marker-assisted selection in wheat - ictsd

Chapter 21 – Marker-assisted selection as a potential tool for genetic improvement: debating the issues 433usefully introduced represented one ofthe main points debated in the conference.Many participants (e.g. Montaldo,18) explicitly stated the need for a conventionalprogramme to be operational prior toimplementation of MAS and others inferredit. Notter (25), on the other hand, suggestedthat animal recording need not precedeimplementation of MAS, and he proposedthey could be implemented together.Referring to animal trypanosomosis inAfrica, De Koning (13) commented thatlack of routine recording of production andhealth traits, with limited national molecularresearch facilities, presented a structuralproblem to implementing a breeding programmeusing MAS. De Koning (20) alsosaid that when livestock were mainly keptby smallholders, each with a handful of animals,there would be no routine recording.Makkar (52) too suggested that in the lowinput systems that characterize many developingcountries, phenotype and pedigreeinformation were often not available, andthis would make it difficult to realize thevalue of MAS. Notter (25) proposed, however,that MAS (or related technologies)could act as a lever to promote implementationof animal recording. He also noted that“MAS without recording is unlikely to bevery beneficial for most traits”.For crops, Singh (61) suggested thatMAS should be an integral part of thebreeding strategy, but Acikgoz (66) wascritical of situations where scientistswithout any experience of traditional plantbreeding programmes entered directly intoMAS. Sridhar (76) and El Ouafi (77), whileacknowledging the importance of MAS, bothsuggested that meaningful breeding programmeswere necessary to make progresswith MAS and Dulieu (23) doubted thattraditional selection methods could easilybe replaced by MAS. Priyadarshan (11) alsobelieved that more basic biological knowledgeabout the intricacies of nature wasneeded to improve selection proceduresfor plants and Montaldo (18) pointed outthat knowledge of genetic control of someimportant traits remained incomplete.MAS in aquaculture in developing countrieswas only briefly discussed in theconference, although Priyadarshan (71)argued that aquaculture merited moreemphasis. Martinez (63) suggested that, foraquaculture, application of DNA technologiesand MAS was scarce even in developedcountries because of the lack of integrationbetween quantitative and moleculargenetics, and that the only successful applicationin aquaculture was that described byToro (50), who said that molecular markerscould be used to assist classical geneticimprovement programmes by constructingpedigrees needed for genetic evaluationin trees and fish where pedigree informationwas otherwise lacking. Martinez (63)noted, however, that economic analysis ofthis strategy compared with individuallyidentifying fish using electronic devices wasscarce. Krause (75) gave an example wheremolecular marker information could beused to reduce the costs of a fish breedingprogramme. Normally, electronicallytagged back-up copies of nucleus breedingpopulations of fish are made as an insuranceagainst loss of a deployed population. Thisis an expensive process that can be avoidedby taking tissue samples from sires anddams that are analysed for the presence ofestablished molecular markers if a nucleusstock is destroyed. This allows a nucleusstock to be regenerated relatively easily andcheaply, if and when necessary.While the merits of applying MAS togenetic improvement of trees in developingcountries were appreciated (e.g.Muralidharan, 7), participants suggested