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Sent: 11 December 2003 10:38
Subject: 78: When MAS should be used in a developing country
This is from Rakotonjanahary Xavier, plant breeder in FOFIFA (National Center of Applied Research for Rural Development), Madagascar. My area is mainly rice but I work also on groundnut.
So far, I followed with interest all the discussions about MAS and my interest is to know which are the types of MAS currently used and which types of traits are linked to these (although molecular markers usually should not have any biological effect). I find some good examples from the messages, and I understand that few molecular markers are till now found for some traits and in some crops. However, I am personally convinced that MAS is efficient for selection and it should speed up selection with reduction in time and effort (cost and labor).
In a developing country like Madagascar, resources for research, both financial and manpower, are scarce. However, breeders should release in the shortest time superior lines both in tolerance to biotic and abiotic stresses and productivity, as well as more nutritious lines to ensure the consumption need of the population. We are obliged to use the most rapid way within our reach, that is mainly visual selection based on physiological traits. DNA collection, genotyping and analysis, and developing molecular markers will require undoubtedly a longer time and it is more costly.
I would contribute for discussion on five points:1. MAS should be used when conventional breeding cannot identify directly the individuals to be used for breeding (i.e parent or individual carrying the genes of interest).
BP 1690, Antananarivo 101,
r.xavier (at) simicro.mg
Sent: 11 December 2003 10:46
Subject: 79: Re: Costs of genotyping
[Upon request, Miguel Toro has provided some additional input to his message 67 (December 4), when he wrote "I am thinking of using markers as a source of information without bothering too much about gene detection (along the line suggested by Lande and Thompson, Hayes and Goddard etc)"...Moderator].
Even if the genetic basis of economic traits is only polygenic, you can get some benefit from using MAS. The reason is that you can use markers as a source of information in a selection index. As long as markers explain some of the additive variance (in a regression framework for example) you will benefit from including them in the index. Obviously, the benefits will increase as the number of genes that affect the trait decreases.
Hayes and Goddard (2003, Livestock Production Science 81: 197-211) consider MAS in a commercial pig enterprise (with a 100 sow nucleus, 1000 sow multiplier and 10,000 sow commercial tier). Using computer simulation, they assume four traits (growth, prolificacy, meat quality and feed intake) and that 7 markers for each of 18 chromosomes can explain 30% of the additive variance. In such a situation, the gain in the index was about 17%. But the cost would be high (1000 progeny x 18 chromosomes x 7 markers x 4$ marker = 504,000 $). However, if the cost decreases to about 0.5 $ they conclude that could be profitable.
Miguel Angel Toro Ibanez
Departamento de Mejora Genetica Animal
Instituto Nacional de Investigacion y Tecnologia Agraria y Agroalimentaria (INIA)
Carretera La Coruna km. 7
Telf: 34 913476807
Fax: 34 913572293
e-mail: toro (at) inia.es