are the following :

1. Understand root-based traits
2. Enhance capacities for root phenotyping
3. Develop strategies for breeding with more effective interactions
4. Use and valorise genetic resources
5. Develop more tolerant crops and trees

Expected achievements :

• Understand coffee and cocoa RSA, root biomass and its temporal dynamics and RSA translation from seedling to adult stage.
• Identify which RSA traits are advantageous for plant growth, drought tolerance, grafting recovery mechanisms water and nitrogen use efficiency.
• Identify candidate genes for RSA traits plasticity to abiotic stresses.
• Unravel the importance of root microbiota in the cultivation of coffee and cocoa and how this knowledge can be incorporated in future breeding for microbiome-optimized tree crops.
• Suitability of automated modern phenotyping systems to resolve the dynamics of RSA in tree species at a young plant stage.
• Optimized image analysis tools suitable for coffee and cocoa based on deep learning for application to other tree species.
• Suitability of RSA plasticity observation by scanning roots in vivo in natural soil under contrasting field conditions.
• Information on comparability of RSA traits across the different phenotyping approaches, environments and plant growth stages will enhance knowledge on tree root system plasticity and identify most relevant tree RSA traits that should be tackled by breeding efforts.
• Predictive models linking microbiome composition to root exudate profiles and RSA traits under diverse coffee and cocoa cultivation conditions and stresses.
• Integrative bioinformatics of metagenomics, metabolomics and phenomics data
• Plant trait lead discovery for genomic selection of elite coffee and cocoa breeding material.
• Demonstration of the possibility of using wild relatives as rootstocks.
• New methods for fast rootstocks breeding in coffee and cocoa.
• Proof of concept that it is possible to produce low-cost, stable and homogeneous rootstocks seeds.
• Technology transferred to coffee and cocoa nurseries and growers to produce resilient plant material that will maintain production and quality under unreliable climates, increase water use efficiency and reduce irrigation costs.
• Scientific evidence of the agronomic performance, productivity, profitability and quality of grafted coffee/cocoa in comparison with non-grafted coffee among farmers in on-field conditions.
• Comprehensive assessments of grafted farming systems connecting environmental performances with soil organic carbon content.
• State-of-the-art knowledge of FTC rootstock propagation and technical and physical upgrade of local nurseries in Vietnam to produce mini-cuttings grafted onto seedlings at a low cost, following relevant horticultural and phytosanitary standards.
• Promoting an open-source instrument that will encourage and facilitate the exchange of the genetic material".