marker-assisted selection in wheat - ictsd

460Marker-assisted selection – Current status and future perspectives in crops, livestock, forestry and fish(some of) these methods and approaches tolivestock, fish and especially forest speciesresearch. Generally, however, these effortsare of a small-scale experimental nature and,particularly in the case of livestock wheremost traits, even for disease resistance, arecomplex, they are unlikely to move beyondthe research stage in the near term becauseof the large numbers of animals required,the limited amount of structured phenotypicdata available and the long generationintervals of many animal species.These countries have both considerablepotential and many options to focusresources for MAS on poverty and hungeralleviation, including:• mobilizing the techniques, tools, geneticresources and phenotypic data alreadyavailable nationally and internationally(e.g. parental lines and segregating populationsfrom international and othernational programmes), tapping the vastand rapidly increasing molecular andgenetic knowledge available internationallythrough collaboration with internationaland advanced agricultural researchcentres, and contributing to genomicsconsortia (e.g. the International RiceGenomics Consortium). Applicationsinclude extending non-transgenic andtransgenic approaches by developing andvalidating markers based on fine genomicmapping of QTL (i.e. by identifying singlenucleotide polymorphisms, [SNPs])for more complex traits like drought,salinity and heat tolerance and nutritionalquality in major food crops;• pursuing MAS for both simple and complextraits in crops that although relativelyminor and scientifically neglectedare of tremendous importance to manypoor households;• recognizing the increasing importance oftrees, livestock and aquaculture to theirrural economies, strengthening effortsto characterize genetic diversity throughboth classical phenotypic and molecularmarker approaches and then developing,validating and eventually using markersfor improving economically importanttraits such as host resistance to diseases.Countries with reasonable capacitiesfor phenotype evaluation andselection and some capacities to applymolecular marker methodsThese countries have less comprehensivebreeding programmes and therefore cancover fewer species. They will likely havebeen relatively “late starters” in MAS andmay not have the latest high-throughputequipment, which is invariably located inone or a number of institutes supportinga particular subsector. Neither of thesefeatures is a major limitation providedthe country prioritizes its work appropriately.This means pursuing justifiable anddoable genetic enhancements to the limitednumber of species for which it has an effectiveselection and breeding programme to:(a) provide the foundation for developingsegregating populations from parentallines and for characterizing and validatingmarkers for the trait(s) in question; and(b) evaluate populations in the environmentsfor the traits that are prioritized.Also, while recognizing the need toadapt specific molecular techniques tolocal circumstances, and markers for particulartraits to their own genotypes, thesecountries should take full advantage of“lessons learned” with respect to both themolecular methods themselves and howbest to integrate these into selection andbreeding programmes. With the caveat thatthese conditions are satisfied, countries inthis general category have the followingoptions: