@ You have written that "each country have genetic material". I think you want to say that plant genetic resources of each country have the genetic material. 

Plant taxonomists, whose number is declining, are doing a very good job to document the plant genetic resources/diversity. 

Different research groups are involved in the documentation of plant species of their research areas. 

The documentation is an important part.

The collected data can be compared with the floras of different countries.

It has also to be seen that recorded species is endemic or exotic.

Based on this data, one can reach close to the answer of your question.

Regards

Exploration trip (Multiple crops) in different parts of your country should be conducted. This may be fine grid exploration or coarse grid exploration. Maintain Passport data sheet during exploration. The explored material should be first identified with the help of a taxonomist or available flora or herbarium. The collected material should be characterize and proper conservation strategy may be adopted. 

Documenting the genetic resources of larger land areas are always been a challenging task worldwide. Addressing to your question I must let you know that there are two ways 1 you have to conduct survey by yourself or you can be dependendent on herbaria/ musea or germplasm bank. It should be taken utmost care for determining the name of species either flora or fauna; expert advice of taxonomist is very essential. 2 you can compile the reports based on earlier work.

 Subseqently you can you study the germplasm using markers.  But of course these study requires a lot of time, money, manpowers and infrastructure.

There is a Guidebook for genetic resources documentation at the following address explaining the following steps to document the genetic resources that can help you:

http://www.bioversityinternational.org/e-library/publications/detail/guidebook-for-genetic-resources-documentation/

Also you should use FAO/IPGRI Multi-Crop Passport Descriptors [MCPD]

http://www.bioversityinternational.org/index.php?id=244&tx_news_pi1[news]=177&cHash=a8d7778e9e4077f1047996a639a51a19

There is also a website that can see where you have a lot of information on the documentation of genetic resources that can help you:

http://www.ecpgr.cgiar.org/working-groups/documentation-information/

I hope this helps you