CBSD is a major threat to food security in the ASARECA region and the development of resistant cultivars is therefore of primary importance to farmers Cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) is becoming the most devastating viral disease that severely reduce cassava production in large areas of Eastern and central Africa. CBSD is caused by two virus species, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV).
In this innovation to identify molecular markers associated with resistance to Cassava Brown Streak Disease (CBSD) two F1 mapping populations were generated between a CBSD resistant genotype (Nachinyaya and Kiroba) and a CBSD susceptible genotype (AR37-80 . The F1 populations were genotyped for 16 SSR markers to determine the integrity of the populations and identify genuine crosses, selfs and off-types. Over 250 true F1 offspring from each cross were genotyped using over
500 SNP markers. SNP-based genetic linkage maps were developed based on these results. Over 200 new SNP markers were placed on the genetic linkage map of cassava. The significance of CBSD resistance markers is that they facilitate the introgression of the CBSD resistance trait into farmer-preferred cassava varieties.
Once molecular markers associated with CBSD resistance are generated, breeders will be able to apply Marker-Assisted Selection (MAS) and improve the accuracy and speed of breeding for CBSD resistance.
The innovation has been developed and is suitable for up scaling/promotion in laboratories at IITA in Tanzania and BeCA in Kenya.
Two F1 mapping populations have been made and genotyped. Genetic linkage maps have also been developed.
The ultimate beneficiaries of this technology are cassava breeders
The dissemination, scaling out/up approaches Were publication of research findings in a journal
Publication of research findings in journals reaches wider circulation globally among sorghum breeders and researchers
Essential partners/stakeholders) to be involved in the further scaling out/up
Key partners needed in the scaling up process are:
- Cassava Breeders and researchers,
- National Cassava breeding Programs
- Biotechnology companies
- National and international Cassava data bases
Current extent of reach of intended users of molecular markers associated with Cassava Brown Streak Disease (CBSD) in Cassava.
The innovation has not reached national cassava breeding programs in the region.
Challenges encountered in respect to further dissemination, adoption and scaling up/out of molecular markers associated with Cassava Brown Streak Disease (CBSD) in Cassava.
- This is basic research which calls for awareness among policy makers to facilitate sustained funding
- Availability of good molecular laboratory facilities
Recommendation for addressing challenges
- Create awareness among policy makers and end users on the innovation
- Forge collaboration linkages with laboratories in advanced countries
- Need for early awareness by policy makers of the use of this modern tool in the development of CBSD varieties in cassava.
- There is need for forge collaboration linkages with advanced laboratories for testing the fine mapping innovations.
- Social, environmental, policy and market conditions necessary to catalyse fine mapping work
- Programmes that increase policy makers awareness
- Conducive institutional mechanisms for cassava variety release
Methodology for the cassava CBSD breeding innovation
Are well documented and have been published.