To my understanding, first of all  you have to specify  that  how close is the putative qtl with the flanking markers, by the extent of LD or confidence interval in bi parental population, you can get a idea that how much recombination is expected if you want  to utilize the information of the flanking markers to do marker assisted selection. i recommend you to  use two markers linked to the qtl  to increase efficiency of your selection.

Hello Davendra,

In the case of Sr31 and rust resistance your suggested approach will probably work. Sr31 is located on the short arm of rye chromosome 1, and the chromosomal segment containing this gene has been widely used in wheat breeding, and tested in multiple environments and genetic backgrounds. I don't work with wheat, so you should check the literature, but I suspect that this gene works in most environments and genetic backgrounds.

As Mohammad suggested flanking markers are a good idea. In the case of this gene, which resides on a chromosomal segment from a different species to wheat, recombination may well be suppressed. Again check the literature to be sure.

However, more generally, I would suggest extreme caution with this approach. The effect of a QTL usually depends on genetic background and environment, and a marker may not be valid in all genotypes.

Your English is good!

Hope this helps,

best wishes,

David

hi devendra,

adding to the above answers, markers for a QTL can flank multiple genetic factors (genes). this depend on, the saturation of the map (dense of markers per cM distance on the chromosomal group). besides, most QTL are population dependent. this means that if it was working very good with specific population it is not necessary to work with all populations. markers for important QTL need to be validated across multiple populations and multiple environments before confirming it is available for MAS, or, public use. conclusion, your strategy is very nice, under certain condition of (well validated QTL markers). Good luck

I agree with Ahmed's answer that first we have to do the robust validation of any DNA markers before applying it for screening. Also while validation try to include as mush as divers contrasting lines so that you get correct answer. If you select many lines but in background they all are from same source then  result may mislead you. Best of luck Devendra

I see this as a very promising area for plant breeders to work on, especially in the long term for assuring durable resistance.  There are of course all the usual caveats concerning being sure that the markers do pertain to resistance in the population(s) concerned, or derivative populations genotypes.  But it appears that major-effect disease resistance genes can often be present even when the biometric properties of disease incidence give no obvious clues to the presence of such alleles, and such alleles are a prime case for capitalising on DNA markers.  For achieving high but durable resistance, the ideal can be to combine hypersensitivity-type ('up-front) resistance withe 'downstream' resistance like 'slow rusting' which will tend to defeat the effects pathogen mutation.  With conventional breeding the former is liable to mask the expression of the latter, a problem that can be overcome using DNA markers.  This point is made by Burdon & Wilcox in Chapter 7 of "Genetics, Genomics and Breeding of Conifers" ed. C Plomion, J Bousquet and C Kole, CRC Press 2011.