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Sent: 03 December 2003 08:33
Subject: 61: Pedigree selection, plants
From Dr Kuldeep Singh, India.
I am happy to see the contribution of Hugh Wallwork (Message 59, December 2) who has taken a positive view of MAS. I fully agree with him that MAS is not required for traits that are easily scorable, like rust resistance in wheat, bacterial blight (BB) resistance in rice and many such diseases. Think of selection for insect resistance, viral resistance, drought etc. Even for easily scorable traits, like rust in wheat, MAS may have its own place like selecting for one gene or two genes (if the two genes in question show differential reaction to the prevalent races, even then MAS is not required; but if one intends to pyramid two genes for durable resistance then MAS is the only strategy).
Concerning cost vs strategy, it will depend on whether one intends to add some desirable genes in an already well-adapted variety through marker assisted backcrossing, or whether it is direct pedigree selection for developing new strains. For the first I have already contributed my viewpoint [Message 44, November 26...Moderator]. For the second approach, my viewpoint is as follows:
1. MAS should be an integral part of the breeding programme and not in isolation, as has been until now (this was necessary for technology development).
2. It is the breeder who should exercise selection first in his first segregation generartion (F2 or BC1F1) and only those plants should be analyzed for markers that are agronomically good. This approach of MAS is possible if rapid protocols are developed for isolating DNA from mature plants. This will reduce the MAS work considerably and it can be used in a large number of crosses. A breeder in general works with large populations - maybe 2,000 F2 plants per cross and several hundred crosses. The selection intensity in F2 is in general not more than 5%, on visual basis. However, if we are using MAS, then the plant breeders could select more plants and these plants can be analysed for desirable markers. In the next generation a plant breeder can carry only those plants which have the desirable genes. If this strategy is adopted, I am sure the cost of MAS will be even lower than the breeder incurs while carrying large junk until advanced generations.
Dr Kuldeep Singh
Dept. Genetics and Biotechnlogy
Punjab Agricultural University
Ludhiana 141 004,
Tel. +91-161-243 30 81 (R)
kuldeep35 (at) yahoo.com
Sent: 03 December 2003 08:57
Subject: 62: Developing countries can use information from developed countries
[While discussions have so far focused on MAS in crop and livestock improvement, there have been no views/experiences from participants on MAS in aquaculture and very few on applications in forestry. Does this mean (by the silence) that participants feel that MAS will be more appropriate or easily applicable in the crop and livestock sectors than in aquaculture or forestry in developing countries?...Moderator].
This is VLN Reddy from the Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India.
In my view, MAS should be used for few traits for which it is difficult to get phenotypic data, like quality traits i.e. amylose content, gel consistency etc. Then only is it economical in developing countries like India. Moreover, developing countries can use genetic and physical maps already prepared by developed countries. For example in rice, genetic and physical maps are available along with complete sequence of the rice genome. This information can be used by developing countries for MAS. Markers flanking the traits can be used straight away for MAS instead of going for mapping QTLs again.
Junior Research Fellow
Laboratory of Molecular Genetics
Centre for DNA Fingerprinting and Diagnostics
ECIL Road, Nacharam, Hyderabad-500 076,
Ph. # 27151344-1102
e-mail:vlnreddy (at) hotmail.com lax_gene (at) yahoo.com lax_gene (at) operamail.com