marker-assisted selection in wheat - ictsd

142Marker-assisted selection – Current status and future perspectives in crops, livestock, forestry and fishMAS for maize improvement indeveloping countriesA rapid analysis of the implementationof MAS in private maize breeding programmespoints to three elements as beingof particular importance: availability ofhigh-quality phenotypic data, access tolow-cost molecular marker data points andaccess to reliable continuous nurseries. Theimportance of high-quality phenotypicanalyses has been clearly recognized bygroups in the private sector (Niebur et al.,2004; Crosbie et al., 2006). Implementationof MAS in maize breeding requires largeamounts of marker data points to be generated.Private groups have spent mucheffort developing technologies and platformsto achieve cost-efficient genotyping.Simultaneously, highly efficient continuousnurseries have been established in tropicalenvironments or local greenhouses.By contrast, maize breeding for developingcountries is rather fragmented.National agricultural research institutionsand international centres of the CGIARsuch as the International Maize and WheatImprovement Center (CIMMYT) focusmuch of their efforts on poor farmers andunderserved regions. Private maize breedingprogrammes are also established ina number of developing countries. Dueto the large up-front costs of assemblinginfrastructure and personnel for genotyping,it is unlikely that individual nationalmarker laboratories could produce datapoints in a cost-efficient manner. However,regional facilities serving the needs of severalnational programmes and supportedby local laboratories that could processsamples (processing samples could be aseasy as taking and air-drying them) andprovide information in a timely manner,would probably be very sustainable alternatives.Such a regional molecular servicelaboratory has been established recentlyin Nairobi, Kenya, in a joint effort bytwo CGIAR centres, CIMMYT and theInternational Livestock Research Institute(ILRI) and Kenya’s Agricultural ResearchInstitute (KARI), under the CanadianInternational Development Agency(CIDA)-funded Biosciences eastern andcentral Africa (BecA) platform, to providetechnical access and training for Africanmaize breeders (Delmer, 2005). Such afacility could be an excellent componentof a comprehensive maize breeding effortif it is possible to establish and maintainhigh-quality personnel and facilities for allof the other aspects of maize breeding inkey target environments. However, withouthigh-quality capabilities in phenotypicevaluation and selection, molecular laboratorieswill be worthless. Research projectsinvolving large-scale (transnational) phenotypicevaluations of key genetic materialand focused on specific traits (tolerance tobiotic or abiotic stresses) should providegenetic information that is both locallyrelevant and broadly applicable (geographicallyand in terms of germplasm). Suchprojects would also spread the cost of phenotypingacross all participants but wouldonly be successful with effective transnationalcoordination.Private companies running MAS inmaize could contribute to its implementationin developing countries in severalways. First, they could make some of theirgenetic information available, thereby addingto that already available in the publicdomain. Much information is being generatedin the private sector on traits ofimportance to developing countries such asdisease resistance (e.g. grey leaf spot, northerncorn leaf blight, Fusarium stalk and earrots), drought tolerance and nitrogen useefficiency. After validation of its relevance