BROAD ONION TEST. “Importantly, the comparison is not restricted to onions versus humans. It could as easily be between pufferfish and lungfish, which differ by ∼350-fold, or members of the genus Allium, which have more than a 4-fold range in genome size that is not the result of polyploidy.”
http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004351