Individual and combined effects of five quantitative trait loci on resistance to the parasitic weed Striga hermonthica in Sorghum bicolor under field conditions in Mali and Sudan

Parasitic weeds have been estimated to infest about 40% of the cereal-producing areas of sub-Saharan Africa. Over 20 million hectares alone are infested with Striga hermonthica and subsistence farmers are the most severely affected. In the past ten years, ICRISAT and the University of Hohenheim have made significant progress in identifying molecular markers for striga resistance in sorghum with funding by BMZ which concluded in September 2008.

During this period, five genomic regions (quantitative trait loci, QTL) associated with stable striga resistance from resistant line N13 were identified across a range of field trials in Mali and Kenya. Over the last four years, ICRISAT in collaboration with four African NARS (Kenya, Eritrea, Sudan and Mali) has been developing striga resistant farmer preferred sorghum varieties (FPSVs) through marker assisted backcrossing. T

he mapped striga resistant QTL, with interval lengths of 20-50 cM, were introgressed into 5 FPSVs in the collaborating countries (Ochuti in Kenya, Tiemarifing and CSM335 in Mali, Hugurtay in Eritrea and Tabat in Sudan). These improved FPSVs are a unique source of genetic materials to investigate the effect of individual QTL as well as epistatic effects between different QTL. For this investigation, multilocation trials in fields with artificial striga infestation will be conducted over two years in order to identify unequivocally the individual and combined effect of the striga resistance QTL.