You can see this on the BBC Four Botany: A Blooming History for a clear picture when using with students. 

This video clip from the BBC (from the TV series Botany: A Blooming History) introduces Russian scientist Nikolai Vavilov, and how his aim to cross different varieties of plants led him to establish the first seed bank. This method of storing genetic material is now internationally important.

Nikolai Vavilov aim to breed 'super crops' combining desirable combinations of characteristics from different varieties is placed in the context of post-revolution Russia, where people were unable to grow enough crops to feed themselves. Vavilov had studied in Europe with Bateson and others and was inspired by the techniques of cross-breeding they had developed. He knew that plants with the characteristics he was looking for could be found all over the world. Hence he collected seeds and established the first seed bank. Seed banks are now found all over the world and are a repository of genetic material from both domesticated varieties and from wild type plants which may have useful combinations of characteristics.

Introduce the ideas of conservation of genetic resources, especially in the context of changes in climate and the damaging effects of human activity which lead to loss of biodiversity. Species which may be of importance to us for a variety of reasons can be stored in gene banks. Seed banks can be discussed and compared to other possible gene banks - such as botanic gardens, zoos, tissue culture etc. Problems and advantages of these various methods can also be debated. Discuss the importance of scientists responding to the needs of society.