Yes,  I have used microsatellite markers in MAS in okra and I got interesting results. So, you can be used microsatellite markers in MAS.

Yes. Please visit GRAMENE website for further SSR markers information in rice wheat and barely according to your need.

Thousands of markers are publically available - a huge genomic resource for commercial and public research programs. 

Pls see check these websites

http://www.wheatgenome.info/resources.php

http://archive.gramene.org/markers/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4248350/

Hope it helps.

What did you mean by 'perfect allele size'?

In these times of smokescreens and race for money, maybe I'll tell a heresy, but the only way to create a variety (e.g. wheat) is to walk the experimental field from morning to evening and that’s the only "marker" that really works. We are living times of terms invention - "phenotyping", "genotyping", “genomics” and so on. Molecular geneticists get so amazed when they “discover” something that geneticists in Agronomy have known for decades that they must to inventing the whole name and the “new” scientific field! Paradigm is “epigenetic”. For “centuries” agricultural geneticists have known something we called “prolonged modifications”. Few decades ago, molecular geneticists have come to the same knowledge, and they got so excited by the “invention” that they invented the whole knew field - Epigenetic! The similar case is the story of “Genomics”. This is due to the entry of molecular biologists in breeding and agronomy. They have no idea about the real genetics and the interaction of genotype and the environment, in particular. They are still viewing genes, almost as isolated units of heredity, and they are late in the comprehension of how the genome works about 30 years, on average, comparing to agricultural geneticists and breeders. They are even proud with the statement that “the advantage of molecular markers is that they exclude the effect of the environment” (!?) and in breeding programs we are relying on GE interaction! If we followed the major genes effects, than we do not need molecular markers, or to be more accurate the costs usually do not correspond to the result. If we follow the effect of minor genes, or QTL correlation to the phenotypic variation for a specific trait, results are commonly totally unconvincing. In other words, a lot of water gonna pass under the bridge, while molecular biologists come up with something that can replace boots and walking the experimental field!

So my dear and respectable colleague, use the SSR in studying genome variability, eventually, in early generations, when you still have no seed enough to establish a field trials. However, the variability in F2, for example, is so huge, that you gotta be a Rockefeller to follow it by SSR. We've had about 3000 crosses per year just in wheat. Can you imagine, using SSR to follow genetic variation in F2! You can use them in fingerprinting, as well, but sometimes and for the internal use, a simple and cheaper approaches could do the work. However, if you liked to get the job done, and to create a real commercial “beauty”, get on your boots, put your hat on, and do some “phenotyping” straight in the nature. No man has ever made a variety in the lab with artificial light instead the Sun above and with no windows to smell the nature around, yet.  :)

Dear Prof Dr.Miodrag Dimitrijevic ,

greetings and thank you for your comment. I am agree with you as the traditional plant breeding still and continue for developing new genotypes. But the classical methods as you mention have each year a lot of materials, wait for next advanced generations and the traits some times escaped in the advanced generation.

Also, their is some promising results using  DNA markers as MAS in qualitative traits and may be in future can help in quantitative.

Thank you for your answer

with best regards

Prof Dr Khaled F M Salem