Micro- and macroevolutionary adaptation through repeated loss of a complete metabolic pathway

What is it about?

An unexpected finding in recent years is that genes underlying many plant chemical defense pathways have convergently evolved to form physically-linked “metabolic clusters.” We test a leading hypothesis for why this occurs: metabolic clusters can ensure co-inheritance of all required genes where the defense is favored, and prevent inheritance of toxic partial pathways where it is not. Using a well-studied adaptive polymorphism for cyanogenic glucoside (CNglc) production in clover, we find that the underlying genes are clustered and that the polymorphism has evolved through repeated deletions of the complete pathway. We further find that the shared ancestor of many important legume crops was likely cyanogenic and that this defense has been lost repeatedly over the last 50 million years.

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