The concept of gene for gene hypothesis was developed in

The concept of the gene-for-gene hypothesis was developed in Linseed.
The gene-for-gene relationship was discovered by Harold Henry Flor who was working with rust (Melampsora lini) of flax (Linum usitatissimum).
Flor showed that the inheritance of both resistance in the host and parasite ability to cause disease is controlled by pairs of matching genes. One is a plant gene called the resistance (R) gene.