|Title||Multiple genes recruited from hormone pathways partition maize diterpenoid defences|
|Publication Type||Journal Article|
|Year of Publication||2019|
|Authors||Ding Y., Murphy K.M, Poretsky E., Mafu S., Yang B, Char S.N, Christensen S.A, Saldivar E., Wu M.X, Wang Q., Ji L.X, Schmitz R.J, Kremling K.A, Buckler E.S, Shen Z.X, Briggs S.P, Bohlmann J., Sher A., Castro-Falcon G., Hughes CC, Huffaker A., Zerbe P., Schmelz E.A|
|Type of Article||Article|
|Keywords||association; biosynthetic gene; ent-kaurene; evolution; gibberellin; natural-products; phytoalexins; Plant Sciences; roles; specialized metabolism; synthases|
Duplication and divergence of primary pathway genes underlie the evolution of plant specialized metabolism; however, mechanisms partitioning parallel hormone and defence pathways are often speculative. For example, the primary pathway intermediate ent-kaurene is essential for gibberellin biosynthesis and is also a proposed precursor for maize antibiotics. By integrating transcriptional coregulation patterns, genome-wide association studies, combinatorial enzyme assays, proteomics and targeted mutant analyses, we show that maize kauralexin biosynthesis proceeds via the positional isomer ent-isokaurene formed by a diterpene synthase pair recruited from gibberellin metabolism. The oxygenation and subsequent desaturation of ent-isokaurene by three promiscuous cytochrome P45Os and a new steroid 5 alpha reductase indirectly yields predominant ent-kaurene-associated antibiotics required for Fusarium stalk rot resistance. The divergence and differential expression of pathway branches derived from multiple duplicated hormone-metabolic genes minimizes dysregulation of primary metabolism via the circuitous biosynthesis of ent-kaurene-related antibiotics without the production of growth hormone precursors during defence.