Vavilov deserves to be much better known!
In my opinion his more important and underrated discovery was Vavilov’s law of homologous series in variation—it’s known among crop geneticists, but its broader implications aren’t widely recognized. It holds that closely-related species will evolve in similar ways to new environmental changes—implying that species aren’t just blindly driven by natural selection, but that they have stored, lineage-specific strategies for evolving in response to potential future changes.