Where are we working?
Cassava (Manihot esculenta), also called yuca or manioc, is extensively cultivated as an annual crop in tropical and subtropical regions. Cassava is the third largest source of food carbohydrates in the world, and plays a particularly important role in agriculture in sub-Saharan Africa because it does well on poor soils and with low rainfall, and because, as a perennial, it acts as a famine reserve.
The extreme temperatures, drought and flooding brought about by climate change are affecting cassava cultivation. New and changed pathogens are threatening to exacerbate these issues, with a new virus causing brown streak disease having been identified as a major threat to cassava cultivation worldwide.
Therefore, it is necessary to develop new cultivars that are adapted to these threats by or genetic transformations based on useful candidate genes.
This Benefit-sharing project is characterizing Cassava germplasm with respect to resistance and tolerance to different biotic and abiotic stresses and applying marker assisted selection (MAS) to develop new Cassava varieties adapted to climate change for sustainable agriculture.

What are we doing?

• Evaluation of cassava accessions (cultivars, breeding clones, land races) for resistance or tolerance to abiotic and biotic stresses related to global climate change;
• Identification of useful candidate genes (CG) for abiotic and associated biotic stresses through use of molecular techniques;
• Molecular characterization of the allelic variation in these CG and determination of allelic composition in the evaluated accessions;
• Association mapping to detect the effects of specific CG alleles or CG allele combinations on the tolerance levels of the analyzed stresses, development of molecular markers for marker-assisted selection and model building to assign parental breeding values and predict progeny performances;
• Pre-breeding activities to combine favorable characteristics and to improve adaptation to climate change by applying the developed markers and models;
• Dissemination of products (accessions and breeding clones).

What has been achieved to date?
15 cassava accessions have been identified for breeding purposes with (combined) resistances and tolerance to different biotic and abiotic stresses. Moreover, 169 promising genes for stress adaptation, productive traits and quality have been identified and are being used by scientists and breeders in partner countries. Libraries for the analysis of differential expression of genes under drought, heat and cold stress conditions have been established successfully and revealed hundreds of promising stress response genes in each case.
About 1500 farmers have received improved cassava materials pre-released from project field demonstration plots, which have then been multiplied and disseminated to a number of farmer groups. Over 100 farmers in the colder Southern part of Tanzania (Njombe), where cassava was not among the crops cultivated due to unavailability of suitable varieties, have received cassava germplasm adapted to local conditions.
Four workshops have been organized with breeders, farmers and other actors of the Cassava value chain, and wide-spread dissemination of project results has been achieved through more than 20 local news papers, 5 local TV stations and radio stations, which has greatly increased farmers’ awareness on the availability of improved cassava materials through project field sites, Extension and Local Government Officers and participating scientists.
The project website has improved communications and linkages between participating scientists and others and may be connected to another related platform by the Indonesia Genome Center to consolidate the knowledge database created.

Who has benefited?
Over 1500 farmers (60% women) have benefited through access to recommended varieties for cultivation, and over 50 phytopathologists, scientists and breeders have benefited by receiving a molecular marker set for the evaluation of biotic and abiotic stresses with potential application in other (related) crop species.
Over 30 (40% women) scientists and researchers have directly benefited through a technology transfer workshop at which they were trained in breeding using candidate genes and marker assisted selection. Over 170 Extension officers (45% women) have directly benefited through training in improved cassava germplasm, production, access and disease management. And five local government officials (all men) directly benefited from consultative meetings and knowledge transfer.

Best practices and success stories
Farmers in marginal areas were introduced to cassava production through this project. Due to lower temperatures in these areas, farmers had hitherto depended on maize and tree crops only, but the project has led to the diversification of their food crops, greatly improving their food security and income generation.