Hello. I have some questions.

I am studying about seed storage protein in wheat.

According to "Catalogue of Gene Symbols for Wheat (2013ed)", there are 5 loci related to Glutenin.

Glu-1 is related to HMW-GS, and the others are related to LMW-GS.

Does the number in loci name mean the discovered order? If not, what is meaning? It seems that it is not related to wheat chromosome number because most of them are located on chromosome 1. 

Also, many researchers have studied mainly on Glu-1 and Glu-3. I don't know why Glu-2, Glu-4, Glu-5 were studied less than Glu-3.

Please help me. I couldn't find the answer. I will be glad to your opinions or some references.