Increasing Food Security and Rural Incomes in Eastern, Central and Southern Africa through Genetic Improvement of Bush and Climbing Beans

• Nineteen Pythium species, including known bean pathogens, putative new species and two potential biological control agents, were identified by sequencing the ITS1 and ITS2 regions of the ribosomal DNA of 130 isolates associated with common bean affected with Pythium root rot in Kenya, Rwanda and Uganda.  

• Seven locus-specific microsatellite derived markers that can distinguish the main pathogen groups (Andean and Mesoamerican) of Phaeoisariopsis griseola, the causal agent of angular leaf spot disease, and between the pathogen groups found in Africa from those found in Latin America were developed and are being validated before being widely used in pathogen characterization in Africa.

• Several resistance genes against P. griseola, that are controlled by major genes that are either dominant or recessive; acting singly or duplicated, and which may interact in an additive manner, with or without epistasis were identified in 12 genotypes including Mex 54, an important source of resistance in Africa, which appears to have more (recessive and dominant) than one resistant gene.

• RAPDs, SSR and AFLP markers linked to some of the angular leaf spot resistance genes were identified in promising parental lines (Mex 54, MAR 1, G 10474, G 1090) and SCARs for some of these markers have been developed and their utility for MAS is being evaluated.    

• Several populations were developed to transfer, combine and pyramid resistance to angular leaf spot, Pythium root rot, fusarium wilt into a number of locally adapted but susceptible commercial bush and climbing bean cultivars.

• Two workshops/courses have been conducted to train project and bean networks partners on the use of biotechnological tools in bean improvement: firstly, on application of molecular techniques in pathogen characterization and secondly, in marker assisted selection where, markers developed for ALS resistance were successfully tested, potential for marker assisted selection breeding under different settings evaluated, and an inventory made of the potential of MAS in bean breeding in Africa, traits that are likely to benefit from MAS, genotypes for which markers are available and when and where markers have a comparative advantage in breeding.