02288naa a2200229 a 450000100080000000500110000800800410001910000170006024501240007726000090020152015200021065000120173065000090174265000130175165300370176470000160180170000140181770000180183170000130184970000150186277301810187716543422009-04-09       2007    bl uuuu     u00u1 u    #d1 aBELLOTTI, A.  aDevelopment of low-cost technologies for pyramiding useful genes from wild relatives of cassava into elite progenitors.  c2007  aMid-year report: 1. Delayed post harvest deterioration (PPD): three backcross populations (BC1), from controlled crossing of the PPD resistant genotype CW 429-1 to two elite genotypes (MTAI 8 and SM 909-25) and open pollination, were developed to identify molecular markers associated with delayed PPD for efficient transfer into cassava gene pools. The BC1 populations were established in vitro from embryo axes, micro-propagated, and 4-10 plants per genotype established in the field. The BC1 populations were harvested in March 2007 and evaluated for PPD at the 7th and 14th day after harvest. In the BC1 family B1PD280, derived from open-pollinated (OP) seeds from CW429-1, 23% of individuals showed delayed PPD trait at 14 days after harvest (DAH). In the BC1 families B1PD 284, cross of CW 429-1 and MTAI 8, and B1PD289, cross of CW 429-1 and SM 909-25, 14.3% and 5.8% respectively of genotypes revealed resistance to PPD. Frequency distributions of delayed PPD in these families are shown in Appendix 1 and 2. The evaluations will be repeated for a second year in a replicated trial of 8 plants per plot and 3 replications. BC1 genotypes with delayed PPD were selected and crossed with CMD resistant genotypes to combine the two traits thus facilitate the testing and use of PPD delayed lines in breeding programmes by NARs partners in Africa. Currently a total of about 6000 crosses have been made and fruits are being harvest for embryo rescue to facilitate shipping of in vitro plants to project partners.  acassava  aGene  aMandioca  aMelhoramento genético de planta1 aFREGENE, M.1 aALVES, A.1 aOKOGBENIN, E.1 aOKAI, E.1 aKAWUKI, R.  tIn: GENERATION CHALLENGE PROGRAMME. Project mid-year and final reports: competitive and commissioned projects: 2007. Mexico, DF: Generation Challenge Programme, 2007. p. 55-57.